| 摘要 |
PURPOSE:To prevent the circumference of a mesa groove from yielding and thereby to enhance surface stability by a method wherein a second semiconductor layer of one conductivity type is formed in a mesa groove provided in a first semiconductor substrate of the same conductivity type and the second semiconductor layer is so formed that it is in contact with an insulating layer provided on the primary surface of the first semiconductor layer in the vicinity of the mesa groove. CONSTITUTION: An opening for diffusion is provided in an insulating film 12, and the insulating film 12 that remains after the formation of the opening serves as a mask for the selective diffusion of a p-type impurity for the formation of a low-resistivity P<+>-type region 13. The insulating film 12 is then removed and another insulating film is formed anew to cover the entire surface of a P-type semiconductor layer 10. A resist pattern is formed wherein a plurality of low-resistivity p<+>-type regions 13 constitute a unit. A process follows wherein the resist pattern serves as a mask for the selective removal of a nitride film 15 and oxide film 14. After the removal of the nitride film 15 and oxide film 14 by using the resist pattern, the nitride film 15 and oxide film 14 that remain serve as a mask wherewith a mesa groove 16 is provided in the P-type semiconductor layer 10, which results in a mesa region wherein the semiconductor layer 10 is surrounded by the mesa groove 16. A uniformly thick semiconductor layer 17 doped with an N-type impurity is formed with its conductivity type same as that of a semiconductor substrate 9. It is so designed that the P-N junction constituted between the semiconductor layer 17 doped with the Ntype impurity and P-type semiconductor layer 10 terminates at a location under a surface oxide film 14.
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