Indian Patents
Title of Invention

ELECTRON BEAM RECORDING APPARATUS
Abstract An electron beam recording apparatus is disclosed that records information onto the surface of a sample by using an electron beam. The electron beam recording apparatus includes an electron source that irradiates the electron beam, a magnetic detector that is configured to move onto and out of an irradiation axis and acquires magnetic information on the irradiation axis, a convergence position control part that calculates a convergence position correction amount for correcting a convergence position of the electron beam with respect to the surface of the sample based on the magnetic information, and a convergence position adjusting part that adjusts the convergence position of the electron beam with respect to the surface of the sample. The convergence position control part causes the convergence position adjusting part to adjust the convergence position of the electron beam with respect to the surface of the sample based on the convergence position correction amount.
Full Text DESCRIPTION
ELECTRON BEAM RECORDING APPARATUS
TECHNICAL FIELD
The present invention relates to an
electron beam recording apparatus that records
information by irradiating an electron beam onto
a predetermined position, and particularly
relates to an electron beam recording apparatus
used for producing a master of optical disks by
printing a pattern with an electron beam.
BACKGROUND ART
In recent years, there has been a
growing demand for accuracy improvement of
microfabrication technology such as exposure
technology for master optical disks and
semiconductor technology. For example, optical
disks are fabricated through a master disk
production process for producing a stamper from
a glass plate and a disk production process for
producing optical disks with use of an injection
mold with the stamper mounted thereon.
In a typical master disk production

process, a master disk production machine emits
a visible light, an ultraviolet laser light, or
the like from the light source in an ambient
atmosphere and focuses the light to have a spot
diameter of the level of wavelength by a high
power objective lens. With this light, a pit
pattern latent image corresponding to
information signals or the like to be recorded
is formed on a glass plate having a photoresist
layer on a principal surface thereof. After
cutting the photoresist layer, the glass plate
goes through a development process or an
electroforming process so as to be a stamper.
While cutting the master disk, the
master disk production machine rotates the
master disk so as to relatively move the
irradiation position of the visible light or the
ultraviolet light in the radial direction of the
master disk. A problem with such a master disk
cutting process using a visible light or an
ultraviolet laser light is that the recording
resolution of information signals to be recorded
is limited due to limitations of a light spot
diameter, resulting in preventing high density
recording.

Cutting by electron beams is able to
form finer patterns compared with cutting by
laser beams.
In a typical master disk production
machine using an electron beam, however, the
electron beam is deflected by magnetic field
fluctuations inside and outside of the machine,
which leads to a variation of a spot position of
the electron beam focused by a focusing unit.
This lowers accuracy of the track pitch of
master disks or causes reproduction jitter.
The causes of the magnetic field
fluctuations inside and outside the machine
include variation of earth magnetism due to
movement of vehicles, elevators, or the like,
electromagnetic waves emitted from power supply
systems such as cabinet panels, and magnetism
generated by a rotating mechanism or a disk
transport mechanism of the master disk
production machine.
Especially, the magnetism generated by
the rotating mechanism, the disk transport
mechanism, or the like causes a significant
variation of the electron beam irradiation
position. There are therefore proposed various

methods for reducing influence of the magnetism
generated by the rotating mechanism or the disk
transport mechanism, or the like (see Patent
Documents 1 - 3).
Patent Document 1 discloses, as a
method of removing noise, a magnetic shield
device that blocks magnetic noise attempting to
enter a box-shaped magnetic shield room having a
wall made of a high permeability member.
The magnetic shield device disclosed in
Patent Document 1 includes a detection coil
passing through through holes of a wall and
wound around the wall for outputting an induced
voltage corresponding to variation of magnetic
noise as a detection signal, a cancel coil
receiving an external current so as to generate
a magnetic field for compensating for the
magnetic noise detected by the detection coil,
and a controller for controlling a current to be
supplied to the cancel coil based on the output
of the detection coil. A pair of Helmholtz coil
is used as the cancel coil that generates a
magnetic field in the same direction as magnetic
flux detected by the detection coil.
Patent Document 2 discloses an

information recorder that includes a rotating
unit for rotating a master of information
recording media, an irradiating unit for
irradiating an information recording electron
beam onto a recording surface of the master, a
transport unit for relatively moving the master
and the irradiating unit in a direction parallel
to the recording surface, and a vacuum
atmosphere forming unit for accommodating the
rotating unit and the irradiating unit in a
vacuum atmosphere.
According to Patent Document 2, the
rotating unit of the information recorder
includes a turntable on which the master is
placed, a spindle shaft for supporting the
turntable, an electromagnetic motor for rotating
the spindle shaft, and a magnetic shield unit
for shielding against magnetism generated in the
electromagnetic motor.
In the information recorder of Patent
Document 2, in order to reduce magnetic noise
from the electromagnetic motor, the entire
electromagnetic motor is surrounded by a
magnetic casing (high permeability material) for
blocking the magnetism, thereby preventing an

electron beam from being influenced by an
electromagnetic field generated by the
electromagnetic motor.
Patent Document 3 discloses an electron
beam irradiation device and a method for
eliminating influence of magnetism generated
from a rotating mechanism or a master transport
mechanism and magnetism in the vicinity of an
electron gun. The electron beam irradiation
device of Patent Document 3 drives an electron
beam deflection electrode according to outputs
of plural magnetic detectors disposed in the
vicinity of an electron beam generator or in a
vacuum chamber, deflects an electron beam in a
direction for canceling deflection of the
electron beam due to variation of magnetic field,
and thus corrects displacement of an electron
beam focus spot on a master due to the variation
of magnetic field.
Japanese Patent
Application Publication No. 2003-124683
Japanese Patent
Application Publication No. 6-131706
Japanese Patent
Application Publication No. 2002-217086

Referring back to the magnetic shield device
disclosed in Patent Document 1, although the
cancel coil needs to be highly accurately
mounted, it is difficult to accurately mount the
Helmholtz coil because of its relatively large
size. If the Helmholtz coil is not formed in an
ideal shape, the magnetic field generated by the
Helmholtz coil is not uniform, resulting in
lowering of device accuracy. Moreover, a
facility using the magnetic shield device of
Patent Document 1 is large and expensive.
Referring to the information recorder
of Patent document 2, the electromagnetic motor
includes a rotating part, and hence it is
difficult to completely shield magnetism of the
entire electromagnetic motor by surrounding the
entire electromagnetic motor with the magnetic
casing (high permeability material).
Another problem with the information
recorder disclosed in Patent Document 2 is that,
if a large amount of high permeability material
is used, the weight of the rotating unit is
increased.
Still another problem with the
information recorder of Patent Document 2 is

that, if a magnetic shield for the entire device
is also provided, a magnetic field is generated
in the direction of the electron beam
irradiation axis in a magnetic shield opening of
the irradiating unit and an opening of the
magnetic casing of the rotating unit. The
generated magnetic field affects the electron
beam, which prevents accurate correction of a
focal point and results in lowering of exposure
quality.
Referring to the electron beam
irradiation device of Patent Document 3,
according to the method of correcting the
displacement of the electron beam focus spot on
the master due to the variation of magnetic
field and adjusting a focal point of the
electron beam relative to a target object, as
the plural magnetic detectors estimate a
magnetic field in the vicinity of an irradiation
point of the electron beam, a disturbance
magnetic field of an electron beam injecting
part cannot be accurately calculated.
Accordingly, the electron beam irradiation
device of Patent Document 3 cannot accurately
correct the focal point, and therefore exposure

quality is lowered.
Further, according to Patent Document 3,
for reasons of device configuration, the entire
electron beam irradiation device needs to be
magnetically shielded for eliminating influence
of earth magnetism. However, since there are
many constraints on workability and structure
such as ventilation and air conditioning
facility, this configuration is not so effective
for variation of a magnetic field generated
inside the shielded device. Furthermore, since
the entire device is magnetically shielded, the
electron beam irradiation device is large and
expensive.
DISCLOSURE OF THE INVENTION
The present invention aims to provide
an electron beam recording apparatus capable of
recording information by irradiating an electron
beam onto a predetermined position of a sample
with high positional accuracy.
In one embodiment of the present
invention, there is provided an electron beam
recording apparatus that records information
onto the surface of a sample by using an

electron beam. The electron beam recording
apparatus comprises an electron source that
irradiates the electron beam, a magnetic
detector that is configured to move onto and out
of an irradiation axis and acquires magnetic
information on the irradiation axis, a
convergence position control part that
calculates a convergence position correction
amount for correcting a convergence position of
the electron beam with respect to the surface of
the sample based on the magnetic information
acquired by the magnetic detector, and a
convergence position adjusting part that adjusts
the convergence position of the electron beam
with respect to the surface of the sample. The
convergence position control part causes the
convergence position adjusting part to adjust
the convergence position of the electron beam
with respect to the surface of the sample based
on the convergence position correction amount.
According to an aspect of the present
invention, the electron beam recording apparatus
can perform the convergence position control of
the electron beam with high accuracy by
calculating a displacement of the convergence

