Provisional Patent Application Serial No. 60/216,918, filed July 8,2000, which is hereby incorporated by reference herein in its entirety.

The present application is related to U. S. Patent Application Serial No. 09/238,241, filed January 29,1999, which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION The present invention relates to methods and apparatus for providing a gas tight seal of an opening. More particularly the present invention relates to a door assembly for sealing an opening of a chamber such as an opening of a load lock chamber of a semiconductor device fabrication tool.

BACKGROUND OF THE INVENTION Semiconductor wafers generally are processed within automated fabrication tools that each may comprise a plurality of chambers designated for wafer loading/unloading to and from the tool (e. g., a load lock chamber), wafer transfer (e. g., a transfer chamber), or wafer processing (e. g., a processing chamber). Typically the environment of each chamber must be selectively isolated from the environments of neighboring chambers to prevent cross contamination, and to enable the various chambers to be maintained at pressures that differ according to the process

to be performed therein. Load locks generally must be selectively isolated from the environment that exists outside the tool. To achieve such selective isolation, each chamber is provided with an opening, such as a slit opening, through which wafer handlers extend to transport wafers to and from the chamber. The slit is selectively sealed with a moveable door (typically referred to as a slit valve for vacuum applications, and as a gate valve for non-vacuum applications).

There remains a general need within semiconductor device manufacturing (and other related areas such as flat panel display manufacturing) for mechanisms that may seal the openings of the various chambers employed during device processing, without occupying a large footprint or generating contaminants during operation.

SUMMARY OF THE INVENTION In accordance with a first aspect of the invention, a first door assembly is provided that is adapted to seal an opening of a chamber. The first door assembly includes (1) a seal plate adapted to seal the opening of the chamber by moving along a first axis that is substantially perpendicular to the opening; (2) a central member adapted to remain stationary along the first axis; and (3) at least one inflatable member located between the seal plate and the central member and adapted to inflate and move the seal plate along the first axis into sealing engagement with the opening.

In accordance with a second aspect of the invention, a second door assembly is provided that is adapted to seal an opening of a chamber. The second door assembly includes (1) a seal plate adapted to seal the opening of the chamber by moving along a first axis that is substantially

perpendicular to the opening; (2) a central member adapted to remain stationary along the first axis; and (3) at least one inflatable member located between the seal plate and a first side of the central member and adapted to inflate and move the seal plate along the first axis into sealing engagement with the opening.

The second door assembly also includes (1) a return beam member disposed along a second side of the central member and coupled to the seal plate; and (2) at least one inflatable member located between the return beam member and the second side of the central member and adapted to inflate and move the return beam member along the first axis away from the opening of the chamber so that the seal plate moves out of sealing engagement with the opening. Additional aspects of the invention also are provided, as are novel systems and methods.

Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side perspective view of an inventive door assembly for sealing a load lock chamber of a semiconductor device fabrication tool; FIGS. 2A-C are side perspective views of the inventive door assembly of FIG. 1 taken along line 2A-C in FIG. 1; FIGS. 3A-C are side perspective views of the inventive door assembly of FIG. 1 taken along line 3A-C in FIG. 1; and FIG. 4 is a top view of the inventive door assembly of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a side perspective view of an inventive door assembly 100 for sealing a load lock chamber 102 of a semiconductor device fabrication tool (not shown). FIGS.

2A-C are side perspective views of the inventive door assembly 100 of FIG. 1 taken along line 2A-C in FIG. 1 (e. g., a direction facing away from the load lock chamber 102). FIGS. 3A-C are side perspective views of the inventive door assembly 100 of FIG. 1 taken along line 3A-C in FIG. 1 (e. g., a direction facing toward the load lock chamber 102). FIG. 4 is a top view of the inventive door assembly 100 of FIG. 1.

