Method for measuring dopant concentration during plasma ion implantation

Abstract

Embodiments of the invention generally provide apparatuses for endpoint detection of dopants. In one embodiment, the apparatus has a plasma chamber containing a body having sidewalls, a lid, and a bottom encompassing an interior volume and a substrate support assembly disposed within the body and having a substrate supporting surface configured to support a substrate. The apparatus also has a processing region disposed between the substrate supporting surface and a gas distribution assembly—which contains a perforated plate disposed above the substrate supporting surface. The apparatus also has a plasma source coupled with the body and configured to form an inductively coupled plasma within the interior region. Additionally, the apparatus has an optical sensor disposed either above or below the substrate supporting surface and coupled with a controller, wherein the controller is configured to derive a current dopant concentration relative to an amount of radiation received by the optical sensor.

1 . An apparatus for doping and detecting a doping concentration of a material disposed on a substrate surface during a plasma doping process, comprising:
 a plasma chamber containing a body having sidewalls, a lid, and a bottom encompassing an interior volume;   a substrate support assembly disposed within the body and having a substrate supporting surface configured to support a substrate;   a gas distribution assembly containing a perforated plate disposed above the substrate supporting surface;   a processing region within the interior region and disposed between the gas distribution assembly and the substrate supporting surface;   a plasma source coupled with the body and configured to form an inductively coupled plasma above the substrate supporting surface within the interior region; and   an optical sensor disposed below the substrate supporting surface and coupled with a controller, wherein the controller is configured to derive a current dopant concentration relative to an amount of radiation received by the optical sensor.   
     
     
         2 . The apparatus of  claim 1 , wherein the optical sensor is positioned to receive the amount of radiation transmitted through the substrate. 
     
     
         3 . The apparatus of  claim 1 , wherein the amount of radiation is light generated by the inductively coupled plasma and the optical sensor is positioned to receive a decreasing amount of the light proportional to an increasing dopant concentration. 
     
     
         4 . The apparatus of  claim 1 , further comprising a laser source disposed above the substrate supporting surface, the amount of radiation is light generated by the laser source, and the optical sensor is positioned to receive a decreasing amount of the light proportional to an increasing dopant concentration. 
     
     
         5 . The apparatus of  claim 1 , wherein the optical sensor is configured to detect light at a predetermined wavelength or frequency emitted from the inductively coupled plasma generated above the substrate supporting surface within the interior region. 
     
     
         6 . The apparatus of  claim 5 , wherein the emitted light is selected from the group consisting of infrared light, visible light, ultraviolet light, and combinations thereof. 
     
     
         7 . The apparatus of  claim 6 , wherein the emitted light is infrared light. 
     
     
         8 . The apparatus of  claim 1 , wherein the plasma source is a toroidal plasma source. 
     
     
         9 . The apparatus of  claim 1 , wherein the amount of radiation is light and the controller is configured to generate an initial signal proportional to the light received by the optical sensor. 
     
     
         10 . The apparatus of  claim 9 , wherein the controller is configured to implant the substrate with a dopant during a dopant implantation process. 
     
     
         11 . The apparatus of  claim 10 , wherein the controller is configured to modulate light received by the optical sensor proportional to an increasing dopant concentration. 
     
     
         12 . The apparatus of  claim 11 , wherein the controller is configured to generate an end point signal proportional to the light received by the optical sensor once the substrate has a final concentration of the dopant. 
     
     
         13 . The apparatus of  claim 12 , wherein the controller is configured to cease the dopant implantation process. 
     
     
         14 . An apparatus for doping and detecting a doping concentration of a material disposed on a substrate surface during a plasma doping process, comprising:
 a plasma chamber containing a body having sidewalls, a lid, and a bottom encompassing an interior volume;   a substrate support assembly disposed within the body and having a substrate supporting surface configured to support a substrate;   a gas distribution assembly containing a perforated plate disposed above the substrate supporting surface;   a processing region within the interior region and disposed between the gas distribution assembly and the substrate supporting surface;   a plasma source coupled with the body and configured to form an inductively coupled plasma above the substrate supporting surface within the interior region; and   an optical sensor disposed above the substrate supporting surface and coupled with a controller, wherein the controller is configured to derive a current dopant concentration relative to an amount of radiation received by the optical sensor.   
     
     
         15 . The apparatus of  claim 14 , wherein the optical sensor is positioned to receive the amount of radiation reflected from the substrate. 
     
     
         16 . The apparatus of  claim 14 , wherein the amount of radiation is light generated by the inductively coupled plasma and the optical sensor is positioned to receive an increasing amount of the light proportional to an increasing dopant concentration. 
     
     
         17 . The apparatus of  claim 14 , further comprising a laser source disposed above the substrate supporting surface, the amount of radiation is light generated by the laser source, and the optical sensor is positioned to receive an increasing amount of the light proportional to an increasing dopant concentration. 
     
     
         18 . The apparatus of  claim 14 , further comprising a laser source disposed below the substrate supporting surface, the amount of radiation is light generated by the laser source, and the optical sensor is positioned to receive a decreasing amount of the light proportional to an increasing dopant concentration. 
     
     
         19 . The apparatus of  claim 14 , wherein the optical sensor is adapted to detect an emitted light selected from the group consisting of infrared light, visible light, ultraviolet light, and combinations thereof. 
     
     
         20 . The apparatus of  claim 19 , wherein the emitted light is infrared light.