| 摘要 |
PURPOSE:To reduce an accident of short circuit of junction under a bird's beak and to lessen the non-uniformity in a current amplification factor of a transistor by a method wherein the bird's beak occurring in the end portion of an insulating film is etched beforehand from above an epitaxial layer to make it recede, before a process of forming an impurity diffusion layer is implemented. CONSTITUTION:A silicon nitride film 18 is formed selectively in a region positioned on a buried layer on the surface of an epitaxial layer, and an N-type epitaxial layer 15 is etched to the depth about half of the thickness of the layer, with said film used as a mask, so as to form a groove. Next, a channel stopper 13 is formed by ion-implanting boron into the groove. Subsequently, the part of the N-type silicon epitaxial layer which is not covered with the silicon nitride film 18 is oxidized selectively to form an isolated insulation film 14. Then, after the silicon nitride film 18 is removed, the fore end portion of a bird's beak 14A located in the end portion of the isolated insulation film on the epitaxial layer 15 is made to recede before an element is formed in the N-type epitaxial layer 15. This method can be accomplished simply by etching the whole surface lightly by using a solution of a hydrofluoric acid, for instance.
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