MICROMECHANICAL DEVICE WITH PIEZOELECTRIC AND ELECTROSTATIC ACTUATION AND METHOD THEREFOR

• US 20090026880A1
• Filed: 07/26/2007
• Published: 01/29/2009
• Est. Priority Date: 07/26/2007
• Status: Active Grant

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Liu, Lianjun
• Granted Patent: US 7,830,066 B2
• Time in Patent Office: Days
• US Class Current: 310/309
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type
• CPC Class Codes: H10N 30/2042 Cantilevers, i.e. having one fixed end

Abstract

A MEMS device uses both piezoelectric actuation and electrostatic actuation and also provides enough electrostatic force to enable very low voltage operation. As the electrostatic actuation uses DC and the piezoelectric actuation uses high frequency, the structure of the device minimizes the coupling of the two actuator structures to reduce noise. In addition, for some embodiments, the location of the physical structures of the piezoelectric actuator and electrostatic actuator generates higher contact force with lower voltage. For some embodiments, the piezoelectric actuator and electrostatic actuator of the device are connected at the contact shorting bar or capacitor plate location. This makes the contact shorting bar or capacitor plate the focal point of the forces generated by all of the actuators, thereby increasing the switch contact force.

Claims

1. A method, comprising:

providing a device having both piezoelectric actuation and electrostatic actuation which operates using a piezoelectric actuation voltage less than or equal to ten volts and which operates using an electrostatic actuation voltage less than or equal to ten volts.

2. A method as in claim 1, wherein the piezoelectric actuation voltage is less than or equal to five volts and the electrostatic actuation voltage is less than or equal to five volts.

3. A method as in claim 1, wherein the piezoelectric actuation voltage is less than or equal to three volts and the electrostatic actuation voltage is less than or equal to three volts.

4. A method as in claim 1, wherein the piezoelectric actuation voltage is approximately equal to the electrostatic actuation voltage.

5. A method as in claim 1, wherein the piezoelectric actuation voltage is approximately equal to a power supply voltage, wherein the electrostatic actuation voltage is approximately equal to the power supply voltage, and wherein the power supply voltage is used to power circuitry on an integrated circuit.

6. A method as in claim 1, wherein no charge pump is used to provide the piezoelectric actuation voltage, and wherein no charge pump is used to provide the electrostatic actuation voltage.

7. A method as in claim 1, wherein the piezoelectric actuation is provided by a piezoelectric actuator, the electrostatic actuation is provided by an electrostatic actuator having at least one of a contact shorting bar or an electrode, and wherein the piezoelectric actuator and the electrostatic actuator are coupled at the at least one of the contact shorting bar or the electrode.

8. A method as in claim 7, wherein the electrode is a capacitor plate.

9. A method as in claim 1, wherein the electrostatic actuation is provided by an electrostatic actuator, wherein the electrostatic actuator comprises at least one of a contact shorting bar or an electrode, and wherein the electrostatic actuator is approximately symmetrical with regard to the at least one of the contact shorting bar or the electrode.

10. A method as in claim 1, wherein the device is used to switch a radio frequency signal.

11. A method as in claim 1, wherein the device is used in a system handling high frequency signal switching.

12. A method, comprising:

providing a system having a power supply voltage less than or equal to ten volts;

providing a piezoelectric actuator which operates using a piezoelectric actuation voltage equal to the power supply voltage of less than or equal to ten volts; and

providing an electrostatic actuator which operates using an electrostatic actuation voltage equal to the power supply voltage of less than or equal to ten volts, the electrostatic actuator having at least one of a contact shorting bar or a capacitor electrode,

wherein the piezoelectric actuator and the electrostatic actuator are coupled at the at least one of the contact shorting bar or the capacitor electrode.

13. A method as in claim 12, wherein no charge pump is used to provide the piezoelectric actuation voltage, and wherein no charge pump is used to provide the electrostatic actuation voltage.

14. A method as in claim 12, wherein the piezoelectric actuation voltage is less than or equal to five volts and the electrostatic actuation voltage is less than or equal to five volts.

15. A method as in claim 12, wherein the piezoelectric actuation voltage is less than or equal to three volts and the electrostatic actuation voltage is less than or equal to three volts.

16. A device, comprising:

a piezoelectric actuator,

wherein the piezoelectric actuator has an actuation voltage less than ten volts; and

an electrostatic actuator,

wherein the electrostatic actuator has an actuation voltage less than ten volts.

17. A device as in claim 16, wherein the electrostatic actuator comprises a contact shorting bar, and wherein the piezoelectric actuator is coupled to the electrostatic actuator at the contact shorting bar.

18. A device as in claim 16, wherein the electrostatic actuator comprises a capacitor electrode, and wherein the piezoelectric actuator is coupled to the electrostatic actuator at the capacitor electrode.

19. A device as in claim 16, wherein the electrostatic actuator comprises a contact shorting bar, a first electrostatic actuator portion, and a second electrostatic actuator portion, and wherein a layout of the first electrostatic actuator portion and a layout of the second electrostatic actuator portion are approximately symmetrical with respect to the contact shorting bar.

20. A device as in claim 16, wherein the electrostatic actuator comprises capacitor electrode, a first electrostatic actuator portion, and a second electrostatic actuator portion, and wherein a layout of the first electrostatic actuator portion and a layout of the second electrostatic actuator portion are approximately symmetrical with respect to the capacitor electrode.