MEMS sensor structure and microfabrication process therefor
First Claim
1. A process for fabricating a micro-electro-mechanical structure having interdigitated projections, said process comprising the steps of:
- providing a first substrate;
etching a cavity within said first substrate;
forming an isolation layer on said first substrate;
providing a second substrate;
doping the top portion of said second substrate to thereby form an etch termination layer;
forming a doped epitaxial layer on the etch termination layer portion of said second substrate such that said etch termination layer portion of said second substrate has a higher doping concentration than said epitaxial layer;
bonding said second substrate to said first substrate such that said epitaxial layer covers said cavity and is bonded to said isolation layer at the periphery of said cavity;
removing the non-termination layer portion of said second substrate from said etch termination layer portion of said second substrate;
removing said etch termination layer portion of said second substrate from said epitaxial layer;
applying photoresist on said epitaxial layer;
patterning said photoresist according to a shape of said micro-electro-mechanical structure;
anisotropically etching through sections of said epitaxial layer disposed over said cavity and revealed through said patterned photoresist to thereby define and release said micro-electro-mechanical structure above said cavity; and
removing said patterned photoresist.
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0 Petitions
Accused Products
Abstract
A micro-electro-mechanical structure including a semiconductor layer mounted to an annular support structure via an isolation layer wherein the semiconductor layer is micromachined to form a suspended body having a plurality of suspension projections extending from the body to the rim and groups of integral projections extending toward but spaced from the rim between said suspension projections. Each projection in said groups has a base attached to the body and a tip proximate the rim. The structure includes a plurality of inward projections extending from and supported on the rim and toward the body. Each such projection has a base attached to the rim and a tip proximate the body; wherein the grouped projections and the inward projections are arranged in an interdigitated fashion to define a plurality of proximate projection pairs independent of the suspension elements such that a primary capacitive gap is defined between the projections of each projection pair. Also, a process is disclosed for fabricating the micro-electro-mechanical structure including the steps of removing a highly doped etch termination layer and thereafter etching through a lightly doped epitaxial layer to thereby define and release the structure.
105 Citations
10 Claims
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1. A process for fabricating a micro-electro-mechanical structure having interdigitated projections, said process comprising the steps of:
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providing a first substrate;
etching a cavity within said first substrate;
forming an isolation layer on said first substrate;
providing a second substrate;
doping the top portion of said second substrate to thereby form an etch termination layer;
forming a doped epitaxial layer on the etch termination layer portion of said second substrate such that said etch termination layer portion of said second substrate has a higher doping concentration than said epitaxial layer;
bonding said second substrate to said first substrate such that said epitaxial layer covers said cavity and is bonded to said isolation layer at the periphery of said cavity;
removing the non-termination layer portion of said second substrate from said etch termination layer portion of said second substrate;
removing said etch termination layer portion of said second substrate from said epitaxial layer;
applying photoresist on said epitaxial layer;
patterning said photoresist according to a shape of said micro-electro-mechanical structure;
anisotropically etching through sections of said epitaxial layer disposed over said cavity and revealed through said patterned photoresist to thereby define and release said micro-electro-mechanical structure above said cavity; and
removing said patterned photoresist. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
determining a minimum capacitive gap between said interdigitated projections of said micro-electro-mechanical structure which are nearest to each other, wherein each projection of said interdigitated projections has a base and a tip at opposite ends;
defining said shape such that each of said projection of said interdigitated projections is proximate to at least one tip of another said projection of said interdigitated projections by a distance substantially equal to said minimum capacitive gap; and
selectively removing said photoresist to reveal bare sections of said epitaxial layer according to said shape.
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Specification