Verfahren zur Herstellung von Strukturen mit vergrabenen Oxidbereichen in einem Halbleitersubstrat

A monocrystalline silicon substrate (2) is subjected to the following operations: implantation of doping impurities in a high concentration to form a planar region (42) of a first type (n), selective anisotropic etching in order to hollow out trenches to a depth greater than the depth of the planar region (42), oxidation of the silicon inside the trenches starting a certain distance from the surface of the substrate, until a silicon dioxide plaque (22) is formed, surmounted by residues of strongly-doped silicon, epitaxial growth between and on top of the silicon residues to close the trenches and to bring about a redistribution of the doping impurities into the silicon grown to produce a buried region (42') with low resistivity in an epitaxial layer (23) of high resistivity.