Methods for forming a frequency bulk acoustic resonator with uniform frequency utilizing multiple trimming layers and structures formed thereby

• US 6,943,648 B2
• Filed: 05/01/2003
• Issued: 09/13/2005
• Est. Priority Date: 05/01/2003
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Wang, Li-Peng, Maiz, Jose, Ma, Qing, Rao, Valluri
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US10/428,692
• Publication Number:
  US 20040217829A1
• Time in Patent Office: 866 Days
• Field of Search: 333186-192, 310/312, 310/364
• US Class Current: 333/188
• CPC Class Codes: H03H 2003/0414 Resonance frequency
• CPC Class Codes: H03H 3/04 for obtaining desired frequency or temperature coefficient
• CPC Class Codes: H03H 9/172 Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume

Abstract

A method of forming a tuned resonator structure by first forming a base resonator structure that comprises a trimming layer on a resonator structure, wherein the trimming layer comprises at least one first low loss acoustic layer on the resonator structure, and at least one second low loss acoustic layer on the first low loss acoustic layer. Then, a “tuned” resonator structure is formed by measuring the frequency of the base resonator structure and removing the number of each of the two different low loss acoustic layers determined to be necessary to achieve the targeted frequency of the base resonator structure, thus improving the frequency control, reliability and performance of the resonating structure.

Claims

1. A method of forming a trimming layer on a resonator structure, comprising:

forming at least one first low loss acoustic layer on the resonator structure; and

forming at least one second low loss acoustic layer on the first low loss acoustic layer, wherein the at least one first low loss acoustic layer and the at least one second low loss acoustic layer form a trimming layer, wherein the trimming layer is adapted to modify a resonating frequency of a base resonator structure.

2. The method of claim 1, wherein forming the trimming layer further comprises alternating a plurality of the first low loss acoustic layer and a plurality of the second low loss acoustic layer to form a trimming layer.

3. The method of claim 1, wherein modifying the resonating frequency of the base resonator structure comprises:

measuring the resonating frequency of a base resonator structure;

determining the number of each of the first low loss acoustic layers and second low loss acoustic layers needed to be removed from the trimming layer to achieve a targeted resonating frequency of the base resonator structure; and

etching the number of each of the first low loss acoustic layers and the second low loss acoustic layers needed to be removed from the base resonator structure to achieve the targeted resonating frequency of the base resonator structure.

4. The method of claim 1, wherein the at least one first low loss acoustic layer etches at a substantially different rate than the at least one second low loss acoustic layer.

5. The method of claim 1 wherein the at least one first low loss acoustic layer and the at least one second low loss acoustic layer each comprise a different one of a low loss acoustic material including aluminum nitride, molybdenum, polysilicon, microcrystal silicon oxide, and tungsten.

6. The method of claim 1 wherein the resonator structure is an FBAR.

7. The method of claim 1 wherein the thickness of a piezoelectric layer within the resonator structure is thinner than required for a targeted frequency of the resonator structure.

8. The method of claim 7 wherein the thickness of the at least one first low loss acoustic layer is less than the tolerance thickness of the piezoelectric layer.

9. The method of claim 7 wherein the thickness of the at least one second low loss acoustic layer is less than the tolerance thickness of the piezoelectric layer.

10. A method of forming a tuned resonating structure, comprising:

forming a base resonator structure further comprising;

forming a bottom electrode on a substrate;

forming a piezoelctric layer on the electrode;

forming a top electrode on the piezoelectric layer to form a resonator structure;

forming a trimming layer on the resonator structure further comprising;

forming at least one first low loss acoustic layer on the resonator structure and at least one second low loss acoustic layer on the at least first low loss acoustic layer to form a base resonator structure; and

forming a tuned resonator structure further comprising;

measuring the frequency of the base resonator structure; and

removing the number of each of the at least one first low loss acoustic layers and the at least one second low loss acoustic layers necessary to achieve the targeted frequency, wherein a tuned resonator structure is formed.

11. The method of claim 10, wherein forming the trimming layer further comprises alternating a plurality of the first low loss acoustic layer and a plurality of the second low loss acoustic layer to form a trimming layer.

12. The method of claim 10 wherein the thickness of the piezoelectric layer is thinner than required for a targeted frequency of the resonator structure.

13. The method of claim 10 wherein the thickness of the at least one first low loss acoustic layer is less than the tolerance thickness of the piezoelectric layer.

14. The method of claim 10 wherein the thickness of the at least one second low loss acoustic layer is less than the tolerance thickness of the piezoelectric layer.

15. The method of claim 10 and wherein by forming the trimming layer on the resonator structure, the resonator structure is made thicker than required for a targeted frequency.

16. The method of claim 10 wherein the resonator structure is an FBAR.

17. An apparatus comprising:

a resonator structure; and

a trimming layer on the resonator structure, wherein the trimming layer comprises alternating layers of a first low loss acoustic layer and a second low loss acoustic layer.

18. The apparatus of claim 17, wherein the first low loss acoustic layer etches at a substantially different rate than the second layer.

19. The apparatus of claim 17 wherein the first low loss acoustic layer and the second low loss acoustic layer each comprise a different one of a low loss acoustic material including aluminum nitride, polysilicon, microcrystal silicon oxide, molybdenum, and tungsten.

20. The apparatus of claim 17 wherein the thickness of the first low loss acoustic layer is less than the tolerance thickness of the piezoelectric layer.

21. The apparatus of claim 17 wherein the thickness of the second low loss acoustic layer is less than the tolerance thickness of the piezoelectric layer.

22. The apparatus of claim 17 wherein the resonator structure is an FBAR.