Dual-diaphragm MEMS transducers with high effective area

1. A microelectromechanical systems (MEMS) diaphragm assembly comprising:

a first diaphragm;

a second diaphragm;

a geometric central region surrounding a geometric center of the diaphragm assembly, the geometric central region being bounded by a constant radius, R 1 , extending from the geometric center; and

a plurality of pillars connecting the first and second diaphragms, each of the plurality of pillars having a cross-sectional shape having a maximum radial dimension, A, and a maximum circumferential dimension, B, the plurality of pillars arranged around the geometric center,

the maximum radial dimension, A, of the plurality of pillars being oriented along a plurality of radials emanating from the geometric center,

the maximum circumferential dimension, B, of the plurality of pillars being oriented circumferentially relative to the geometric center,

wherein at least a first subset of the plurality of pillars is disposed within the geometric central region and wherein A is greater than B for the at least first subset.

2. The MEMS diaphragm assembly of claim 1 , wherein A and B are constant within the geometric central region, and A is smaller at an outer periphery of the MEMS diaphragm assembly than within the geometric central region.

3. The MEMS diaphragm assembly of claim 2 , wherein an outer edge of the geometric central region is disposed in a range of about 30% to 70% of the distance between the geometric center and the outer periphery of the MEMS diaphragm assembly.

4. The MEMS diaphragm assembly of claim 3 , wherein the outer edge of the geometric central region is disposed in a range of about 50% to 70% of the distance between the geometric center and the outer periphery of the MEMS diaphragm assembly.

5. The MEMS diaphragm assembly of claim 4 , wherein the outer edge of the geometric central region is disposed at about 60% to 70% of the distance between the geometric center and the outer periphery of the MEMS diaphragm assembly.

6. The MEMS diaphragm assembly of claim 2 , wherein A is constant from an outer edge of the geometric central region to the outer periphery of the MEMS diaphragm assembly.

7. The MEMS diaphragm assembly of claim 2 , wherein the region between an outer edge of the geometric central region and the outer periphery comprises a plurality of concentric annular regions, and wherein A and B are constant within each of the plurality of concentric annular regions.

8. The MEMS diaphragm assembly of claim 2 , wherein B is constant and A decreases from the geometric center out to an outer edge of the geometric central region and both A and B remain constant from the outer edge of the geometric central region to the outer periphery of the MEMS diaphragm assembly.

9. The MEMS diaphragm assembly of claim 8 , wherein the geometric central region comprises a central core region surrounded by a plurality of concentric annular regions, and wherein A and B are constant within each of the central core region and the plurality of concentric annular regions.

10. The MEMS diaphragm assembly of claim 1 , wherein the cross-sectional shape is selected from the group of shapes consisting of an ellipse, a rectangle, a diamond shape, an irregular pentagon, an irregular hexagon, an egg shape, an irregular heptagon, an irregular octagon, an irregular ten-sided polygon, an irregular twelve-sided polygon, a triangle, and combinations thereof.

11. A microelectromechanical system (MEMS) die, comprising:

a substrate having an opening formed therein; and

a MEMS diaphragm assembly attached around a periphery thereof to the substrate and over the opening, wherein the diaphragm assembly comprises:

a first diaphragm;

a second diaphragm;

a geometric central region surrounding a geometric center of the diaphragm assembly, the geometric central region being bounded by a constant radius, R 1 , extending from the geometric center; and

a plurality of pillars connecting the first and second diaphragms, each of the plurality of pillars having a cross-sectional shape having a maximum radial dimension, A, and a maximum circumferential dimension, B, the plurality of pillars arranged around the geometric center,

the maximum radial dimension, A, of the plurality of pillars being oriented along a plurality of radials emanating from the geometric center,

the maximum circumferential dimension, B, of the plurality of pillars being oriented circumferentially relative to the geometric center,

wherein at least a first subset of the plurality of pillars is disposed within the geometric central region and wherein A is greater than B for the at least first subset;

wherein A and B are constant within the geometric central region, and A is smaller at an outer periphery of the MEMS diaphragm assembly than within the geometric central region; and

wherein an outer edge of the geometric central region is disposed in a range of about 30% to 70% of the distance between the geometric center and the outer periphery of the MEMS diaphragm assembly.

12. A microphone device, comprising:

the MEMS die of claim 11 ;

a housing having a sound port;

wherein the MEMS die is disposed within the housing; and

wherein the sound port is acoustically coupled to the MEMS die.

13. The MEMS die of claim 11 , wherein the outer edge of the geometric central region is disposed in a range of about 50% to 70% of the distance between the geometric center and the outer periphery of the MEMS diaphragm assembly.

14. The MEMS die of claim 11 , wherein the outer edge of the geometric central region is disposed at about 60% to 70% of the distance between the geometric center and the outer periphery of the MEMS diaphragm assembly.

15. The MEMS die of claim 11 , wherein A is constant from the outer edge of the geometric central region to the outer periphery of the MEMS diaphragm assembly.

16. The MEMS die of claim 11 , wherein the region between the outer edge of the geometric central region and the outer periphery comprises a plurality of concentric annular regions, and wherein A and B are constant within each of the plurality of concentric annular regions.

17. The MEMS die of claim 11 , wherein B is constant and A decreases from the geometric center out to the outer edge of the geometric central region and both A and B remain constant from the outer edge of the geometric central region to the outer periphery of the MEMS diaphragm assembly.

18. The MEMS die of claim 16 , wherein the geometric central region comprises a central core region surrounded by the plurality of concentric annular regions, and wherein A and B are constant within each of the central core region and the plurality of concentric annular regions.

19. The MEMS diaphragm assembly of claim 11 , wherein the cross-sectional shape for the at least first subset of the plurality of pillars can be any regular or irregular shape wherein A is greater than B.

20. The MEMS diaphragm assembly of claim 19 , wherein the cross-sectional shape is selected from the group of shapes consisting of an ellipse, a rectangle, a diamond shape, an irregular pentagon, an irregular hexagon, an egg shape, an irregular heptagon, an irregular octagon, an irregular ten-sided polygon, an irregular twelve-sided polygon, a triangle, and combinations thereof.