Patent Publication Number: US-2010127201-A1

Title: Interlocking valve chamber and lid

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention generally relate to apparatus for sealing a first region from a second region, and more specifically to techniques for forming a seal between regions of different pressures. 
     2. Description of the Related Art 
     Certain process applications require isolation valves that can form an effective seal between a chamber at a certain pressure and an adjacent chamber at a different pressure. For example, in glass substrate processing systems, efficient production line processing requires rapid movement of glass substrates from one work station to another, and between vacuum environments and atmospheric environments. Processing of glass substrates in process chambers is typically performed in a vacuum or under low pressure. Movement of glass substrates between processing chambers, thus, requires the use of valve mechanisms which are capable of effectively closing the especially wide apertures to provide vacuum-tight seals while minimizing contamination between chambers. 
     In the past, a variety of isolation valves have been used to isolate two regions from one another. One exemplary construction of an isolation valve employs a slit valve having an internal dividing wall or plate within the valve chamber separating the two regions, the valve having a slit or opening to allow passage of the substrate from one region to the other. To close the valve, a gate or door may then slide over the internal wall to cover the slit, thereby forming a seal to prevent flow through the valve. 
     Oftentimes, the valve chamber will have a removable lid that allows access to the valve chamber for maintenance. Certain problems, however, are associated with using this particular configuration of valve chamber having a removable service access lid. In this configuration, the internal dividing wall may only be attached to the floor and sides of the chamber, such as by welding. The lower portion of the dividing wall will tend to resist deflection, while the upper portion of the wall will not be similarly constrained, and can deflect a considerable amount. Because the two regions of the valve chamber at either side of the internal dividing wall are at different pressures, and the internal dividing wall is typically held in place only along the bottom and side edges, with the top edge lacking structural support, the differential pressure between the two regions will tend to deflect the dividing wall, causing the seal in the gate to fail. Typically, the larger the valve chamber, such as those used for processing large glass substrates, the greater the deflection of the internal dividing wall. For example, when the dividing wall is about 196 inches long by about 28 inches wide with a maximum thickness of about 4 inches and the deflecting force across the dividing wall is 8,200 pounds, the deflection of the internal dividing wall may be as much as 0.5 inches along the axis perpendicular to the face of the dividing wall. 
     In the past, the deflection problem encountered when using an internal dividing wall in a valve chamber with a removable lid has been remedied by increasing the thickness of the internal dividing wall. However, for larger valve chambers, this approach results in impractical, extraordinarily thick dividing walls and an increased cost of manufacturing the valve. Another remedy has been to attach beam sections to the internal wall for added support. However, this approach results in unserviceable valve chambers. 
     Therefore, there is a need for a mechanism that will reduce the deflection of the internal dividing wall in a valve chamber with a removable lid separating two regions under different pressures. 
     SUMMARY OF THE INVENTION 
     The present invention generally relates to apparatus for sealing a first region from a second region, and more specifically to techniques for forming a seal between regions of different pressures. In one embodiment, a valve chamber for isolating two regions at different pressures is provided, comprising a chamber having a floor, an open top face, and side walls having at least two apertures opposite one another, a dividing plate disposed within the chamber, wherein the dividing plate is attached with the floor and the side walls of the chamber, and wherein the dividing plate has at least one opening opposite each aperture and the dividing plate forms a first region and a second region within the chamber, and a lid comprising a plate, wherein a bottom surface of the plate is configured to couple with the dividing plate when the lid is placed on the top face of the chamber and wherein the lid closes the top face of the chamber when placed thereon. 
     In one aspect, the valve chamber further comprises grooves and an elastomeric sealing member on upward facing surfaces of the side walls and the dividing plate. In another embodiment, the elastomeric sealing member comprises at least one O-ring. In yet another embodiment, the at least one opening has a generally oblong shape. In another embodiment, the lid further comprises side walls attached with a top surface opposite the bottom surface of the plate so as to form a box-like structure. In a further embodiment, the first region of the valve chamber operates at a first pressure and the second region operates at a second pressure different from the first pressure. 
     In another embodiment, the dividing plate further comprises at least one interlocking pin protruding from an upward facing surface of the dividing plate and the lid further comprises an opening to receive the at least one interlocking pin when the lid is placed on the top face of the chamber. 
     In yet another embodiment, the lid further comprises at least one interlocking pin protruding from a bottom surface of the plate of the removable lid, and the dividing plate further comprises an opening on the upward facing surface of the dividing plate to receive the interlocking pin when the lid is placed on the top face of the chamber. 
