| 摘要 |
PROBLEM TO BE SOLVED: To improve the etching anisotropy of silicon nitride by making larger the etch selectivity to silicon and a silicon oxide by making a fluorine compound gas of CH2 F2 , CH3 F, or CHF3 and an inert gas to flow to a dry etching atmosphere. SOLUTION: After a silicon oxide film 12 is formed on a silicon substrate 11, a silicon nitride film 13 is formed on the film 12 and a resist film 14 having an opened element separating area is formed on the film 13. Then the silicon nitride film 13 in the area which is not covered with the resist film 14 is etched. An etching gas composed of CH2 F2 , CH3 F, or CHF3 is introduced to a reduced- pressure atmosphere together with an inert gas composed of an argon gas or helium gas. It is preferable to adjust the etching rate of the silicon nitride layer to 200 nm/min. Thereafter, a field oxide film 15 composed of a silicon oxide is formed by selectively oxidizing the surface of the substrate 11 in the area not covered with the silicon nitride film 13. |
