Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional Application of U.S. patent application Ser. No. 12/040,291, filed Feb. 29, 2008 now U.S. Pat. No. 7,988,129, which application claims benefit of U.S. Provisional Patent Application Ser. No. 60/892,442, filed Mar. 1, 2007. Each application is herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention generally relate to a slit valve for interfacing with a transfer chamber. 
     2. Description of the Related Art 
     In order to efficiently perform consecutive processes upon one or more substrates, multiple processing chambers may be coupled together. Efficiency is particularly important in semiconductor, flat panel display, photovoltaic, and solar panel manufacturing because it is common to perform numerous consecutive processes upon the substrates. To transfer substrates from one processing chamber to another processing chamber, a transfer chamber may be coupled with one or more processing chambers. The transfer chamber may remove one or more substrates from a processing chamber and transfer the substrate to one or more other processing chambers, another transfer chamber, or even a load lock chamber. A processing chamber may be directly coupled to another processing chamber or a load lock chamber. Additionally, a load lock chamber may be coupled to another load lock chamber. 
     At each interface between chambers, a slit valve may be present. The slit valve, when opened, permits one or more substrates to be transferred between adjacent chambers. When the slit valve is closed, substrates may not be transferred between the chambers. The slit valve thus may seal the chambers from adjacent chambers so that each chamber may have its own environment isolated from an adjacent chamber. 
     Therefore, there is a need in the art for a slit valve to provide an effective seal between chambers. 
     SUMMARY OF THE INVENTION 
     The present invention generally relates to a floating slit valve for interfacing with a chamber. A floating slit valve moves or “floats” relative to another object such as a chamber. The slit valve may be coupled between two chambers. When a chamber coupled with the slit valve is heated, the slit valve may also be heated by conduction. As the slit valve is heated, it may thermally expand. When a vacuum is drawn in a chamber, the slit valve may deform due to vacuum deflection. By disposing a low friction material spacer between the chamber and the slit valve, the slit valve may not rub against the chamber during thermal expansion/contraction and/or vacuum deflection and thus, may not generate undesirable particle contaminants. Additionally, slots drilled through the chamber for coupling the slit valve to the chamber may be sized to accommodate thermal expansion/contraction and vacuum deflection of the slit valve. 
     In one embodiment, a slit valve comprises a slit valve body having an opening therethrough. The opening may be sized to permit passage of a substrate through the opening. The body may also have a first groove carved into a surface of the body and circumscribing the opening. The body may also have a plurality of second grooves carved into a same surface of the body as the first groove and disposed radially outside of the first groove. The plurality of second grooves may extend along a substantially linear path. The slit valve may also comprise one or more spacer elements disposed in at least one of the plurality of second grooves. 
     In another embodiment, an apparatus comprises a transfer chamber, a slit valve, and an O-ring coupled between the slit valve and the transfer chamber. The transfer chamber comprising a transfer chamber body. The transfer chamber body may have a first opening through the transfer chamber body. The first opening may have a first width. One or more second openings may be present through the transfer chamber body. Each second opening may have a second width less than the first width. One or more third openings through the transfer chamber body may also be present. Each third opening may have a third width greater than the second width and less than the first width. The slit valve comprises a slit valve body having an opening therethrough. The opening may be sized to permit passage of a substrate through the opening. The body may also have a first groove carved into the body and circumscribing the opening. The body may also have one or more second grooves carved into the body. One or more spacer elements may be disposed in at least one of the one or more second grooves. 
     In yet another embodiment, a method of sliding a slit valve along a transfer chamber is disclosed. The method comprises heating a processing chamber and conductively heating the slit valve. The slit valve may be coupled to the processing chamber and the transfer chamber. The method may also comprise expanding the slit valve. The expanding may comprise sliding the one or more spacer elements along a first surface of the transfer chamber. The transfer chamber comprises a first opening through the transfer chamber body. The first opening may have a first width. One or more second openings through the transfer chamber body may also be present. Each second opening may have a second width less than the first width. One or more third openings through the transfer chamber body may also be present. Each third opening may have a third width greater than the second width and less than the first width. The slit valve comprises a slit valve body having an opening therethrough. The opening may be sized to permit passage of a substrate through the opening. The body may also have a first groove carved into the body and circumscribing the opening. The body may also have one or more second grooves carved into the body and one or more spacer elements disposed in at least one of the one or more second grooves. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a schematic diagram of a slit valve disposed between two chambers. 
