| 摘要 |
PURPOSE:To make it possible to expand the upper limit of the thickness of an epitaxial layer to a range so that the thickness can be controlled, by providing a high- concentration layer and an embedded layer beneath an embedded oxide film, utilizing the difference in diffusion coefficients of both layers, and forming a channel-cutting region by upheaving diffusion in the succeeding process. CONSTITUTION:Sb is diffused in a P-type substrate 10 to a depth of 2-4mum. Thereafter, P is diffused selectively in order to form a high concentration embedded layer 21. Then, an N-type epitaxial layer 2 is formed so that it comes into a film thickness range of 2-3mum. Silicon etching is performed in order to form an embedded oxide film 6. A film thickness of 1mum is obtained by burning oxidation. Under this state, the position of the bottom surface of the embedded oxide film 6 is separated from the surface of the epitaxial layer 2 by 1.1-1.2mum. When the forming process for the embedded oxide film 6 is finished, the embedded layer 21 is upheaved by about 1mum in a heat treatment process since the diffusion coefficient of the P is larger than the diffusion coefficient of the Sb. When the embedded layer 21 is not present, the layer 2 having the maximum thickness of about 1mum remains beneath the embedded oxide layer 6. Thus the thickness of the epitaxial layer can be expanded to the upper limit of the range so that the film thickness can be controlled.
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