     In another embodiment, the plate of the removable lid is bolted to the dividing plate after the lid is placed on the top face of the chamber. 
     In yet another embodiment, the lid further comprises at least one bar disposed on a bottom surface of the plate and the dividing plate further comprises at least one notch for receiving the at least one bar when the lid is placed on the top face of the chamber. 
     In one embodiment, a valve chamber for isolating two regions at different pressures is provided, comprising a chamber having a floor, an open top face, and side walls having at least two apertures opposite one another, a dividing plate disposed within the chamber, wherein the dividing plate is attached with the floor and the side walls of the chamber, wherein the dividing plate has at least one opening opposite each aperture and the dividing plate forms a first region and a second region within the chamber, and a lid comprising a plate having at least one pair of parallel bars attached with a bottom surface of the plate, wherein the bars define a notch for receiving a top edge of the dividing plate when the lid is placed on the top face of the chamber and wherein the lid closes the top face of the chamber when placed thereon. 
     In another embodiment, a slit valve for isolating two regions at different pressures is provided, comprising a chamber having a floor, an open top face, and side walls having at least two apertures opposite one another, a dividing plate disposed within the chamber, wherein the dividing plate is attached with the floor and the side walls of the chamber, and wherein the dividing plate has at least one opening opposite each aperture and the dividing plate forms a first region and a second region within the chamber, and a lid comprising a plate, wherein a bottom surface of the plate is configured to couple with the dividing plate when the lid is placed on the top face of the chamber and wherein the lid closes the top face of the chamber when placed thereon. The chamber further comprises at least one gate, wherein the gate can be positioned between a closed position over a first surface of the dividing plate so as to cover the at least one opening and seal the first region from the second region, and an opened position wherein the first and second regions are in communication through the at least one opening. In another embodiment, the first region has a higher operating pressure than the second region. In another embodiment, the first surface faces the first region. In yet another embodiment, the slit valve further comprises at least one second gate, wherein the second gate can be positioned in a closed position over a second surface of the dividing plate opposite the first surface so as to cover the at least one opening and seal the first region from the second region, and an opened position wherein the at least one opening is uncovered at the second surface. 
    
    
     
       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 partial longitudinal elevated view of a valve chamber, with the interlocking lid suspended above it, shown in open configuration, according to one embodiment of the present invention. 
         FIG. 2  is a partial elevated cross-sectional view of the valve chamber of  FIG. 1 , with the interlocking lid suspended above the valve chamber, shown in open configuration. 
         FIG. 3  is a partial elevated cross-sectional view of the valve of  FIG. 2 , with the interlocking lid placed on the valve chamber, shown in open configuration. 
         FIG. 4  is cross-sectional view of one embodiment of the interlocking valve chamber and lid, shown in closed configuration. 
     
    
    
     It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
     DETAILED DESCRIPTION 
     Embodiments of the present invention provide an interlocking valve chamber and lid, wherein the lid is configured to couple with an internal dividing plate inside the chamber so as to prevent a slit valve door or gate from being moved away from a slit valve opening in the internal dividing plate due to deflection of the plate caused by differential pressure across the dividing plate. In one embodiment, the coupling or support mechanism may include al least two bars attached in parallel to the bottom of the lid at a certain distance apart so as to fit on either side of the upper edge of the dividing plate once the lid is placed on the chamber. In another embodiment, the lid may be coupled with the internal dividing plate by bolting the lid to the internal dividing plate. In yet another embodiment, the lid may be coupled with the internal dividing plate using at least one interlocking pin on the lid and at least one corresponding opening in the internal dividing plate, or at least one interlocking pin on the internal dividing plate and at least one corresponding opening in the lid. In another embodiment, the lid may comprise a bar disposed on a bottom surface of the plate and the dividing plate may comprise a notch for receiving the bar when the lid is placed on the top face of the chamber. The support mechanism or method of coupling the lid with the internal dividing plate is not limited to such embodiments. 
     The coupling or support mechanism reduces deflection of the dividing plate, thereby ensuring that the gate remains sealed. In general, the valve can be used, for example, to isolate one process chamber from another process chamber, or to isolate different regions from one another. Although some of the embodiments refer to the interlocking valve chamber and lid in the context of a substrate processing chamber, the interlocking valve chamber and lid can be used in any similar vessel design that experiences a significant pressure differential and includes a removable service access lid. 