With reference to FIGS. 1-4, the door assembly 100 comprises a central frame member 104 through which a seal plate 106 (FIG. 2B) and a return beam member 107 (FIG. 3B) are slidingly coupled so that the seal plate 106 and the return beam member 107 may move toward and/or away from the load lock chamber 102 as a unit. Specifically, with reference to FIG. 4, the sealing plate 106 and the return beam member 107 are rigidly coupled together via a plurality of dowels D and D (FIG. 3C and FIG. 4) that each slidingly extends through a different hole (hole Hl and hole H2, respectively, in FIG. 4) in the central frame member 104 and couples to the seal plate 106 on a first side S1 of the central frame member 104 and couples to the return beam member 107 on a second side S2 of the central frame member 104 as shown. In this manner, the seal plate 106 and the return beam member 107 may move together as a unit either toward or away from the load lock chamber 102 as described further below.

Mounted on (e. g., at least partially recessed in) the first side S1 of the central frame member 104 are a first plurality of pneumatically inflatable"pucks"or cylinders

(e. g.,"closing"cylinders 108a-b in FIG. 2C and in FIG. 4) that may be inflated so as to exert a force against both the central frame member 104 and the seal plate 106, and so as to move the central frame member 104 and the seal plate 106 away from one another.

Mounted on (e. g., at least partially recessed in) the second side S2 of the central frame member 104 are a second plurality of pneumatically inflatable"pucks"or cylinders (e. g., opening cylinders 109a-b in FIG. 3C and in FIG. 4) that may be inflated so as to exert a force against both the central frame member 104 and the return beam member 107, and so as to move the central frame member 104 and the return beam member 107 away from one another. Suitable pneumatically actuated pucks/cylinders that may be employed as the closing cylinders 108a-b and/or as the opening cylinders 109a-b are manufactured by Festo, Inc. Other shapes or types of inflatable members may be employed in place of (or in addition to) the cylinders 108a-b and/or 109a-b, such as bladders or bellows.

The central frame member 104 is slideably coupled to a plurality of guide rails 110a-b (FIG. 2B) which are designed to be rigidly coupled to a sealing face 112 (FIG. 1) of the load lock chamber 102 (to prevent horizontal motion of the central frame member 104 relative to the load lock chamber's sealing face 112 when the closing cylinders 108a-b or the opening cylinders 109a-b are inflated as described below).

Any suitable fastening mechanism may be employed to coupled the guide rails 110a-b to the sealing face 112 of the load lock chamber 102 (e. g., screws, bolts, adhesives or the like).

The door assembly 100 is mounted to an air cylinder platform 114 that is adapted to move the door assembly 100 vertically relative to a slit 116 (FIG. 1) in the sealing

face 112 of the load lock chamber 102 (e. g., a slit that allows a semiconductor wafer (not shown) to be loaded into and unloaded from the load lock chamber 102). Any other suitable lifting/lowering mechanism may be employed to move the door assembly 100 vertically relative to the slit 116.

In operation, to seal the load lock chamber 102, air pressure is applied to the air cylinder platform 114 from a source of compressed air (not shown). In response to the air pressure, the air cylinder platform 114 raises the door assembly 100 (along the rails 110a-b) until the seal plate 106 is at the same elevation as the slit 116 (as shown in FIG. 1).

Once the seal plate 106 and the slit 116 are at the same elevation, the source of compressed air (not shown), or another source of compressed air (not shown), applies air pressure to the closing cylinders 108a-b. In response to this air pressure, the closing cylinders 108a-b inflate and exert a force against both the central frame member 104 and the seal plate 106. However, because the rails 110a-b are coupled to the sealing face 112 of the load lock chamber 102, and because the central frame member 104 is coupled to the rails 110a-b, the central frame member 104 remains horizontally stationary as the closing cylinders 108a-b inflate. Thus, as the central frame member 104 is horizontally stationary, the seal plate 106 moves away from the central frame member 104, toward the sealing face 112 of the load lock chamber 102 as the closing cylinders 108a-b inflate.

Specifically, the seal plate 106 moves toward the sealing face 112 and eventually contacts the sealing face 112 at a sealing perimeter 118 of the sealing face 112 (shown in phantom in FIG. 1). Preferably a sealing member (e. g., an o-ring (not shown)) is coupled to either the

sealing perimeter 118 of the sealing face 112 of the load lock chamber 102 or to the surface of the seal plate 106 that contacts the sealing perimeter 118.

