Semiconductor devices and processes for making them

摘要

A semiconductor device such as a flash EEPROM has oxide/nitride/oxide sandwich structure deposited on a semiconductor substrate. Optical lithography and plasma-assisted etching are used to remove portions of the structure that extend over active regions. Since the nitride layer of the etched sandwich structure has oxidation proof, oxygen radical is prevented from reaching the substrate. Thus, the bird's beak is prevented from appearing.