Abstract:
A method is provided that includes isolating a sealing surface from a chamber wall of a chamber and sealing the chamber between the sealing surface and the chamber wall. An apparatus is provided that includes a chamber wall section prone to deflection, a stationary section providing a sealing surface, and a flexible bellows attached to the chamber wall section and the stationary section. A system is also provided that includes a chamber including a chamber wall having an opening, a door disposed to seal the opening, a sealing surface adjacent the opening and isolated from the chamber wall, and a seal between the sealing surface and the chamber wall. Numerous other aspects are provided.

Description:
[0001]     The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/598,039, filed Aug. 2, 2004 entitled “Methods And Apparatus For Providing A Floating Seal For Chamber Doors,” which is hereby incorporated by reference herein in its entirety for all purposes.  
         [0002]     The present application also claims priority from and is a continuation-in-part of U.S. patent application Ser. No. 11/145,018, filed Jun. 2, 2005 and entitled “Methods And Apparatus For Sealing A Chamber” which itself claims priority to both U.S. Provisional Patent Application Ser. No. 60/587,114, filed Jul. 12, 2004 and U.S. Provisional Patent Application Ser. No. 60/576,906, filed Jun. 2, 2004, all of which are hereby incorporated by reference herein in their entirety for all purposes. 
     
    
     FIELD OF THE INVENTION  
       [0003]     The present invention relates generally to flat panel display and/or electronic device manufacturing chambers and methods and apparatus for sealing doors of such chambers.  
       BACKGROUND OF THE INVENTION  
       [0004]     In many electronic device fabrication processes, vacuum process chambers are widely used for conducting various chemical or physical processes. For instance, vacuum process chambers are widely used in deposition processes such as chemical vapor deposition or physical vapor deposition; in coating processes such as a spin coating process for a photoresist material or a spin-on-glass material; and various other fabrication processes. In addition, to protect against contamination from foreign particles, transfer chambers may also be operated under vacuum conditions. Conventional chambers are sealed using doors that rely upon an O-ring or similar sealing element in the door that contacts a sealing surface on the wall of the chamber around the door opening. In order to prevent leaks, the door must seal reliably each time it is closed. Thus, methods and apparatus for reliably sealing a door of a chamber are desirable.  
       SUMMARY OF THE INVENTION  
       [0005]     In one aspect, the present invention provides a method including isolating a sealing surface from a chamber wall of a chamber and sealing the chamber between the sealing surface and the chamber wall.  
         [0006]     In another aspect, the present invention provides an apparatus including a chamber wall section prone to deflection, a stationary section providing a sealing surface, and a flexible bellows attached to the chamber wall section and the stationary section.  
         [0007]     In an additional aspect, the present invention provides a system that includes a chamber including a chamber wall having an opening, a door disposed to seal the opening, a sealing surface adjacent the opening and isolated from the chamber wall, and a seal between the sealing surface and the chamber wall.  
         [0008]     In yet another aspect, the present invention provides a replaceable part including a flexible bellows that includes a first flange portion, a second flange portion, and a flexible portion attached to the first and second flange portions.  
         [0009]     Other features and aspects of the present invention will become more fully apparent from the following detailed description of exemplary embodiments, the appended claims, and the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0010]      FIG. 1A  is a cross-sectional view of a chamber opening with an example of a floating seal using flexible bellows according to some embodiments of the present invention.  
         [0011]      FIG. 1B  is a perspective drawing of the chamber opening of  FIG. 1A .  
         [0012]      FIG. 2  is a cut-away perspective view of an example of a floating seal using a molded rubber bellows according to some embodiments of the present invention.  
         [0013]      FIG. 3  is a cut-away exploded view of an example of a portion of floating seal according to some embodiments of the present invention.  
         [0014]      FIG. 4  is a cross-sectional perspective view of an example of a floating seal using a flexible metal bellows according to some embodiments of the present invention.  
         [0015]      FIG. 5  is a cut-away perspective view of an example of a portion of floating seal according to some embodiments of the present invention.  
         [0016]      FIG. 6A  is a perspective view of the chamber opening of  FIG. 4 .  
         [0017]      FIG. 6B  is a detail view of the encircled portion of  FIG. 6A .  
         [0018]      FIG. 6C  is a cross-sectional view taken along line C-C in the encircled portion of  FIG. 6A .  
         [0019]      FIG. 6D  is an exploded perspective view of a portion of a flexible bellows according to some embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]     The present invention provides improved methods and apparatus for sealing chambers (e.g., processing chambers, transfer chambers, loadlocks, etc.) and other devices that require airtight seals. By providing a stationary floating sealing surface, the present invention prevents a sealing surface from moving relative to the door sealing element. This avoids abrasion and wear of the door sealing element and prevents the generation of contaminate particles. Thus, by providing a mechanically isolated sealing surface (e. g., a sealing surface surrounding a chamber opening), the present invention ensures that the chamber door is able to consistently achieve a seal upon closure even when chamber walls experience significant deflection. In various embodiments, the sealing surface “floats” relative to the chamber wall and is thus not subject to displacement as the chamber wall deflects due to vacuum pressure changes or thermal expansion/contraction. Thus, the inventive methods and apparatus may prevent a sealing surface from sliding relative to a door sealing element, prevent the generation of particles, prevent the abrasion and wear of the sealing element, and provide means to ensure proper sealing performance.  