         FIG. 2  is a front view of an interface between a slit valve and a transfer chamber looking through the transfer chamber according to one embodiment of the invention. 
         FIG. 3  is a front view of an interface between a slit valve and a transfer chamber looking through the transfer chamber in which the slit valve has not been thermally expanded and/or vacuum deformed according to one embodiment of the invention. 
         FIG. 4  is a front view of the interface between the slit valve and the transfer chamber of  FIG. 3  in which the slit valve has been thermally expanded and/or vacuum deformed according to one embodiment of the invention. 
         FIG. 5  is a cross sectional view of an interface between a transfer chamber and a slit valve according to one embodiment of the invention. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
     DETAILED DESCRIPTION 
     The present invention will be described below in reference to a slit valve coupled with a transfer chamber and a process chamber. Exemplary transfer chambers, process chambers, and load lock chambers are available from AKT, a subsidiary of Applied Materials, Inc., located in Santa Clara, Calif. It is contemplated that the invention is equally applicable to other transfer chambers, processing chambers, and load lock chambers, including those produced by other manufacturers. Additionally, it is to be understood that while the description discusses a slit valve coupled with a transfer chamber and a processing chamber, the slit valve may be coupled between any two chambers including transfer chambers, process chambers, load lock chambers, and combinations thereof. 
       FIG. 1  is a schematic diagram of a slit valve  108  disposed between a transfer chamber  102  and a process chamber  104 . A processing system  100  may comprise one or more process chambers  104  coupled to a transfer chamber  102 . A slit valve  108  may be disposed between the transfer chamber  102  and the process chamber  104 . It is to be understood that while only one process chamber  104  has been shown coupled with the transfer chamber  102 , multiple process chambers  104  may be coupled with the transfer chamber  102 . At each point where a process chamber  104  couples with the transfer chamber  102 , a slit valve  108  may be coupled therebetween. Similarly, when any two chambers are coupled together, a slit valve  108  may be coupled therebetween. 
     The process chamber  104  may be any suitable process chamber  104  for processing substrates such as a plasma enhanced chemical vapor deposition (PECVD) chamber, a physical vapor deposition (PVD) chamber, or other chamber. The substrates processed may be semiconductor substrates, flat panel display substrates, solar panel substrates, or any other substrate. Within each process chamber  104 , one or more substrates may be processed. 
       FIG. 2  is a front view of an interface  200  between a slit valve and a transfer chamber looking through the transfer chamber according to one embodiment of the invention. When the slit valve is open, an opening  202  is present between the transfer chamber and the process chamber to permit passage of one or more substrates therebetween. The slit valve may be sealed to the transfer chamber by one or more O-rings  208 . One or more spacers  204  may be present between the transfer chamber and the slit valve. Additionally, one or more fasteners  206  may be coupled between the slit valve and the transfer chamber. The one or more fasteners  206  may be disposed along a common axis  210 . 
       FIG. 3  is a front view of an interface  300  between a slit valve and a transfer chamber looking through the transfer chamber in which the slit valve has not been thermally expanded and/or vacuum deformed according to one embodiment of the invention. As noted above, one or more O-rings  306  may be disposed between the slit valve and the transfer chamber to seal the transfer chamber to the slit valve. Additionally, one or more spacers  322  may be present between the transfer chamber and the slit valve. The one or more spacers  322  move with the slit valve when the slit valve moves relative to the transfer chamber. The one or more spacers  322  reduce the opportunity for the slit valve and the transfer chamber to rub against each other and generate particles that may contaminate any substrates. When the slit valve is opened, one or more substrates may pass through the opening  302  between the transfer chamber and the processing chamber. 
     One or more fastening mechanisms  304  may additionally couple the transfer chamber to the slit valve. In one embodiment, each fastening mechanism may be aligned with a corresponding spacer  322 . Each fastening mechanism  304  may be disposed within a slot  308 ,  310 ,  312 ,  314 ,  316 ,  318  disposed through the transfer chamber. It is to be understood that while six slots  308 ,  310 ,  312 ,  314 ,  316 ,  318  have been shown, more or less slots  308 ,  310 ,  312 ,  314 ,  316 ,  318  may be present. For example, one or more slots may be present below the opening  302  between the process chamber and the transfer chamber. Additionally, one or more slots may be present on the other side of the center  320  of the interface  300 . 