position of the electron beam with respect to
the sample due to the magnetic field on the
irradiation axis. Therefore, the electron beam
is irradiated onto a predetermined position of
the sample with high positional accuracy for
recording the information. Moreover, since the
electron beam is irradiated onto a predetermined
position of the sample with high positional
accuracy, printing on the surface of the sample
can be performed with high shape accuracy.
According to another aspect of the
present invention, in the electron beam
recording apparatus, since focal position
displacement of the electron beam with respect
to the sample due to the magnetic field on the
irradiation axis is experimentally calculated
based on focal position adjustment information
obtained when a focal position is adjusted with
respect to particles on the surface of a test
substrate, focal position control of the
electron beam can be performed with high
accuracy. Therefore, the electron beam is
irradiated onto a predetermined position of the
sample with high positional accuracy for
recording the information. Moreover, since the

electron beam is irradiated onto a predetermined
position of the sample with high positional
accuracy, printing on the surface of the sample
can be performed with high shape accuracy.
Furthermore, since the displacement of the
convergence position is experimentally computed
using the test substrate with the particle on
the surface, the electron beam recording
apparatus is simple and inexpensive.
According to still another aspect of
the present invention, in the electron beam
recording apparatus, since an irradiation
position displacement of the electron beam with
respect to the sample due to the magnetic field
on the irradiation axis is experimentally
calculated based on irradiation position
adjustment information obtained when an
irradiation position is adjusted with respect to
particles on the surface of a test substrate,
irradiation position control of the electron
beam can be performed with high accuracy in
addition to the focal position control of the
electron beam. Therefore, the electron beam is
irradiated onto a predetermined position of the
sample with higher positional accuracy for

recording the information. Moreover, since the
electron beam is irradiated onto a predetermined
position of the sample with higher positional
accuracy, printing on the surface of the sample
can be performed with higher shape accuracy.
According to a further aspect of the
present invention, since the convergence
position adjusting part includes an
electrostatic lens, the electron beam recording
apparatus can perform convergence position
adjustment (focal position) adjustment with high
responsivity and can perform printing
(recording) with high shape accuracy even when
driven at high speed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram showing
an electron beam recording apparatus according
to a first embodiment of the present invention;
FIG. 2 is a schematic diagram showing a
structure of an electrostatic deflection
electrode of the electron beam recording
apparatus according to the first embodiment of
the present invention;
FIG. 3 is a block diagram showing a

structure of a focal position control part of
the electron beam recording apparatus according
to the first embodiment of the present
invention;
FIG. 4 is a schematic diagram
illustrating the convergence position of an
electron beam;
FIG. 5 is a graph showing a
characteristic curve of magnetic flux density in
the Z direction with respect to mobile body
position, where the vertical axis represents the
magnetic flux density in the Z direction and the
horizontal axis represents the mobile body
position;
FIG. 6 is a graph showing a convergence
position characteristic of an electron beam with
respect to mobile body position, where the
vertical axis represents correction voltage and
the horizontal axis represents the mobile body
position;
FIG. 7 is a graph showing a sensitivity
characteristic of a height sensor, where the
vertical axis represents output of height
detection and the horizontal axis represents
detected displacement;

FIG. 8 is a graph showing a sensitivity
characteristic of an electrostatic lens, where
the vertical axis represents voltage applied to
an electrostatic lens and the horizontal axis
represents focal position adjustment amount;
FIG. 9 is a schematic diagram showing
an electron beam recording apparatus according
to a second embodiment of the present invention;
FIG. 10 is a block diagram showing a
structure of an irradiation position control
part of the electron beam recording apparatus
according to the second embodiment of the
present invention;
FIG. 11 is a schematic diagram showing
a structure of an electrostatic deflection
electrode of the electron beam recording
apparatus according to the second embodiment of
the present invention;
FIG. 12A is a side elevational view
schematically showing a test substrate;
FIG. 12B is a plan view schematically
showing the test substrate of FIG. 12A;
FIG. 13 is a graph showing a
convergence position characteristic of an
electron beam with respect to mobile body

position, where the vertical axis represents the
convergence position and the horizontal axis
represents the mobile body position;
FIG. 14 is a schematic diagram
illustrating displacement of irradiation
position of an electron beam;
FIG. 15 is a graph showing
characteristic curves of magnetic flux densities
in the X direction and the Y direction with
respect to mobile body position, where the
vertical axis represents the magnetic flux
density in the X direction and the Y direction
and the horizontal axis represents the mobile
body position;
FIG. 16 is a graph showing an
irradiation position characteristic of an
electron beam with respect to mobile body
position, where the vertical axis represents
correction voltage and the horizontal axis
represents the mobile body position; and
FIG. 17 is a graph showing a travel
distance characteristic of an electron beam with
respect to the position of a mobile body, where
the vertical axis represents the travel distance
of the electron beam and the horizontal axis

represents the mobile body position.
BEST MODE FOR CARRYING OUT THE INVENTION
In the following, an electron beam
recording apparatus according to the present
invention is described with reference to the
accompanying drawings. FIG. 1 is a schematic
diagram showing an electron beam recording
apparatus 10 according to a first embodiment of
the present invention.
The electron beam recording apparatus
10 is used, for example, for producing an
optical disk master by printing a pattern on a
glass substrate.
The electron beam recording apparatus
10 includes a printing part 12, an electron beam
generator 14, a host controller 20, a focal
position control part 21, a feed control part 22,
a position detecting part 23, a rotation control
part 24, and a rotational angle detecting part
25 .
The host controller 20 is connected to
and controls the focal position control part
(convergence position control part) 21, the feed
control part 22, and the rotation control part

24.
The host controller 20 is also
connected to and controls, for example, an
electron source 62 described below.
The printing part 12 is disposed, for
example, below the electron beam generator 14
(the electron source 62), and is provided with,
inside a vacuum chamber 30, a feed mechanism
unit 32, a rotating mechanism unit 34, a
magnetic detector 36, and a height sensor 38.
The vacuum chamber 30 is arranged, for example,
on a vibration isolation mechanism part (not
shown) such as an air pressure servo mounter.
The vacuum chamber 30 has an opening
part 30a at the upper side thereof, to which the
electron beam generator 14 (a tip end portion
60a of a lens barrel 60) is connected.
A magnetic shield plate 40 is disposed
on the entire inner surface of the vacuum
chamber 30. The magnetic shield plate 40 is made
of a material of a high magnetic permeability
such as permalloy so as to reduce disturbance
due to such as the earth's magnetism.
The feed mechanism unit 32 includes a
drive motor 42, a base 43, a platform 44, a

mobile body 45, a feed screw 46, and a position
sensor 47.
The base 43 is disposed on a bottom
part 30b of the vacuum chamber 30 with the
magnetic shield plate 40 interposed therebetween
The platform 44 is arranged on the base 43. The
mobile body 45 is disposed on the platform 44
with, e.g., a rolling bearing (not shown) such
as a sphere or a cylindrical roller arranged in
the feed direction, interposed therebetween.
A guide 47a is provided under the
mobile body 45. A detector 47b is also provided,
which constitutes the position sensor 47
together with the guide 47a. While the guide 47a
is provided on the mobile body 45, the detector
47b is provided on the platform 44. The position
sensor 47 is, e.g., a linear scale such as a
laser scale.
The position sensor 47 is connected to
a position detecting part 23 so that the
position sensor 47 outputs a detection signal
representing the position of the mobile body 45
(a sample S) to the position detecting part 23.
The position detecting part 23 outputs a
detection signal (position information of the

sample S) to the focal position control part 21.
The mobile body 45 has a receiving
screw portion (not shown), into which the feed
screw 46 is threaded. An end of the feed screw
46 projecting outside the vacuum chamber 30 is
connected to the drive motor 42 mounted outside
the vacuum chamber 30. The feed screw 46
includes a ball screw, for example.
The drive motor 42 is connected to the
feed control part 22. The feed control part 22
controls rotation of the drive motor 42.
The mobile body 45 is moved in the X
direction by the rotation of the drive motor 42
controlled by the feed control part 22. In the
feed mechanism unit 32, the position sensor 47
outputs the detection signal to the position
detecting part 23 to provide current position
information of the mobile body 45, and then the
position detecting part 23 outputs the current
position information of the mobile body 45 to
the feed control part 22. The rotation of the
drive motor 42 is controlled according to an
output signal of the feed control part 22
provided based on the current position
information, so that the mobile body 45 is moved

in the X direction. The feed mechanism unit 32
is provided with the rotating mechanism unit 34.
The rotating mechanism unit 34 includes
an air spindle 50, an optical rotary encoder 51,
a rotary drive motor 52, a turntable 53, and a
magnetic fluid seal 54. The rotating mechanism
unit 34 is moved together with the mobile body
45 in the X direction. The sample S is placed on
and rotated by the turntable 53.
In the rotating mechanism unit 34, the
air spindle 50 is fixed to the mobile body 45.
The air spindle 50 is hydrostatically floated in
the radial direction and the thrust direction by
compressed air. The compressed air for the air
spindle 50 is supplied from the outside of the
vacuum chamber 30.
The turntable 53 is provided over the
air spindle 50. The rotary drive motor 52 is
provided below the air spindle 50. The rotary
drive motor 52 is connected to the rotation
control part 24, by which rotation of the rotary
drive motor 52 is controlled. The rotation
control part 24 is connected to and controlled
by the host controller 20.
The optical rotary encoder 51 is fixed