         [0021]     The inventors of the present invention have noticed that due to deflection of the chamber wall that results from chamber pressure and temperature differentials between the chamber and its surrounding environment (e.g., from adjacent chambers and/or atmospheric pressure outside the chamber), O-rings or similar sealing elements alone may not consistently create a good seal. The inventors have further observed that sealing elements used as seals in conventional chamber doors are subject to abrasion from moving sealing surfaces as the chamber walls deflect under pressure and/or due to thermal expansion. This abrasion results in the generation of contaminating particles, wear of the sealing elements, and ultimately poor sealing performance. The problem increases over time as a chamber cycles through different processes and the sealing element further degrades from wear. The problem is particularly acute in chambers such as loadlocks that require frequent “pumping down” (depressurization) and venting (re-pressurization).  
         [0022]     Further, in tool designs with multiple chambers that share a common wall, such as large “stacked” chambers (e.g. double and triple loadlocks), the different chambers may be under different pressures at the same time and the deflection of the chamber walls may be cumulative from one chamber to another. This situation may result in significant displacement of sealing surfaces relative to the door sealing element.  
         [0023]     In some embodiments of the present invention, the sealing surface may be supported by a flexible bellows that allows the sealing surface to remain stationary against the door sealing element when the chamber wall deflects. The flexible bellows may also seal the gap between the chamber wall and the sealing surface. In some embodiments, the bellows may include a molded rubber bellows attached to both the sealing surface and a flexible seat or plate. The flexible seat may be mounted to the chamber wall where deflection is minimal or to a rigid support member within the chamber (or external to it) that is not subject to displacement when the chamber wall deflects.  
         [0024]     In alternative or additional embodiments, the size of the gap between the chamber wall and the sealing surface may be chosen to accommodate the largest possible amount of chamber deflection. For example, in the AKT-25KA model transfer chamber manufactured by Applied Materials, Inc., the amount of deflection of the chamber at the center of the door opening may be approximately 4 mm and, in accordance with the present invention, a gap to accommodate such deflection may be approximately 8 mm. Likewise, the size and elasticity of the bellows may be chosen to accommodate the largest possible amount of chamber deflection.  
         [0025]     In some embodiments, only the sealing surface above and below a chamber opening (e.g., a door opening) may be isolated from the chamber wall deflection. In such floating seal embodiments, any deflection of the sealing surface at the sides of the chamber door opening may not be significant.  FIG. 1A  is a cross-sectional view, and  FIG. 1B  is a partial perspective view, each depicting an example embodiment of such a floating seal apparatus  100  according to the present invention. Note that the chamber door  102  contacts the fixed sealing surface  104  which is separated by a gap  106  from the chamber body  108 . Note also that the gap  106  is sealed by the flexible bellows  110 .  
         [0026]     Referring to the particular example floating seal apparatus  100  illustrated in  FIGS. 1A and 1B , in some embodiments, the individual features and components of the invention may be proportioned relative to each other as depicted. In some embodiments, the features and components may be proportioned very differently than depicted. For example, in the AKT-25KA model transfer chamber mentioned above, the height (H) of the chamber door opening  112  may be approximately 127 mm; and the width (W) of the chamber door opening  112  (and/or deflection gaps  106 ) may be approximately 1524 mm. In such a apparatus  100 , in at least one embodiment of the invention, the size (G) of the gaps  106  between the chamber body  108  and sealing surface  104  may be approximately 8 mm; and the distance (D) between the chamber door opening  112  and the gaps  106  may be approximately 25 mm. The thickness (T) of the chamber body  108  near the door  102  may be approximately 50 mm and further into the chamber (e.g., at dimension U), approximately 113 mm.  
         [0027]     Note that the cumulative size (e.g., two times dimension G) of the two gaps  106  may be selected so that together the two gaps  106  can jointly accommodate the maximum amount of chamber body/wall  108  deflection possible.  
         [0028]     Turning to  FIG. 2 , a more detailed cut-away perspective view of the above-described embodiment of the floating seal apparatus  100  according to the present invention is provided. During pumping and venting, the sealing surface  104  attached to the flexible seat/plate  202  remains stationary relative to the door sealing element  204 , even when the chamber wall  108  deflects. Thus, the present invention prevents or reduces sealing element abrasion and contaminant particle generation.  
