Provisional Patent Application Serial No. 60/216,868, filed July 7, 2000, which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION The present invention relates to methods and apparatuses for providing a seal for an opening. More particularly, the present invention relates to a door assembly, such as a gate valve or a slit valve, for sealing chambers of a semiconductor device fabrication tool.

BACKGROUND OF THE INVENTION Semiconductor wafers are processed within automated fabrication tools comprising a plurality of chambers designated for wafer loading/unloading to and from the tool (i. e., a loadlock), wafer transfer, or wafer processing.

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. Loadlocks also 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 is a need for an improved slit/gate valve that may have a higher sealing force and that has a small footprint.

SUMMARY OF THE INVENTION The present invention provides an improved slit/gate valve adapted to selectively seal an opening such as a slit opening of a semiconductor fabrication tool. The inventive slit/gate valve comprises a door having a sealing surface adapted to seal an opening, a linking mechanism coupled to the door, and an actuator coupled to the linking mechanism. The actuator is adapted to move the linking mechanism and the linking mechanism is adapted to translate actuation (e. g., movement) of the linking mechanism in a first direction into movement of the door in a second direction.

The present invention also provides a method of sealing an opening in a chamber, the method including elevating a sealing portion of a door via application of upward movement to a position adjacent an opening to be sealed; contacting a vertical motion stop; continuing the application of upward movement; and translating the continued application of upward movement into horizontal movement of the sealing portion of the door such that the sealing portion of the door seals the opening.

Other features of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view of an inventive slit/gate valve; FIG. 2 is a front view of the inventive slit/gate valve of FIG. 1; FIGS. 3A-C are sequential side views of the inventive slit/gate valve of FIGS 1 and 2; and FIG. 4 is a top plan view of an automated semiconductor device fabrication tool that employs the inventive slit/gate valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In operation, a sealing surface of the inventive slit/gate valve selectively seals and unseals an opening of a chamber, such that the chamber's internal environment may be altered (e. g., pumped to a vacuum pressure) when the opening is sealed. To selectively seal and unseal the opening, the sealing surface must be capable of lifting and lowering to and from a position adjacent the opening, and must be capable of moving forward so as to contact and seal against the surface surrounding the opening and so as to move backward so as to unseal therefrom.

To achieve the desired motion the inventive slit/gate valve employs an actuator for selectively applying a lifting and a lowering force, a vertical stop for stopping the sealing surface at a position adjacent the opening, and a linkage system for translating continued vertical actuation (i. e., vertical actuation applied after the vertical motion stop has been contacted) into horizontal movement. The linkage system may comprise a link 35 coupled (e. g., indirectly via a shaft 21) to the sealing surface 17 and to a mounting plate 27, and a link 33 coupled to the link 35, to the actuator, and to the mounting plate 27. The mounting

plate 27 is slideably mounted between a pair of guide rails 41, and slideably mounted to a leverage surface 43. The leverage surface 43 is a surface a fixed distance from the opening. The links are coupled (e. g., indirectly via the mounting plate) to the leverage surface. Accordingly, because the leverage surface is horizontally fixed, the links move horizontally so as to extend from and retract toward the leverage surface 43, as described further below.

Alternatively, the leverage surface 43 may be omitted, and the guide rails 41 may provide sufficient horizontal fixation.

The components of an inventive slit/gate valve 11 are described with reference to FIGS. 1-3C. FIG. 1 is a side view of the inventive slit/gate valve 11, and FIG. 2 is a front view of the inventive slit/gate valve 11. FIGS. 3A-C are sequential side views of the inventive slit/gate valve 11. The inventive slit/gate valve 11 comprises a moveable door assembly (the components of which are described below) coupled to a linking mechanism 15, wherein the linking mechanism 15 is adapted to translate vertical actuation (e. g., motion) into horizontal movement of the moveable door assembly, as described below.

The moveable door assembly comprises a sealing surface 17 adapted to occlude and seal a slit 19 formed in a surface 20, an elongated shaft portion 21 that extends downward from the sealing surface 17, and a door plate 23 positioned on the elongated shaft portion 21. A first uniball bearing 25 couples the sealing surface 17 to a remaining portion of the moveable door assembly. The first uniball bearing 25 may allow the sealing surface 17 to be freely oriented so as to ensure that the sealing surface 17 completely seals against the slit 19. Thus, the first uniball bearing 25 is adapted to enable the sealing surface

17 to self-align upon contact with the surface surrounding the slit 19.