to the lower part of the rotary drive motor 52.
The optical rotary encoder 51 generally outputs
thousands of A phase pulses and B phase pulses
per one turn and one Z phase pulse per one turn.
The optical rotary encoder 51 is
connected to the rotational angle detecting part
25, which detects a rotational, angular position
based on an output signal of the optical rotary
encoder 51 and acquires rotational speed
information. The rotational angle detecting part
25 is connected to the rotation control part 24.
The rotation control part 24 controls rotation
of the rotary drive motor 52 based on the
rotational speed information acquired by the
rotational angle detecting part 25. Rotation of
the rotary drive motor 52 causes rotation of the
turntable 53. The turntable 53, together with
the mobile body 45, is moved also in the X
direction (in-plane) orthogonal to an
irradiation axis C by the feed mechanism unit 32
The irradiation axis C is a vertical
line extending downward from the electron source
62.
The inside of the vacuum chamber 30 is
evacuated to a vacuum. When the air spindle 50

is provided in vacuum as described above, it is
common to provide the magnetic fluid seal 54 on
the outer periphery of the air spindle 50 for
the purpose of vacuum seal. In addition to the
magnetic fluid seal 54, a seal mechanism such as
differential evacuation is generally provided on
the outer periphery of the air spindle 50.
The magnetic detector 36 is provided in
the vacuum chamber 30. The magnetic detector 36
can move onto and out of the irradiation axis C
and acquire magnetic information on the
irradiation axis C.
The magnetic detector 36 is connected
to a tip end of an arm 48b of a rotary shaft 48a
extending in the vertical direction of a rotator
48 provided on an upper face portion 30c of the
vacuum chamber 30.
The rotary shaft 48a of the rotator 48
can be moved by air pressure. The magnetic
detector 36 moves onto the irradiation axis C of
an electron beam b only when performing
measurement of magnetic fields and otherwise
stays out of the irradiation axis C.
The magnetic detector 36 is connected
to the focal position control part 21, and

outputs information of measured magnetic flux
density (magnetic information) of each position
of the mobile body 45 to the focal position
control part 21.
The magnetic detector 36 is able to
acquire the magnetic flux density information
(magnetic information) of three directions, i.e.,
a focus direction in which a focal position is
adjusted (hereinafter referred to as the Z
direction), the X direction that is orthogonal
to the Z direction and is the moving direction
of the mobile body 45, and the Y direction
orthogonal to the Z direction and the X
direction. The magnetic detector 36 is not
limited to specific sensors and may be any
sensor well known in the art.
The magnetic detector 36 is not limited
to the one capable of measuring magnetic flux
density in three directions (the X, Y, and Z
directions). In this embodiment, as described
below, the magnetic detector 36 is for
controlling the focal position of the electron
beam b in the Z direction, and may be any
detector capable of acquiring magnetic flux
density information (magnetic information) at

least in the Z direction.
The height sensor 38 is provided on the
upper face portion 30c of the vacuum chamber 30.
The height sensor 38 detects the surface height
of the sample S or the height displacement of
the sample S when the sample S is rotated or
moved, and is based on laser triangulation.
The surface height of the sample S
indicates, e.g., a distance from the surface of
the turntable 53 as a datum plane in the Z
direction. The height displacement of the sample
S indicates, e.g., a displacement amount from
the surface of the turntable 53 as a datum plane
in the Z direction.
The height sensor 38 includes a light
emitting part 38a and a light receiving part 38b
The light emitting part 38a emits, e.g.,
a semiconductor laser beam (not shown). The
light receiving part 38b receives a reflection
light of the laser beam emitted by the light
emitting part 38a and reflected by the surface
of the sample S, and calculates the height of
the sample S (height displacement of the sample
S) based on the position where the reflection
light is received. The light receiving part 38b

includes a position sensitive detector (PSD)
(not shown) and an arithmetic part (not shown).
The light receiving part 38b is
connected to the focal position control part 21
so as to output the height calculated by the
height sensor 38 as an output signal (height
information) to the focal position control part
21.
The following describes the electron
beam generator 14.
The electron beam generator 14
irradiates an electron beam b onto the surface
of the sample S so as to record information on
the surface of the sample S.
The electron beam generator 14 includes
various component parts in the lens barrel 60.
The lens barrel 60 includes the conically-shaped
tip end portion 60a having an open tip end. The
lens barrel 60 also includes a closed rear end
portion 60b.
In the electron beam generator 14, the
lens barrel 60 accommodates therein the electron
source 62, a blanking electrode 64, an axis
alignment coil 66, a focusing lens 68, a
selector aperture 70, an astigmatism correction

coil 72, an electrostatic deflection electrode
(convergence position adjusting part) 74, an
objective lens 76, and an electrostatic lens
(convergence position adjusting part) 78, in
this order from the rear end portion 60b. The
tip end portion 60a of the lens barrel 60 is
connected to the opening part 30a of the vacuum
chamber 30.
A magnetic shield plate 41 is disposed
on the outer periphery of the tip end portion
60a of the lens barrel 60 in order to reduce
disturbance due to such as the earth's magnetism,
The magnetic shield plate 41 is made of a
material of a high magnetic permeability such as
permalloy.
In the electron beam generator 14, the
electron source (electron gun) 62 is of a
thermal field irradiation type, and is arranged
in an ultrahigh vacuum. The electron source 62
irradiates the electron beam b toward the
turntable 53.
The irradiation of the electron beam b
by the electron source 62 is controlled by the
host controller 20.
The electron beam b irradiated by the

thermal field irradiation type electron source
62 has a small diameter of about 20 through 50
nm. Therefore, in terms of obtaining the
electron beam b with a small diameter, there is
no need to reduce the diameter of the electron
beam b focused on the surface of the sample S at
a high reduction ratio relative to the diameter
of the electron beam b irradiated by the
electron source 62.
The blanking electrode 64 is used for
controlling irradiation (ON/OFF) of the electron
beam b onto the sample S in synchronization with
scanning of the electron beam b when forming a
printing pattern. More specifically, when the
electron beam b is not deflected by the blanking
electrode 64, the electron beam b is irradiated
onto the surface of the sample S (ON). On the
other hand, when the electron beam b is
deflected by the blanking electrode 64, the
electron beam b is not irradiated onto the
surface of the sample S (OFF).
The blanking electrode 64 is connected
to a blanking drive circuit 26. The blanking
drive circuit 26 receives a printing blanking
signal corresponding to the printing pattern to

be printed on the surface of the sample S from
the host controller 20, and outputs a control
signal so as to control the irradiation of the
electron beam b to the sample S.
The axis alignment coil 66 is disposed
under the blanking electrode 64. The axis
alignment coil 66 corrects an axial displacement
of the electron beam b to be incident on the
focusing lens 68.
The focusing lens 68 is a magnetic lens
(electromagnetic lens) that focuses the electron
beam b, of which axial displacement is corrected
by the axis alignment coil 66, onto a crossover
point CP. The objective lens 76 is a magnetic
lens that focuses the electron beam b, which is
focused on the crossover point CP by the
focusing lens 68, onto the surface of the sample
S. The focusing lens 68 and the objective lens
76 are arranged under the axis alignment coil 66
in this order.
The selector aperture 70 controls ON
(writing)/OFF (stop writing) of the electron
beam b based on information to be written during
information writing process. More specifically,
when the electron beam b is not deflected by the

blanking electrode 64, the electron beam b
passes through an opening 70a of the selector
aperture 70 so as to be incident on the surface
of the sample S (ON). On the other hand, when
the electron beam b is deflected by the blanking
electrode 64, the electron beam b is shielded by
the selector aperture 70 (OFF).
The astigmatism correction coil 72
corrects astigmatism of the electron beam b and
is arranged under the selector aperture 70.
The electrostatic deflection electrode
74 adjusts the irradiation position of the
electron beam b in at least one of two
directions (the X direction and the Y direction)
orthogonal to a direction (the Z direction) in
which the irradiation axis C extends. The
electrostatic deflection electrode 74 is able to
adjust the convergence position, especially the
irradiation position.
The electrostatic deflection electrode
74 deflects the electron beam based on the
information to be written during an information
writing process so as to control the irradiation
(spot) position of the electron beam b on the
surface of the sample S. The electrostatic

deflection electrode 74 is interposed between
the astigmatism correction coil 72 and the
objective lens 76.
As shown in FIG. 2, the electrostatic
deflection electrode 74 includes a pair of first
deflection electrode plates 74a facing each
other in the X direction and a pair of second
deflection electrode plates 74b facing each
other in the Y direction. Each of the pair of
the first deflection electrode plates 74a and
the pair of the second deflection electrode
plates 74b is connected to the host controller
20.
In this embodiment, for deflecting the
electron beam b in the X direction, the host
controller 20 applies a voltage corresponding to
the amount of deflection to the pair of the
first deflection electrode plates 74a. Thus the
position of the electron beam b to be irradiated
onto the sample S in the X direction is adjusted
For deflecting the electron beam b in the Y
direction, the host controller 20 applies a
voltage corresponding to the amount of
deflection to the pair of the second deflection
electrode plates 74b. Thus the position of the

