| 摘要 |
PURPOSE:To form a diffused region having low resistance value in a boundary between a semiconductor substrate and an epitaxial layer of the upper layer of the substrate by polishing the second main surface of the substrate to form a main surface of the state isolated into a plurality of islands via insulating films. CONSTITUTION:With mask layers 27, 28 by an SiO2 film as masks isolated slots 29 are formed by anisotropic etching. A low withstand element semiconductor region which contains N<+> type diffused layer 24 and a high withstand element semiconductor region which does not contain N<+> type diffused layer are isolated by the slots 29. Then, after the layers 27, 28 are removed, an SiO2 film 30 is formed as an insulating film by thermal oxidizing, and a polycrystalline silicon layer 31 of the same degree of thickness as a silicon semiconductor substrate 23 is further formed as a polycrystalline semiconductor layer on the upper surface of the film 30. Then, the main surface 22 of the substrate 23 is polished, thereby formed the main surface 30 of the state completely isolated at the substrate 23 into a plurality of island regions via the insulating films 32. |