Once the seal plate 106 has contacted the sealing perimeter 118, the load lock chamber 102 is evacuated (via a vacuum pump (not shown)). As the load lock chamber 102 is evacuated, the seal plate 106 is pulled against the sealing perimeter 118, forming a gas tight seal that isolates the interior of the load lock chamber 102 from the atmosphere that surrounds the load lock chamber 102.

To open the slit 116 of the load lock chamber 102, the load lock chamber 102 is vented to atmospheric pressure (e. g., with nitrogen, argon or some other inert gas so as to remove the pressure differential that exists across the seal plate 106). The source of compressed air (not shown), or another source of compressed air (not shown), applies air pressure to the opening cylinders 109a-b (and air pressure is no longer applied to the closing cylinders 108a-b). In response to this air pressure, the opening cylinders 109a-b inflate and exert a force against both the central frame member 104 and the return beam member 107. However, because the rails 110a-b are coupled to the sealing face 112 of the load lock chamber 102, and because the central frame member 104 is coupled to the rails 110a-b, the central frame member 104 remains horizontally stationary as the opening cylinders 109a-b inflate. Thus, as the central frame member 104 is horizontally stationary, the return beam member 107 moves away from the central frame member 104, and away from the sealing face 112 of the load lock chamber 102 as the opening cylinders 109a-b inflate. The seal plate 106, which is coupled to the return beam member 107 as previously described, thereby is pulled away from (or is"retracted" from) the sealing perimeter 118 of the load lock chamber 102

as the return beam member 107 moves away from the central frame member 104. Once the seal plate 106 has"retracted" from the sealing perimeter 118, the air cylinder platform 114 lowers the door assembly 100 to an elevation below the slit 116 (e. g., to allow a semiconductor wafer to be loaded into or to be removed from the load lock chamber 102).

In at least one embodiment of the invention, a plurality of springs 120a-b (FIG. 3C and FIG. 4) are located between the central frame member 104 and the return beam member 107 and surround the dowels D and D2, respectively, so as to"bias"the return beam member 107 away from the central frame member 104. Thus, in the absence of the application. of air pressure either to the closing cylinder 108a-b or to the opening cylinders 109a-b, the return beam member 107 will be spaced apart from the central frame member 104 and the seal plate 106 will be spaced apart from the sealing perimeter 118 of the load lock chamber 102 due to the bias applied by the springs 120a-b. Other biasing mechanisms may be employed such as flexure plates, resilient washers or the like.

Note that because the horizontal motion of the door assembly 100 (controlled by the closing cylinders 108a-b and by the opening cylinders 109a-b) and the vertical motion of the door assembly 100 (controlled by the air cylinder platform 114) are independently controllable, the sealing surface of the seal plate 106 moves toward the slit 116 in a linear fashion rather than in an arcing motion (which may cause the sealing surface of the seal plate 106 to slide along the sealing perimeter 118 of the slit 116 and to generate particles that may contaminate substrates loaded into or out of the load lock chamber 102). The guide rails 110a-b ensure that during retraction of the door assembly 100 from the sealing face 112 of the load lock chamber 102,

the full"retract force"of the second set of opening cylinders 109a-b is applied to the seal plate 106 and is not diminished by mechanism deflections such as a cantilever type force that may otherwise occur. The door assembly 100 also has a small footprint.

The foregoing description discloses only the exemplary embodiments of the invention ; modifications of the above-disclosed apparatus and method which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For instance, the seal plate 106 and the return beam member 107 may be coupled by any suitable mechanism (e. g., the dowels D and D2, screws, bolts, etc.) or may be integrally formed (e. g., machined from a single piece of material). In at least one embodiment, the seal plate 106 is formed from aluminum and the return beam member 107 is formed from aluminum. Other materials may be employed. The inventive door assembly 100 may be employed to similarly seal an opening of any vacuum chamber such as a load lock chamber, a processing chamber, a transfer chamber, a buffer chamber, etc., used during the manufacture of semiconductor devices, flat panel displays or the like.

Accordingly, while the present invention has been disclosed in connection with the preferred embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.