electron beam b to be irradiated onto the sample
S in the X direction is adjusted. In this way,
the host controller 20 controls the deflection
direction and deflection amount of the electron
beam b.
The electrostatic lens (convergence
position adjusting part) 78 adjusts the
convergence position, especially adjusts the
focal position of the electron beam b to meet
the surface of the sample S. The electrostatic
lens 78 is provided with a focus control part
(not shown) for changing a focal length. The
focus control part is capable of changing the
focal length of the electrostatic lens 78 as
desired.
The focus control part is connected to
the focal position control part 21. The focal
length of the electrostatic lens 78 is
controlled by an output signal from (a voltage
applied from) the focal position control part 21,
so that the focal position of the electron beam
b relative to the surface of the sample S is
adjusted.
As the electrostatic lens 78 converges
the electron beam b by electric field force, the

responsiveness of the electrostatic lens 78 is
higher than that of a magnetic lens that
converges the electron beam b by magnetic field
force.
In the electron beam generator 14 of
this embodiment, the electron source 62 emits
the electron beam b. After the axis alignment
coil 66 corrects the axial displacement of the
electron beam b, the focusing lens 68 focuses
the electron beam b onto the crossover point CP.
Then, the electron beam b passes through the
opening 70a of the selector aperture 70. After
that, the astigmatism correction coil 72
corrects astigmatism, and the objective lens 76
and the electrostatic lens 78 corrects the focal
point. Thus the electron beam b is focused onto
the surface of the sample S.
In the electron beam generator 14 of
this embodiment, when writing information, the
electron beam b irradiated from the electron
source 62 is controlled ON and OFF by the
blanking electrode 64 and the selector aperture
70 through the blanking drive circuit 26. The
electron beam b that has passed through the
opening 70a of the selector aperture 70 to be

incident on the objective lens 76 is deflected
by the electrostatic deflection electrode 74 in
the X direction or the Y direction according to
the information to be written. Thus, the spot
position on the surface of the sample S is
controlled. That is, the electron beam b scans
on the surface (the X-Y plane) of the sample S
to write information on predetermined positions
of the surface of the sample S.
The following describes the
configuration of the focal position control part
21. The focal position control part 21
calculates a correction voltage (correction
amount) for controlling the focal position of
the electron beam b according to the position of
the mobile body 45 (turntable 53) detected by
the position sensor 47 and the magnetic flux
density information (magnetic information) on
each position of the mobile body 45 acquired by
the magnetic detector 36. Based on this
correction voltage, the focal position control
part 21 causes the electrostatic lens 78 to
adjust the focal position of the electron beam b
to an appropriate position.
FIG. 3 is a block diagram showing a

structure of the focal position control part 21
according to the present embodiment.
Referring to FIG. 3, the focal position
control part 21 includes a CPU 80, a ROM 81 with
a program written therein for computing a
convergence position characteristic arithmetic
expression, a RAM 82, a magnetic flux density
measuring circuit 83, a D/A converter circuit 85,
an adder 86, an amplifier 87, and a drive
circuit 88.
The CPU 80 is connected through a bus
to the ROM 81, the RAM 82, the magnetic flux
density measuring circuit 83, the D/A converter
circuit 85, the host controller 20, and the
position detecting part 23 (position sensor 47).
The CPU 80 reads out the computation
program for a convergence position
characteristic arithmetic expression from the
ROM 81, and computes a convergence position
characteristic arithmetic expression according
to the output signal of the position detecting
part 23 (position sensor 47) and the magnetic
flux density information of each position of the
mobile body 45 by using the computation program
for a convergence position characteristic

arithmetic expression. The convergence position
characteristic arithmetic expression is a high-
order polynomial such as, e.g., a quintic
function. The CPU 80 calculates coefficients of
the high-order polynomial.
The magnetic flux density measuring
circuit 83 measures the magnetic flux density in,
e.g., the Z direction based on the output signal
of the magnetic detector 36.
The RAM 82 holds the coefficients of
the convergence position characteristic
arithmetic expression (high-order polynomial)
calculated by the CPU 80.
The D/A converter circuit 85 converts
digital applied voltage data for the
electrostatic lens 78, which is calculated by
the CPU 80, into analog voltage data.
In the focal position control part 21,
the D/A converter circuit 85 is connected to the
adder 86. The adder 86 is connected to the
amplifier 87, and the amplifier 87 is connected
to the drive circuit 88.
The adder 86 adds the analog voltage
data (output signal) of the D/A converter
circuit 85 to the output signal of the height

sensor 38 representing the surface height of the
sample S, and outputs an addition signal.
The amplifier 87 amplifies, with a
predetermined amplification factor, the addition
signal of the adder 86 to the level necessary
for the electrostatic lens 78. The drive circuit
88 is connected to the electrostatic lens 78.
The focal length of the electrostatic lens 78 is
changed by an output signal (correction voltage)
of the drive circuit 88, so that the focal point
of the electrostatic lens 7 8 is adjusted to
focus the electron beam b onto the surface of
the sample S.
The following describes a method of
controlling the focal point of the electron beam
b in the electron beam generator 14. First, with
reference to FIG. 4, the focal position of the
electron beam b affected by a magnetic field Bz
is described.
FIG. 4 shows an electron beam flow of a
convergence half angle 9 relative to a Z axis
representing the focus direction (the Z
direction). An electron e with a velocity of V
starts rotating about the Z axis in response to
Lorentz force due to a velocity component VR and

a magnetic field Bz. As the velocity component
VR is proportional to the convergence half angle
9 (9 distance r from the Z axis. The rotating
electron e receives a force in a direction
perpendicular to the Z axis due to the magnetic
field Bz, so that a 50 orbital is bent. The 56
is proportional to the electron beam diameter R
and converges onto a convergence point Zc. A
convergence point ZD of the entire electron beam
flow is uniformly displaced by a displacement
amount 5Z in the focus direction (the Z
direction).
Accordingly, if the magnitude of the
electric field, i.e., the magnetic flux density
is known, the displace amount 5Z in each
position can be calculated by integrating in the
radial direction and the Z direction.
The following describes correction of
the displacement amount of the convergence point
of the electron beam b.
FIG. 5 is a graph showing a
characteristic curve of magnetic flux density in
the Z direction with respect to mobile body
position, where the vertical axis represents the

magnetic flux density in the Z direction and the
horizontal axis represents the mobile body
position. The curve shown in FIG. 5 representing
the Z-direction magnetic flux density in each
position of the mobile body 45 is referred to as
a characteristic curve.
The mobile body position indicates the
position of the turntable 5 3 in the X direction
with reference to the position of the rotational
center of the turntable 53 (rotating mechanism
unit 34) on which the electron beam b is
irradiated when not affected by a magnetic field
(i.e., X=0 mm).
In this embodiment, the magnetic flux
density of the characteristic curve shown in FIG
5 is integrated in the radial direction and the
Z direction, thereby calculating the correction
voltage to the electrostatic lens 78 for each
position of the mobile body 45 as shown in FIG.
6. This correction voltage is to be applied from
the drive circuit 88 to the electrostatic lens
78 .
It is to be noted that, in this
embodiment, for calculation of the correction
voltage (voltage to be applied to the

electrostatic lens 78) by the focal position
control part 21, height detection sensitivity of
the height sensor 38 shown in FIG. 7 and
sensitivity of the electrostatic lens 78 shown
in FIG. 8 are measured in advance.
Further, in this embodiment, because
the influence of the magnetic field varies
depending on the position of the mobile body 45,
the correction voltage needs to be changed
depending on the position of the mobile body 45.
Therefore, the focal position control part 21
successively calculates the correction voltage
based on the mobile body position information.
For example, the RAM 82 holds
coefficients of polynomial approximation (a
function of the mobile body position) by which
the characteristic shown in FIG. 6 is
approximated. With the polynomial approximation,
a correction voltage corresponding to the
present mobile position information is
calculated. The calculation of the correction
voltage is performed by the CPU 80 by reading
out coefficient data of the coefficients from
the RAM 82 according to the calculation program
read out from the ROM 81 and using output data

of the position detecting part 23. The
calculation result is output to the D/A
converter circuit 85. If the amplification
factor of the amplifier 87 is 1, the correction
voltage shown in FIG. 6 is output from the D/A
converter circuit 85 to the amplifier 87. If the
amplification factor of the amplifier 87 is 10,
1/10 of the correction voltage shown in FIG. 6
is output from the D/A converter circuit 85 to
the amplifier 87.
In the electron beam generator 14 of
the electron beam recording apparatus 10 of this
embodiment, when the amount of a current of the
electron source 62 required for recording into
(printing onto) the sample S is determined, the
magnetic detector 36 is moved to the vicinity of
a work distance position on the irradiation axis
C of the electron beam b before recording is
performed. Thus, the magnetic detector 36
measures magnetic flux density in the Z
direction of each mobile body position so as to
compute the convergence position characteristic
(see FIG. 6).
When recording (printing) is performed,
the adder 86 adds the output signal

