Gas-purged vacuum valve

Abstract

A vacuum valve assembly for use in a vacuum processing chamber includes a seat defining an opening in the vacuum valve, with the seat having a sealing face adjacent the opening and normal to the direction of the opening; and a gate having a sealing face adapted to mate with the seat sealing face, the gate being movable toward and away from the seat sealing face to seal and open the vacuum valve opening. A continuous elastomeric seal extends around the vacuum valve opening between the gate sealing face and the seat sealing face of sufficient size such that when the gate is positioned to seal the vacuum valve opening, there exists a gap between the gate sealing face and the seat sealing face. A purge gas port system, disposed in the seat or in the gate, has an inlet for a purge gas, an essentially continuous outlet extending around the vacuum valve opening and adjacent the elastomeric seal and gap, and a manifold system connecting the inlet and the outlet. When a purge gas is introduced through the inlet, the manifold distributes the gas to the outlet which evenly distributes the gas to the vicinity of the continuous elastomeric seal around the vacuum valve opening in the gap between the gate sealing face and the seat sealing face.

Thus, having described the invention, what is claimed is:  
     
         1 . A vacuum valve assembly for use in a vacuum processing chamber comprising: 
 a vacuum processing chamber vacuum valve;    a seat defining an opening in said vacuum valve, said seat having a sealing face adjacent said opening and normal to the direction of said opening;    a gate having a sealing face adapted to mate with the seat sealing face, said gate being movable toward and away from the seat sealing face to seal and open the vacuum valve opening;    a continuous elastomeric seal around the vacuum valve opening between the gate sealing face and the seat sealing face of sufficient size such that when the gate is positioned to seal the vacuum valve opening, there exists a gap between the gate sealing face and the seat sealing face;    a purge gas port system having an inlet for a purge gas, an essentially continuous outlet extending around the vacuum valve opening and adjacent the elastomeric seal and gap, and a manifold system connecting the inlet and the outlet, such that when a purge gas is introduced through the inlet, the manifold distributes the gas to the outlet which evenly distributes the gas to the vicinity of the continuous elastomeric seal around the vacuum valve opening in the gap between the gate sealing face and the seat sealing face.    
     
     
         2 . The vacuum valve of  claim 1  wherein the purge gas port system is disposed in the seat.  
     
     
         3 . The vacuum valve of  claim 1  wherein the purge gas port system is disposed in the gate.  
     
     
         4 . The vacuum valve of  claim 3  wherein the purge gas port system outlet is defined by a first gate portion having the continuous elastomeric seal secured on the gate sealing face and a second gate portion secured within the first gate portion and facing the vacuum valve opening, the purge gas outlet being formed by a gap between the first and second gate portions extending essentially continuously around the first gate portion adjacent the elastomeric seal.  
     
     
         5 . The vacuum valve assembly of  claim 4  wherein the gap between the first and second gate portions forming the purge gas outlet is smaller than the gap between the gate sealing face and the seat sealing face.  
     
     
         6 . The vacuum valve assembly of  claim 1  wherein the purge gas outlet is formed by an opening narrower than the gap between the gate sealing face and the seat sealing face.  
     
     
         7 . The vacuum valve of  claim 1  wherein the purge gas port system outlet comprises a porous media adjacent the elastomeric seal.  
     
     
         8 . The vacuum valve of  claim 1  wherein the purge gas port system outlet comprises a porous portion of the elastomeric seal.  
     
     
         9 . A vacuum processing chamber comprising: 
 a vacuum processing chamber having a vacuum valve;    a seat defining an opening in said vacuum valve, said seat having a sealing face adjacent said opening and normal to the direction of said opening;    a gate having a sealing face adapted to mate with the seat sealing face, said gate being movable toward and away from the seat sealing face to seal and open the vacuum valve opening, said gate including a continuous elastomeric seal on the gate sealing face around the vacuum valve opening of sufficient size such that when the gate is positioned to seal the vacuum valve opening, there exists a gap between the gate sealing face and the seat sealing face;    a purge gas port system in the gate having an inlet for a purge gas, an essentially continuous outlet in the gate sealing face extending around the vacuum valve opening and within and adjacent the elastomeric seal, and a manifold system connecting the inlet and the outlet, such that when a purge gas is introduced through the inlet, the manifold distributes the gas to the outlet which evenly distributes the gas to the vicinity of the continuous elastomeric seal around the vacuum valve opening in the gap between the gate sealing face and the seat sealing face.    
     
