Title of Invention

A SYSTEM AND METHOD FOR TREATING OBJECTS UNDER VACCUM

Abstract

This invention relates to a system (1) for treating objects under vacuum, comprising a plurality of chambers (2, 3, 4); and an evacuation device having at least one forevacuum pump (5) with several pumping stages (11, 12, 13), each of said several pumping stages being provided with one inlet (14, 15, 16) each connectable to one of said several pumping stages. Plurality of chambers (2, 3, 4) comprises a process chamber (2) with at least one pre-chamber (3, 4) linked to the process chamber (2), and in that the pumping stages (11, 12, 13) of tha forevacuum pump (5) have different pumping capacities, the stage with the highest capacity being connected to the process chamber (2).

Full Text

FIELD OF INVENTION The invention relates to a multi-chamber installation for treating objects under vacuum, comprising an evacuation system that is connected to the chambers. Moreover, the present invention relates to a method for evacuating said installation as well as an evacuation system therefor. BACKGROUND OF INVENTION Multi-chamber installations of the aforementioned kind are known. They serve the purpose of degassing, coating (metallization, for example) or etching substrates. Known methods of this kind are CVD or DVD processes. Commonly, such an installation is equipped with a process chamber, with one or several pre- chambers with load lock function being located upstream. The load locks are opened for the period of time while introducing or removing substrates, so that high pressure variations occur differing from chamber to chamber. In the instance of a multi-chamber installation equipped with two chambers, it is known to employ two separate vacuum pumps in order to be able to evacuate as rapidly as possible each of the chambers after closing the corresponding load lock. Typical forevacuum pumps are oil-sealed rotary pumps as they are known, for example, from DE-U-90 07 544. US patent 6251192 B1 discloses a vacuum exhaust system which can improve the operating efficiency of the vacuum exhaust system while reducing the system cost, to quickly attain a vacuum in the auxiliary chambers without increasing the size of the vacuum pumps. The vacuum exhaust system comprises a first pumping section and a second pumping section disposed downstream of and in series with the first pumping section. A main exhaust passage is provided to communicate a main chamber with a suction port of the first pumping section, and an auxiliary exhaust passage is provided to communicate an auxiliary chamber with a suction port of the second pumping section. OBJECT OF INVENTION It is the task of the present invention to reduce in the instance of multi-chamber installations of the aforementioned kind or similar kind, the complexity for the evacuation system. SUMMARY OF INVENTION Accordingly, in a first aspect of the invention, there is provided a system for treating objects under vacuum, comprising a plurality of chambers; and an evacuation device having at least one forevacuum pump with several pumping stages, each of said several pumping stages being provided with one inlet each connectable to one of said several pumping stages. The plurality of chambers comprises a process chamber with at least one pre-chamber linked to the process chamber, and in that the pumping stages of the forevacuum pump have different pumping capacities, the stage with the highest capacity being connected to the process chamber. In a second aspect of the invention, there is provided A method for operating a system for treating objects under vacuum, the system having a process chamber with at least one pre-chamber connected to the process chamber, the required vacuum pressures are produced in the chambers by adapting an evacuation device having at least one forevacuum pump with several stages, each stages having different pumping capacities. The vacuum pressure is produced with the several pumping stages operated in parallel; the pumping stages each provided with one inlet which each being connectable to one of the chambers, and in that the process chamber is evacuated with the aid of a pumping stage having the highest pumping capacity. Thus, the system is characterized in that each of the stages is equipped with an inlet and in that each of the inlets is connected to one of the chambers, now only one vacuum pump is required in order to produce the desired pressure - be......... they approximately the same or also different - in the different chambers as rapidly as possible and maintain these. Several pumps each with a drive motor are no longer required. Also installation complexity - both mechanical and also electrical - is reduced. Preferably the pump stages are operated in parallel so that they have the function of two independent pumps. