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Method of forming trench gate field effect transistor with recessed mesas

  • US 7,504,306 B2
  • Filed: 04/04/2006
  • Issued: 03/17/2009
  • Est. Priority Date: 04/06/2005
  • Status: Active Grant
First Claim
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1. A method of forming a field effect transistor comprising an active area and a termination region surrounding the active area, the method comprising:

  • forming gate trenches extending into a silicon region of a first conductivity type;

    forming a well region of a second conductivity type in the silicon region;

    forming a recessed gate in each gate trench;

    forming a dielectric cap over each gate;

    recessing all exposed surfaces of the well region to form a recess in the well region between every two adjacent trenches such that the recess has sloped walls and a bottom located between a top surface of the dielectric cap and a top surface of the recessed gate; and

    without masking any portion of the active area, performing a zero-degree blanket implant to form a heavy body region of the second conductivity type in the well region between every two adjacent trenches whereby the heavy body region is self-aligned to the gate trenches.

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