Apparatus and method for front side protection during backside cleaning

Abstract

Embodiments of the present invention provide apparatus and method for front side protection while processing side and backside of a substrate. One embodiment of the present invention provides a showerhead configured to provide a purge gas to a front side of a substrate during a backside etch processing. The showerhead comprises a body configured to be disposed over the front side of the substrate. The body has a process surface configured to face the front side of the substrate. The process surface has an outer circular region, a central region, a middle region between the outer central region and the central region. The first plurality of holes are distributed in the outer circular region and configured to direct the purge gas towards an edge area of the front side of the substrate. No gas delivery hole is distributed within a substantial portion of the middle region.

1 . An injection nozzle, comprising:
 an input pipe having an input channel; and   a nozzle head having a narrow end and a wide end, wherein the narrow end of the nozzle head is attached to the input pipe, and the nozzle head has a substantially flat shape and is configured to deliver a processing gas from the input channel to a narrow region corresponding to an edge of a substrate.   
     
     
         2 . The injection nozzle of  claim 1 , wherein the wide end is curved. 
     
     
         3 . The injection nozzle of  claim 2 , wherein the nozzle head has a wide opening formed along the wide end, and the wide opening is in fluid communication with the input channel. 
     
     
         4 . The injection nozzle of  claim 2 , wherein the nozzle head has two injection ports formed on the wide end, and the two injection ports are connected to the input channel. 
     
     
         5 . The injection nozzle of  claim 4 , wherein the two injection ports are formed on opposite ends of the wide end, and each injection port is configured to direct a gas flow tangential to the edge of the substrate. 
     
     
         6 . The injection nozzle of  claim 2 , wherein the nozzle head has a plurality of injection ports evenly distributed along the wide end of the nozzle head, and the plurality of injection ports are connected to the input channel. 
     
     
         7 . The injection nozzle of  claim 2 , wherein the wide end is configured to arc around a portion of the substrate. 
     
     
         8 . The injection nozzle of  claim 1 , wherein the nozzle head has an arc shaped body configured to curve around a portion of the substrate, and a plurality of injection nozzles are evenly distributed along the arc shaped body. 
     
     
         9 . An apparatus for delivering processing a substrate, comprising:
 a chamber body defining a processing volume;   a substrate support disposed in the processing volume, wherein the substrate support is configured to support the substrate on a backside allowing an edge region of the substrate exposed; and   an injection nozzle disposed in the processing volume at one side of the substrate support, wherein the injection nozzle comprises:
 an input pipe having an input channel adapted to connect with a gas source; and 
 a nozzle head having a narrow end and a wide end, wherein the narrow end of the nozzle head is attached to the input pipe, the wide end of the nozzle head faces the substrate support, and the nozzle head has a substantially flat shape and is configured to deliver a processing gas to a narrow region corresponding to an edge of a substrate disposed on the substrate support. 
   
     
     
         10 . The apparatus of  claim 9 , wherein the wide end is curved around the substrate support. 
     
     
         11 . The apparatus of  claim 9 , wherein the nozzle head has a wide opening formed along the wide end, and the wide opening is configured to inject a process gas to the substrate disposed on the substrate support. 
     
     
         12 . The apparatus of  claim 9 , wherein the nozzle head has two injection ports formed on opposite ends of the wide end, and each injection port is configured to direct a gas flow tangential to the edge of the substrate. 
     
     
         13 . The apparatus of  claim 9 , wherein the nozzle head has a plurality of injection ports evenly distributed along the wide end of the nozzle head. 
     
     
         14 . The apparatus of  claim 9 , further comprising a remote plasma source connected to the input channel of the injection nozzle. 
     
     
         15 . A method for cleaning a backside of a substrate, comprising:
 positioning the substrate on a substrate support with an edge region of the substrate over hanging the substrate support, wherein a front side of the substrate is facing up and the backside of the substrate partially contacts the substrate support;   directing a purge gas towards the front side of the substrate; and   flowing a processing gas towards the edge region of the substrate using an injection nozzle disposed on one side of the substrate support.   
     
     
         16 . The method of  claim 15 , wherein flowing the processing gas comprises directing the processing gas from a substantially flat nozzle head to a vertically narrow region corresponding to the edge region of the substrate. 
     
     
         17 . The method of  claim 16 , wherein flowing the processing gas further comprises directing the processing gas flow to be tangential to the substrate. 
     
     
         18 . The method of  claim 16 , wherein flowing the processing gas further comprises dividing the processing gas flow into a plurality of sub-flows along a significant portion of the edge of the substrate. 
     
     
         19 . The method of  claim 15 , wherein directing the purge gas comprises direction the purge gas towards a restricted region of the front side, and the restricted region comprises an outer circular region near the edge of the substrate. 
     
     
         20 . The method of  claim 19 , wherein directing the purge gas comprises flowing the purge gas from a showerhead disposed above the front side of the substrate, the showerhead has a first plurality of holes configured for gas delivery, the first plurality of holes are distributed in an outer circular region corresponding to an edge area of the front side of the substrate, no gas delivery hole is distributed within a middle region radially inward of the first plurality of holes, and the middle region corresponds to a substantial surface area of the front side.