In-Situ Control of Wafer Charge Neutralization During High Current Ion Implants

Abstract

Ion implantation in semiconductor devices frequently leads to a substantial wafer surface charge build up. Control of this charge during high current implantation is a major process issue, as it may affect the yield and reliability of thin dielectric layers. In addition, the charge build up may affect the ion beam resulting in a non-uniform implant and a reduction in device yield. Control of a specific machine parameter, that will give the charge condition of the ion implanter will enable to neutralize the charge build up.In this study, Disk Current Monitoring (DCM) is shown to be a reliable method for monitoring the Electron Shower (ES) performance in real time. A correlation was found between DCM level and yields, and between DCM level and breakdown voltage, as well as different maintenance activities regarding me ES. A simple 5 steps method is described to achieve a reliable, real time charge monitor, to insure operation within the “High Yield Range”.