Micro-electromechanical system devices

• US 8,319,254 B2
• Filed: 02/14/2011
• Issued: 11/27/2012
• Est. Priority Date: 02/14/2011
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: Kionix Incorporated (ROHM Co., Ltd.)
• Inventors: Adams, Scott G., Minnick, Andrew J., Blackmer, Charles W., Devoe, Mollie K.
• Primary Examiner(s): Louie, Wai Sing
• Application Number:
  US13/027,209
• Publication Number:
  US 20120205753A1
• Time in Patent Office: 652 Days
• Field of Search: 257/108, 438/50, 438/52
• US Class Current: 257/108
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 3/0008 Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01L 29/747 Bidirectional devices, e.g. triacs
• CPC Class Codes: H01L 29/87 Thyristor diodes, e.g. Shockley diodes, break-over diodes

Abstract

A micro-electromechanical system (MEMS) device includes a substrate, a first beam, a second beam, and a third beam. The first beam includes first and second portions separated by an isolation joint. The first and second portions each comprise a semiconductor and a first dielectric layer. An electrically conductive trace is mechanically coupled to the first beam and electrically coupled to the second portion'"'"'s semiconductor but not the first portion'"'"'s semiconductor. The second beam includes a second dielectric layer. The profile of each of the first second, and third beams has been formed by a dry etch. A cavity separates a surface of the substrate from the first, second, and third beams. The cavity has been formed by a dry etch. A side wall of each of the first, second, and third beams has substantially no dielectric layer disposed thereon, and the dielectric layer has been removed by a vapor-phase etch.

Claims

1. A micro-electromechanical system (MEMS) device, comprising:

a substrate;

a first beam suspended relative to a surface of the substrate, the first beam comprising a first portion and a second portion that are separated by an isolation joint, wherein the first and second portions each comprise a semiconductor and a first dielectric layer, wherein an electrically conductive trace is mechanically coupled to the first beam and electrically coupled to the semiconductor of the second portion but not the semiconductor of the first portion;

a second beam suspended relative to the surface of the substrate, the second beam comprising a second dielectric layer to promote curvature of the second beam; and

a third beam suspended relative to the surface of the substrate;

wherein each of the first, second, and third beams has a profile defining a side wall, the profile of each of the first, second, and third beams having been formed by a dry etch;

wherein a cavity separates the surface of the substrate from the first, second, and third beams, the cavity having been formed by a dry etch; and

wherein a side wall of each of the first, second, and third beams has substantially no dielectric layer disposed thereon, the dielectric layer having been removed by a vapor-phase etch.

2. The MEMS device of claim 1, wherein the electrically conductive trace comprises a metal.

3. The MEMS device of claim 1, wherein the electrically conductive trace comprises a semiconductor.

4. The MEMS device of claim 1, wherein the first dielectric layer is formed by thermal oxidation.

5. The MEMS device of claim 1, wherein the second dielectric layer is formed by thermal oxidation.

6. The MEMS device of claim 1, wherein the dry etch that forms the profile of each of the first, second, and third beams is a plasma, dry etch.

7. The MEMS device of claim 1, wherein the dry etch that forms the cavity between the substrate and the first, second, and third beams is a plasma, dry etch.

8. The MEMS device of claim 1, wherein the third beam consists essentially of a semiconductor.

9. The MEMS device of claim 8, wherein the third beam consists essentially of silicon.

10. The MEMS device of claim 1, wherein the semiconductor of the first beam comprises silicon, and wherein the second and third beams comprise silicon.