Method of making a single-crystal-silicon 3D micromirror
First Claim
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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Abstract
First and second n-doped regions are formed at a surface of a p-doped single crystal silicon substrate. An aluminum layer is patterned overlying some of the second n-doped regions to form thermal actuators. A dielectric layer is deposited overlying the patterned aluminum layer and an underlying thermal oxide layer. A metal layer is deposited thereover and patterned to form bond pads to the thermal actuators and to form reflecting mirror surfaces overlying others of the second n-doped regions to form micromirrors. The substrate is etched away from the backside stopping at the first and second n-doped regions. Then the wafer is diced into mirror array chips. Portions of the first n-doped regions are etched away from the frontside to form flexible springs wherein the second n-doped regions covered by the patterned aluminum layer form thermal actuators and wherein the flexible springs connect the micromirrors to the thermal actuators.
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Citations
26 Claims
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1. A method of fabricating a silicon mirror device comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of fabricating a silicon mirror device comprising:
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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 oxide 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 wherein said flexible springs connect said micromirrors to said thermal actuators and wherein each mirror element in each of said mirror array chips comprises one micromirror and four thermal actuators. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification