| 摘要 |
PURPOSE:To eliminate the deterioration in voltage resistance and to attain high integration by a method wherein the surface of an epitaxial layer in a position wherein a diffused layer of P-type or N-type impurities is to be formed is etched prior to the formation of the diffused layer, so as to reduce the thickens of the epitaxial layer sufficiently, and thereafter the introduction of the impurities and heat treatment of high temperature are conducted. CONSTITUTION:Impurities of high concentration having a couductivity type opposite to the one of a semiconductor single-crystal substrate 1 are introduced into the surface of the substrate, and an epitaxial layer 2 having a conductivity type opposite to that of the substrate is formed thick thereon. Next, the surface of the epitaxial layer in a position wherein a diffused layer for element isolation is to be formed is etched to form a recessed portion 4. Then, impurities having the same conductivity type as the substrate are introduced Into a region wherein the recessed portion is formed, and thereafter heat treatment of high temperature is applied to form the diffused layer 3 for element isolation which is deep enough to reach the substrate. On the occasion, the impurities introduced into the surface of the substrate are also diffused by the heat treatment, so as to form a buried layer 5. Subsequently, element formation layers 6 and 7 are formed by diffusion in the epitaxial layer isolated by the diffused layer. Since the time for heat treatment of high temperature can be shortened by this method, the rise up of the buried layer is reduced and the deterioration of voltage resistance can be prevented in the case of an element of high voltage resistance which has a thick epitaxial layer.
|
