Methods for post polysilicon etch photoresist and polymer removal with minimal gate oxide loss

摘要

The present invention pertains to methods for cleaning semiconductor wafers, more specifically, for removing polymeric and other residues from a wafer using dry plasmas generated with microwave (MW), electromagnetic field (inductively-coupled plasma (ICP)), and radio frequency (RF) energy. First, a wafer is treated by applying a microwave-generated plasma or an inductively-coupled plasma. Second, a radio frequency generated plasma is applied. Each of the microwave-generated plasma and the inductively-coupled plasma is produced from a gas mixture, which includes an oxygen source gas, a fluorine source gas, and a hydrogen source gas. Using such plasmas provides more controllable etch rates than conventional plasmas via control of fluorine concentration in the plasma. Application of a radio frequency generated (preferably oxygen-based) plasma is used for additional photoresist and polymer removal. The use of this two-step approach provides superior wafer cleaning compared to conventional wet and dry clean methods.