Fast recovery reduced p-n junction rectifier
First Claim
1. A rectifier, comprising:
- a n-type epitaxial semiconductor substrate;
a plurality of first p-type semiconductor regions disposed in said n-type epitaxial semiconductor substrate;
a second p-type semiconductor layer disposed in said n-type epitaxial semiconductor substrate and separated into a plurality of segments by said plurality of first p-type semiconductor regions, wherein said second p-type semiconductor layer has a smaller depth than each first p-type semiconductor region, wherein said doping concentration of said first p-type semiconductor is higher than said second p-type semiconductor; and
a third p-type semiconductor layer disposed above both said plurality of first p-type semiconductor regions and said second p-type semiconductor layer, wherein said third p-type semiconductor layer has smaller depth than said second p-type semiconductor layer and higher doping concentration than each first p-type semiconductor region.
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Abstract
A fast recovery rectifier structure with the combination of Schottky structure to relieve the minority carriers during the forward bias condition for the further reduction of the reverse recovery time during switching in addition to the lifetime killer such as Pt, Au, and/or irradiation. This fast recovery rectifier uses unpolished substrates and thick impurity diffusion for low cost production. A reduced p-n junction structure with a heavily p-type doped thin film is provided to terminate and shorten the p-n junction space charge region. This reduced p-n junction with less total charge in the p-n junction to further improve the reverse recovery time. This reduced p-n junction can be used alone, with the traditional lifetime killer method, with the Schottky structure and/or with the epitaxial substrate.
30 Citations
15 Claims
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1. A rectifier, comprising:
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a n-type epitaxial semiconductor substrate; a plurality of first p-type semiconductor regions disposed in said n-type epitaxial semiconductor substrate; a second p-type semiconductor layer disposed in said n-type epitaxial semiconductor substrate and separated into a plurality of segments by said plurality of first p-type semiconductor regions, wherein said second p-type semiconductor layer has a smaller depth than each first p-type semiconductor region, wherein said doping concentration of said first p-type semiconductor is higher than said second p-type semiconductor; and a third p-type semiconductor layer disposed above both said plurality of first p-type semiconductor regions and said second p-type semiconductor layer, wherein said third p-type semiconductor layer has smaller depth than said second p-type semiconductor layer and higher doping concentration than each first p-type semiconductor region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A semiconductor device, comprising:
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a n-type epitaxial semiconductor substrate; a plurality of first p-type semiconductor regions disposed in said n-type epitaxial semiconductor substrate; a second p-type semiconductor layer disposed in said n-type epitaxial semiconductor substrate and separated into a plurality of segments by said plurality of first p-type semiconductor regions, wherein said second p-type semiconductor layer has a smaller depth than each first p-type semiconductor region, wherein said doping concentration of said first p-type semiconductor is higher than said second p-type semiconductor; and a third p-type semiconductor layer disposed above both said plurality of first p-type semiconductor regions and said second p-type semiconductor layer, wherein said third p-type semiconductor layer has smaller depth than said second p-type semiconductor layer and higher doping concentration than each first p-type semiconductor region. - View Dependent Claims (14, 15)
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Specification