Integrated circuit (IC) chips are typically manufactured in multi-chambered vacuum equipment. Each chamber may contain a different environment, e.g. atmosphere, temperature, and pressure, than adjacent chambers. Chambers are typically isolated from each other by gate valves (or slit valves). Such valves may be utilized for moving semiconductor wafers from one chamber to another. In addition, pendulum valves may be employed to separate chambers from a vacuum source and for the feeding or exhausting of gases. In both gate valves and pendulum valves, sealing is affected by closing a sealing member, also referred to as a disk or door, portion of the valve. Generally, the door comprises a metal plate, sized and shaped for covering the opening within the valve, and a deformable seal, or O-ring, mounted on the sealing surface of the door, near its periphery. The deformable seal is typically made from an elastomeric or thermoplastic polymer.
During use in the manufacture of IC chips, the deformable door seal is exposed to high temperatures and to corrosive plasmas. The latter conditions, coupled with repeated opening and closing of the door, causes the deformable seal ring to deteriorate and, eventually need to be replaced. Deformable seal replacement has been problematic.
Early door designs featured a dovetail-shaped groove running along the periphery of the door sealing surface. The groove was used to hold a deformable O-ring seal or a modified O-ring (U.S. Pat. No. 5,482,297). However, in use, the deformable seal ring could undesirably pop out of the groove when the gate valve door was opened. It could also be difficult and time consuming to install a replacement seal ring within the groove without damaging the seal.
A more recent door design is disclosed in U.S. Pat. No. 6,089,543 wherein the gate valve door comprises a mounting member and a seal plate attached thereto, wherein a deformable seal ring is mounted onto the outer surface of the seal plate. In this design, the deformable seal ring is preferably bonded, by molding in place, onto the seal plate. When it is desired to replace a worn deformable seal ring, the seal plate/deformable seal assembly is readily detached from the mounting member and discarded. A new seal plate/deformable seal assembly is then attached to the mounting member. This design has the economic and environmental disadvantage of not re-using the old seal plate.
U.S. Pat. No. 5,579,718 discloses a slit valve door having a removable O-ring seal that is held in place within a groove that is partially formed by the door and partially formed by a removable wedge insert. However, it may be difficult to install the O-ring seal in this door groove without twisting the O-ring. Twisting can cause premature seal failure.
It is an object of the present invention to provide a valve door having a securely mounted deformable seal element which may be quickly replaced when desired, without the need for replacing a large portion of the door and without damaging the seal element.