Method for fabricating quartz-based nanoresonators

• US 7,559,130 B2
• Filed: 05/04/2007
• Issued: 07/14/2009
• Est. Priority Date: 04/30/2002
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Kubena, Randall L., Chang, David T., Kim, Jinsoo
• Primary Examiner(s): Kim; Paul D
• Application Number:
  US11/800,289
• Publication Number:
  US 20070216490A1
• Time in Patent Office: 802 Days
• Field of Search: 29/253.5, 295/94, 296/091, 216/62, 216/63, 216/66, 310/321, 310/328, 310330-332, 381/396, 381/398
• US Class Current: 29/594
• CPC Class Codes: H03H 2003/0414 Resonance frequency
• CPC Class Codes: H03H 2009/241 Bulk-mode MEMS resonators
• CPC Class Codes: H03H 3/04 for obtaining desired frequency or temperature coefficient
• CPC Class Codes: H03H 9/19 consisting of quartz
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/4908 Acoustic transducer
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49165 by forming conductive walled aperture in base

Abstract

A method for fabricating a quartz nanoresonator which can be integrated on a substrate, along with other electronics is disclosed. In this method a quartz substrate is bonded to a base substrate. The quartz substrate is metallized so that a bias voltage is applied to the resonator, thereby causing the quartz substrate to resonate at resonant frequency greater than 100 MHz. The quartz substrate can then be used to drive other electrical elements with a frequency equal to its resonant frequency. The quartz substrate also contains tuning pads to adjust the resonant frequency of the resonator. Additionally, a method for accurately thinning a quartz substrate of the resonator is provided. The method allows the thickness of the quartz substrate to be monitored while the quartz substrate is simultaneously thinned.

Claims

1. A method for fabricating a resonator comprising the steps of:

providing a first substrate having a cavity etched therein;

providing a quartz substrate;

bonding the quartz substrate to the first substrate and over the cavity;

thinning the quartz substrate while optically monitoring a thickness of the quartz substrate;

removing a portion of the thinned quartz substrate;

bonding the thinned quartz substrate to a base substrate; and

removing the first substrate from the thinned quartz substrate, thereby releasing the thinned quartz substrate from the thinned quartz substrate.

2. The method of claim 1, wherein the step of thinning the quartz substrate thins the quartz substrate to a thickness of less than ten micrometers.

3. The method of claim 1, wherein the first substrate comprises a member selected from the group consisting of Si and GaAs.

4. The method of claim 1, wherein the base substrate comprises a member selected from the group consisting of group III-V elements, and SiGe.

5. The method of claim 1, further comprising the steps of:

removing a portion of the base substrate thus obtaining a modified base substrate;

and depositing at least one probe pad on the modified base substrate.

6. The method of claim 5, wherein the quartz substrate comprises a first surface and a second surface, the resonator further comprising at least one first electrode on the first surface, and at least one second electrode on the second surface.

7. The method of claim 6, wherein the quartz substrate further comprises at least one via connected to the at least one first electrode and the at least one second electrode, wherein the at least one via is filled with a metal.

8. The method of claim 7, wherein the quartz substrate further comprises at least one tuning pad for tuning the quartz substrate to a desired resonant frequency.

9. The method of claim 8, wherein the step of bonding the quartz substrate to the base substrate, comprises the step of bonding the at least one probe pad to the at least one second electrode, thereby allowing a signal to flow between the at least one probe pad and the at least one second electrode.

10. The method of claim 8, wherein the at least one tuning pad is ablated to adjust the resonant frequency.

11. The method of claim 8, wherein the tuning pad is one among the at least one first electrode and the at least one second electrode.

12. The method of claim 1 wherein thinning the quartz substrate is performed using a lap and polishing process and reactive ion etching.

13. The method of claim 12, wherein the lap and polishing process uses aluminum oxide.

14. The method of claim 12, wherein the lap and polishing process uses silica or cerium oxide.

15. The method of claim 12 wherein reactive ion etching uses a gas having a fluorine chemistry.

16. The method of claim 1 wherein optically monitoring comprises spectropic ellipsometry.

17. The method of claim 1 wherein optically monitoring comprises reflectometry.