Trench sidewall patterned by vapor phase etching

摘要

Hydrogen fluoride undercut of oxide layers may be reduced by using a low pressure mixture of gaseous hydrogen fluoride and gaseous ammonia mixture. Organic photoresists can be used as a masking material when using the gaseous hydrogen fluoride/ammonia mixture without resulting in an enhanced reaction rate. In addition, because of the reaction conditions, the dimensions in the oxide layer being etched can be specifically sized smaller than openings made in the overcoating masking material.