GHz Surface Acoustic Resonators in RF-CMOS

• US 20100007444A1
• Filed: 03/17/2009
• Published: 01/14/2010
• Est. Priority Date: 04/20/2006
• Status: Abandoned Application

• Current Assignee: George Washington University
• Original Assignee: George Washington University
• Inventors: Nordin, Anis Nurashikin, Zaghloul, Mona
• Application Number:
  US12/405,503
• Publication Number:
  US 20100007444A1
• Time in Patent Office: Days
• US Class Current: 333/195
• CPC Class Codes: G01N 2291/0255 (Bio)chemical reactions, e.g. on biosensors
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/326 compensating for temperature variations
• CPC Class Codes: H03H 3/08 for the manufacture of resonators or networks using surface acoustic waves
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

An improved SAW resonator fabricated using RF-CMOS technology is disclosed. The SAW resonator is capable of a resonant frequency of from about 1 GHz to about 3.12 GHz. Several different embodiments namely both single and double port resonators implemented in standard CMOS (0.6 μm) and RF-CMOS (0.18 μm) technologies are presented.

Claims

1. A SAW resonator fabricated using RF-CMOS technology, wherein the SAW resonator is capable of a resonant frequency of from about 1 GHz to about 3.12 GHz.

2. The SAW resonator of claim 1, further comprising wherein the SAW resonator has a quality factor about 285 or greater.

3. The SAW resonator of claim 1, further comprising wherein the SAW resonator has interdigital transducers and reflectors having submicron width.

4. The SAW resonator of claim 1, further comprising wherein the SAW resonator is miniature having length and width dimensions of less than about 500 μ

m.

5. The SAW resonator of claim 1, further comprising wherein the SAW resonator is miniature having length and width dimensions of less than about 300 μ

m.

6. The SAW resonator of claim 1, further comprising wherein the SAW resonator has integrated, stacked, submicron reflectors which provides significant increase in quality factors of the device.

7. The SAW resonator of claim 1, further comprising wherein the SAW resonator has an integrated ground shield layer underneath the entire device to isolate it from electromagnetic feed-through and undesired coupling through the Si substrate.

8. The SAW resonator of claim 1, further comprising wherein the SAW resonator has an integrated heat-control structure consisting of a polysilicon heater placed underneath the ground shield layer. The ground shield has dual purpose of electromagnetic feedthrough and as a heat distributing plate.

15. An integrated circuit chip having the SAW resonator of claim 1 as an on-chip component.

16. The chip of claim 15, wherein the chip is a microprocessor.

17. The chip of claim 15, wherein the chip is a programmable integrated circuit.

18. The chip of claim 15, wherein the chip is a microelectromechanical system (MEMS).

19. The chip of claim 15, wherein the chip is a nanoelectromechanical system (NEMS).

20. The integrated circuit chip of claim 15, fuirther comprising an embedded heater structure.

21. An LC circuit which comprises the SAW resonator of claim 1 and an amplifier on the same chip.

22. A local oscillator, which comprises the LC circuit of claim 21 connected to a Pierce oscillator.

9. A process for fabricating a GHz-capable SAW resonator device using commercial RF-CMOS technology, comprising:

i) patterning the SAW resonator'"'"'s electrodes during RF-CMOS fabrication, and ii) removal of the double passivation layers, SiN and SiO₂, and iii) depositing piezoelectric material on top of SAW resonator'"'"'s electrodes, and iv) performing wet-etching such that the piezoelectric material covers only the resonator region wherein a reactive ion etch releases the SAW resonator electrodes from the dielectric layer before the piezoelectric material is deposited, wherein the SAW resonator is capable of a resonant frequency of from about 1 GHz to about 3.12 GHz.

10. The process of claim 9, wherein the piezoelectric material is ZnO.

11. The process of claim 9, wherein the wet-etching uses a very dilute acid solution.

12. The process of claim 11, wherein the very dilute acid solution is a two acid mixture, wherein each acid of the two acid mixture is selected from the group consisting of acetic acid, hydrochloric acid, and phosphoric acid.

13. The process of claim 11, wherein the CMOS process sequence includes fabricating an isolation structure under the interdigital transducers and reflectors of the SAW resonator, wherein the isolation structure comprises a single, integrated metal shield and provides isolation from electromagnetic feed-through.

14. A SAW device made by the process of claim 9.