Microelectromechanical resonator

Patent metadata

Field	Value
Publication number	US-9712128-B2
Application number	US-201615186510-A
Country	US
Kind code	B2
Filing date	Jun 19, 2016
Priority date	Feb 9, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

In a MEMS device having a substrate and a moveable micromachined member, a mechanical structure secures the moveable micromachined member to the substrate, thermally isolates the moveable micromachined member from the substrate and provides a conduction path to enable heating of the moveable micromachined member to a temperature of at least 300 degrees Celsius.

First claim

What is claimed is:

1. A microelectromechanical system (MEMS) resonator comprising:
a layer of degenerately-doped polycrystalline silicon;
a layer of degenerately-doped single-crystal silicon; and
a layer of piezoelectric material sandwiched between the degenerately-doped polycrystalline silicon layer and the degenerately-doped single-crystal silicon layer.

2. The MEMS resonator of claim 1 wherein the layer of piezoelectric material comprises aluminum nitride.

3. The MEMS resonator of claim 1 wherein the degenerately-doped single-crystal silicon layer is at least 10 times thicker than the layer of piezoelectric material.

4. The MEMS resonator of claim 1 wherein the layers of degenerately-doped polycrystalline silicon, degenerately-doped single-crystal silicon and piezoelectric material form a resonator body and one or more tethering structures that mechanically couple the resonator body to anchoring points within a field area.

5. The MEMS resonator of claim 4 wherein the layer of degenerately-doped polycrystalline silicon comprises a first electrode within the resonator body and a first conductive path within each of the one or more tethering structures to enable the first electrode to be electrically coupled, through at least one of the tethering structures, to a first node of a voltage source external to the resonator.

6. The MEMS resonator of claim 5 wherein the layer of degenerately-doped single-crystal silicon comprises a second electrode within the resonator body and a second conductive path within each of the one or more tethering structures to enable the second electrode to be electrically coupled to a second node of the voltage source external to the resonator such that a voltage generated by the voltage source yields an electrostatic potential across the layer of piezoelectric material.

7. The MEMS resonator of claim 5 wherein the one or more tethering structures comprise at least two tethering structures that enable the first electrode to be coupled between the first node of the voltage source external to the resonator and a second node of the voltage source external to the resonator such that a potential difference is applied across the first electrode.

8. The MEMS resonator of claim 5 wherein the first electrode is patterned to form a resistive region with sufficient resistance to heat the resonator body to a temperature of at least 300 degrees Celsius when a current is conducted through the resistive region.

9. The MEMS resonator of claim 5 wherein the one or more tethering structures thermally isolate the resonator body from the anchoring points and exhibit sufficient electrical resistivity to enable heating of the resonator body to a temperature of at least 300 degrees Celsius when a joule heating current is conducted through the one or more tethering structures.

10. The MEMS resonator of claim 5 wherein the one or more tethering structures comprise two tethering structures coupled to the first electrode at opposite sides of the resonator body.

Assignees

• SiTime Coporation
• Sitime Corp

Inventors

• Doll Joseph C
• Miller Nicholas
• Grosjean Charles I
• Hagelin Paul M
• Hill Ginel C

Classifications

• H03H2009/02181

  by application of heat from a heat source · CPC title

• H03H9/125 Primary

  Driving means, e.g. electrodes, coils · CPC title

• H03H9/1057

  for microelectro-mechanical devices · CPC title

• H03H2009/02307

  Dog-bone-like structure, i.e. the elongated part of the "bone" is doubly clamped · CPC title

• H03H2003/027

  the resonators or networks being of the microelectro-mechanical [MEMS] type · CPC title