     During substrate processing, the processing chamber or adjacent chamber may be heated to a temperature greater than about 300 degrees Celsius. Due to conduction, the slit valve may also be heated. In one embodiment, the slit valve may be conductively heated to a temperature of about 120 degrees Celsius to about 200 degrees Celsius. In another embodiment, the slit valve may be conductively heated to a temperature of about 120 degrees Celsius to about 130 degrees Celsius. Because the slit valve is heated, the slit valve may expand. Once the slit valve cools, it may then contract. Conversely, the transfer chamber, because it may not be directly coupled to the process chamber but instead may be directly coupled to the slit valve, may not experience a significant amount of thermal expansion/contraction. Hence, the slit valve may expand and contract relative to the transfer chamber. Due to the expansion and contraction of the slit valve relative to the relatively stationary transfer chamber, the slit valve may be permitted to slide along the interface  300  between the transfer chamber and the slit valve. Similarly, when a vacuum is drawn in the process chamber, the slit valve may deform relative to the transfer chamber due to the vacuum pressure exerted on the slit valve. 
     Due to the thermal expansion/contraction and/or vacuum deformation, the slit valve may expand and/or contract relative to the transfer chamber. Thus, the fastening mechanisms  304  and spacers  322  may move with the slit valve as the slit valve expands and contracts relative to the transfer chamber. The further the distance away from the center  320  of the interface  300 , the greater than amount of expansion that the slit valve may have and hence, the greater the amount of movement that the fastening mechanisms  304  and spacers  322  may have. Therefore, the slots  308 ,  310 ,  312 ,  314 ,  316 ,  318  in the transfer chamber may be successively larger the further distance away from the center  320  of the interface  300 . 
     Slot  308  closest to the center  320  of the interface  300  has a width represented by arrows A and may have little room for movement of the fastening mechanism  304  due to the proximity of the slot  308  to the center  320 . The center of the fastening mechanism  304  in slot  308  may be positioned a distance G from the center  320  of the interface  300 . Slot  310 , which has a width represented by arrows B, may be spaced a greater distance H from the center  320  of the interface  300  than slot  308 . The width B of slot  310  may be greater than the width A of slot  308 . 
     Slot  312 , which has a width represented by arrows C, may be spaced a greater distance I from the center  320  of the interface  300  than slot  310 . The width C of slot  312  may be greater then the width B of slot  310 . Slot  314 , which has a width represented by arrows D, may be spaced a greater distance J from the center  320  of the interface  300  than slot  312 . The width D of slot  314  may be greater then the width C of slot  312 . Slot  316 , which has a width represented by arrows E, may be spaced a greater distance K from the center  320  of the interface  300  than slot  314 . The width E of slot  316  may be greater then the width D of slot  314 . Slot  318 , which has a width represented by arrows F, may be spaced a greater distance L from the center  320  of the interface  300  than slot  316 . The width F of slot  318  may be greater then the width E of slot  316 . Thus, the further the distance from the center  320  of the interface  300 , the larger the slot. 
       FIG. 4  is a front view of the interface  300  between the slit valve and the transfer chamber of  FIG. 3  in which the slit valve has been thermally expanded and/or vacuum deformed according to one embodiment of the invention. The fastening mechanisms  304  have moved relative to the transfer chamber due to the thermal expansion and/or vacuum deformation of the slit valve. The movement of the fastening mechanisms  304  relative to the transfer chamber is shown by the distance that the fastening mechanisms  304  have moved within the slots  310 ,  312 ,  314 ,  316 ,  318  of the transfer chamber. The fastening mechanism  304  in slot  308  may not have appreciably moved relative to the transfer chamber due to its proximity to the center  320  of the interface  300 . Hence, the fastening mechanism  304  in slot  308  remains substantially at distance G from the center  320  of the interface  300 . However, the fastening mechanisms  304  in each of the other slots  310 ,  312 ,  314 ,  316 ,  318  have moved relative to the transfer chamber due to the thermal expansion of the slit valve. 
     The center of the fastening mechanism  304  disposed in slot  310  may be a distance M from the center  320  of the interface  300 . The distance M is greater than the distance H. The center of the fastening mechanism  304  disposed in slot  312  may be a distance N from the center  320  of the interface  300 . The distance N is greater than the distance I. The center of the fastening mechanism  304  disposed in slot  314  may be a distance P from the center  320  of the interface  300 . The distance P is greater than the distance J. The center of the fastening mechanism  304  disposed in slot  316  may be a distance R from the center  320  of the interface  300 . The distance R is greater than the distance K. The center of the fastening mechanism  304  disposed in slot  318  may be a distance S from the center  320  of the interface  300 . The distance S is greater than the distance L. Additionally note that the spacers  322  have also moved. The spacers  322  slide along the transfer chamber during expansion/contraction/deformation. 
