| 摘要 |
PURPOSE:To lower the cost of the thyristor device by forming an isolation band region, emitter layer and further base layer on a thick semiconductor substrate beforehand when forming the thyristor, reducing the thickness of the emitter layer partly, correcting the impurity density thereat, and thereby enabling use of a substrate of large diameter. CONSTITUTION:A p type emitter layer 11 is diffused on the back surface of an n type Si substrate 9 formed to be thicker, a p type isolation band 10 reaching the layer 11 is diffused from the surface, is diffused in an island shape 9. A p type base region 4 is then diffused in the island-shaped substrate 9, and a cutting line 12 is lapped from the back surface to become desired impurity density in the layer 11. Thereafter, an n type emitter region 5 is diffused in the region 4, electrodes 6, 7 are attached to the regions 5, 4 respectively, and an electrode 8 is coated through a p<+> type layer 13 on the back surface of the layer 11. Thus, the thermal stress to the substrate 9 can be suppressed to a minimum limit on the midway of the step, and a plurality of thyristors can be formed on a substrate of large diameter. |
