| 摘要 |
PURPOSE:To reduce the unevenness of the punch through voltage of the semiconductor device when an epitaxial laryer is made to grow on a semiconductor substrate and a base region is provided in it to produce a punch through type constant voltage diode by a method wherein the impurity concentration of the base region is made to be higher than that of the epitaxial layer. CONSTITUTION:A P-type layer 2 is formed by epitaxial growth on an N-type Si substrate 1, a P-type impurity ion is implanted in it to high concentration and is heat-treated to form a P<+>-type base region 8 slightly thinner than the thickness of the layer 2. By this way, the impurity concentration of the layer 8 is made to be higher than that of the layer 2, an appointed mash pattern is provided on the region 8 with an SiO2 film 3, and an N-type region 4 reaching to the substrate 1 is formed by diffusion to separate the region 8 to be an island-shape. Then the film 3 is renewed to the film 3 covering the whole surface, and appointed openings are provided in it. A ring-form N<+>-type region 9 is formed by diffusion in the region 8, and a sharrow N-type emitter region 5 is provided in it making the edge part to come in contact with the region 9. The whole surface is covered with a protective film 6 and an opening is prepared in it to stick a base-emitter short circuiting electrode 7 being in contact with the region 5 and the region 9. |
