Acoustic MEMs resonator and filter with fractal electrode and method for producing the same

• US 10,277,194 B2
• Filed: 09/15/2017
• Issued: 04/30/2019
• Est. Priority Date: 09/15/2017
• Status: Active Grant

• Current Assignee: Vanguard International Semiconductor Singapore Pte. Ltd. (Vanguard International Semiconductor Corporation)
• Original Assignee: Globalfoundries Singapore Pte Limited (GlobalFoundries, Inc.)
• Inventors: Campanella-Pineda, Humberto, Qian, You, Kumar, Rakesh
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US15/706,304
• Publication Number:
  US 20190089327A1
• Time in Patent Office: 592 Days
• Field of Search: 333187, 333189, 310365
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/0211 of reflections
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/02157 Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/205 having multiple resonators crystal tuning forks H03H9/21
• CPC Class Codes: H03H 9/54 comprising resonators of piezoelectric or electrostrictive material H03H9/64 takes precedence

Abstract

Methods of designing a BAW resonator having fractal geometry and the resulting devices are provided. Embodiments include providing a fractal generator function; providing three or more line segments; applying the fractal generator function to each of the three or more line segments to form three or more respective fractal line segments, each of the three or more fractal line segments having a respective start point and endpoint and at least four sub-segments; and connecting an endpoint of each one of the three or more fractal line segments to a successive start point of another of the three or more fractal line segments to form a closed-loop contour line representative of an area of an electrode of a BAW resonator, the closed-loop contour line having a fractal dimension that is greater than one and less than two.

Claims

1. A method comprising:

providing a fractal generator function;

providing three or more line segments;

applying the fractal generator function to each of the three or more line segments to form three or more respective fractal line segments, each of the three or more fractal line segments having a respective start point and endpoint and at least four sub-segments; and

connecting an endpoint of each one of the three or more fractal line segments to a successive start point of another of the three or more fractal line segments to form a closed-loop contour line representative of an area of an electrode of a bulk acoustic wave (BAW) resonator, the closed-loop contour line having a fractal dimension that is greater than one and less than two.

2. The method according to claim 1, wherein the fractal generator function is a Koch function, an other parameterized fractal function or an arbitrary suitable function that is subject to parametrization and fractalization.

3. The method according to claim 2, wherein a parameter of the Koch function includes a unit length of the three or more line segments, an angular value of an equilateral triangle, a perimeter of an equilateral triangle, an area of an equilateral triangle, a height of an equilateral triangle, an iteration order value or a combination thereof.

4. The method according to claim 2, wherein the Koch function forms the three or more line segments into a snowflake-shaped closed-loop contour line.

5. The method according to claim 1, further comprising:

determining whether a target quality (Q) factor, a target area and a target perimeter are met for the BAW resonator based on analysis of the closed-loop contour line and specification information for the BAW resonator.

6. The method according to claim 5, wherein the determining of whether the target Q factor, the target area and the target perimeter are met includes analyzing the closed-loop contour line based on modeling or particle counting.

7. The method according to claim 5, further comprising:

applying the fractal generator function to each of the three or more fractal line segments of the closed-loop contour line to form an updated closed-loop contour line until the target Q factor, target area and target perimeter are met for the BAW resonator.

8. A device comprising:

a first electrode made of conductive material, a perimeter of at least one first electrode being defined by a closed-loop contour with fractal dimensions greater than one and less than two and a parameterized fractal function or an arbitrary suitable function that is subjected to parametrization and fractalization;

an acoustic layer adjacent to the first electrode, the first electrode interfacing with a first plane of the acoustic layer; and

a second electrode adjacent to the acoustic layer, the second electrode made of conductive material and interfacing with a second plane of the acoustic layer.

9. The device according to claim 8, wherein the second electrode has the fractal dimensions and is patterned based on the parameterized fractal function or the arbitrary suitable function that is subjected to parametrization and fractalization.

10. The device according to claim 9, wherein the parameterized fractal function comprises a Koch function, a Cesare function, a Cantor function, a Sierpienski function, or a Peano function.

11. The device according to claim 8, wherein the acoustic layer is a piezoelectric material.

12. The device according to claim 8, wherein the interfacing of the second electrode with the second plane of the acoustic layer and the interfacing of the first electrode with the first plane of the acoustic layer forms a resonator or a plurality of bulk acoustic wave (BAW) resonators, respectively.

13. The device according to claim 12, wherein the plurality of BAW resonators is formed, the device further comprising:

interconnects for operatively coupling the plurality of BAW resonators to form an acoustic filter.

14. A method comprising:

providing a target Q factor for a resonator;

providing a first pattern representative of a first electrode, the pattern having a closed-loop contour line having fractal dimensions based on a parameterized fractal function or an arbitrary suitable function that is subjected to parametrization and fractalization, the fractal dimensions being greater than one and less than two;

providing a second pattern representative of an area of a second electrode to be layered with the first electrode, the layering of the second pattern and the first pattern representing an effective area of the resonator; and

determining whether the target Q factor is met for the resonator based on the area and the perimeter of the closed-loop contour line.

15. The method according to claim 14, wherein the determining of whether the target Q factor is met includes analyzing the closed-loop contour line based on modeling or particle counting.

16. The method according to claim 14, further comprising:

updating the first pattern until the target Q factor is met for the resonator, the target Q factor being based on specification information for the resonator; and

storing the updated first pattern as a final pattern for forming the first electrode once the target Q factor is met.

17. The method according to claim 16, wherein the step of updating the first pattern includes applying a fractal generator function to the closed-loop contour line, the fractal generator function having self-similarity to the fractal dimensions of the closed-loop contour line.

18. The method according to claim 14, further comprising:

updating the second pattern until the target Q factor is met for the resonator, the target Q factor being based on specification information for the resonator; and

storing the updated second pattern as a final pattern for forming the second electrode once the target Q factor is met.

19. The method according to claim 18, wherein the step of updating the second pattern includes applying a fractal generator function to a closed-loop contour line of the second pattern, the closed-loop contour line of the second pattern having fractal dimensions based on a parameterized fractal function or an arbitrary suitable function that is subjected to parametrization and fractalization, the fractal dimensions being greater than one and less than two.

20. The method according to claim 18, wherein the fractal generator function has self-similarity to the fractal dimensions of the closed-loop contour line of the second pattern.