Wafer processing system

Abstract: A system for multichamber processing of semiconductor wafers providing flexibility in the nature of processing available in a multiprocessing facility. To accommodate changing processing demands and chamber replacement, a mobile processing chamber selectively docks with a multiple chamber system to form one of its processing chambers. The capabilities of the multiprocessing multichamber system are enhanced by extending the system to other multichamber systems through intermediate buffer storage wafer cassette and elevator systems. The extended multichamber system is further provided with intermediate access wafer storage elevator cassettes.

Description: The present invention relates to the processing of semiconductor wafers in plural chambers. As shown in our commonly assigned U.S. Patent No. 4,715,921, issued December 29, 1987 and U.S. Patent Applications Serial No. 853,775, filed April 18, 1986, and Serial No. 115,774, filed October 30, 1987, the use of plural chambers to process semiconductor wafers permits more efficient, rapid and flexible semiconductor wafer plasma environment processing. In that disclosure the ability is provided to address the wafers in an individual cassette to different ones or multiples of processing chambers associated with that one cassette. In the use of multiple chambers it can occur that one or more chambers must be serviced. Time is lost in the process of repairing or converting those chambers to other functions due to the extended period of time needed to bring chambers to the vacuum state needed to process semiconductor wafers. WO87/04414 discloses a method for transporting disc-shaped products from one manufacturing process to another in which the products are placed in a sealed magazine which is evacuated and transported to the equipment for the second processing step. The magazine is connected to the equipment under vacuum, whereupon the products are removed one-by-one, and are conveyed inside the equipment into a second, empty magazine. EP-A-272 141 discloses an integrated modular multiple chamber vacuum processing system including a load lock having a plurality of processing chambers about the periphery of the load lock. An external cassette elevator is adapted for housing a multiplicity of cassettes and or moving the cassettes via an indexing system to present selected wafers to the load lock. According to one aspect of the invention there is provided a portable semiconductor processing chamber assembly matable with a stationary housing of a multi-processing semiconductor processing station having a semiconductor wafer transfer mechanism comprising: a mobile housing, a sealing mechanism for releasably docking said mobile housing with said stationary housing having said wafer transfer mechanism to permit transfer of a wafer between said stationary housing and said mobile housing along a wafer transport path, means for providing a controlled environment along said wafer transport path, characterized in that said processing chamber is a mobile processing chamber supported by said housing for movement therewith and for controlled environment processing of said wafer, means operated under microprocessor control for establishing a controlled evacuated environment within said chamber to provide selected wafer processing and in that said sealing mechanism having said wafer transfer mechanism in such a way that said chamber communicates with the wafer transfer mechanism to permit transfer of a wafer between said stationary housing and said chamber along said wafer transport path. These and other features of the present invention are more fully described below in the solely exemplary detailed description and accompanying drawing of which: Fig. 1 is an overhead view of a multichamber multiprocessing system having plural multichamber facilities and mobile processing chambers with a wafer buffer storage cassette and elevator system between multichamber facilities; Fig. 2 is an elevational partially interior partially sectional view of a docked mobile chamber for use in the embodiment of Fig. 1; Fig. 3 is an illustration of a wafer transport system for transporting wafers between buffer storage cassette elevator systems and providing access along the transport path for wafer insertion and removal; and Fig. 4 is a view of the transport mechanism within a controlled environment enclosure of Fig. 3. The present invention contemplates a system for providing multi-chamber multiprocessing of semiconductor wafers in which individual processing chambers are mobile to permit easy exchange of processing chambers without requiring the down time for complete system evacuation and further for permitting flexible extension of processing capabilities by joining multiprocessing multichamber facilities through a wafer buffer storage cassette and elevator system that may include intermediate buffer storage that permits wafer insertion and removal from the wafer processing system. Such system is illustrated in Fig. 1 in which a multichamber multiprocessing facility 10 is connected to a second such multichamber multiprocessing facility 12 through an intermediate cassette system 14 which typically comprises a multi wafer containing cassette and elevator for positioning each wafer slot in the cassette at a point where it can be accessed by a transfer arm contained within respective transfer mechanisms 16 and 18 of the multiprocessing facilities 10 and 12. Each transport mechanism 16 and 18 is typically provided with a vacuum pump 20 capable of evacuating at least the interior of the transport mechanism 16. Arrayed about each transport mechanism 16 are a plurality of multiprocessing chambers. Those arrayed about the transfer mechanism 16 are illustrative of a typical single multiprocessing facility. As shown there processing modules 22 and 24 are of a type which may be permanently associated with the transfer mechanism 16 while processing modules 26 and 28 are mobile processing modules, more fully illustrated below in Fig. 2. Each of the chambers 22, 24, 26 or 28 are coupled to the transport mechanism 16 through a valved access port and docking mechanism comprising first parts 32 containing a slit access valve, as more fully illustrated in Fig. 2, through which a semiconductor wafer may be passed from the transport mechanism 16 on an arm 34 into and out of the respective chambers 22, 24, 26, 28 (or mobile chamber 30 for mechanism 8) through a further valve and docking mechanism 36 associated with each of the chambers 22, 24, 26, 28 (and/or 30 for mechanism 18). The cassette elevator 14 is similarly coupled through a valve and docking mechanism 38 of the same type associated with the transport mechanism 16 and spacer collars 40 associated with