| 摘要 |
A process for forming a resist mask pattern includes the steps of forming a resist layer of organic material in a multilevel resist process on a layer to be etched, and selectively etching a planarizing lower layer used in the resist layer by using an etching gas of oxygen under a plasma condition, in which a compound gas of at least one element selected from the group consisting of B, Si, Ti, Al, Mo, W and S is added to the etching gas. For example, the compound gas comprises BCl3, BH3, TiCl4, S2Cl2, SiCl4 or the like. During the etching, a compound oxide, e.g., B2O3, SiO2 or the like, is deposited on sidewalls of the lower layer to form a protective layer which prevents undercutting.
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