Method for shaping photoresist mask to improve high aspect ratio ion implantation

摘要

A method for making a ULSI MOSFET chip includes masking areas such as transistor gates with photoresist mask regions. Prior to ion implantation, the top shoulders of the mask regions are etched away, to round off the shoulders. This promotes subsequent efficient quasi-vertical ion implantation, commonly referred to as “high aspect ratio implantation” in the semiconductor industry.