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Further advantages and details of the present invention shall be explained with reference to the examples of embodiments depicted schematically in the accompanying drawings 1 to 4: Figure 1: a multi-chamber installation with three chambers and a three stage forevacuum pump, Figure 2: a multi-chamber installation with two vacuum chambers and a two- stage forevacuum pump, Figure 3: a multi-chamber installation according to drawing figure 2 with an additional high vacuum pump and Figure 4: a sectional view through a two-stage forevacuum pump. DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION In the drawing figures, the multi-chamber installation is generally designated as 1, the chambers with 2, 3 and 4, and the evacuation system with 5. In the instance of the chambers 2 to 4 these consist each of a process chamber 2, to which further chambers 3, 4 (drawing figure in 1) respectively only 4 (drawing figures 2, 3) are associated which may, for example, have the function of load locks. Slotted load locks are schematically depicted and designated as 6, 7 and 8. The evacuation system 5 is designed by way of a multi-stage forevacuum pump. In the example of the embodiment in accordance with drawing figure 1, three chambers 2, 3, 4 are present. Correspondingly, the forevacuum pump 5 has three stages 11, 12, 13 each with one inlet 14, 15, respectively 16. Each of the inlets 14,15,16 is connected via one each connecting line 17,18, respectively in 19 to one of the chambers 2, 3,4. The outlets 20, 21, 22 of the pump stages 11, 12,13 open out within the pump 5 into a joint discharge line, so that the pump 5 has only one outlet 23. In the instance of the pumping stages 11, 12, 13 having different pumping capacities, it is then expedient to connect the stage with the highest pumping capacity to the process chamber 2, so that there sufficiently low pressures are attainable as rapidly as possible. In the embodiment according to drawing figure 2, only two chambers 2, 4 and correspondingly two pump stages 11,13 are provided. Located in the connecting lines 17 and 19 are valves 24 and 25 in order to separate from the evacuation system 5 one or both chambers 2,4 in case these are vented. In the embodiment according to drawing figure 3, there is located in the connecting line 17 a turbomolecular vacuum pump 26 and - on its delivery side - a valve 27. High vacuum pumps of this kind excel through higher pumping capacities and lower ultimate pressures compared to forevacuum pumps, however, they require a forevacuum pump which in the instance of the case presented, forms the pumping stage 11. This embodiment is expedient for processes being performed in the process chamber 2 in which relatively low pressure (102 mbar, for example) shall be attained as rapidly as possible. Forevacuum pumps are also capable of attaining ultimate pressures of approximately 1 mbar to 5x10-2 mbar, however, through the utilization of high vacuum pumps it is possible to attain even lower pressures significantly faster. Drawing figure 4 depicts a partial sectional view through a commercial two-stage forevacuum pump 5 which has been modified for utilization in a multi-chamber installation. Said forevacuum pump is equipped with an outer casing 28 with an oil sump 29. Accommodated in the outer casing 28 is the actual pump 31, a rotary vane vacuum pump 31 with two stages 11 and 13. It comprises three discs 32, 33, 34 with pump rings 35, 36 accommodated in between. The pump rings 35, 36 form of the pump chambers 37, 38, in which there is located one each eccentrically arranged rotor 41, respectively 42 with its vanes 43, respectively 44. The rotor 42 is linked to the shaft 45 of a drive motor net depicted. Moreover, the bearing stubs of the rotors 41, 42 are linked to each other in the area of the disk 33. The diameter of the rotors 41, 42 is equal, their lengths are different. Thus there result for the two pump stages 11, 13 different pumping capacities. When employing the presented pump as a two-stage vacuum pump with series connected pump stages 11,13, the longer pump stage forms the inlet pump stage and the shorter one the delivery pump stage. The pump 5 presented has been modified such that the pump stages 11,13 may be operated in parallel. The inlet equipped with an anti-suck back valve 46 which is present in any case in pumping stage 11 serves as inlet 14. The outlet of pumping stage 11, not depicted in detail, is no longer linked to the inlet of the pumping stage 13, but instead opens out below the felt hat 47. The pumping stage 13 has been equipped with an independent intake port 48 forming the inlet 16. The intake port 