the present invention relates to a plasma etching method and apparatus , and more particularly to a plasma etching method and apparatus which are well suited for etching the samples of semiconductor device substrates , etc . in cooling a sample to a temperature not higher than 0 ° c . which is a minimum temperature of water and subjecting the sample to an etching process with a gas plasma , an acceleration voltage which accelerates ions in the gas plasma toward the sample is repeatedly changed , whereby in a process based on low - temperature etching , an etching process producing no residue , being anisotropic and being highly selective is realized .