     In one embodiment, a valve chamber for isolating two regions at different pressures is provided comprising a chamber having a floor, an open top face, and side walls having at least two apertures opposite one another. The chamber further comprises a dividing plate disposed within the chamber, wherein the dividing plate is attached with the floor and the side walls of the chamber, and wherein the dividing plate has at least one opening opposite each aperture and the dividing plate forms a first region and a second region within the chamber. The chamber further includes a lid comprising a plate, wherein a bottom surface of the plate is configured to couple with the dividing plate when the lid is placed on the top face of the chamber. The lid closes the top face of the chamber when placed thereon. 
       FIG. 1  is a perspective view of one embodiment of an interlocking valve chamber and lid, with a lid  102  suspended above a valve chamber  101 , shown in open configuration (actual valve not shown). The valve chamber may comprise sidewalls and a floor. In one embodiment, as shown in  FIG. 1 , the valve chamber  101  comprises a floor or bottom wall  122 , a first pair of opposite and parallel side walls  103 , and a second pair of opposite and parallel side walls  104  to form a box-like structure with an open top face. In another embodiment, the valve chamber may comprise sidewalls and a floor to form a circular or elliptical box-like structure. As shown in  FIG. 1 , side walls  104  may overhang floor  122  and side walls  103 . Side walls  104  may each contain at least two apertures  105 . The at least two apertures  105  may be opposite one another. In an alternative embodiment, side walls  104  may comprise four apertures, with one pair of apertures opposite the other. Apertures  105  are sized and adapted to allow for the transfer of an object, such as a glass substrate, through valve chamber  101 . The object may enter the chamber through at least one aperture on a side wall at one end of the chamber and exit the chamber through at least one aperture on a side wall at the opposite end of the chamber. Valve chamber  101  may be made of aluminum or stainless steel, or another material or combination or materials, depending on the application. 
     Valve chamber  101  may also comprise a dividing wall or plate  106  disposed inside of chamber  101  and attached with the floor and the sidewalls of the chamber. As shown in  FIG. 1 , in one embodiment, dividing plate  106  may be disposed in between and parallel to the second pair of side walls  104 . In one embodiment, the dividing plate  106  may be attached with the floor  122  and side walls  103  by welding. The dividing plate  106  may be attached with the floor  122  and the first pair of side walls  103  to form a first region and a second region within the valve chamber  101 . In one embodiment, the first region and the second region may have different operating pressures. In one example, the first region may have a higher operating pressure than the second region. For example, in one embodiment, the first region may operate under atmospheric pressure, whereas the second region may operate under vacuum conditions. In another embodiment, the second region may have a higher operating pressure than the first region. 
     The dividing plate  106  may comprise at least one opening  207  (not shown in  FIG. 1 ; see  FIG. 2 ) opposite the apertures  105 .  FIG. 2  is a partial elevated cross-sectional view of the interlocking valve chamber and lid of  FIG. 1 , with the interlocking lid suspended above the box chamber, shown in open configuration. Opening  207  may be sized and adapted to allow passage of an object from a first region of valve chamber  202  to a second region of valve chamber  202 . In one embodiment, opening  207  may be long enough and wide enough to allow for the passage of a large glass substrate. For example, opening  207  may be 3 meters long by 45 millimeters wide. Opening  207  may be oblong, or rectangular in shape, or elliptical, or have a rectangular shape with rounded corners. In one embodiment, opening  207  may be formed within a recess  208  in dividing plate  206  of a certain depth and shape. The recess  208  may be formed on one or both interior surfaces or sides of plate  206 . Recess  208  may move valve gates  421  (see  FIG. 4 ) closer together to minimize distance between conveyor rolls (not shown) on either side of valve gates  421 . 
     In one embodiment, as shown in  FIG. 1 , at least one groove or recess  109  may be formed along a length of an upper edge of each side of the dividing plate  106 .  FIG. 2  shows two grooves or recesses  209  formed on either side of dividing plate  206 , in accordance with one embodiment. In one example, groove  109  may be formed over the entire length of dividing plate  106 . In another example, groove  109  may be formed over less than the entire length of dividing plate  106 . Groove  109  may have a certain depth, in a direction along the thickness of the dividing plate  106 , depending on the application. As shown in  FIG. 2 , groove  209  may also have a width extending further down the dividing plate  206 , towards the opening  207 , depending on the size of the dividing plate and the amount of deflection sought to be avoided. Grooves  209  may have rounded edges, sharp edges, or a combination thereof. 