The inventive slit/gate valve 11 also comprises a mounting-'plate 27 (to which a number of the slit/gate valve 11 components are mounted as described below), and an actuator 29, such as a pneumatic cylinder, which may have a piston (not shown) and a rod 31 adapted to move the inventive slit/gate valve 11 upwardly, so as to place the sealing surface 17 of the moveable door assembly in position to seal (e. g., at the same elevation as) the slit 19. The rod 31 is also adapted to move the inventive slit/gate valve 11 downwardly, so as to expose the slit 19, thereby allowing substrates to be transferred therethrough.

The rod 31 of the actuator 29 is coupled to the linking mechanism 15 and is adapted to lift and lower so as to move the linking mechanism 15 between a lifted position (FIG. 3B) (e. g., where the sealing surface 17 is at the same elevation as the slit 19) and a lowered position (FIG. 3A) (e. g., where the sealing surface 17 is at a lower elevation than the slit 19 so as to expose the slit 19). The linking mechanism 15 may comprise a first link 33, and a second link 35, rotatably coupled via a joint 37, such that at least a portion of the first link 33 extends from a first side of the joint 37, and such that at least a portion of the second link 35 extends from a second side of the joint 37. The first link 33 comprises a first portion 39 and a second portion 41, wherein the joint 37 is positioned between the first portion 39 and the second portion 41.

The first link 33 is adapted to pivot to an extended-locked position (FIG. 3C) as the rod 31 of the actuator 29 (which is coupled to the second portion 41 of the first link 33) moves vertically upward and to pivot to a retracted-unlocked position (FIGS. 3A and 3B) (e. g., a

position wherein the first link 33 is less horizontal than it is in the extended-locked position) as the rod 31 moves vertically downward.

In the extended-locked position, the horizontal distance between the first portion 39 of the first link 33 and the second portion 41 of the first link 33 is represented by the distance X (FIG. 3C). In the retracted-unlocked position, the horizontal distance between the first portion 39 and the second portion 41 is represented by the distance Y (FIG. 3B). As is evident from the drawings, the horizontal distance X (e. g., when the first link 33 is in the extended- locked position) is greater than the horizontal distance Y (e. g., when the first link 33 is in the retracted-unlocked position).

The first link 33 is fixedly coupled, via the first portion 39, to the mounting plate 27. The first link 33 is coupled so as to be horizontally stationary at a fixed horizontal distance from the opening to be sealed. This may be accomplished by coupling the link to the mounting plate and by coupling the mounting plate to a horizontally fixed surface. A leverage surface 43 and/or guide rails 47 may be employed to provide such horizontal fixation. In this example, the first link 33 is coupled (via the mounting plate) to the leverage surface 43, positioned on the first side of the joint 37. The leverage surface 43 is coupled to the actuator 29, via a bracket 44 adapted to support the actuator 29. The leverage surface 43 may comprise a horizontally stationary surface which forms a surface a fixed distance from the opening which the sealing surface 17 is to seal. The leverage surface 43 serves as a horizontally fixed position from which the links are extended and retracted to position the sealing surface 17 for sealing and unsealing the opening. The second link 35 is coupled to the moveable door

assembly, which is positioned on the second side of the joint 37, preferably via a second uniball bearing 45. Because the first link 33 is coupled to the second link 35, at the joint 37, and the second link 35 is coupled to the moveable door assembly, (e. g., via the second uniball bearing 45) the second link 35 and the moveable door assembly move horizontally toward the surface 20, leveraging off the leverage surface 43 as the first link 33 moves (the distance X-Y) between the retracted-unlocked position (FIG. 3A) and the extended-locked position (FIG. 3C), respectively.

