High frequency crystal resonator

• US 5,436,523 A
• Filed: 05/31/1994
• Issued: 07/25/1995
• Est. Priority Date: 11/06/1992
• Status: Expired due to Term

• Current Assignee: Pericom Semiconductor Corporation (Diodes Incorporated)
• Original Assignee: Avancer Technologies Incorporated
• Inventors: Staudte, Juergen H.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/252,050
• Time in Patent Office: 420 Days
• Field of Search: 310/324, 310/330, 310/340, 310/348, 310/366, 310/368
• US Class Current: 310/348
• CPC Class Codes: H03H 9/19 consisting of quartz

Abstract

A high frequency oscillator with operating frequencies of 30 MHz or greater having an etched quartz thickness shear resonator with resonating means. The resonator has a support structure and a much thinner resonating membrane cantilevered from the support structure. In a preferred embodiment, the design of the support structure is such that a sloped edge is provided between the support structure and the membrane, thus facilitating the application of electrode resonating means extending from the support structure to the membrane. In another preferred embodiment, a plurality of resonators having a support structure and cantilevered membrane with at least one sloped edge are formed on a quartz wafer in a manner similar to semiconductor chip fabrication.

Claims

1. In a high-frequency, thickness shear mode resonator, a resonating structure comprising:

a support structure having a monocrystalline substrate providing a pair of opposed, generally flat faces;

a membrane monolithic with said substrate defining a monocrystalline resonating region which is thinner than the distance between said faces and which when electrically driven vibrates by thickness shear, said membrane being cantilevered from said support structure; and

at least two electrodes respectively disposed on opposing side surfaces of the resonating structure and extending from the support structure to the resonating region of said cantilevered resonating membrane to provide electrical power to said region for causing thickness shear vibration thereat.

2. The combination of claim 1 wherein the resonating structure is substantially quartz crystal.

3. The combination of claim 1 wherein the resonating structure is generally rectangular.

4. The combination of claim 1, wherein both of said electrodes substantially are aluminum.

5. The combination of claim 1 wherein there are at least three of said electrodes with two of the same on one of said opposing side surfaces.

6. The combination of claim 1 further comprising a contact electrically coupling the electrode on one surface of said resonator to the opposing side surface.

7. The combination of claim 1 further comprising gold conducting elements for coupling said electrodes to a source external to the resonating structure.

8. The combination of claim 7, further comprising an adhesion layer applied to the resonating structure for improving adhesion between the gold and said resonating structure.

9. The combination of claim 8, wherein the adhesion layer is substantially chromium.

10. The combination of claim 1, wherein the resonating membrane is defined by chemical etching.

11. The combination of claim 1, further comprising a header assembly on which the resonating structure is mounted, the header assembly further comprising means for coupling the remainder of the combination to the header assembly, and means for coupling the header assembly to an external source;

and means for enclosing said resonating structure hermetically sealed to said header assembly.

12. The combination of claim 11, wherein said enclosure means is a cylindrical metal cap.

13. The combination of claim 1 wherein said resonator has a sloped edge at the joint between the support structure and the membrane, defining a ramp therebetween.

14. The combination of claim 13 wherein said support structure is generally U-shaped and provides said ramp, and said membrane is cantilevered at the open end of the U.

15. In a high-frequency, thickness shear mode resonator, a resonating structure comprising:

a support structure having a monocrystalline substrate defining a pair of opposed, generally flat faces;

a resonating membrane cantilevered at the support structure, said membrane having a monocrystalline resonating region which is thinner than the distance between said support structure flat faces and which when electrically driven vibrates by thickness shear; and

a ramp extending from one face of said support structure to the resonating membrane.

16. The combination of claim 15 wherein the resonating structure is substantially quartz crystal.

17. The combination of claim 15, wherein the support structure has a sloped edge at the joint between the support structure and the resonating membrane defining said ramp therebetween.

18. The combination of claim 17, wherein said support structure is generally U-shaped and provides said ramp, and said resonating membrane is cantilevered at the open end of the U.

19. The combination of claim 15 further comprising at least two electrodes respectively disposed on opposing sides of the resonating region of said membrane, each electrode extending from the support to said resonating region, and wherein said electrodes are substantially aluminum.

20. The combination of claim 15, wherein the resonating membrane is defined by chemical etching.

21. The combination of claim 15, further comprising at least two electrodes respectively disposed on opposing side surfaces of the resonating membrane and extending from the support structure to the resonating region of said membrane to provide electrical power to said region for causing thickness shear vibration thereat, and gold conducting elements for coupling said electrodes of said resonating membrane to a source external to said resonating membrane.

22. The substrate of claim 21, further comprising an adhesion layer applied to the wafer for improving adhesion between the gold and the wafer.

23. The combination of claim 22, wherein the adhesion layer is substantially chromium.

24. A wafer of resonating material comprising:

a plurality of individually defined resonating structures adjacent to one another, each of which includes;

a support structure having a monocrystalline substrate providing a pair of opposed, generally flat faces; and

a resonating membrane monolithic with said substrate and cantilevered therefrom, said membrane having a monocrystalline resonating region;

which is thinner than the distance between said support structure flat faces; and

which when electrically driven vibrates by thickness shear.

25. The wafer of claim 24, wherein the resonating membrane of each resonating structure is defined by chemically etching the wafer.

26. The wafer of claim 25, wherein the wafer is substantially quartz crystal.

27. The wafer of claim 25 wherein each resonating structure is generally rectangular.

28. The wafer of claim 24, wherein each resonating membrane further comprises at least two electrodes disposed on opposing sides of said membrane and extending from the support structure to said resonator region, said electrodes being substantially aluminum.

29. The wafer of claim 24, wherein each resonating structure has at least one sloped edge at the joint between the support structure and the resonating membrane defining a ramp therebetween.

30. The combination of claim 24, wherein said support structure is generally U-shaped and provides said ramp, and said membrane is cantilevered at the open end of the U.

31. The wafer of claim 24, wherein the support structure of each resonating structure has a sloped edge at the joint between the support structure and the resonating membrane defining a ramp therebetween.