| 摘要 |
PURPOSE:To permit an Si3N4 film to be selectively etched without forming any undercut, by providing a step of forming a photoresist with an opening formed in a predetermined pattern, and a step of effecting a reactive ion etching. CONSTITUTION:An SiO2 film 2 is formed on a silicon substrate 1 by thermal oxidation, and an Si3N4 film 3 is formed on the film 2. An SiO2 film 10 is formed by CVD or sputtering. Thereafter, a photoresist 11 is applied in a predetermined pattern. A reactive ion etching (RIE) is effected in an atmosphere formed by mixing a Freon gas (CF4 gas, for example) and hydrogen to etch the SiO2 film 10. Then, RIE is effected in an atmosphere formed by mixing CF4 gas and oxygen. The Si3N4 film 3 is thereby etched within several tens of minutes. Although the photoresist 11 is completely etched away during the period of time, the SiO2 films 2, 10 are left as they are. |
