MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To enable to perform selective etching of a silicon nitride film having the groundwork of a silicon oxide film by a method wherein fluorine ions are selectively implanted previously to the silicon nitride film. CONSTITUTION:A photo resist film 15 applied on the silicon nitride film 14 is selectively exposed and developed to form opening parts 16, 17a, 17b, 18a, 18b. Then, fluorine ions are implanted into the silicon nitride film 14 from the opening parts 16, 17a, 17b, 18a, 18b using the photo resist film 15 as the mask, and then the silicon nitride film 14 is etched according to reactive ion etching. Then the photo resist film 15 is exfoliated, a photo resist film 17 is adhered newly, and exposure and development are performed selectively. Then, the silicon oxide film 13 is etched according to reactive ion etching using the photo resist film 17 and the silicon nitride film 14 as the mask, and openings are formed in the silicon oxide film 13 on a base diffusion layer 12.