| 摘要 |
PURPOSE:To provide a narrow separating groove by separating an etching resistant film and an oxidation resistant film to uniformly isotropically etch the films by dry etching. CONSTITUTION:A thermal oxide film 2, an Si3N4 film 3 and an SiO2 film 4 are superposed on an N-type Si substrate 1, and etched by RIE to open a hole 5. It is covered with the film 2, a CVD Si3N4 film 7 is superposed, etched by RIE, and the film 7 remains on the sidewall. The whole surface is again covered with an SiO2 film 8, etched by RIE, and remains only on the sidewall. With the films 4, 8 as masks it is isotropically etched by microwave discharge with CF4+O2. Then, even a gap of the film 8 of 0.2um or thinner can be preferably etched to obtain a narrow element separating groove. Then, it is oxidized under high pressure to insulate and separate an element region 10 of the substrate 1 by an oxide film 11 from the substrate.
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