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Semiconductor device including a bipolar structure

  • US 5,981,981 A
  • Filed: 09/02/1997
  • Issued: 11/09/1999
  • Est. Priority Date: 10/13/1993
  • Status: Expired due to Fees
First Claim
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1. A semiconductor device comprising a semiconductor body having a pair of major surfaces and a pair of main electrodes being connected to said pair of major surfaces respectively, said semiconductor body including a bipolar structure, wherein:

  • said bipolar structure has a first semiconductor layer of first conductivity type, second and third semiconductor layers of second conductivity type, and a fourth semiconductor layer of first conductivity type being successively stacked from first to second ones of said pair of major surfaces, said third semiconductor layer having a thickness L, wherein said fourth layer is separated into portions having centers, said centers being each separated by a predetermined distance;

    the concentration of a second conductivity type impurity in said second semiconductor layer is higher than that in said third semiconductor layer; and

    said bipolar structure further comprises,a semiconductor region having a shorter carrier lifetime than that in said second semiconductor layer,said semiconductor region is selectively formed to have a distance D from another semiconductor region and a width W along said pair of major surfaces to be at least partially overlapped with or to be adjacent to said second semiconductor layer, anda relative distance value D/L equal to the distance D divided by the thickness L and a relative width W/L equal to the width W divided by the thickness L defining a two-dimensional space, wherein said distance D, said width W, and said thickness L have respective values within a region of the two-dimensional space bounded by, but not containing, a first segment having respective coordinates (0, 0.12) and (0.22, 0.44) and a second segment having respective coordinates (0,0) and (0.22,0), anda combined distance of said distance D and said width W being less than said predetermined distance of respective portions of the fourth semiconductor layer.

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