corresponding to the amount of focal position
displacement due to the magnetic field to the
output signal of the height sensor 38, and a
voltage is applied through the amplifier 87 and
the drive circuit 88 to the electrostatic lens
78. Thus the electrostatic lens 78 controls the
focal point of the electron beam b. In this
focal control of the electron beam b, since
influence of the magnetic field is reduced, the
electric beam b can be irradiated onto a
predetermined position of the sample S with high
focal position accuracy so as to record
information. Moreover, due to high focal
position accuracy of the electron beam b, the
printing pattern can be recorded on the sample S
with high shape accuracy.
A second embodiment of the present
invention is described below.
FIG. 9 is a schematic diagram showing
an electron beam recording apparatus 10a
according to the second embodiment of the
present invention. FIG. 10 is a block diagram
showing a structure of an irradiation position
control part 100 of the electron beam recording
apparatus 10a according to the second embodiment

of the present invention. FIG. 11 is a schematic
diagram showing a structure of an electrostatic
deflection electrode 74 of the electron beam
recording apparatus according to the second
embodiment of the present invention. Component
parts of the electron beam recording apparatus
10a identical to those of the electron beam
recording apparatus 10 of the first embodiment
of the present invention shown in FIGS. 1
through 8 are denoted by the same reference
numerals and are not described in detail.
The electron beam recording apparatus
10a of the second embodiment is different from
the electron beam recording apparatus 10 (see
FIG. 1) of the first embodiment in being able to
adjust the irradiation position (convergence
position) of the electron beam b in the X
direction and the Y direction in addition to
being able to adjust the focal position
(convergence position) of the electron beam b.
The electron beam recording apparatus
10a of this embodiment has a function of
adjusting displacement of the irradiation
position in the X direction and the Y direction
in addition to the function of the electron beam

recording apparatus 10 of the first embodiment
of correcting the displacement of the focal
position (defocus).
The inventor of this invention has
found that the focal position displacement and
the irradiation position displacement in the X
direction and the Y direction occur
independently from each other, and that the
focal position displacement and the irradiation
position displacement can be corrected without
being affected by each other even if the
corrections are separately conducted.
Accordingly, correction of the focal position
displacement and correction of the irradiation
position displacement may be performed in any
order.
Referring to FIG. 9, the electron beam
recording apparatus 10a of the second embodiment
is different from the electron beam recording
apparatus 10 (see FIG. 1) of the first
embodiment also in having a secondary electron
detector 49 in the vacuum chamber 30, an image
retrieving part 27 for forming an image based on
a signal output from the secondary electron
detector 49 when the electron beam b scans on

the X-Y plane, an image processing part 28 for
processing the image formed by the image
retrieving part 27, a display part for
displaying an image, and the irradiation
position control part (convergence position
control part) 100 for controlling the
irradiation position of the electron beam b.
Except for these differences, the configuration
of the electron beam recording apparatus 10a is
the same as the configuration of the electron
beam recording apparatus 10 (see FIG. 1) of the
first embodiment, and is not described in detail
The irradiation position control part
100 of the electron beam recording apparatus 10a
of this embodiment calculates a correction
amount for correcting the irradiation position
of the electron beam b in at least one of the X
direction and the Y direction that are
orthogonal to each other, calculates a
correction voltage (correction amount) for
controlling the irradiation position of at least
one of the X direction and the Y direction, and
adjusting the irradiation position of the
electron beam b on the surface of the sample S
using the electrostatic deflection electrode 74

in at least one of the X direction and the Y
direction.
The irradiation control part 100 is
able to correct the irradiation position when
the host controller 20 performs scanning of the
electron beam b on the surface of the sample S
in the X-Y plane.
The secondary electron detector 49
detects secondary electrons generated when the
electron beam b scans on the surface of the
sample S in the X-Y plane.
The image retrieving part 27 forms a
secondary electron reflection image based on the
detection result of the secondary electrons by
the secondary electron detector 49.
In the electron beam recording
apparatus 10a of this embodiment, the host
controller 20 scans the electron beam b on the
surface of the sample S in the X-Y plane. The
secondary electron detector 49 detects the
secondary electrons generated when the scanning
is performed. The image retrieving part 27 forms
the secondary electron reflection image. Then,
the display part 29 displays the secondary
electron reflection image.

The image processing part 28 has a
length measuring function of measuring the
distance of a subject of the secondary electron
reflection image displayed on the display part
29 .
The image processing part 28 executes
image processing and calculates, as described
below, a displacement amount of the convergence
point and a displacement amount of the
irradiation position in the X direction and the
Y direction. Image processing results (the
displacement amount of the convergence point and
the displacement amount of the irradiation
position in the X and Y directions) of the image
processing part 28 can be output to the display
part 29 so as to be displayed thereon.
The image processing result (the
displacement amount of the convergence point) of
the image processing part 28 is output to the
focal position control part 21, as described
below, so that a correction amount is calculated
so as to relocate the focal position for
achieving accurate focus.
The image processing result (the
irradiation position displacement amount) of the

image processing part 28 is output to the
irradiation position control part 100, as
described below, so that a correction amount is
calculated so as to locate the irradiation
position to an appropriate position.
The irradiation position control part
100 calculates a correction voltage for
controlling the irradiation position of the
electron beam b according to the position of the
mobile body 45 (turntable 53) detected by the
position sensor 47 and the X-direction magnetic
flux density information (magnetic information)
and the Y-direction magnetic flux density
information (magnetic information) on each
position of the mobile body 45 acquired by the
magnetic detector 36. The irradiation position
control part 100 adds this correction voltage to
a voltage to be applied for deflection from the
host controller 20 so as to adjust the
irradiation position of the electron beam b to
an appropriate position.
Referring to FIG. 10, the irradiation
position control part 100 is different from the
focal position control part 21 (see FIG. 3) in
not being connected to the height sensor 38, not

having the adder 86, and having a ROM 81a with a
program written thereon for computing an
irradiation position characteristic arithmetic
expression. Except for these differences, the
configuration of the irradiation position
control part 100 is generally the same as the
configuration of the focal position control part
21 .
In the irradiation position control
part 100, as in the focal position control part
21, a CPU 80a is connected through a bus to the
ROM 81a, a RAM 82a, a magnetic flux density
measuring circuit 83a, a D/A converter circuit
85a, the position detecting part 23 (position
sensor 47), and the image processing part 28.
The CPU 80a reads out the computation
program for an irradiation position
characteristic arithmetic expression from the
ROM 81a, and computes an irradiation position
characteristic arithmetic expression according
to the output signal of the position detecting
part 23 (position sensor 47) and the magnetic
flux density information of each position of the
mobile body 45 in the X direction and the Y
direction by using the computation program for

an irradiation position characteristic
arithmetic expression. The irradiation position
characteristic arithmetic expression is a high-
order polynomial such as, e.g., a quintic
function. The CPU 80a calculates coefficients of
the high-order polynomial.
The magnetic flux density measuring
circuit 83a measures, e.g., magnetic flux
density in the Z direction and magnetic flux
density in the Y direction based on the output
signal of the magnetic detector 36.
The RAM 82a holds the coefficients of
the irradiation position characteristic
arithmetic expression (high-order polynomial)
calculated by the CPU 80a.
Further, a correction digital voltage
to be applied to the electrostatic deflection
electrode 74 (a pair of first deflection
electrode plates 74a and a pair of second
deflection electrode plates 74b) necessary for
correcting the irradiation position calculated
by the CPU 80a is converted to a predetermined
analog correction voltage by the D/A converter
circuit 8 5a.
In the irradiation position control

part 100, the D/A converter circuit 85a is
connected to the amplifier 87a. The amplifier
87a is connected to a drive circuit 88a.
The amplifier 87a amplifies, with a
predetermined amplification factor, the
correction voltage (analog voltage) to the level
required by the electrostatic deflection
electrode 7 4.
The drive circuit 88a is connected to
the electrostatic deflection electrode 74. An
output signal (correction voltage) of the drive
circuit 88a changes the irradiation position of
the electron beam b of the electrostatic
deflection electrode 74, so that the irradiation
position of the electron beam b is adjusted.
Thus the electron beam b is focused onto a
predetermined irradiation position on the
surface of the sample S if not affected by a
magnetic field.
In the electron beam recording
apparatus 10a of this embodiment, when the host
controller 20 deflects the electron beam b, the
irradiation position control part 100 corrects
the irradiation position. As for the focal
position, the focal position control part 21

controls the focal position so as to focus the
electron beam b onto the surface of the sample S
as in the first embodiment.
The following describes a focal
position controlling method of the electron beam
recording apparatus 10a of this embodiment.
The focal position controlling method
of the electron beam recording apparatus 10a of
this embodiment is different from that of the
electron beam recording apparatus 10 of the
first embodiment only in inspecting for focal
position displacement using naked eyes and is
not described in detail.
FIG. 12A is a side elevational view
schematically showing a test substrate 90, and
the FIG. 12B is a plan view schematically
showing the test substrate 90 of FIG. 12A. FIG.
13 is a graph showing a convergence position
characteristic of the electron beam b with
respect to the position of the mobile body 45,
where the vertical axis represents the
convergence position and the horizontal axis
represents the mobile body position.
With reference to FIGS. 12A and 12B,
according to the focal position controlling

