Patent ID: 9613824
Date: 2017-04-04
CPC Classifications: H01L

Claim:
1. A method of simultaneously etching a first region and a second region of a workpiece, wherein the first region includes a multi-layer film in which silicon oxide films and silicon nitride films are alternately stacked, the second region includes a silicon oxide film having a film thickness thicker than a film thickness of the silicon oxide films in the first region, and the workpiece includes a mask for providing openings on the first region and the second region, the method comprising: a first step of generating a plasma of a first processing gas which contains a fluorocarbon gas and a hydrofluorocarbon gas, in a processing container of a plasma processing apparatus in which the workpiece is prepared; and a second step of generating a plasma of a second processing gas which contains a hydrofluorocarbon gas and a nitrogen gas, in the processing container, wherein a plurality of sequences each of which includes the first step and the second step are performed, the first step and the second step are consecutively performed, an execution period for the second step includes a first period including a start point of the second step, a second period subsequent to the first period, and a third period which is subsequent to the second period and includes an end point of the second step, the second processing gas further contains a hydrogen gas in the second period, and a ratio of a flow rate of the hydrogen gas to a flow rate of the second processing gas in the first period immediately after an execution period for the first step and the third period immediately before the execution period for the first step is set to be smaller than the ratio of the flow rate of the hydrogen gas to the flow rate of the second processing gas in the second period.