US 6,472,692 B1Granted

Semiconductor device

AssigneeMitsubishi Denki Kabushiki Kaisha

InventorsKatsumi Satoh, Kazuhiro Morishita, Shinji Koga

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Abstract

To suppress spike voltage generated at turn-off operation, a semiconductor device according to the invention comprises a first region composed of a first conductor, a second region composed of a second conductor formed on top of the first region, a third region composed of the first conductor formed on top of the second region and a fourth region composed of the second conductor formed on top of the third region. The second region is comprised of a depletion-layer forming auxiliary layer having a short lifetime and formed in the vicinity of the third region, a tail-current suppression layer having a shorter lifetime than that of the depletion-layer forming auxiliary layer and formed in the vicinity of the first region and a depletion-layer forming suppression layer having a longer lifetime than that of the depletion-layer forming auxiliary layer and formed between the depletion-layer forming auxiliary layer and the tail-current suppression layer.

Claims11

Dependent claims

The semiconductor device comprising:

a first region having a first conductivity type;
a second region having a second conductivity type, said second region being formed on top of said first region;
a third region having said first conductivity type, said third region being formed on
top of said second region;
and
a fourth region having said second conductivity type, said fourth region being formed on top of said third region;
said second region being comprised of a depletion-layer forming auxiliary layer having a short lifetime and formed in the vicinity of said third region;
a tail-current suppression layer having a shorter lifetime than that of said depletion-layer forming auxiliary layer and formed in the vicinity of said first region;
and a depletion-layer forming suppression layer having a longer lifetime than that of said depletion-layer forming auxiliary layer and formed between said depletion-layer forming auxiliary layer and said tail-current suppression layer,
wherein lifetime of said depletion-layer forming suppression layer is formed in such a manner that lifetime on said third region side is shorter than that on said first region side.

7 more elements

Dependencies are inferred from the claim text.