Patent ID: 7351665

Claim:
A plasma etching method of forming a hole by an etching process in a silicon oxide film through a mask, comprising: forming said silicon oxide film; and conducting an etching process through said mask using etching gases containing fluorocarbon gasses, respectively, under a condition that the fluorocarbon gas used in an initial period of the etching process and the fluorocarbon gas used in a final period of the etching process contain no hydrogen and contain oxygen, and the C/F ratios of the fluorocarbon gasses used in the initial period and the final period are within a range of 5/8-2/3, and a condition that the fluorocarbon gas used in an intermediate period of the etching process contains no hydrogen and contains oxygen, and the C/F ratio of the fluorocarbon gas used in the intermediate period is 1/2 or lower so as to form said hole with a diameter of 0.13 μm or smaller and an aspect ratio of 15 or higher in said silicon oxide film, wherein said mask is made of amorphous carbon.