     As shown in  FIG. 1 , lid  102  may comprise a plate that fits over chamber  101  so as to fully cover the open top face of chamber  101 . Lid  102  may be rectangular in shape. However, lid  102  is not limited to a rectangular shape so long as lid  102  covers the open top face of chamber  101  when placed thereon. In one embodiment, lid  102  may have an open box-like shape or structure with a floor and sidewalls. The box-like shape or structure may be a rectangular box or a circular or elliptical box, or a box of a different shape having a generally open top face. As shown in  FIG. 1 , in one embodiment, lid  102  may have an open box-like shape or structure with a floor  112  and two pairs of opposite and parallel side walls  113  and  114  perpendicular to floor  112 . In one embodiment, one pair of sidewalls  114  may comprise apertures  115 . Apertures  115  can allow access to lid  102  components for maintenance. Lid  102  may be lowered over valve chamber  101  so that floor  112  is disposed over the top face of valve chamber  101 , thereby further enclosing valve chamber  101 . In one embodiment, as shown in  FIG. 1 , lid  102  is placed over valve chamber  101  such that side walls  113  are located above and parallel to side walls  104  of the valve chamber  101  and side walls  114  are located above and parallel to side walls  103  of the valve chamber  101 . In one example, floor  112  of lid  102  may be larger than the area defined by side walls  113  and  114  so that it forms a ledge at the bottom of lid  102 , as shown in  FIG. 1 . 
       FIG. 2  is a cross-sectional partial side and front perspective of the interlocking valve chamber and lid in  FIG. 1 , showing lid  202  suspended above valve chamber  201  (actual valve not shown). As shown in  FIG. 2 , lid  202  may comprise two bars  216  disposed longitudinally and parallel to each other on a bottom surface of floor  212  of lid  202 . Bars  216  may be set apart from each other a certain distance that should generally correspond to the thickness of the upper edge of dividing plate  206 . The bars  216  may form a notch for receiving the upper edge of dividing plate  206  when lid  202  is placed on chamber  201 . In one aspect, bars  216  may be set apart from each other at a certain distance that should generally correspond to the thickness at the location of grooves or recesses  209  on dividing plate  206 . In one embodiment, the grooves or recesses  209  may be a machined surface of a controlled width that fits with minimum clearance between bars  216  in order to obtain a close fit when lid  202  is placed on the open top face of chamber  201 . Minimizing clearance between bars  216  and the grooves or recesses  209  of the dividing plate  206  will limit the free deflection of the dividing plate  206 . Bars  216  may be made of aluminum or stainless steel, or another material or combination of materials, depending on the application. In one embodiment, bars  216  may be welded onto the bottom surface of floor  212  of lid  202 . In another embodiment, bars  216  may be bolted onto the bottom surface of floor  212  of lid  202 . In another embodiment, bars  216  and floor  212  of lid  202  may be machined from a single piece of material. In one embodiment, as shown in  FIG. 2 , bars  216  may have inside longitudinal corners  217  tapered or cut at an angle so as to facilitate mating of the lid  202  with the valve chamber  201 . 
     In another embodiment, instead of having just two bars on the bottom surface of floor  212  of lid  202 , two pairs of parallel bars may be disposed longitudinally and in line on a bottom surface of floor  212  of lid  202 , wherein the pairs of bars are positioned so that they may receive the upper edge of the dividing plate  206  when the lid  202  is placed on the valve chamber  201 . In another embodiment, there may be three, or four, or more pairs of bars disposed longitudinally and in line on a bottom surface of floor  212  of lid  202  to engage the upper edge of the dividing plate  206  when the lid  202  is placed on the valve chamber  201 . 
     In one embodiment, bars  216  may have a height in a direction away from floor  212  corresponding to the width of grooves  209 , so that bars  216  cover the entirety of grooves  209  when lid  202  is placed over valve chamber  201 . In another embodiment, bars  216  may have a height in a direction away from floor  212  which is smaller than the width of grooves  209 , so that a portion of the width of grooves  209  remains exposed to the inside of chamber  201  when lid  202  is placed over valve chamber  201  (i.e. the bars  216  do not completely cover grooves  209 ). 
     In order to prepare valve chamber  201  for use, such as after maintenance, lid  202  will be lowered upon the top of valve chamber  201  so that bars  216  engage into grooves  209  causing lid  202  and valve chamber  201  to interlock, whereby each bar  216  is disposed on either side of and adjacent to a top portion of dividing plate  206  having grooves  209 . Lid  202  may be lowered onto chamber  201  using a crane, depending on the size and weight of lid  202 . 
