Method of forming capacitive MEMS sensor devices

Patent metadata

Field	Value
Publication number	US-10107830-B2
Application number	US-201615148086-A
Country	US
Kind code	B2
Filing date	May 6, 2016
Priority date	Feb 27, 2013
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

A method of forming a capacitive micro-electro-mechanical system (MEMS) sensor device includes at least one capacitive MEMS sensor element with at least one capacitive MEMS sensor cell. A patterned dielectric layer including a thick dielectric region and a thin dielectric region is formed on a top side of a first substrate. A second substrate is bonded to the thick dielectric region to provide at least one sealed micro-electro-mechanical system (MEMS) cavity. The second substrate is thinned to reduce a thickness of said second substrate to provide a membrane layer. Vias are etched through the membrane layer and said thick dielectric region extending into the first substrate to form embedded vias. A dielectric liner which lines the embedded vias is formed within the first substrate. The embedded vias are filed with electrically conductive TSV filler material to form a plurality of through-substrate vias (TSVs), said plurality of TSVs extending to at least a top of said membrane layer. A patterned metal cap layer including metal caps is formed on top of said plurality of TSVs. Trenches are etched through regions of the membrane layer for releasing a first portion of the membrane layer over said MEMS cavity to provide a MEMS electrode and to define a fixed electrode. A third substrate including an inner cavity and outer protruding portions framing said inner cavity is bonded to the thick dielectric. The protruding portions are bonded to the thick dielectric region and, together with said first substrate vacuum, seals said MEMS electrode. The plurality of TSVs on a bottom side of said first substrate are exposed.

First claim

What is claimed is:

1. A method of forming a capacitive micro-electro-mechanical system (MEMS) sensor device including at least one capacitive MEMS sensor element with at least one capacitive MEMS sensor cell, comprising:
forming a patterned dielectric layer including a thick dielectric region and a thin dielectric region on a top side of a first substrate;
bonding a second substrate to said thick dielectric region to provide at least one sealed micro-electro-mechanical system (MEMS) cavity;
thinning said second substrate to reduce a thickness of said second substrate to provide a membrane layer;
etching vias through said membrane layer and said thick dielectric region extending into said first substrate to form embedded vias;
forming a dielectric liner which lines said embedded vias within said first substrate;
filling said embedded vias with electrically conductive TSV filler material to form a plurality of through-substrate vias (TSVs), said plurality of TSVs extending to at least a top of said membrane layer;
forming a patterned metal cap layer including metal caps on a top of said plurality of TSVs;
etching trenches through regions of said membrane layer for releasing a first portion of said membrane layer over said MEMS cavity to provide a MEMS electrode and to define a fixed electrode;
bonding a third substrate including an inner cavity and outer protruding portions framing said inner cavity, wherein said protruding portions bond to said thick dielectric region and together with said first substrate vacuum seals said MEMS electrode, and
exposing said plurality of TSVs on a bottom side of said first substrate.

2. The method of claim 1 , wherein said bonding said second substrate comprises bonding said membrane layer of a semiconductor on insulator (SOI) substrate having a handle opposite said membrane layer and a buried dielectric layer in between said handle and said membrane layer; and said thinning said second substrate comprises removing said handle, further comprising removing said buried dielectric layer said filling said embedded vias.

3. The method of claim 1 , wherein said bonding said second substrate and said bonding said third substrate both comprise vacuum fusion bonding.

4. The method of claim 1 , wherein said forming a patterned dielectric layer comprises a high pressure oxidation (HiPOx) growth process.

5. The method of claim 1 , wherein said third substrate comprises a silicon wafer.

6. The method of claim 1 , wherein said TSV filler material comprises copper, further comprising forming protruding TSV tips for said plurality of TSVs that protrude from said bottom side of said first substrate.

7. The method of claim 1 , wherein said first substrate has a resistivity less than or equal to (≤)0.1 Ω-cm, further comprising a patterned metal layer on a bottom side of said first substrate, wherein said first substrate provides a third electrode for said capacitive MEMS sensor cell to enable 3 dimensional (3D) capacitive sensing for said capacitive MEMS sensor device.

8. The method of claim 1 , wherein said capacitive MEMS sensor device includes a plurality of said capacitive MEMS sensor elements, wherein each of said plurality of capacitive MEMS sensor elements include a plurality of said capacitive MEMS sensor cells, and wherein said capacitive MEMS sensor elements are individually addressable by contacting one of said plurality of TSVs.

9. The method of claim 8 , wherein each of said plurality of capacitive MEMS sensor cells in each of said plurality of capacitive MEMS sensor elements are connected in parallel by said membrane layer which couples together said MEMS electrodes.

10. A method of forming a capacitive micro-electro-mechanical system (MEMS) sensor device including at least one capacitive MEMS element with at least one capacitive MEMS sensor, comprising:
forming a patterned dielectric layer including a thick dielectric region and a thin dielectric region on a top side of a first substrate;
bonding a membrane layer of a semiconductor on insulator (SOI) substrate having a handle opposite said membrane layer and a buried dielectric layer in between said handle and said membrane layer to said thick dielectric region to provide said MEMS cavity;
removing said handle of said SOI substrate;
etching vias through said membrane layer and said thick dielectric region extending into said first substrate to form embedded vias;
forming a dielectric liner which lines said embedded vias within said substrate;
filling said embedded vias with electrically conductive TSV filler material to form a plurality of through-substrate vias (TSVs), said plurality of TSVs extending to at least a top of said membrane layer;
forming a patterned metal cap layer including metal caps on a top of said plurality of TSVs,
etching trenches through regions of said membrane layer for releasing a first portion of said membrane layer over said MEMS cavity to provide a MEMS electrode and to define a fixed electrode;
bonding a third substrate including an inner cavity and outer protruding portions framing said inner cavity, wherein said protruding portions bond to said thick dielectric region and together with said first substrate vacuum seals said MEMS electrode, and
exposing said plurality of TSVs on a bottom side of said first substrate.

11. The method of claim 10 , wherein said bonding said membrane layer and said bonding said third substrate both comprise vacuum fusion bonding.

Assignees

• Texas Instruments Inc

Inventors

• Wygant Ira Oaktree
• Johnson Peter B

Classifications

• B81C1/00301

  Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias · CPC title

• G01P15/125 Primary

  by capacitive pick-up · CPC title

• H03H9/2468

  Tuning fork resonators · CPC title

• H04R19/005

  using semiconductor materials · CPC title

• B81C2203/0109

  Bonding an individual cap on the substrate · CPC title