PLASMA ETCHING METHOD, PLASMA ETCHING APPARATUS AND COMPUTER-READABLE STORAGE MEDIUM

A plasma etching method is provided to perform a plasma etching on a silicon oxide film or a silicon nitride film formed below an amorphous carbon film by using a pattern of the amorphous carbon film as a final mask in a multilayer mask including a photoresist layer having a predetermined pattern, an organic bottom anti-reflection coating (BARC) film formed below the photoresist layer, an SiON film formed below the BARC film, and the amorphous carbon film formed below the SiON film. An initial mask used at the time when the plasma etching of the silicon oxide film or the silicon nitride film is started is under a state in which the SiON film remains on the amorphous carbon film and a ratio of a film thickness of the amorphous carbon film to a film thickness of the residual SiON film is smaller than or equal to about 14.