METHOD OF PLASMA PROCESSING

摘要

A plasma is generated from fluorocarbon-containing gas introduced into a process chamber of an etching device to etch a SiO2 layer deposited on a wafer. The contents of etchant and by-products in the plasma are measured by infrared laser absorption analysis. The measured contents are compared with predetermined contents of the etchant and by-products corresponding to an increase in aspect ratio of contact holes. The amount of O2 to be added is adjusted so that the measured contents may agree with the predetermined contents. The amount of O2 added to the process gas is continuously increased with the increase in the aspect ratio. Contact holes can be formed in the SiO2 layer without damage to the photoresist layer while preventing etch stops.