method of the electron beam recording apparatus
10a of this embodiment, the test substrate 90
that is used has a tabular base 92 on which
particles 94, such as e.g., gold particles and
latex spheres, with diameters of about tens of
nanometers thorough hundreds of nanometers are
supplied.
According to the focal position
controlling method of the electron beam
recording apparatus 10a of this embodiment, the
host controller 20 scans the electron beam b on
the surface of the test substrate 90 in the X-Y
plane by using the electrostatic deflection
electrode 74. The secondary electron detector 49
detects the secondary electrons generated when
the scanning is performed. The image retrieving
part 27 forms a secondary electron reflection
image based on the detection result of the
secondary electron detector 49. Then, the
display part 29 displays the secondary electron
reflection image. The focal position
displacement (defocus) due to the magnetic field
on each position of the turntable 53 (the
rotating mechanism unit 34) is inspected with
naked eyes using the secondary electron

reflection image displayed on the display part
29, and the focal position is adjusted for
achieving accurate focus by manually applying a
voltage to the electrostatic lens 78. The
voltage applied for achieving accurate focus is
obtained as focal position adjustment
information (defocus amount). Then, a
convergence position characteristic of the
electron beam b shown in FIG. 13 is computed.
The focal position control part 21 calculates a
correction voltage based on the convergence
position characteristic of the electron beam b.
Based on the correction voltage, the focal
length of the electrostatic lens 78 is adjusted,
so that the focal position of the electron beam
b relative to the surface of the sample S is
adjusted. Thus, the focal position of the
electron beam b is relocated to an appropriate
pos ition.
In the electron beam recording
apparatus 10a of this embodiment, the turntable
5 3 is moved to a position of X=0 mm, and the
focus of the electron beam b is adjusted to the
part icles 9 4.
Then, a convergence position, i.e., a

defocus amount (the voltage applied for
achieving accurate focus) of each particle 94 on
the surface of the base 92 is calculated. An
approximate expression is computed using the
calculated defocus amounts and then written into
the ROM 81 as a program.
According to the electron beam
recording apparatus 10a of this embodiment, it
is preferable that the ROM 81 of the focal
position control part 21 be a flash ROM or the
like so that coefficient data of the convergence
position characteristic computed by calculating
the defocus amount be written at the time of,
for example, recording (exposure) onto the
sample S. The focal position control part 21 may
have an input part so that the coefficients of
the approximate expression are input by the
input part .
The following describes a method of
controlling the irradiation position of the
electron beam b in the electron beam irradiation
device 14 of the electron beam recording
apparatus 10a of this embodiment.
First, with reference to FIG. 14,
displacement of the irradiation position of the

electron beam b affected by a magnetic field B
i s described.
Referring to FIG. 14, an electron e
with a mass m accelerated at an accelerating
voltage Va passes through a deflection magnetic
field area with a magnetic flux density B. In
this case, the expression R=(2m•Va/e)1/2x1/B is
satisfied, where R represents cyclotron radius.
The electron e is deviated from the Z
axis by a displacement amount 5S when moved a
distance δZ1 from a position Zo to a position Zp
The relationship between the distance
δZ1 and the displacement amount 5S is
represented by the following expression
according to a geometric relationship:
5S=(δZ1)2/2R.
Based on the cyclotron radius R and the
relationship between δZ1 and the displacement
amount 5S, the displacement amount 6S is
represented by the following expression:
δS=((δZ1) 2xB)/(2.(2m.Va/e)1/2).
Accordingly, if the magnetic flux
density distribution is known, the displacement
amount 5S of the irradiation position of the
electron beam b is determined by integrating in

the Z direction.
The following describes correction of
the displacement amount of the irradiation
position of the electron beam b.
FIG. 15 is a graph showing a
characteristic curve of magnetic flux density in
the X direction and the Y direction with respect
to mobile body position, where the vertical axis
represents the magnetic flux density in the X
direction and the Y direction and the horizontal
axis represents the mobile body position. In FIG
15, a curve representing the X-direction
magnetic flux density on each position of the
mobile body 45 is referred to as a
characteristic curve D1, and a curve
representing the Y-direction magnetic flux
density is referred to as a characteristic curve
D2.
The mobile body position indicates the
position of the turntable 53 in the X direction
with reference to the position of the rotational
center of the turntable 5 3 (rotating mechanism
unit 34) on which the electron beam b is
irradiated (i.e., X=0 mm).
In this embodiment, the magnetic flux

densities of the characteristic curves D1 and D2
shown in FIG. 15 are integrated in the Z
direction, thereby calculating the correction
voltage to the electrostatic deflection
electrode 74 for each position of the mobile
body 45 as shown in FIG. 16. This correction
voltage is to be applied from the drive circuit
88a to the electrostatic deflection electrode 74
It is to be noted that the turntable 53 is
stopped when calculating the correction voltage
for the irradiation position.
In this embodiment, for calculation of
the correction voltage (the voltage to be
applied to the electrostatic deflection
electrode 74 (the first deflection electrode
plates 74a and the second deflection electrode
plates 74b)) by the irradiation position control
part 100, sensitivity of the electrostatic
deflection electrode 74 (the first deflection
electrode plates 74a and the second deflection
electrode plates 74b) is measured in advance. In
this embodiment, the sensitivity of the
electrostatic deflection electrode 74 (the first
deflection electrode plates 74a and the second
deflection electrode plates 74b) is, e.g., in a

range of 1 through 5 um/V.
Further, in this embodiment, because
the influence of the magnetic field on the
displacement of the irradiation position varies
depending on the position of the mobile body 45,
the correction voltage for the electrostatic
deflection electrode 74 (the first deflection
electrode plates 74a and the second deflection
electrode plates 74b) needs to be changed
depending on the position of the mobile body 45.
Therefore, the focal position control part 21
successively calculates the correction voltage
for the electrostatic deflection electrode 74
(the first deflection electrode plates 74a and
the second deflection electrode plates 74b)
based on the mobile body position information.
For example, the RAM 82a holds coefficients of
polynomial approximation (a function of the
mobile body position) by which the
characteristic shown in FIG. 16 is approximated.
With the polynomial approximation, an
irradiation position correction voltage
corresponding to the present mobile position
information is calculated. The calculation of
the irradiation position correction voltage is

performed by the CPU 80a by reading out
coefficient data of the coefficients from the
RAM 82a according to the calculation program
read out from the ROM 81a and using output data
of the position detecting part 23. The
calculation result is output to the D/A
converter circuit 85a. If the amplification
factor of the amplifier 87a is 1, the correction
voltage shown in FIG. 16 is output from the D/A
converter circuit 85a to the amplifier 87a. If
the amplification factor of the amplifier 87a is
10, 1/10 of the correction voltage shown in FIG.
16 is output from the D/A converter circuit 85a
to the amplifier 87a. Thus the displacement of
the irradiation position of the electron beam b
is corrected.
With the irradiation position
controlling method of the electron beam
recording apparatus 10a of this embodiment, the
irradiation position of the electron beam b can
be corrected not only in the above described
manner but also by using the secondary electron
reflection image displayed on the display part
29 .
For correction using the secondary

electron reflection image, a fixed stage (not
shown) is hung from an opening of the tip end
portion 60a of the lens barrel 60, and the test
substrate 90 is placed on the fixed stage.
Then, the host controller 20 scans the
electron beam b on the surface of the test
substrate 90 in the X-Y plane by using the
electrostatic deflection electrode 74. The
secondary electron detector 49 detects a
secondary electron when the scanning is
performed. The image retrieving part 27 forms a
secondary electron reflection image. Then, the
display part 29 displays the secondary electron
reflection image.
The positions of the particles 94 of
the test substrate 90 are estimated in advance.
The positions of the particles 94 of the test
substrate 90 and the position of the particles
in the secondary electron reflection image
displayed on the display part 29 are compared so
as to measure positional shifts of the particles
94 using the length measuring function of the
image processing part 28.
Irradiation position displacement due
to the magnetic field on each position of the

turntable 53 (the rotating mechanism unit 34) is
inspected with naked eyes using the length
measuring function of the image processing part
28. Then, a voltage is manually applied to the
electrostatic deflection electrode 74. The
irradiation position is adjusted to an
appropriate position such that the particles
appear in the secondary electron reflection
image if there is no influence of the magnetic
field. It is to be noted that the turntable 53
is stopped when calculating the correction
voltage for the irradiation position.
The voltage applied for adjusting the
irradiation position to the appropriate position
is obtained as irradiation position adjustment
information. Then, a travel distance
characteristic of the electron beam b shown in
FIG. 17 is computed. Based on the travel
distance characteristic of the electron beam b,
a correction voltage is computed in the
irradiation position control part 100, so that
the irradiation position of the electron beam b
is adjusted to the appropriate irradiation
pos ition.
In the electron beam recording

apparatus 10a of this embodiment, the turntable
53 is moved to a position of X=0 mm, and a
secondary electron image is obtained.
Then, positional shifts of the
particles 94, i.e., an irradiation position
displacement amount (the voltage applied for
adjusting to the appropriate irradiation
position) of each particle 94 on the surface of
the base 92 is calculated using the length
measuring function.
The irradiation position displacement
amount (the voltage applied for adjusting to the
appropriate irradiation position) is
successively calculated while changing the
position of the turntable 53. An approximate
expression is computed using the calculated
irradiation position displacement amounts and
then written into the ROM 81a as a program.
According to the electron beam
recording apparatus 10a of this embodiment, it
is preferable that the ROM 81a of the
irradiation position control part 100 be a flash
ROM or the like so that coefficient data of the
irradiation position characteristic computed by
calculating the irradiation position

