Exclusion of polymer film from semiconductor wafer edge and backside during film (CVD) deposition

A structure and method are provided to exclude polymer film deposition from the backside and edge of a wafer during CVD processing. An electrostatic chuck (ESC), with radial and circular channels and grooves on its surface, secures a wafer to be processed. An inert gas, preferably argon, flows outward from these channels and grooves along the backside of the wafer. A uniform flow of the gas from underneath the wafer into the process chamber prevents monomer molecules from depositing on the wafer backside. For edge exclusion, a showerhead is placed slightly above the outer diameter of the wafer to keep most of the monomer molecules within the process chamber and redirect the remaining monomer molecules across the surface of the wafer below the outer edge of the showerhead. As a result, monomer molecules are prevented from depositing on the wafer edge because the redirected and limited flow across the wafer surface flows upward in the process chamber to be pumped out and because a cloud of gas formed about the edge of the wafer from the gas exiting the backside of the wafer prevents any additional monomer molecules from depositing on the wafer edge.