Plasma etching method for selectively etching silicon oxide with respect to silicon nitride

Abstract

An etching method is provided for selectively etching a first region of silicon oxide with respect to a second region of silicon nitride by performing plasma processing on a target object including the first region and the second region. In the etch method, first, a plasma of a processing gas including a fluorocarbon gas is generated in a processing chamber where the target object is accommodated. Next, the plasma of the processing gas including the fluorocarbon gas is further generated in the processing chamber where the target object is accommodated. Next, the first region is etched by radicals of fluorocarbon contained in a deposit which is formed on the target object by the generation and the further generation of the plasma of the processing gas containing the fluorocarbon gas. A high frequency powers used for the plasma generation is smaller than a high frequency power used for plasma further generation.