Method for fabricating a semiconductor unit

摘要

The invention provides a method for fabricating a semiconductor unit, in which the following steps are carried out: forming an insulator layer (2) on a semiconductor substrate (1); selectively forming an oxidation-preventing film (3) on the surface of the insulator layer (2); depositing polycrystalline silicon (9) on the entire surface of the substrate (1), including the oxidation-preventing film (3); selectively etching the polycrystalline silicon (9), so that the polycrystalline silicon remains only around the sides of the oxidation-preventing film (3), by an etching process which proceeds in a direction perpendicular to the surface of the substrate (1); introducing ions as impurities to prevent an inversion of the substrate (1), the mask employed being formed by the oxidation-preventing film (3) and the polycrystalline silicon (8) which remains around it; and forming an area-insulating film (6) which contains an oxide of the polycrystalline silicon (9), by oxidation of the surface of the substrate (1). The process according to the invention provides greater compactness and greater reliability of the elements. <IMAGE>