a method of forming separate buried layers close to one another in a semiconductor component . this method includes the steps of forming , by implantation , doped areas in a semiconductor substrate ; performing an anneal just sufficient to eliminate crystal defects resulting from the implantation ; depositing an epitaxial layer ; digging trenches delimiting each implanted region ; and annealing the buried layers , the lateral diffusion of which is blocked by said trenches , said trenches being deeper than the downward extension of the diffusions resulting from said implantations .