Gas flow control during semiconductor fabrication

Abstract

A method is provided. The method includes introducing a process gas into an interior space of a processing chamber through a gas inlet port, wherein a substrate is supported within the interior space. The process gas is evacuated from the interior space by a vacuum source through an exhaust port in fluid communication with the interior space of the process chamber. A flow of the process gas is controlled by supporting an exhaust baffle within a flow path of the process gas being evacuated from the interior space through the exhaust port.

1 . A process chamber for semiconductor fabrication comprising:
 a peripheral wall extending upward from a floor to define an interior space;   a substrate support disposed within the interior space;   a gas inlet port through which a process gas enters the interior space to be exposed to a surface of a substrate supported by the substrate support;   an exhaust port through which the process gas is removed from the interior space, wherein the exhaust port is configured to be fluidly coupled to a vacuum source to generate a vacuum that establishes a flow of the process gas over the substrate supported by the substrate support; and   an exhaust baffle supported within a flow path of the process gas being removed from the interior space through the exhaust port, wherein the exhaust baffle comprises a first region that restricts to a first degree the flow path of the process gas toward the exhaust port, and a second region that restricts to a second degree, different than the first degree, the flow path of the process gas toward the exhaust port.   
     
     
         2 . The process chamber of  claim 1 , wherein the first region of the exhaust baffle comprises a shield surface formed from a material that is impermeable by the process gas. 
     
     
         3 . The process chamber of  claim 1 , wherein a first flow rate of a first portion of the process gas over a first portion of the substrate is substantially equal to a second flow rate of a second portion of the process gas over a second portion of the substrate due to an orientation of the exhaust baffle relative to the exhaust port. 
     
     
         4 . The process chamber of  claim 2 , wherein the shield surface defines a plurality of vent apertures with dimensions that restrict the flow path of the process gas. 
     
     
         5 . The process chamber of  claim 4 , wherein the plurality of vent apertures comprise a collective cross-sectional flow area that is less than a cross-sectional flow area of an aperture defined by the second region of the exhaust baffle. 
     
     
         6 . The process chamber of  claim 1 , wherein the peripheral wall and the floor define a cylindrical interior space, the substrate support is disposed at a central region of the cylindrical interior space, and the exhaust port is offset from the central region of the interior space. 
     
     
         7 . The process chamber of  claim 6 , wherein the exhaust baffle comprises an annular shape, and the first region of the exhaust baffle extends an angular extent of between thirty degrees (30°) and two hundred seventy degrees (270°) about the annular shape. 
     
     
         8 . The process chamber of  claim 7 , wherein the angular extent of the first region is between ninety degrees (90°) and one hundred eighty degrees (180°) about the annular shape. 
     
     
         9 . A semiconductor processing system comprising:
 a gas source that supplies a process gas;   a vacuum source; and   a process chamber comprising:
 a peripheral wall extending upward from a floor to define an interior space; 
 a substrate support disposed within the interior space; 
 a gas inlet port through which the process gas enters the interior space to be exposed to a surface of a substrate supported by the substrate support; 
 a vacuum aperture in fluid communication with the vacuum source, wherein the vacuum source establishes a partial vacuum at the vacuum aperture to establish a flow of the process gas through the process chamber; 
 an exhaust port through which the process gas is removed from the interior space, wherein the vacuum aperture is offset from the exhaust port; and 
 an exhaust baffle supported adjacent to the exhaust port within a flow path of the process gas being removed from the interior space through the exhaust port, wherein the exhaust baffle comprises a first region that restricts to a first degree the flow path of the process gas toward the exhaust port, and a second region that restricts to a second degree, different than the first degree, the flow path of the process gas toward the exhaust port, and wherein a portion of the first region of the exhaust baffle is arranged in vertical alignment with a portion of the vacuum aperture to influence the flow of the process gas through the process chamber. 
   
     
     
         10 . The semiconductor processing system of  claim 9 , wherein the exhaust baffle defines a plurality of vent apertures to influence the flow of the process gas through the process chamber. 
     
     
         11 . The semiconductor processing system of  claim 10 , wherein the plurality of vent apertures comprise a first vent aperture having a first cross-sectional flow area and a second vent aperture having a second cross-sectional flow area different than the first cross-sectional flow area. 
     
     
         12 . The semiconductor processing system of  claim 11 , wherein the first vent aperture has a first shape and the second vent aperture has a second shape different than the first shape. 
     
     
         13 . The semiconductor processing system of  claim 10 , wherein the plurality of vent apertures comprise a first vent aperture and a second vent aperture, and the first vent aperture is closer to at least one of an outer edge of the exhaust baffle or an inner edge of the exhaust baffle than the second vent aperture. 
     
     
         14 . The semiconductor processing system of  claim 9 , wherein the exhaust baffle is discontinuous such that a first end of the exhaust baffle does not touch a second end of the exhaust baffle. 
     
     
         15 . The semiconductor processing system of  claim 9 , wherein the first region of the exhaust baffle overlaps an arcuate region of the vacuum aperture. 
     
     
         16 . The semiconductor processing system of  claim 15 , wherein an extent to which the first region of the exhaust baffle overlaps the arcuate region of the vacuum aperture is greater than an extent to which the second region of the exhaust baffle overlaps the arcuate region of the vacuum aperture. 
     
     
         17 .- 20 . (canceled) 
     
     
         21 . An exhaust baffle of a process chamber for semiconductor fabrication comprising:
 a first region comprising a shield surface comprising a material that is impermeable by a process gas of the process chamber, wherein the shield surface defines a plurality of vent apertures; and   a second region comprising a first aperture having a cross-sectional flow area providing a first flow path of the process gas toward an exhaust port of the process chamber, wherein:
 a collective cross-sectional flow area of the plurality of vent apertures providing a second flow path of the process gas toward the exhaust port of the process chamber is less than the cross-sectional flow area of the first aperture. 
   
     
     
         22 . The exhaust baffle of  claim 21 , wherein:
 the exhaust baffle comprises an annular shape, and the first region of the exhaust baffle extends an angular extent of between thirty degrees (30°) and two hundred seventy degrees (270°) about the annular shape.   
     
     
         23 . The exhaust baffle of  claim 21 , wherein:
 the exhaust baffle comprises an annular shape, and   the first region of the exhaust baffle extends an angular extent of between ninety degrees (90°) and one hundred eighty degrees (180°) about the annular shape.   
     
     
         24 . The exhaust baffle of  claim 21 , wherein:
 a cross-sectional flow area of a first vent aperture of the plurality of vent apertures is different than a cross-sectional flow area of a second vent aperture of the plurality of vent apertures.