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Method of making a single-crystal-silicon 3D micromirror

  • US 7,091,057 B2
  • Filed: 12/19/2003
  • Issued: 08/15/2006
  • Est. Priority Date: 12/19/2003
  • Status: Expired due to Fees
First Claim
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1. A method of fabricating a silicon mirror device comprising:

  • providing a p-doped single crystal silicon substrate wafer having a frontside and a backside;

    forming first and second n-doped regions at a surface of said substrate wherein said first n-doped regions have a first thickness and said second n-doped regions have a second thickness larger than said first thickness;

    forming a hard mask on said backside of said wafer;

    depositing a silicon oxide layer on said frontside of said wafer;

    depositing an aluminum layer on said silicon oxide layer and patterning said aluminum layer to leave aluminum on said silicon oxide layer overlying some of said second n-doped regions to form thermal actuators;

    depositing a dielectric layer overlying said patterned aluminum layer and said silicon oxide layer and patterning said dielectric layer to form a mask for flexible springs over portions of said first n-doped regions;

    depositing and patterning a metal layer overlying said dielectric layer to form bond pads to said thermal actuators contacting said patterned aluminum layer through openings in said dielectric layer and to form reflecting mirror surfaces overlying others of said second n-doped regions not covered by said patterned aluminum layer to form micromirrors;

    thereafter etching away said substrate from said backside of said wafer stopping at said first and second n-doped regions;

    thereafter dicing said wafer into mirror array chips;

    thereafter etching away said dielectric layer from said frontside of said wafer to expose portions of said first n-doped regions; and

    etching away from said frontside said exposed first n-doped regions not covered by said mask to form flexible springs in said first n-doped regions wherein said second n-doped regions covered by said patterned aluminum layer form thermal actuators and said wherein said flexible springs connect said micromirrors to said thermal actuators.

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