Elimination of Watermark on Extremely High-Doped Poly-Silicon Surfaces Using HF-Vapor Cleaning

摘要

This study was carried out to solve the watermark problem on highly doped P+ polysilicon and N+ polysilicon. Modification of the conventional clean to include HF-vapor-last cleaning has successfully resolved the watermark issue on the cleaning process prior to WSix deposition using a Dual Poly Gate scheme. By configuring the HF vapor process conditions to minimize particle additions and target a T-OX removal of less than 20 A, the chemical oxide produced during the APM clean was completely removed with no adverse impact on the electrical parameters of the device.