     In one embodiment, valve chamber  201  may comprise grooves  210  along upward facing edges of the chamber side walls and the dividing plate  206 . In yet another embodiment, these grooves may further comprise an elastomeric seal, such as an O-ring, to form a seal between valve chamber  201  and lid  202 . 
       FIG. 3  is a partial elevated cross-sectional view of the embodiment of the interlocking valve chamber and lid of  FIG. 2 , with lid  302  placed on valve chamber  301 , shown in open configuration (actual valve not shown). In one embodiment, as shown in  FIG. 3 , bars  316  may have a width larger than the depth of grooves  309  so that bars  316  extend outward beyond grooves  309  in a direction towards side walls  304  when lid  302  is placed over valve chamber  301  (i.e. outer vertical surfaces of bars  306  will not be flush with the vertical surfaces of dividing plate  306  when lid  302  is placed over valve chamber  301 ). 
     In one embodiment, bars  316  may extend the entire length of grooves  309 . Preferably, bars  316  will be of a sufficient length, height and width so as to prevent deflection of dividing plate  306  under chamber operating conditions by transferring some of the deflecting forces to lid  302 . In one embodiment, the width and height of bars  316  may be increased in order to achieve a greater degree of engagement between valve chamber  301  and lid  302 . 
     As shown in  FIG. 4 , valve chamber  401  may comprise a maintenance valve  421  attached to dividing plate  406  that seals opening  407  from either side when it is in a closed configuration (as shown in  FIG. 4 ). It should be noted that different types of valves may be used in conjunction with the interlocking valve chamber and lid. The maintenance valve shown in  FIG. 4  is an example of a type of valve which can be used to form the seal between the two chamber regions defined by the dividing plate  406 . 
     After, for example, a glass substrate has passed through the valve chamber  401 , maintenance valves  421  may radially swing down onto each side of the dividing plate from an open position to a closed position so as to cover opening  407  (see  FIG. 4 ). Alternatively, after the substrate has passed through the valve chamber  401 , a valve may radially swing down onto the surface of the dividing plate  406  facing the chamber region of higher operating pressure so as to cover opening  407 , isolating the regions on either side of dividing plate  406 . 
     In one example, the region on one side of the dividing plate  406  will be at atmospheric pressure, or about 15 psi, while the region on the other side of the dividing plate  406  will be under vacuum, or 0 psi. The bars  416  on the lid  402  which interlock with the internal dividing plate  406  will help transfer deflection forces caused by the pressure differential to the lid  402  so as to reduce deflection of the dividing plate  406  and prevent valve leaks. 
     The coupling of the lid with the dividing plate may also be achieved with apparatus other than parallel bars disposed on the lid. In one embodiment, the dividing plate may comprise at least one interlocking pin protruding from an upward facing surface of the dividing plate and the lid may comprise at least one opening to receive the at least one interlocking pin when the lid is placed on a top face of the chamber. In another embodiment, the lid comprises at least one interlocking pin protruding from a bottom surface of the plate of the removable lid, and the dividing plate comprises at least one opening on the upward facing surface of the dividing plate to receive the interlocking pin when the lid is placed on the top face of the chamber. In yet another embodiment, the plate of the removable lid may be bolted to the dividing plate after the lid is placed on the top face of the chamber. 
     In another embodiment, the lid may comprise at least one bar disposed on a bottom surface of the plate and the dividing plate may comprise at least one notch for receiving the at least one bar when the lid is placed on the top face of the chamber. The notch may run lengthwise along the top surface of the dividing plate. The bar may be wide enough and deep enough to provide sufficient support for the dividing plate when the lid is placed on the top face of the chamber to prevent deflection of the dividing plate along an axis perpendicular to the face of the dividing plate. 
     Although the invention has been described in accordance with certain embodiments and examples, the invention is not meant to be limited thereto. For instance, although some of the embodiments referred to herein describe the use of the interlocking valve chamber and lid in a glass substrate processing chamber, it should be appreciated that the interlocking valve chamber and lid can be used in any similar vessel design that experiences a significant pressure differential and requires a removable service access lid. Also, although some of the embodiments referred to herein describe certain apparatus for coupling the lid with the dividing plate inside the valve chamber, other apparatus may be used to couple the lid with the dividing plate to support the dividing plate and prevent deflection thereof by forces generated during processing. 
     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.