displacement amount be written at the time of,
for example, recording (exposure) onto the
sample S. The irradiation position control part
100 may have an input part so that the
coefficients of the approximate expression are
input by the input part.
Although the fixed stage (not shown)
for the test substrate 90 hung from the opening
of the tip end portion 60a is provided, the
configuration is not limited thereto. For
example, in an alternative embodiment, the
magnetic detector 36 is used as a fixed stage.
In this alternative embodiment, particles such
as e.g., gold particles and latex spheres, with
diameters of about tens of nanometers thorough
hundreds of nanometers are supplied on the
surface of the magnetic detector 36 onto which
the electron beam b is to be irradiated, and a
secondary electron image is observed. In another
alternative embodiment, particles such as e.g.,
gold particles and latex spheres, with a
diameter of about tens of nanometers thorough
hundreds of nanometers are applied to the
surface of the turntable 53 in the form of, e.g.,
a cross or a sguare, and a secondary electron

image on the surface of the turntable 53 is
observed.
In the second embodiment, even when the
convergence position characteristic is
calculated in the above described way, the same
advantages as in the first embodiment are
obtained. Moreover, the irradiation position in
the X direction and the Y direction is corrected
Therefore, compared with the first embodiment,
the electron beam b is irradiated onto a
predetermined position of the sample S with high
focal position accuracy and high irradiation
position accuracy for recording information.
Similarly, printing patterns are also recorded
on the sample S at high quality. In this
embodiment, since the displacement of the
convergence position is experimentally computed
using the test substrate 90 with the particles
94 on the surface, the electron beam recording
apparatus 10 is simple and inexpensive.
As described above, according to the
present invention, the convergence position
displacement due to the magnetic field under the
point from which the laser beam b is irradiated
to the sample S is calculated or experimentally

calculated, so that the focal position of the
electron beam b is controlled with high accuracy
Moreover, the irradiation position displacement
due to the magnetic field under a point from
which the laser beam b is irradiated onto the
sample S is calculated or experimentally
calculated, so that the irradiation position of
the electron beam b is controlled with high
accuracy. That is, the electron beam b is
irradiated to a predetermined position of the
sample S with high focal position accuracy and
high irradiation position accuracy for recording
information.
The focal position controlling method
and the irradiation position controlling method
of the electron beam recording apparatus 10a of
this embodiment are not limited to the method of
inspection using naked eyes. For example, the
focal position controlling method and the
irradiation position controlling method of the
electron beam recording apparatus 10a of this
embodiment may be automated by using the image
processing part 28.
The following describes a second method
of controlling the focus of the electron beam b

in the electron beam irradiation device 14 of
the electron beam recording apparatus 10a of
this embodiment.
The second method of controlling the
focus in the electron beam recording apparatus
10a is the same as the above-described focal
position controlling method of the electron beam
recording apparatus 10a except correcting focal
position displacement by image processing. The
second focus controlling method is therefore not
described in detail.
According to the second focus
controlling method, a fixed stage (not shown) is
hung from an opening of the tip end portion 60a
of the lens barrel 60, and a test substrate 90
is placed on the fixed stage. The test substrate
90 may be the one shown in FIG. 12A and FIG. 12B
Then, the host controller 20 scans the
electron beam b on the surface of the sample
substrate 90 in the X-Y plane. The secondary
electron detector 49 detects the secondary
electron generated when the scanning is
performed. The image retrieving part 27 forms a
secondary electron reflection image based on the
detection result of the secondary electro

detector 49. Then, the image processing part 28
analyzes the secondary electron reflection image
The image processing part 28 computes
the size of the particles 94 in the secondary
electron reflection image, and compares the
computed size of the particles 94 with the size
of the particles 94 measured in advance so as to
calculate a focal position displacement amount
(defocus amount).
Then, the size of the particles 94 in
the secondary electron reflection image is
calculated for each position of the turntable 53
so as to calculate a focal position displacement
(defocus amount) on each position due to a
magnetic field.
A voltage applied for achieving
accurate focus and calculated for each position
of the turntable 53 is obtained as focal
position adjustment information (defocus amount)
Thus the convergence position characteristic of
the electron beam b is obtained. Based on the
convergence position characteristic of the
electron beam b, a correction voltage is
computed in the focal position control part 21,
so that the focal position of the electron beam

b is adjusted to beat the appropriate focal
position.
In the electron beam recording
apparatus 10a of this embodiment, the turntable
53 is moved to a position of X=0 mm, and the
focus of the electron beam b is adjusted to the
particles 94 .
Then, a convergence position, i.e., a
defocus amount (the voltage applied for
achieving accurate focus) of each particle 94 on
the surface of the base 92 is calculated. An
approximate expression is computed using the
calculated defocus amounts and then written into
the ROM 81 as a program.
The following describes a second method
of controlling the irradiation position of the
electron beam b in the electron beam irradiation
device 14 of the electron beam recording
apparatus 10a of this embodiment.
The second method of controlling the
irradiation position in the electron beam
recording apparatus 10a is the same as the
above-described irradiation position controlling
method of the electron beam recording apparatus
10a except correcting irradiation position

displacement by image processing. Therefore, the
second irradiation position controlling method
is not described in detail.
According to the second focal position
controlling method, a fixed stage (not shown) is
hung from an opening of the tip end portion 60a
of the lens barrel 60, and a test substrate 90
is placed on the fixed stage.
Then, the host controller 20 scans the
electron beam b on the surface of the test
substrate 90 in the X-Y plane. The secondary
electron detector 49 detects secondary electrons
when the scanning is performed. The image
retrieving part 27 forms a secondary electron
reflection image and outputs the image to the
display part 28.
The size and position of the particles
94 of the test substrate 90 are measured in
advance, and the measured size and position of
the particles 94 are stored in the image
processing part 28.
The image processing part 28 compares
the stored size and position of the particles 94
with the position of the particles 94 in the
secondary electron reflection image so as to

calculate a positional shift of the particles 94
Then, a voltage to be applied to the
electrostatic deflection electrode 74 for
relocating the particles 94 to the original
position based on the positional shift of the
particles 94, thereby calculating a correction
voltage for each position. It is to be noted
that the turntable 53 is stopped when
calculating the correction voltage for the
irradiation position.
Thus a travel distance characteristic
of the electron beam b is computed. Based on the
travel distance characteristic of the electron
beam b, a correction voltage is computed in the
irradiation position control part 100, so that
the irradiation position of the electron beam b
is adjusted to beat the appropriate irradiation
position.
In the electron beam recording
apparatus 10a of this embodiment, the turntable
53 is moved to a position of X=0 mm, and a
secondary electron image is obtained.
Then, the image processing part 28
calculates a positional shift of the particles
94, i.e., an irradiation position displacement

amount (the voltage applied for adjusting to the
appropriate irradiation position) of each
particle 94 on the surface of the base 92.
The irradiation position displacement
amount (the voltage applied for adjusting to the
appropriate irradiation position) is
successively calculated while changing the
position of the turntable 53. An approximate
expression is computed using the calculated
irradiation position displacement amounts and
then written into the ROM 81a as a program.
The second focal position control
method and the second irradiation position
control method of the electron beam recording
apparatus 10a of this embodiment described above
achieve the same advantages as the first
described methods.
While the electron beam recording
apparatus of the present invention has been
described in terms of preferred embodiments, it
will be apparent to those skilled in the art
that the present invention is not limited to the
preferred embodiments illustrated herein, and
variations and modifications may be made without
departing from the scope of the invention.

The present application is based on
Japanese Priority Application No. 2006-067977
filed on March 13, 2006, and Japanese Priority
Application No. 2007-005045 filed on January 12,
2007, with the Japanese Patent Office, the
entire contents of which are hereby incorporated
by reference.

CLAIMS
1. An electron beam recording
apparatus that records information onto the
surface of a sample by using an electron beam,
comprising:
an electron source that irradiates the
electron beam;
a magnetic detector that is configured
to move onto and out of an irradiation axis and
acquires magnetic information on the irradiation
axis ;
a convergence position control part
that calculates a convergence position
correction amount for correcting a convergence
position of the electron beam with respect to
the surface of the sample based on the magnetic
information acquired by the magnetic detector;
and
a convergence position adjusting part
that adjusts the convergence position of the
electron beam with respect to the surface of the
sample;
wherein the convergence position
control part causes the convergence position

adjusting part to adjust the convergence
position of the electron beam with respect to
the surface of the sample based on the
convergence position correction amount.
2. The electron beam recording
apparatus as claimed in Claim 1,
wherein the convergence position
includes a focal position of the electron beam;
the convergence position adjusting part
adjusts the focal position of the electron beam
with respect to the surface of the sample; and
the convergence position control part
calculates a focal position correction amount
for correcting the focal position of the
electron beam in a direction in which the
irradiation axis extends, and causes the
convergence position adjusting part to adjust
the focal position of the electron beam with
respect to the surface of the sample based on
the focal position correction amount.
3. The electron beam recording
apparatus as claimed in Claim 1 or Claim 2,
wherein the convergence position

