MOS Gate Etching Using an Advanced Magnetron Etching System

Abstract

A new type of magnetron etching system, RAMRIE, has been developed. Its characteristics for poly-Si gate etching with Cl₂ has been investigated as a function of RF power and etching pressure in comparison with those for RIE whose structure and operating conditions are the same as those of RAMRIE. It was found that the profile of etched poly-Si is determined only by the etch selectivity of poly-Si to SiO₂ (S _SiO) and that the pattern profile changes from an overhung shape to an undercut shape with increasing S _SiO for both systems. Good anisotropy was obtained with RAMRIE when S _SiO is about 20, which is two times as large as that with RIE. Under this condition, a 0.2 µm gate pattern was successfully delineated with RAMRIE. The characteristics of MOS capacitors prepared with RAMRIE and RIE have also been studied, but no etching-induced damage has been observed.