Patent ID: 8404595

Claim:
A plasma processing method for processing a target substrate, which, at least, includes a resist layer having a pattern formed thereon; an etching target layer composed of a silicon dioxide (SiO 2 ) film under the resist layer; and a base layer composed of a single crystalline layer or a silicon nitride (SiN) film under the etching target layer, by using a plasma processing apparatus including a vacuum evacuable processing vessel that accommodates the target substrate therein; a lower electrode disposed in the processing vessel and connected to a first RF power supply applying an RF power of a first frequency for plasma generation and a second RF power supply applying an RF power of a second frequency for ion attraction, the lower electrode also serving as a mounting table for mounting the target substrate thereon; and an upper electrode disposed to face the lower electrode and only connected to a DC supply, the method comprising: loading the target substrate into the processing vessel; supplying a processing gas containing fluorocarbon in the processing vessel; generating a plasma of the processing gas in the processing vessel by applying to the lower electrode the RF power of the first frequency from the first RF power supply and the RF power of the second frequency from the second RF power supply; applying a voltage consisting essentially of a negative DC voltage to the upper electrode; and etching the etching target layer of the silicon dioxide (SiO 2 ) film, by the plasma by using the resist layer as an etching mask, thus forming recesses on the etching target layer, wherein the negative DC voltage has an absolute value ranging from 100 V to 900 V to obtain a high etching rate of the silicon dioxide (SiO 2 ) film and a high etching selectivity of the silicon dioxide (SiO 2 ) film against the base layer of the single crystalline layer or the silicon nitride (SiN) film.