The inventive slit/gate valve 11 further comprises a stationary guide rail 47, wherein the moveable door assembly is slideably coupled thereto so as to slide upward and downward along the stationary guide rail 47. In one aspect, the moveable door assembly, the joint 37 between the links 33,35, and the mounting plate 27 are operatively coupled to the stationary guide rail 47 so as to move vertically along the stationary guide rail 47 when the actuator 29 is energized. The mounting plate 27 may contact a vertical motion stop 49 as the inventive slit/gate valve 11 moves vertically upward, thereby stopping further vertical motion of the mounting plate 27. When the mounting plate 27 stops moving vertically upward, the first portion 39 of the first link 33 which is fixedly coupled to the mounting plate 27, the second link 35 which is coupled to the first link 33, and the moveable door assembly, which is coupled to the second link 35, also stop moving vertically upward.

In one aspect, the vertical motion stop 49 is positioned above the mounting plate 27. In general, however, the vertical motion stop 49 is positioned such that when the mounting plate 27 contacts the vertical motion stop 49, the sealing surface 17 of the moveable door assembly is in position to engage (e. g., at the same elevation as) the slit

19. Hence, the vertical motion stop 49 may serve as a datum point to provide accurate alignment of the inventive slit/gate valve 11 so as to facilitate proper positioning of the sealing surface 17 relative to the slit 19.

A bellows 51 is positioned adjacent the vertical motion stop 49 and is coupled to the door plate 23 of the moveable door assembly so as to encase part of the elongated shaft portion 21 that extends above the remainder of the inventive slit/gate valve. Thus, this part of the elongated shaft 21 may move within a controlled environment with minimal particle generation, and the remainder of the inventive slit/gate valve may be positioned outside/below the controlled environment. The bellows 51 may expand as the moveable door assembly moves vertically upward and may retract as the moveable door assembly moves vertically downward, and is adapted to contain particles generated when the components of the inventive slit/gate valve 11 move and contact each other.

The operation of the inventive slit/gate valve 11 is described with reference to the sequential views of FIGS.

3A-C, which show the movement of the inventive slit/gate valve 11. The moveable door assembly is initially in the lowered position (e. g., the sealing surface 17 is at a lower elevation than the slit 19 so as to expose the slit 19) and the first link 33 is initially in the retracted-unlocked position (e. g., wherein the first link is less horizontal than it is when in the extended-locked position) as shown in FIG. 3A.

In operation, the actuator 29 is energized and the rod 31 moves vertically upward so as to move the linking mechanism 15, via the second portion 41 of the first link 33, vertically upward to the lifted position as shown in FIG. 3B.

As the linking mechanism 15 moves vertically upward, the

mounting plate 27 and the moveable door assembly, both coupled to the linking mechanism 15, also move vertically upward along the stationary guide rail 47. The bellows 51 expands as the door plate 23 moves vertically upward past the vertical motion stop 49.

As the inventive slit/gate valve 11 moves vertically upward, the mounting plate 27 eventually contacts the vertical motion stop 49 so as to prevent the mounting plate 27 from further upward movement. The first portion 39 of the first link 33, the second link 35, and the moveable door assembly thereby also are prevented from further upward movement. When the mounting plate 27 contacts the vertical motion stop 49, the sealing surface 17 of the moveable door assembly is in position to engage (e. g., at the same elevation as) the slit 19 as shown in FIG. 3B.

The rod 31 continues to move vertically upward such that the first link 33, which is coupled to the rod 31 via the second portion 41 thereof, pivots from the retracted- unlocked position (FIG. 3B) to the extended-locked position (FIG. 3C). As the first link 33 pivots to the extended- locked position from the retracted-unlocked position, the horizontal distance between the end of the first portion 39 and the end of the second portion 41 increases from the distance Y to the distance X, which, via the joint 37, causes the second link 35 and the moveable door assembly coupled to the second link 35, to move horizontally toward the slit 19.

As the moveable door assembly moves horizontally toward the slit 19, the sealing surface 17 may be locked against the slit 19 with infinite sealing force that results when the first portion 39 of the first link 33, the second link 35, and the joint 37 therebetween are in line as shown in FIG.

3C.

Thereafter, to open the slit 19, the actuator 29 reverses direction, and the rod 31 moves vertically downward carrying with it the first link's second portion 41, which is coupled thereto; such that the first link 33 pivots from the extended-locked position (FIG. 3C) to the retracted-unlocked position (FIG. 3B). As the first link 33 moves to the retracted-unlocked position, the second link 35 and the moveable door assembly move horizontally away from the slit 19 as shown in FIG. 3B. The sealing surface 17 unlocks the slit 19 and also moves horizontally away from the slit 19.

