Abstract:
A method and system for reducing the cost of a vacuum processing system by utilizing separately fabricated parts for the walls and the tops and bottoms of chambers. Walls are formed from cylinders (e.g., aluminum tubing or rolled ring forgings), and plates are then hermetically sealed to the top and bottom of the cylinder. Fasteners (and the vacuum inside the chamber) clamp the plates to the cylinder.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention is directed to a cylinder-based vacuum processing system and a method of making the same, and, in one embodiment, to a tubing or rolled ring forging-based chamber wall. 
   2. Discussion of the Background 
   Known manufacturers have traditionally built process chambers and robotic transfer chambers of plasma processing systems from billets of material, i.e. blocks of aluminum. Those chambers are built at considerable cost due to both the cost of the original material and the cost of machining. In fact, a large portion of the original material often becomes waste in the machining process. For example, the total cost for manufacturing a chamber suitably sized for 200 mm substrate processing can exceed $25K when using the aforementioned fabrication practices. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a method of manufacturing those chambers that reduces their costs. This object and other objects of the present invention are addressed by utilizing separately formed wall and end pieces instead of machining out a solid billet of material. In one such embodiment, the chamber walls are formed from the inner wall of a tubing or forging, and the top of the tubing or forging is smoothed to allow O-ring sealing (e.g., to standard smooth plates that are separately manufactured). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
       FIG. 1  is a cross-section of a plasma processing chamber formed by utilizing a chamber wall formed from a ring and top and bottom plates, wherein the ring is formed separately from the plates; and 
       FIG. 2  is a cross-section of a plasma processing chamber formed by utilizing (1) a chamber wall formed from plural rings and (2) top and bottom plates, wherein the plural rings are formed separately from the plates. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Turning now to  FIG. 1 , a vacuum processing system  1  comprising a chamber  10  formed according to the present invention includes a cylinder (e.g., aluminum tubing or rolled ring forging) acting as a chamber wall  20  to which top  22  and bottom  24  chamber plates are hermetically sealed. For example, manufacturing the chamber wall  20  from a rolled ring forging can reduce fabrication costs, including material cost and machining cost, of a processing system suitable for 200 mm materials processing by more than a factor of five (5), i.e. a reduction in the fabrication cost from $25K (as described above) to $5K. An equivalent cost saving, if not larger, can be attained for larger processing systems, i.e. 300 mm, 400 mm, etc. 
   In order to provide a good seal, preferably O-rings  26  are placed between the cylinder and the plates. The components are then held together using a series of fasteners. 
   As shown in  FIG. 1 , one possible set of fasteners includes all-thread fasteners  30  with associated nuts and washers  32 . In the illustrated configuration, the fasteners  30  are placed into the top plate  22  and extend out of the bottom plate  24  where the nuts and washers  32  are placed on them. As would be understood, the direction of the fasteners  30  could be reversed. Moreover, as is shown, the fasteners  30  need not be machined through the chamber wall  20  in order to properly seal the plates  22 ,  24  to the chamber wall  20 . This further reduces machining costs. 
   In light of the fact that the chamber wall  20  is so easily accessible and cost effective, it is possible to build the chamber  10  with a chamber wall  20  comprising a “protective” or “sacrificial” layer  40  as shown in  FIG. 1 . Therein, the chamber wall  20  itself comprises the process liner  40 , and when dirty or used, the entire chamber wall  20  is simply replaced with a new chamber wall  20 , and the top  22  and bottom  24  plates are reconnected. The process liner  40  can comprise an aluminum oxide layer formed on the inner surface of the chamber wall  20  by an anodization process, or it can comprise a spray coating such as spray-coated Y2O3. 
   In an alternate embodiment, the process liner  40  is separate from the chamber wall and comprises a replaceable consumable to be inserted within the inner diameter of chamber wall  20 . The process liner  40  can be fabricated from silicon, silicon carbide, carbon, quartz, or any other conventionally employed material. 
   In an alternate embodiment (not shown), the top plate  22  is not bolted on to the top of the chamber wall  20 , but is rather connected by a hinge and a latch. In this configuration, the top of the chamber  10  can be accessed quickly such that components therein (e.g., the chamber liner  40 ) can be maintained or replaced. In such an embodiment, the bottom plate  24  may be attached to the bottom of the chamber wall using bolts that screw into threads machined into chamber wall  20 . Similarly, the hinge may be bolted to the chamber wall using threads formed in the chamber wall  20 . Alternatively, like the embodiment of  FIG. 1 , the hinge may couple directly to bolts passing through the bottom plate  24 . 
   In an alternate embodiment, grounding components are also placed between the chamber wall  20  and the plates  22 ,  24  so as to ensure proper grounding. These elements can be added at the same time that the O-rings are added. An exemplary element utilized to improve the electrical connection between chamber components includes Spira-Shield®. 
   As described above, the fasteners  30  clamping the top  22  and bottom  24  plates to the chamber wall  20  need not be run in channels machined into the chamber wall. It is, however, possible to do so, but would likely require an increased time and/or expense. If machining in the chamber walls  20  is performed, the channels created can be used for any number of functions. One such function is to provide temperature control of the chamber wall  20 . Either coolant can be run through the channels or heating coils can be placed therein. In either configuration, the target temperature of the chamber wall  20  is monitored, and the heating and/or cooling is controlled accordingly. 
   In a preferred embodiment, the vacuum processing system  1  is a plasma processing system for materials processing of a substrate  50  (e.g., a semiconductor wafer or a liquid crystal display panel). As shown in  FIG. 1 , the vacuum processing system  1  includes an upper electrode assembly  60  for generating a process plasma and further comprises a substrate holder (or chuck)  62  to support the substrate  50 . The system described in reference with  FIG. 1  is a capacitively coupled plasma (CCP) reactor. 
   In light of the relatively fast assembly process, it is possible to quickly change the chamber height when changing between processes or wafer sizes. By replacing a shorter chamber wall  20  with a longer chamber wall  20  (or vice versa), the height-to-diameter ratio is easily changed. In addition, as shown in  FIG. 2 , the height can quickly be increased by taking off the top plate, adding at least one additional chamber wall  200  on top of the original chamber wall  20  via alignment plate  210 , and replacing the top plate  22 . Similarly, the height can be decreased by removing chamber wall components in an existing stack of chamber wall components. To aid in (1) aligning the stack of chamber walls  20 ,  200 , etc. and (2) forming a seal, each chamber wall component can optionally include recesses in their tops and bottoms such that alignment pins can be introduced therein. The top  22  and bottom  24  plates may also be sealed to the chamber wall  20  utilizing bolts threading directly into the chamber wall  20 . 
   Chambers  10  according to the present invention are not limited to the capacitively coupled plasma reactors as shown in  FIG. 1 . Other configurations are possible, but may require machining openings or slits in the side of the cylinder wall. 
   Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.