JPS5567141A - Method for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE: To obtain a diffusion opening of accurate dimensions, by producing an anti-oxidation film only on the impurity diffused region of a semiconductor substrate, surrounding the film with an oxide film and using a photoresist film and a selective photomask to remove only the anti-oxidation film.

CONSTITUTION: An anti-oxidation film 5 is produced only on the impurity diffused region of a semiconductor substrate 1. The film 5 is used as a mask to perform heat treatment to grow an oxide film 2a on both the sides of the film 5. The oxide film 2a extends into the surface part of the substrate 1. A negative photoresist film 6 is coated on the total surface of the films 5, 2a which form a step. A selective photomask 7 is overlapped on the film 6 so that a light interception part 71 is located over the film 5 and a light transmission part 72 is located over the film 2a. The light interception part 71 is provided with a width a+2α which is determined in consideration of the width (a) of the film 5 and the deviation α of the mask. Exposure is effected to transmit light around into the space between the film 6 and the mask 7 to irradiate the light upon only the film 6 over the other 2a. Development is effected to remove the film 6 from the other 5. The exposed film 5 is etched to make a diffusion opening of the same width (a) as the film 5.

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