| 摘要 |
PURPOSE:To obtain narrow-width isolation regions with good area efficiency by a method wherein radiant rays are irradiated at parts forming the isolation regions only and lateral diffusion is reduced. CONSTITUTION:In a semiconductor wafer 10 forming a P base layer 3 and an N emitter layer 4, and a P emitter layer 2 on both the upper and the lower surfaces of a substrate 1, respectively Al 5 are arranged at main surface parts corresponding to the parts 6a forming isolation regions. Next, the upper surface of a wafer is covered by a metal mask 7 for irradiating radiant rays 8 at the parts 6a only. The metal mask 7 is formed thin at the parts 7b corresponding to the parts 6a and thick at the other part 7a. Then, perforated P type isolation regions 6 are obtained by forming a temperature gradient between both main surfaces after bombarding infrared rays at the wafer 10. However, Al diffusion speed is fast and little Al diffusion to the parts except the isolation regions occurs. |