48 is linked via pipe section 49 run out of the casing 28 to the pump chamber 37. The not depicted outlet of this pumping stage 13 also opens out under the felt hat 47. The felt hat 47 serves the purpose of calming down the flow and coarsely separating the oil. Further separators which need to be connected to the outlets 23 need, compared to the state-of-the-art, to be present only once. We Claim 1. A system (1) for treating objects under vacuum, comprising a plurality of chambers (2, 3, 4); and an evacuation device having at least one forevacuum pump (5) with several pumping stages (11, 12, 13), each of said several pumping stages being provided with one inlet (14, 15, 16) each connectable to one of said several pumping stages, characterized in that said plurality of chambers (2, 3, 4) comprises a process chamber (2) with at least one pre-chamber (3, 4) linked to the process chamber (2), and in that the pumping stages (11, 12, 13) of the forevacuum pump (5) have different pumping capacities, the stage with the highest capacity being connected to the process chamber (2). 2. The system as claimed in claim 1, wherein the pumping stages (11, 12, 13) of the forevacuum pump (5) are arranged in parallel. 3. The system as claimed in claim 1 or 2, wherein the number of chambers (2, 3, 4) and the number of pumping stages (11, 12, 13) of the forevacuum pump (5) is equal. 4. The system as claimed in claim 3, comprising a high vacuum pump (26), preferably a turbomolecular vacuum pump, disposed in the connecting line between the process chamber (2) and the inlet (14) of the corresponding pumping stage (11). 5. A method for operating a system for treating objects under vacuum, the system having a process chamber (2) with at least one pre-chamber (3,4) connected to the process chamber (2), the required vacuum pressures are produced in the chambers (2, 3, 4) by adapting an evacuation device having at least one forevacuum pump (5) with several stages (11,12,13), each stages having different pumping capacities, characterized in that the vacuum pressure is produced with the several pumping stages (11, 12, 13) operated in parallel; the pumping stages each provided with one inlet (14, 15, 16) which each being connectable to one of the chambers (2, 3, 4), and in that the process chamber (2) is evacuated with the aid of a pumping stage (11) having the highest pumping capacity. 6. Method as claimed in claim 5, wherein the process chamber (2) is evacuated with the aid of a high vacuum pump (26) and wherein the forevacuum pressure required by the high vacuum pump is produced by one of the pumping stages (11,12,13). 7. Evacuation device for a system (1) for treating objects under vacuum, the system having a plurality of chambers (2, 3, 4), wherein said evacuation device is designed in the form of a multistage forevacuum pump (5) where each of the pumping stages (11, 12, 13) exhibits an inlet (14, 15, 16), and wherein each of the inlets providing a connection with one of the chambers (2, 3,4) of the system (1). 8. Evacuation device as claimed in claim 7, wherein the pumping stages (11, 12,13) of the pump (5) are arranged in parallel. 9. Evacuation device as claimed in claim 7 or 8, comprising a high vacuum pump (26), wherein one of the stages (11, 12, 13) of the forevacuum pump (5) producing the forevacuum required by the high vacuum pump (26). This invention relates to a system (1) for treating objects under vacuum, comprising a plurality of chambers (2, 3, 4); and an evacuation device having at least one forevacuum pump (5) with several pumping stages (11, 12, 13), each of said several pumping stages being provided with one inlet (14, 15, 16) each connectable to one of said several pumping stages. Plurality of chambers (2, 3, 4) comprises a process chamber (2) with at least one pre-chamber (3, 4) linked to the process chamber (2), and in that the pumping stages (11, 12, 13) of tha forevacuum pump (5) have different pumping capacities, the stage with the highest capacity being connected to the process chamber (2).

Documents:

472-kolnp-2004-granted-abstract.pdf

472-kolnp-2004-granted-claims.pdf

472-kolnp-2004-granted-correspondence.pdf

472-kolnp-2004-granted-description (complete).pdf

472-kolnp-2004-granted-drawings.pdf

472-kolnp-2004-granted-examination report.pdf

472-kolnp-2004-granted-form 1.pdf

472-kolnp-2004-granted-form 18.pdf

472-kolnp-2004-granted-form 2.pdf

472-kolnp-2004-granted-form 26.pdf

472-kolnp-2004-granted-form 3.pdf

472-kolnp-2004-granted-form 5.pdf

472-kolnp-2004-granted-letter patent.pdf

472-kolnp-2004-granted-priority document.pdf

472-kolnp-2004-granted-reply to examination report.pdf

472-kolnp-2004-granted-specification.pdf

472-kolnp-2004-granted-translated copy of priority document.pdf