| 摘要 |
PURPOSE:To obtain the semiconductor device containing a lateral P-N-P transistor having high hFE, high withstand voltage between a collector and an emitter and low Early's effect without increasing the number of processes of manufacture by a method wherein, after a P-type low density region has been formed, a P-type high density region is formed by diffusing P-type impurities using the insulating film formed on the side face of an aperture part as a mask. CONSTITUTION:An insulating film 20 is formed on one main surface of an N-type semiconductor substrate 3, and aperture parts 21, 22 and the like are formed on the prescribed position by selectively performing an anisotropic dry-etching on the insulating film 20. Then, a P-type low density region 24 is formed by ion-implanting P-type impurities in said aperture parts 21 and 22, and after the second insulating film 25 has bee formed on the side face of said insulating film 20, P-type high density regions 6 and 7 are formed by diffusing P-type impurities using the insulating films 20 and 25 as a mask. For example, an N-type buried region 2, an N-type epitaxial layer 3, a P-type isolation region 4 and an N-type high density region 5 are formed on a P-type semiconductor substrate 1. Then, an oxide film 20 is formed, and after aperture parts 21, 22 and the like have been formed, a P-type low density region 24 is formed by ion-implanting boron. Subsequently, an SiO2 film 25 is formed on the side face of the oxide film 20, boron is diffused, and a P-type high density region, which is turned to an emitter region 6 and a collector region 7, is formed by diffusing boron.
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