Abstract of the Disclosure

In the fabrication of semiconductor devices involving the use of a silicon dioxide type mask for control of the diffusion of impurities, fabrication of patterns of openings in the oxide mask on the surface of a semiconductive body substrate is achieved by the following steps:

(1) expose the semiconductive body to a direct current plasma discharge in a gaseous mixture of oxygen and silicon tetrabromide in such proportions as to form a silicon dioxide type coating;
(2) bombard the oxide coating with kev. electrons according to the pattern of windows desired;
(3) expose the oxide coating to an alkaline hydroxide solution, until the coating is selectively dissolved in accordance with the desired pattern of openings therein.

• a flow diagram of the method accordance with this invention.

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3,156,591  11/1964  Hale et al
3,471,291  10/1969  Schaefer