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Power transistor

  • US 7,091,573 B2
  • Filed: 09/18/2003
  • Issued: 08/15/2006
  • Est. Priority Date: 03/19/2002
  • Status: Active Grant
First Claim
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1. A power transistor having at least one trench transistor cell in a semiconductor body, comprising:

  • a drain zone, a drift zone, a channel zone, and a source zone formed in each case successively and substantially horizontally in the semiconductor body;

    the semiconductor body having a trench formed therein with a base and a defined body height opposite a pn junction between said drift zone and said channel zone;

    a first dielectric layer cladding said trench substantially to said body height, and a gate oxide cladding said trench between said body zone and a semiconductor body surface; and

    a field electrode extending in said trench substantially from said trench base to an upper edge of said first dielectric layer, said field electrode being connected to be at a fixed potential or at a source potential;

    a gate electrode disposed substantially between said body height and the semiconductor body surface, said gate electrode being electrically insulated from the semiconductor body by said gate oxide and having a lower edge with a profile, said profile having a horseshoe shape with two jaws projecting at edges thereof and a center between said jaws having an inward bulge in which said field electrode enters beyond said pn junction; and

    a second dielectric layer formed between said gate electrode and said field electrode.

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