the cassette elevator 14. Because the cassette elevator 14 does not contain a gaseous wafer processing environment it is normally unnecessary that the spacer 40 have a valve associated with it, but a spacer 40 is provided so that the distance between wafers in the cassette 14 and the pivot point of arm 34 can be made the same as the distance between that pivot point and the point at which wafers are placed within each of the processing chambers 22, 24, 26, 28, and 30. Reference is additionally made to United States Patent No. 4,715,921, issued December 29, 1987 and U.S. Patent Applications Serial No. 853,775, filed April 18, 1986 and Serial No. 115,774, filed October 30, 1987 in which portions of the structure of the Fig. 1 apparatus are additionally illustrated. The details of mobile processing chambers 26, 28 and 30 are illustrated more fully below with respect to Fig. 2. As shown in Fig. 2 each of the chambers 26, 28 and 30 includes a housing 50 in which a module 52 is installed and that contains a chamber 54, having a pedestal 56 supporting a cathode 58 on which a wafer 60 is typically placed below an anode 62 from which, in the example of plasma processing, an electric field emanates to produce a plasma discharge for processing of the wafer 60. The module 52 additionally includes electronics 64 which in the case of plasma discharge provides the appropriate field between the anode 62 and cathode 58 as known in the art. The module 52 may also contain an environmental gas control system 66 to supply appropriate etching gases in the case of plasma etching or gases for other purposes as described below. The control of the electronics and environmental gas supplies 64 and 66 is under the direction of a micro-processor 68 located within the housing 50. The module 52, in the specific illustration of Fig. 2, is intended for plasma etching of the surface of the wafer 60. Other modules can be provided that will employ other processing technologies such as chemical vapor deposition, sputtering, rapid thermal processing, rapid thermal annealing, plasma cleaning to name a few, and utilizing technology and apparatus already known in the art. The module 52, as installed within the housing 50, mates, for wafer exchange and transfer, with the wafer transfer mechanism 18 through coupling and docking valves 32 and 36. In particular each such valve includes a conduit 70 and 72 which are fastened to the mechanism 18 and module 52 respectively. The conduits 70 and 72 have outer beveled flanges 74 and 76 respectively which are joined through a quick connect band 78 typically hinged at a hinge 80 and coupled with a clamp 82. Locating pins 84 are typically provided to accurately align the conduits 70 and 72 and thus module 52 with respect to the transfer mechanism 18 so that a wafer may be inserted through the conduit 70 and 72 into the chamber 54 and onto the cathode 58. To facilitate this alignment, the housing 50 rolls upon a dolley system 86 which is adjustably supported from the base of the housing 50 through adjustment screws 88. Conduits 70 and 72 are typically elongated in the dimension in out of the page in order to accommodate the full width of a semiconductor wafer. In order to seal the controlled environment within the transfer mechanism 18 and within the chamber 54, valve assemblies 90 and 92 are provided within the conduits 70 and 72 respectively to seal access ports 91 and 93 into the respective interiors. Valves of this type are illustrated in the above-identified, commonly assigned patent and applications. Seals 94 may be additionally provided in the facing surfaces of the conduits 70 and 72. The interior of the chamber 54 is connected through a manifold 100 through a series of conduits 102, 104, 106 and computer controlled valve 108 to a turbo pump 110 which is in turn conducted through an output conduit 112 to an exhaust manifold 114, computer controlled exhaust valve 116 into an exhaust pipe 118 which exits through the housing 50 for attachment to a further exhaust and vacuum pump and to processing equipment for exhaust gases. A conduit 120 feeds directly off the conduit 102 into the manifold 114 and then through the controlled valve 116 to the outlet 118. In operation the computer 68 controls the turbo pump 110 and its power supply 122 in conjunction with the valves 108 and 116 and additional vacuum pump systems external of the housing 50 to provide rough and final exhausting of the chamber 54. Vacuum pump 20 evacuates the conduits 70 and 72 after docking. Fig. 3 illustrates a further embodiment of the invention wherein a pair of cassette elevators 140 and 142 are coupled to a respective pair of transfer mechanisms 144 and 146 through associated valve interfaces 148 and 150, corresponding to the mechanisms 32 and 36 shown above. Wafers are transferred through a conduit 152 between the elevator systems 140 and 142. Intermediate along the transfer conduit 152 is an elevator cassette 154 providing access to the conduit 150 for the insertion and removal of wafers to be processed or after processing. The actual transfer mechanism within the conduit 152 is illustrated in greater detail in Fig. 4. As shown there a linear guide 160 has a slide 162 driven along it by a drive mechanism 164. On top of slide 162 is an arm 166 and a further slide 168 running thereon, under positional control of the drive mechanism 164. The slide 168 contains a wafer arm 170 which can be extended into the cassette of elevators 140, 142, and 154 for the retrieval or insertion of a semiconductor wafer. The arm 166 is positioned either parallel to the guide 160, facing in either direction, or perpendicularly disposed into the elevator cassette 154 when in a central housing 172 positioned along the conduit 152. The position of the guide arm 166 is controlled by a rotatable hand 174 which can be elevated and dropped to engage the arm 166 at a central point 176 under the control of a drive and elevation mechanism 178 (Fig. 3) either automatically under computer control or by manual manipulation. In this manner cassettes can be applied to the multichamber multiprocessing system associated with either of the transfer mechanisms 144 and 146 by loading into the corresponding cassette elevator systems 140 and 146 through the conduit 152 from the elevator 154. In this manner wafers can be exchanged between the elevators 140, 142 and 154 in any desired sequenced to accomplish a broad range of wafer processing activities within the respective multiprocessing systems associated with each transfer mechanism 144 and 146. A plurality of additional intermediate elevator cassettes 150 of the type of 154 may be applied along the conduit path or the path of conduit 152 in order to include as many multi-processing facilities as is desired.