     By permitting the slit valve to move relative to the transfer chamber, the O-ring  306  may remain sealed to the transfer chamber. Absent the ability to move in relation to the transfer chamber, the slit valve may buckle due to the need to expand when conductively heated, damage the O-ring, and unseal from the transfer chamber. 
       FIG. 5  is a cross sectional view of an interface  500  between a transfer chamber  502  and a slit valve  504  according to one embodiment of the invention. An O-ring  508  may be disposed between the transfer chamber  502  and the slit valve  504 . The O-ring  508  may be partially disposed within a groove  518  in the slit valve  504 . One or more spacers  506  may be disposed between the slit valve  504  and the transfer chamber  502 . The one or more spacers  506  may be countersunk into the slit valve  504  and extend a distance T outside the slit valve. 
     The one or more spacers  506  may comprise a low friction and low thermal conductivity material. In one embodiment, the low friction and low thermal conductivity material may comprise ceramics, engineering plastic, polyamide, polyimide, NiB coated metal, WS 2  coated metal, and combinations thereof. In one embodiment, the metal comprises stainless steel. The low thermal conductivity of the material reduces the amount of heat conducted from the slit valve to the transfer chamber. The low friction permits the spacers  506  to slide along the side  520  of the transfer chamber that interfaces with the slit valve  504 . The spacer  506  may slide along the side  520  of the transfer chamber  502  when the slit valve  504  moves due to thermal expansion/contraction and/or vacuum deformation. The spacer  506  may also slide along the side  520  of the transfer chamber  502  when the slit valve contracts. 
     The one or more spacers  506  may be disposed on the atmospheric side of the O-ring  508 . Because the spacers  506  are on the atmospheric side of the O-ring  508 , any particles generated by the spacers  506  and/or the side  520  of the transfer chamber  502  as the spacers  506  slide along the side  520  of the transfer chamber  502  may not enter into the processing space contained within the transfer chamber  502  and processing chamber and contaminate the process. The spacers  506  may help to maintain a distance T between the transfer chamber  502  and the slit valve  504 . Maintaining a distance T between the transfer chamber  502  and the slit valve  504  reduces the likelihood that the slit valve  504  and the transfer chamber  502  may rub against each other when the slit valve  504  thermally expands/contracts and/or vacuum deforms. If the slit valve  504  and the transfer chamber  502  rub against each other, particles may flake off the slit valve  504 , transfer chamber  502 , or both. The particles may contaminate the substrate. The distance T may be set based upon the expected thermal expansion/contraction and/or vacuum deformation of the slit valve  504 . The distance T may be of sufficient distance to permit an effective vacuum seal between the slit valve  504  and the transfer chamber  502  while reducing the likelihood of the transfer chamber  502  and slit valve  504  rubbing against each other. 
     A fastening mechanism  510  may additionally couple the slit valve  504  to the transfer chamber  502 . The fastening mechanism  510  may comprise a threaded portion  516  threadedly coupled with the slit valve  504 . A smooth portion  522  may be disposed within the slot  524  extending through the transfer chamber  502 . The smooth portion  522  may move within the slot  524  as the slit valve  504  thermally expands and/or vacuum deforms and slides along the side  520  of the transfer chamber  502 . The fastening mechanism  510  may comprise a cap portion  512  having a flange portion  514 . The flange portion  514  may rest against a side  526  of the transfer chamber  502 . The flange portion  514  may prevent the fastening mechanism  510  from over tightening and pinching the slit valve  504  to the transfer chamber  502 . The combination of the spacer  506  and the flange  514  resting against a side  526  of the transfer chamber  502  may help to maintain the distance T between the transfer chamber  502  and the slit valve  504 . The combination of the spacer  506  and the flange  514  resting against a side  526  of the transfer chamber  502  may also help to seal the O-ring  508  between the transfer chamber  502  and the slit valve  504 . 
     By compensating for expected thermal expansion/contraction and/or vacuum deformation of the slit valve during processing, a slit valve may not buckle or rub against an adjacent chamber and produce harmful contaminants. Without the buckling of the slit valve or rubbing against adjacent chambers, an effective seal may be maintained between the slit valve and the chamber. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

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