Accurate Dose Control with Pressure Compensation System on Single-Wafer Ion Implanters

Abstract

On ion implanters, dosimetry is generally controlled by monitoring an electrical current detected with Faraday cup(s) instead of the actual number of dopants. In some cases, ions in a beam undergo charge exchange phenomenon, interacting with residual gas molecules in a beamline. This charge exchange of ions causes variations of the detected beam currents which result in inaccurate dosimetry of implanted dopants. We will introduce to you a system similar to Pressure Compensation of the batch‐type ion implanters to single‐wafer ion implanters, that is, the SHX high current ion implanter and the MC3‐II medium current ion implanter. The system converts the beam current detected with Faraday cups to an adequate value for dose control as a function of beamline pressure and brings accurate dosimetry also in these single‐wafer ion implanters.