Integrated quartz MEMS tuning fork resonator/oscillator

• US 10,581,402 B1
• Filed: 08/13/2018
• Issued: 03/03/2020
• Est. Priority Date: 12/17/2015
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Kubena, Randall L.
• Primary Examiner(s): Dougherty, Thomas M
• Application Number:
  US16/102,469
• Time in Patent Office: 568 Days
• Field of Search: 310365, 310366, 310370
• CPC Class Codes: H03H 2003/026 the resonators or networks being of the tuning fork type
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/0547 consisting of a vertical arrangement H03H9/0566 takes precedence
• CPC Class Codes: H03H 9/1021 the BAW device being of the cantilever type
• CPC Class Codes: H03H 9/125 Driving means, e.g. electrodes, coils
• CPC Class Codes: H03H 9/13 for networks consisting of piezoelectric or electrostrictive materials H03H9/145 takes precedence
• CPC Class Codes: H03H 9/215 consisting of quartz

Abstract

A piezoelectric quartz tuning fork resonator having a pair of tines formed from a common quartz plate, with a middle electrode and two outer electrodes being disposed at or on top and bottom surfaces of each of the pair of tines and interconnected such that the outer electrodes at or on the top and bottom surfaces of a first one of the pair of tines are connected in common with the middle electrodes on the top and bottom surfaces of a second one of the pair of tines and further interconnected such that the outer electrodes at or on the top and bottom surfaces of the second one of the pair of tines are connected in common with the middle electrodes on the top and bottom surfaces of the first one of the pair of tines.

Claims

1. A piezoelectric quartz tuning fork resonator in combination with an integrated chip, the piezoelectric quartz tuning fork resonator having a pair of tines formed from quartz, with metal electrodes formed only on top and/or bottom major surfaces of said tines and with interconnections disposed on and in said quartz, the integrated chip having circuitry therein for providing an AC current that is applied, in use, to said metal electrodes by way of said interconnections, said interconnections on said piezoelectric quartz tuning fork resonator being directly bonded to said integrated chip, said tines vibrating in response to said AC current in a tuning fork mode.

2. The piezoelectric quartz tuning fork resonator of claim 1 wherein the quartz is a quartz plate and wherein both tines are made from said quartz plate.

3. The piezoelectric quartz tuning fork resonator of claim 2 in which the quartz plate is Z cut and the top and bottom surfaces are normal to a Z′

direction of the Z cut plate.

4. The apparatus of claim 1 wherein a HF, VHF or UHF frequency quartz shear mode resonator is also mated to said integrated chip and interconnected with circuitry formed in said integrated chip.

5. The piezoelectric quartz tuning fork resonator of claim 1 wherein said metal electrodes each have a common linewidth.

6. The piezoelectric quartz tuning fork resonator of claim 5, wherein said metal electrodes comprise two outer electrodes and a middle electrode disposed on a top and a bottom surface of each said pair of tines.

7. The piezoelectric quartz tuning fork resonator of claim 6, wherein the two outer electrodes disposed on the top and bottom surfaces of each of said tines are disposed away from, but no more than a linewidth away from, side edges of the tines.

8. A method of making a piezoelectric quartz tuning fork resonator which is integrated on a semiconductor substrate, the method comprising:

applying metal forming at least six elongated electrodes to a top side of a quartz substrate;

bonding the quartz substrate to a handle wafer;

thinning the quartz substrate to a desired thickness;

etching two openings or vias through the quartz substrate and etching the quartz substrate so that it has two elongate tines with three of said six elongated electrodes disposed on the top side of each tine thereof;

applying metal forming three elongated electrodes to a bottom side of the quartz substrate on each tine thereof;

applying metal for forming bonding pads on the bottom side of the piezoelectric quartz tuning fork resonator;

bonding the etched resonator to said semiconductor substrate; and

releasing the resonator from the handle wafer.

9. The method of claim 8 wherein the semiconductor substrate has active electronics embedded in it.

10. The method of claim 8 wherein another resonator is bonded to said semiconductor substrate, said another resonator being a shear mode resonator.

11. The method of claim 8 wherein said another resonator and said piezoelectric quartz tuning fork resonator are encapsulated within a common enclosure.

12. The method of claim 8 wherein said another resonator is resonate in the range of 5-100 MHz and said piezoelectric quartz tuning fork resonator is resonate in the range of 10-100 kHz.

13. The method of claim 8 wherein said bonding pads are laterally spaced from said two openings or vias.

14. The method of claim 8 wherein a first one of said bonding pads intersects an outline of a first one of said two openings or vias.

15. The method of claim 8 wherein a second one of said bonding pads intersects a second one of said two openings or vias.

16. A piezoelectric quartz tuning fork resonator having a pair of tines formed from quartz, with a middle electrode and two outer electrodes being disposed at or on surfaces of each of said pair of tines and interconnected such that the outer electrodes at or on the top and bottom surfaces of a first one of said pair of tines are connected in common with the middle electrodes on the top and bottom surfaces of a second one of said pair of tines and further interconnected such that the outer electrodes at or on the top and bottom surfaces of the second one of said pair of tines are connected in common with the middle electrodes on the top and bottom surfaces of the first one of said pair of tines, wherein the two outer electrodes are disposed on the top and bottom surfaces of each of said pair of tines and the middle electrode and the two outer electrodes disposed on the top and bottom major surfaces of each of said pair of tines each have a common linewidth, the side surfaces of said tines being electrode free.

17. The piezoelectric quartz tuning fork resonator of claim 16 wherein the two outer electrodes are disposed away from, but no more than a linewidth away from, side edges of the tines.