MEMS device with micromachined thermistor

Patent metadata

Field	Value
Publication number	US-9677948-B1
Application number	US-201514681848-A
Country	US
Kind code	B1
Filing date	Apr 8, 2015
Priority date	Sep 9, 2011
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A micromachined apparatus includes micromachined thermistor having first and second ends physically and thermally coupled to a substrate via first and second anchor structures to enable a temperature-dependent resistance of the micromachined thermistor to vary according to a time-varying temperature of the substrate. The micromachined thermistor has a length, from the first end to the second end, greater than a linear distance between the first and second anchor structures.

First claim

What is claimed is:

1. A microelectromechanical system (MEMS) device comprising:
a substrate;
a microelectromechanical resonator secured to the substrate at a first location;
a micromachined thermistor having first and second ends secured to the substrate at respective second and third locations, and having a length from the first end to the second end greater than a linear distance between the second and third locations, the micromachined thermistor being thermally coupled to the microelectromechanical resonator to enable a temperature-dependent resistance of the micromachined thermistor to vary according to a time-varying temperature of the microelectromechanical resonator; and
circuitry electrically coupled to the micromachined thermistor and electrically coupled to the microelectromechanical resonator.

2. The MEMS device of claim 1 wherein the micromachined thermistor is thermally coupled to the microelectromechanical resonator via one or more thermal coupling structures that are distinct from the substrate.

3. The MEMS device of claim 1 wherein the circuitry is disposed on a substrate that is distinct from the substrate to which the microelectromechanical resonator and micromachined thermistor are secured.

4. The MEMS device of claim 1 wherein the circuitry generates temperature information based, at least in part, on the temperature-dependent resistance of the micromachined thermistor and generates a clock signal having a temperature-compensated frequency based on mechanical motion of the microelectromechanical resonator and based on the temperature information.

5. The MEMS device of claim 1 wherein the circuitry is thermally isolated from the micromachined thermistor.

6. The MEMS device of claim 1 further comprising first and second anchor structures disposed at the second and third locations, respectively, and physically coupled to the first and second ends of the micromachined thermistor to secure the micromachined thermistor to the substrate.

7. The MEMS device of claim 6 wherein the micromachined thermistor is thermally coupled to the microelectromechanical resonator, at least in part, via the at least one of the first and second anchor structures.

8. The MEMS device of claim 1 wherein the circuitry comprises:
measurement circuitry to generate temperature information based at least in part on the temperature-dependent resistance of the micromachined thermistor; and
output circuitry to generate an output signal in accordance with a signal indicative of mechanical motion of the microelectromechanical resonator and dependent, at least in part, on the temperature information.

9. The MEMS device of claim 8 wherein the output circuitry to generate the output signal in accordance with the signal indicative of mechanical motion of the microelectromechanical resonator and dependent, at least in part, on the temperature information comprises circuitry to generate a clock signal in accordance with the signal indicative of mechanical motion of the microelectromechanical resonator and to adjust the frequency of the clock signal based on the temperature information.

10. The MEMS device of claim 8 wherein the output circuitry to generate the output signal in accordance with the signal indicative of mechanical motion of the microelectromechanical resonator and dependent, at least in part, on the temperature information comprises circuitry to generate a clock signal in accordance with the signal indicative of the mechanical motion of the microelectromechanical resonator and to control the mechanical motion of the microelectromechanical resonator based, at least in part, on the temperature information.

11. A non-transitory machine-readable medium that stores data representative of a microelectromechanical system (MEMS) device comprising:
a microelectromechanical resonator secured to a substrate at a first location;
a micromachined thermistor having first and second ends secured to the substrate at respective second and third locations, and having a length from the first end to the second end greater than a linear distance between the first and second locations, the micromachined thermistor being thermally coupled to the microelectromechanical resonator to enable a temperature-dependent resistance of the micromachined thermistor to vary according to a time-varying temperature of the microelectromechanical resonator; and
circuitry electrically coupled to and thermally isolated from the micromachined thermistor and electrically coupled to the microelectromechanical resonator.

12. A method of fabricating a microelectromechanical system (MEMS) device, the method comprising:
forming, with respect to a first substrate of the MEMS device, a microelectromechanical resonator that is secured to the substrate at a first location, and a micromachined thermistor having first and second ends secured to the substrate at respective second and third locations, the micromachined thermistor having a length from the first end to the second end greater than a linear distance between the second and third locations, and being thermally coupled to the microelectromechanical resonator to enable a temperature-dependent resistance of the micromachined thermistor to vary according to a time-varying temperature of the microelectromechanical resonator; and
implementing circuitry within the MEMS device that is electrically coupled to both the micromachined thermistor and the microelectromechanical resonator.

13. The method of claim 12 wherein forming the micromachined thermistor that is thermally coupled to the microelectromechanical resonator comprises thermally coupling the micromachined thermistor to the microelectromechanical resonator via one or more thermal coupling structures that are distinct from the substrate.

14. The method of claim 12 wherein implementing the circuitry within the MEMS device that is electrically coupled to both the micromachined thermistor and the microelectromechanical resonator comprises forming the circuitry on a substrate that is distinct from the first substrate.

15. The method of claim 12 wherein implementing the circuitry comprises implementing circuitry that generates temperature information based, at least in part, on the temperature-dependent resistance of the micromachined thermistor and generates a clock signal having a temperature-compensated frequency based at least in part on (i) mechanical motion of the microelectromechanical resonator and (ii) the temperature information.

16. The method of claim 12 wherein implementing the circuitry electrically coupled to both the micromachined thermistor and the microelectromechanical resonator comprises thermally isolating the circuitry from the micromachined thermistor.

17. The method of claim 12 wherein forming the micromachined thermistor having first and second ends secured to the substrate at respective second and third locations comprises securing the first and second ends of the micromachined thermistor to the substrate via respective first and second anchor structures disposed at the second and third locations.

18. The method of claim 17 wherein the micromachined thermistor is thermally coupled to the microelectromechanical resonator, at least in part, via the at least one of the first and second anchor structures.

19. The method of claim 12 wherein implementing the circuitry comprises implementing (i) measurement circuitry to generate temperature information based at least in part on the temperature-dependent resistance of the micromachined thermistor, and (ii) output circ

Assignees

• Sitime Corp

Inventors

• Arft Carl
• Partridge Aaron
• Hagelin Paul M

Classifications

• H03L1/00

  Stabilisation of generator output against variations of physical values, e.g. power supply · CPC title

• G01K7/226 Primary

  using microstructures, e.g. silicon spreading resistance · CPC title

• G01K13/02

  for measuring temperature of moving fluids or granular materials capable of flow · CPC title