Method of plasma processing

摘要

An SiO₂ film layer formed at a wafer placed inside a process chamber of an etching device is etched by generating plasma from a process gas containing fluorocarbon which has been introduced into the process chamber. The contents of an etchant and the byproducts are measured through infrared laser absorption analysis. The individual contents thus measured are compared with the contents of the etchant and the byproducts in the plasma corresponding to the increase in the aspect ratio of a contact hole set in advance. The quantity of O₂ added into the process gas is adjusted to match the measured contents with the predetermined contents. The quantity of O₂ added into the process gas is continuously increased as the aspect ratio becomes higher. As a result, a contact hole is formed at the SiO₂ film layer without damaging the photoresist film layer or inducing an etch stop.