| 摘要 |
PURPOSE:To eliminate the suppression of the spreading of a depletion layer due to the effect of wiring in a high-withstand voltage part and to contrive the improvement of the withstand voltage by a method wherein a high-concentration buried layer is formed up to the whole surface of an isolation wall in the low-withstand voltage part without forming the high-concentration buried layer in the vicinity of the surface of the high-withstand voltage part. CONSTITUTION:The first main surface of a semiconductor substrate 21 is anisotropically etched using an insulating film 22 as a mask to form a plurality of grooves or recesses 23 having the desired depth. After the film 22 is removed, first V-shaped grooves 25 are formed on the bottom surfaces of the recesses 23 using a new insulating film 24 as a mask. After the film 24 is removed, an impurity 26 having the same conductive type as that of the substrate 21 is diffused in the main surface of the substrate 21. The desired region on the main surface side is removed by performing an Si-anisotropic etching providing an insulating film 27 as a mask on the substrate 21 to form second V-shaped grooves 28. An insulating film 30 is formed in the first main surface side of the substrate 21 to form a supporting member layer in a thickness in the same degree as that of the substrate 21. The substrate 21 is removed by polishing or etching until tip ends of the grooves 28 are exposed from an opposite main surface.
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