| 摘要 |
PURPOSE:To obtain a mask pattern having a highly accurate minute opening by a method wherein a silicon oxide film is formed between a silicon nitride film and a polycrystalline silicon film while a silicon oxide film pattern is formed by oxidizing the polycrystalline film pattern. CONSTITUTION:A silicon nitride film 31, a silicon oxide film 32 and a polycrystalline silicon film 33 are formed in succession on a silicon substrate 30. A resist film is formed on the silicon film 33; it is patterned; a resist pattern 34 having an opening 34a is formed. The silicon film 33 is etched by using the pattern 34 as a mask; a polycrystaline silicon film pattern 43 having an opening 43a with a width L11 is formed. The pattern 43 is thermally oxidized in an atmosphere of oxygen, and a silicon oxide film pattern 53 is formed. Because, during this process, the pattern 53 is supplied with oxygen also from the silicon film 32 under it, side walls of an opening 53a become straight in the upward and downward direction. The silicon film 32 is etched, and a silicon oxide film pattern 42 is formed.
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