     
         10 . The vacuum valve of  claim 9  wherein the purge gas port system outlet is defined by a first gate portion having the continuous elastomeric seal secured on the gate sealing face and a second gate portion secured within the first gate portion and facing the vacuum valve opening, the purge gas outlet being formed by a gap between the first and second gate portions extending essentially continuously around the first gate portion adjacent the elastomeric seal.  
     
     
         11 . The vacuum valve assembly of  claim 10  wherein the gap between the first and second gate portions forming the purge gas outlet is smaller than the gap between the gate sealing face and the seat sealing face.  
     
     
         12 . A vacuum processing chamber comprising: 
 a vacuum processing chamber having a vacuum valve;    a seat defining an opening in said vacuum valve, said seat having a sealing face adjacent said opening and normal to the direction of said opening;    a gate having a sealing face adapted to mate with the seat sealing face, said gate being movable toward and away from the seat sealing face to seal and open the vacuum valve opening, said gate including a continuous elastomeric seal on the gate sealing face around the vacuum valve opening of sufficient size such that when the gate is positioned to seal the vacuum valve opening, there exists a gap between the gate sealing face and the seat sealing face;    a purge gas port system in the seat having an inlet for a purge gas, an essentially continuous outlet in the seat sealing face extending around the vacuum valve opening and within and adjacent the elastomeric seal, and a manifold system connecting the inlet and the outlet, such that when a purge gas is introduced through the inlet, the manifold distributes the gas to the outlet which evenly distributes the gas to the vicinity of the continuous elastomeric seal around the vacuum valve opening in the gap between the gate sealing face and the seat sealing face.    
     
     
         13 . The vacuum valve assembly of  claim 12  wherein the gap between the first and second gate portions forming the purge gas outlet is smaller than the gap between the gate sealing face and the seat sealing face.  
     
     
         14 . A method of extending life to a seal in a vacuum valve used in a vacuum processing chamber comprising: 
 providing a semiconductor wafer processing chamber having a vacuum valve seat, a gate closing the vacuum valve seat, and a seal between the gate and the vacuum valve seat, the seal being exposed to the chamber;    introducing a reactive gas mixture to the chamber to process a semiconductor wafer therein, the reactive gas mixture comprising a reactive gas, adapted to react with a portion of the semiconductor wafer, diluted by a carrier gas, said reactive gas also being reactive with said seal;    introducing said carrier gas through an essentially continuous opening into the vicinity of the seal between the gate and the vacuum valve seat, the carrier gas continuously flowing so as to initially shield the seal from the reactive gas and then subsequently pass into the chamber and mix with the reactive gas.    
     
     
         15 . The method of  claim 14  wherein the seal forms a gap between opposing sealing faces of the gate and seat, and wherein the carrier gas is introduced through an essentially continuous opening adjacent to narrower than the gap between the gate and seat sealing faces.  
     
     
         16 . A method of extending life to a seal in a vacuum valve used in a vacuum processing chamber comprising: 
 providing a microelectronic circuit processing chamber having a vacuum valve seat, a gate closing the vacuum valve seat, and a seal between the gate and the vacuum valve seat, the seal being exposed to the chamber;    introducing a reactive gas mixture to the chamber to process a microelectronic device therein, the reactive gas mixture comprising a reactive gas adapted to react with a portion of the microelectronic device, diluted by a carrier gas, said reactive gas also being reactive with said seal;    introducing a portion of the reactive gas, such as oxygen into the vicinity of the seal between the gate and the vacuum valve seat, the reactive gas portion flowing so as to initially shield the seal and then subsequently pass into the chamber and mix with the remaining reactive gas.    
     
     
         17 . The method of  claim 16  wherein the carrier gas comprises oxygen.  
     
     
         18 . The method of  claim 16  wherein the reactive gas portion is introduced through an essentially continuous opening into the vicinity of the seal between the gate and the vacuum valve seat.  
     
     
         19 . The method of  claim 16  wherein the seal forms a gap between opposing sealing faces of the gate and seat, and wherein the reactive gas portion is introduced through an essentially continuous opening in the gate or seat.  
     
     
         20 . The method of  claim 19  wherein the reactive gas includes NF 3 .