Claims: A semiconductor processing chamber assembly matable with a first housing (16) of a semiconductor wafer transfer mechanism (34) of a multi chamber processing system said assembly comprising: a second housing being mobile, a sealing mechanism (32) for releasably docking said second housing (26) with said first housing (16) to permit transfer of a wafer between said first and second housings along a wafer transport path (70 72), means (90, 92) for providing a controlled environment along said wafer transport path (70, 72) and a processing chamber (54), characterized in that said processing chamber (54) is housed within said second housing (26) for movement therewith and for controlled environment processing of said wafer, means operated under microprocessor control (68, 110, 122) are provided for establishing a controlled evacuated environment within said chamber (54) and to provide selected wafer processing and in that said sealing mechanism(32) is associated with said wafer transfer mechanism (34) in such a way that said chamber communicates with the wafer transfer mechanism (34) to permit transfer of a wafer between said first housing (16) and said chamber (54) along said wafer transport path (70 72). The assembly of claim 1, characterized in that said second housing (26) includes means (84,88) for adjusting the height and attitude of said second housing to permit accurate docking. The assembly of claim 1 or 2 characterized in that said means for establishing a controlled environment within said chamber includes a gas evacuation apparatus mounted within said second housing (26). The assembly of claim 3, characterized in that said gas evacuation apparatus includes means for coupling to a further evacuation apparatus separate from said second housing (26). Multichamber processing system, comprising a first and second pluralities of assemblies according to any one of the previous claims, characterized by a first cassette (154) for storing wafers, a first transfer station (146), wafer processing chambers of said first plurality being arrayed with said first transfer station and arranged to receive wafers transferred thereto by said first transfer station from said cassette, a second transfer station (144), wafer processing chambers of said second plurality being arrayed with said second transfer station and arranged to receive substrates transferred thereto by said second transfer station from said cassette, a conduit (152) for providing a controlled substrate transfer environment between said first and second transfer stations, said cassette (154) being located between said first and second transfer stations and in communication with said conduit, in that one of said first and second pluralities of processing chambers further includes said mobile housing (26). System of claim 5 characterized by second (140) and third (142) cassettes for storing wafers positioned along said conduit in spaced-apart relation, a transfer mechanism (172) disposed in said conduit for transferring wafers between said first, said second and said third cassettes, said transfer mechanism cooperating with said first transfer station to permit transfer of wafers between said first transfer station and any one chamber of said first plurality of processing chambers, and in that said transfer mechanism cooperates with said second transfer station to permit transfer of wafers between said second transfer station and any one chamber of said second plurality of processing chambers, said conduit extending between said first and said second transfer stations. System of claim 6, characterized in that said first (140) and said second (142) cassettes are spaced apart along a line, and said third (154) cassette is intermediate the first and second cassettes, and in that said transfer mechanism includes an arm (170), a track (160), a drive mechanism (164) for guiding said arm along said track between said first and second cassettes past said intermediate cassette, and a slide (168) for extending said arm from said track into said first, second and third storing means. System of claim 7, characterized by including a control mechanism (174) for changing a direction of said arm between pointing along said track toward said first or second cassettes and away from said track toward said third cassette. System of claim 8, characterized by including means for providing said transfer mechanism with a controlled environment. Multichamber processing system, comprising a plurality of assemblies according to any one of claims 1-4, characterized by a cassette (14) for storing substrates, wafer processing chambers (22, 24, 26) of said plurality being arrayed about said housing of said transfer mechanism (34), said transfer mechanism providing transfer of substrates between said storage cassette and said processing chambers.

Inventors: MAHER JOSEPH A, NAPOLI JOSEPH D, VOWLES JOHN E, MAHER, JOSEPH A., NAPOLI, JOSEPH D., VOWLES, JOHN E.
Applicants: GEN SIGNAL CORP, GENERAL SIGNAL CORPORATION
Application year: 1990
Main classification: H01L21
IPC codes: H01L21