Method to protect gate stack material during source/drain reoxidation

摘要

A process of manufacturing a gate stack whereby the integrity of both the gate sidewalls and the substrate surface is maintained. Nitride spacers are constructed on the sidewalls of a gate which has been etched only to the top of the polysilicon layer. This allows more of the polysilicon sidewall to be exposed during subsequent reoxidation while at the same time minimizing effects such as bird's beak resulting during reoxidation. After the nitride spacers are constructed the subsequent etch is performed in two steps in order to minimize degradation of the substrate surface in underlying active regions.