Post Extension Ion Implant Photo Resist Strip for 32 nm Technology and beyond

Abstract:

The most advanced technology nodes require ultra shallow extension implants (low energy) which are very vulnerable to ash related substrate oxidation, silicon and dopant loss, which can result in a dramatic increase of the source/drain resistance and shifted transistor threshold voltages. A robust post extension ion implant ash process is required in order to meet cleanliness, near zero Si loss and dopant loss specifications. This paper discusses a performance comparison between fluorine-free, reducing and oxidizing, ash chemistries and “as implanted – no strip” process conditions, for both state-of-the-art nMOS and pMOS implanted fin resistors. Fluorine-free processes were chosen since earlier experiments with fluorine containing plasma strips exhibited almost a 10x increase in sheet resistance in the worse case.