Patent ID: 7713757

Claim:
A method for detecting a doping concentration on a substrate surface during a plasma doping process, comprising: positioning a substrate within a process chamber, wherein the substrate has a topside and a backside and is at a temperature of less than about 250° C.; generating a plasma above the substrate within the process chamber; transmitting a light generated by the plasma through the substrate, wherein the light enters the topside and exits the backside of the substrate; receiving the light by a sensor positioned below the substrate; generating a signal proportional to the light received by the sensor; implanting the substrate with a dopant during a doping process; generating multiple light signals proportional to a decreasing amount of the light received by the sensor during the doping process; generating an end point signal proportional to the light received by the sensor once the substrate comprises a final concentration of the dopant; and ceasing the dopant implantation of the substrate.