The rod 31 continues to move vertically downward such that the linking mechanism 15, the moveable door assembly, and the mounting plate 27 move vertically downward to the lowered position (FIG. 3A) so as to again expose the slit 19, thereby allowing a wafer handler (not shown) to transport wafers (not shown) through the slit 19.

FIG. 4 is a top plan view of an automated semiconductor device fabrication tool 101 that employs the inventive slit/gate valve 11. The fabrication tool 101 comprises a first transfer chamber 103 and a second transfer chamber 105, which contain a first wafer handler 107 and a second wafer handler 109, respectively. The first transfer chamber 103 is operatively coupled to a pair of loadlocks 111,113 and to a pair of pass-through chambers 115,117.

Other chambers such as degassing or cool-down chambers (shown in phantom) also may be coupled to the first transfer chamber 103. The second transfer chamber 105 is coupled to the pass- through chambers 115,117, and to a plurality of processing chambers 119,121,123, and 125, which are configured for performing various semiconductor fabrication processes (e. g., chemical vapor deposition, sputter deposition, etc.).

Each chamber of the fabrication tool 101 may be sealed by one or more of the inventive slit/gate valves 11.

When the inventive valve is used to seal a process chamber of system shown in FIG. 4, a second moveable door and linking assembly, facing in the opposite direction from the direct ion from the first seal plate may be coupled to the same actuator to achieve sealing in both directions.

A controller 131 comprising a microprocessor 133 and memory 135 is operatively coupled to the first and second wafer handlers 107,109, to the loadlocks 111,113, and to the inventive slit valve 11, which selectively seal the loadlocks 111,113, the pass-through chambers 115,117 and the processing chambers 119,121,123,125. The controller 131 thus controls wafer transfer and processing within the fabrication tool 101. The inventive slit/gate valve may be employed within any fabrication tool, and is particularly advantageous for sealing the process chamber of the carousel transfer chamber system described in U. S. Provisional Patent Application Serial No. 60/217,144 (AMAT No. 5232/L/FET/DV), filed 7/7/2000. The entire disclosure of U. S. Provisional Patent Application Serial No. 60/217,144 (AMAT No.

5232/L/FET/DV), is incorporated herein by this reference.

The inventive slit/gate valve 11 of the present invention may require less space than conventional slit/gate valves and therefore may enable the overall footprint of the first transfer chamber 103 and the second transfer chamber 105 to be reduced, which would reduce clean room costs.

Further advantages of the inventive slit/gate valve 11 may include simple, inexpensive design, sealing surface self- alignment, nearly infinite sealing force, distributed sealing force which may minimizes the tendency for sealing surface deflection and may enable a thinner sealing surface to be employed. A particular advantage may be the ability to enable the pneumatics to be turned off and the seal to be

maintained by the force from the locked linking mechanism.

Further, the vertical motion stop 49 provides a convenient datum point that allows the position of the sealing surface 17 to be accurately controlled relative to the slit 19.

Alternatively, rather than reducing the footprint of the first transfer chamber 103 and the second transfer chamber 105, the first and second transfer chambers 103,105 may be maintained at their conventional size, in which case the inventive slit/gate valve 11's smaller size provides increased space for robot operating volume and allows use of robots with longer extended arm lengths.

The foregoing description discloses only the preferred 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 example, the shape of the various components and the specific coupling therebetween may vary. The inventive slit/gate valve 11 may be easily scaled (e. g., for use in 200mm or 300mm wafer systems) by changing the size of the inventive slit/gate valve 11's sealing surface.

The linking mechanism 15 may be similarly employed to translate horizontal actuation into vertical movement of the moveable door assembly. In fact, the linking mechanism 15 is adapted to allow actuation in a first direction to be translated into movement of the moveable door assembly in a second direction, (e. g., which may be perpendicular to the first direction). Thus, actuation need not be purely horizontal or purely vertical. Likewise, the components of the inventive slit/gate valve 11 may move horizontally as long as a horizontal motion stop is included and a vertically stationary surface is provided against which the linking mechanism 15 may leverage. Moreover, the actuator, linking

mechanism and the leverage surface may be positioned on the side of the elongated shaft nearest the surface 20, or in other positions, as needed for a specific space.

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.