         [0029]     Turning to  FIG. 3 , an exploded cut-away partial perspective view is provided that depicts more detail of an upper portion of the above described embodiment  100  and illustrates an example of a molded rubber bellows  110  that may be used to seal the gap  106  between a flexible seat/plate  202  (upon which the sealing surface  104  mounts) and chamber body  108 . Note that in the example depicted, a mounting frame  304  is used to clamp (or otherwise fasten) one flange edge  306  of the bellows  110  to the chamber body  108  and the sealing surface  104  is used to clamp (or otherwise fasten) the other flange edge  308  of the bellows  110  to the flexible seat/plate  302 . When employed with the AKT-25KA transfer chamber example embodiment discussed above, a flexible portion  310  of the flexible bellows  110  (e.g., the portion not including flange portions  306 ,  308  for clamping the bellows  110  to the chamber  108  and sealing surface  104 ) may be dimensioned to fit tightly within the gaps  106  between the chamber body  108  and sealing surface  104 /flexible seat/plate  302  and thus may be approximately 9 mm high (including a contact bead (not shown) running the length of the bellows  110 ). The thickness of such bellows  110 , for example, may be approximately 2.3 mm.  
         [0030]     In some embodiments, the bellows  110  may be made from any suitable material such as a fluorocarbon (FKM) rubber compound. Alternatively, in some embodiments, other compounds such as butyl (IIR), ethylene propylene (EPDM), fluorosilicone (FVMQ), hydrin (CO/ECO), neoprene (CR), nitrile (NBR), silicone (VMQ), styrene butadyene (SBR), or the like may be used. Bellows made from rubber compounds provide a relatively low cost, low maintenance, easy to replace, and easy to manufacture means of sealing the gap between the sealing surface (and/or flexible seat/plate) and the chamber wall.  
         [0031]     In some embodiments, the flexible bellows may be implemented using a thin, flexible convolution of sheet metal. Any suitable metal may be used such as, for example, stainless steel. A flexible bellows formed from thin folded metal may be more durable and reliable than rubber compounds and thus, may be suitable for use in inaccessible locations or difficult-to-maintain applications such as the seal between a process chamber and a transfer chamber. As with the rubber compound bellows embodiments discussed above, the flexible metal bellows absorbs any deflection of the chamber wall without displacing the sealing surface.  
         [0032]     An example embodiment of the present invention using a metal bellows  400  is depicted in  FIG. 4 .  FIG. 4  is a cut-away perspective drawing illustrating that the sealing surface  104  is mounted to a rigid structure  402  outside the chamber to maintain a stationary position while a flexible section  404  is mounted to the chamber wall  108  and will deflect as the wall  108  deflects. A metal bellows  400  is disposed between the stationary sealing surface  104  and the flexible section  404  to create a flexible seal in the slit or gap  106  between the sealing surface  104  and the flexible section  404 . In some embodiments, the slit/gap size may be chosen to accommodate the largest anticipated amount of chamber wall deflection possible.  
         [0033]     Turning now to  FIG. 5 , a perspective cut-away view of just the flexible bellows  400 , the stationary sealing surface section  104 , and the flexible section  404  is provided. Note that the image in  FIG. 5  is rotated ninety degrees from the depiction in  FIG. 4 . Also note that only a portion of the sections  104 ,  404  are depicted to illustrate the bellows  400 . In some embodiments, a complete flexible floating seal may frame the entire chamber opening  112  ( FIG.4 ).  
         [0034]     Turning to  FIGS. 6A through 6D , details of the construction of an example embodiment of a flexible metal bellows  400  are depicted.  FIG. 6A  is a perspective view of the chamber opening  112  of  FIG. 4 .  FIG. 6B  is a detail view of the encircled portion  604  of  FIG. 6A .  FIG. 6C  is a cross-sectional view taken along line C-C in the encircled portion  604  of  FIG. 6A .  FIG. 6D  is an exploded perspective view of a portion of a flexible bellows  400 .  
         [0035]     Referring specifically to  FIG. 6A , note that in the depicted example embodiment, the sealing surfaces  104  above and below the chamber door opening  112  are isolated from the chamber wall  108  but the sides  602  are not. As indicated above, in some embodiments the deflection on either side  602  of the chamber door opening  112  may not be significant. As shown in  FIGS. 6B and 6D , corner blocks  606  or cones may be attached (e.g., welded) to both ends of a thin folded sheet of metal  608  such as stainless steel to form a single-piece flexible metal bellows  400 . An example of such a single-piece flexible metal bellows  400  may be approximately 1550 mm long, 8 mm high, 12 mm deep, and made from sheet metal approximately 0.15 mm thick. The edges  610  of the bellows  400  may then be welded to the sealing surface  104  and the chamber wall  108  as shown in  FIG. 6C . Note that, as depicted in  FIG. 6C , in some embodiments, grooves  612  may be milled in the chamber wall  108  and the sealing surface  104  along either side of the deflection gap  104  to provide edges  614 ,  616  of suitable thickness for which to weld the flexible metal bellows  400 . In some embodiments for example, the grooves  612  may be approximately 4 mm deep and 2 mm wide.  
         [0036]     Also note that as with a rubber compound bellows, the size and elasticity of the flexible metal bellows  400  may be chosen to accommodate the largest possible amount of chamber deflection.  
         [0037]     While the present invention has been described at some length and with some particularity with respect to the several described embodiments, it is not intended that it should be limited to any such particulars or embodiments or any particular embodiment, but it is to be construed with reference to the following claims so as to provide the broadest possible interpretation of such claims in view of the prior art and, therefore, to effectively encompass the intended scope of the invention.