includes an irradiation position of the electron
beam in at least one of two directions that are
orthogonal to each other and are orthogonal to
the direction in which the irradiation axis
extends;
the convergence position adjusting part
adjusts the irradiation position of the electron
beam with respect to the surface of the sample
in at least said one of the two directions
orthogonal to each other; and
the convergence position control part
calculates an irradiation position correction
amount for correcting the irradiation position
of the electron beam in at least said one of the
two directions orthogonal to each other, and
causes the convergence position adjusting part
to adjust the irradiation position of the
electron beam with respect to the surface of the
sample in at least said one of the two
directions orthogonal to each other based on the
irradiation position correction amount.
4. The electron beam recording
apparatus as claimed in Claim 1, further
comprising:

a rotating mechanism unit that includes
a rotatable turntable on which the sample is
placed;
a feed mechanism unit that moves the
turntable of the rotating mechanism unit into a
plane orthogonal to the irradiation axis of the
electron beam;
a position sensor that is provided in
the feed mechanism unit and detects a position
of the sample to acquire position information of
the sample; and
a height sensor that detects a height
of the surface of the sample being rotated by
the rotating mechanism unit and being moved by
the feed mechanism unit to acquire height
information of the sample; wherein
the convergence position includes a
focal position of the electron beam;
the convergence position adjusting part
adjusts the focal position of the electron beam
with respect to the surface of the sample; and
the convergence position control part
calculates a focal position correction amount
for correcting the focal position of the
electron beam based on the magnetic field

information in the direction in which the
irradiation axis extends, the magnetic field
information being acquired by the magnetic
detector and corresponding to the height
information of the sample acquired by the height
sensor and the position information of the
sample acquired by the position sensor, and
causes the convergence position adjusting part
to adjust the focal position of the electron
beam with respect to the surface of the sample
based on the focal position correction amount.
5. The electron beam recording
apparatus as claimed in Claim 1, further
comprising:
a rotating mechanism unit that includes
a rotatable turntable on which the sample is
placed;
a feed mechanism unit that moves the
turntable of the rotating mechanism unit into a
plane orthogonal to the irradiation axis of the
electron beam;
a position sensor that is provided in
the feed mechanism unit and detects a position
of the sample to acquire position information of

the sample; and
a height sensor that detects a height
of the surface of the sample being rotated by
the rotating mechanism unit and being moved by
the feed mechanism unit to acquire height
information of the sample; wherein
wherein the convergence position
includes an irradiation position of the electron
beam in at least one of two directions that are
orthogonal to each other and are orthogonal to
the direction in which the irradiation axis
extends;
the convergence position adjusting part
adjusts the irradiation position of the electron
beam with respect to the surface of the sample
in at least said one of the two directions
orthogonal to each other;
wherein the magnetic sensor acquries
magnetic informatrion in at least said one of
the two directions orthogonal to each other; and
the convergence position control part
calculates an irradiation position correction
amount for correcting the irradiation position
of the electron beam in at least said one of the
two directions orthogonal to each other based on

the magnetic field information in at least said
one of the two directions orthogonal to each
other, the magnetic field information being
acquired by the magnetic detector and
corresponding to the height information of the
sample acquired by the height sensor and the
position information of the sample acquired by
the position sensor, and causes the convergence
position adjusting part to adjust the
irradiation position of the electron beam with
respect to the surface of the sample in at least
said one of the two directions orthogonal to
each other based on the irradiation position
correction amount.
6. The electron beam recording
apparatus as claimed in Claim 1, further
comprising:
a rotating mechanism unit that includes
a rotatable turntable on which the sample is
placed;
a feed mechanism unit that moves the
turntable of the rotating mechanism unit into a
plane orthogonal to the irradiation axis of the
electron beam; and

a position sensor that is provided in
the feed mechanism unit and detects a position
of the sample to acquire position information of
the sample; wherein
the convergence position includes a
focal position of the electron beam;
the convergence position adjusting part
adjusts the focal position of the electron beam
with respect to the surface of the sample;
the convergence position control part
acquires focal position adjustment information
for each position of the sample by adjusting the
focal position of the electron beam onto a
particle applied to a surface of a test
substrate placed on the turntable; and
the convergence position control part
causes the convergence position adjusting part
to adjust the focal position of the electron
beam based on the focal position adjustment
information.
7. The electron beam recording
apparatus as claimed in Claim 1,
wherein the convergence position
includes an irradiation position of the electron

beam in at least one of two directions that are
orthogonal to each other and are orthogonal to
the direction in which the irradiation axis
extends;
the convergence position adjusting part
adjusts the irradiation position of the electron
beam with respect to the surface of the sample
in at least said one of the two directions
orthogonal to each other;
the convergence position control part
acquires irradiation position adjustment
information for each position of the sample by-
adjusting the irradiation position of the
electron beam onto a particle applied to a
surface of a test substrate placed on the
turntable; and
the convergence position control part
causes the convergence position adjusting part
to adjust the irradiation position of the
electron beam in at least said one of the two
directions orthogonal to each other based on the
irradiation position adjustment information.
8. The electron beam recording
apparatus as claimed in Claim 1, wherein the

convergence position adjusting part includes an
electrostatic lens for adjusting the focal
position of the electron beam.

An electron beam recording apparatus is
disclosed that records information onto the
surface of a sample by using an electron beam.
The electron beam recording apparatus includes
an electron source that irradiates the electron
beam, a magnetic detector that is configured to
move onto and out of an irradiation axis and
acquires magnetic information on the irradiation
axis, a convergence position control part that
calculates a convergence position correction
amount for correcting a convergence position of
the electron beam with respect to the surface of
the sample based on the magnetic information,
and a convergence position adjusting part that
adjusts the convergence position of the electron
beam with respect to the surface of the sample.
The convergence position control part causes the
convergence position adjusting part to adjust
the convergence position of the electron beam
with respect to the surface of the sample based
on the convergence position correction amount.

Documents:

3696-KOLNP-2008-(01-04-2013)-CORRESPONDENCE.pdf

3696-KOLNP-2008-(01-04-2013)-FORM 3.pdf

3696-KOLNP-2008-(01-12-2014)-CLAIMS.pdf

3696-KOLNP-2008-(01-12-2014)-CORRESPONDENCE.pdf

3696-KOLNP-2008-(17-03-2014)-CORRESPONDENCE.pdf

3696-KOLNP-2008-(17-03-2014)-OTHERS.pdf

3696-KOLNP-2008-(18-06-2014)-ABSTRACT.pdf

3696-KOLNP-2008-(18-06-2014)-ANNEXURE TO FORM 3.pdf

3696-KOLNP-2008-(18-06-2014)-CLAIMS.pdf

3696-KOLNP-2008-(18-06-2014)-CORRESPONDENCE.pdf

3696-KOLNP-2008-(18-06-2014)-DESCRIPTION (COMPLETE).pdf

3696-KOLNP-2008-(18-06-2014)-DRAWINGS.pdf

3696-KOLNP-2008-(18-06-2014)-FORM-1.pdf

3696-KOLNP-2008-(18-06-2014)-FORM-2.pdf

3696-KOLNP-2008-(18-06-2014)-OTHERS.pdf

3696-KOLNP-2008-(18-06-2014)-PA.pdf

3696-KOLNP-2008-(18-06-2014)-PETITION UNDER RULE 137.pdf

3696-kolnp-2008-abstract.pdf

3696-KOLNP-2008-ASSIGNMENT.pdf

3696-kolnp-2008-claims.pdf

3696-KOLNP-2008-CORRESPONDENCE-1.1.pdf

3696-kolnp-2008-correspondence.pdf

3696-kolnp-2008-description (complete).pdf

3696-kolnp-2008-drawings.pdf

3696-kolnp-2008-form 1.pdf

3696-kolnp-2008-form 18.pdf

3696-KOLNP-2008-FORM 3-1.1.pdf

3696-kolnp-2008-form 3.pdf

3696-kolnp-2008-form 5.pdf

3696-kolnp-2008-gpa.pdf

3696-kolnp-2008-international publication.pdf

3696-kolnp-2008-international search report.pdf

3696-KOLNP-2008-PA.pdf

3696-kolnp-2008-pct priority document notification.pdf

3696-kolnp-2008-pct request form.pdf

3696-kolnp-2008-specification.pdf

abstract-3696-kolnp-2008.jpg


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Patent Number 264487
Indian Patent Application Number 3696/KOLNP/2008
PG Journal Number 01/2015
Publication Date 02-Jan-2015
Grant Date 31-Dec-2014
Date of Filing 10-Sep-2008
Name of Patentee RICOH COMPANY, LTD.
Applicant Address 3-6, NAKAMAGOME 1-CHOME OHTA-KU, TOKYO 143-8555 JAPAN
Inventors:
# Inventor's Name Inventor's Address
1 MIYAZAKI, TAKESHI C/O CRESTEC CORPORATION, 1-9-2, OWADA-MACHI, HACHIOJI-SHI, TOKYO, 1920045 JAPAN
2 OBARA, TAKASHI 22-4, NAKATAHIGASHI 2-CHOME, IZUMI-KU, YOKOHAMA-SHI, KANAGAWA, 2450013 JAPAN
PCT International Classification Number G11B 7/26, G11B 9/10
PCT International Application Number PCT/JP2007/055330
PCT International Filing date 2007-03-12
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2007-005045 2007-01-12 Japan
2 2006-067977 2006-03-13 Japan