Condenser microphone with non-circular membrane
A non-uniform stress distribution of a MEMS microphone having a non-circular shape is compensated by a structured back plate that has a compensating structure to provide a stress distribution opposite to that of the membrane.
1. Condenser microphone comprising
a membrane
a back plate, arranged in parallel but distant to the membrane
anchor means clamping together membrane and back plate or clamping membrane and back plate to a common substrate body such that membrane and back plate are in intimate mechanical contact
wherein the membrane has a non-circular shape and hence a non-uniform mechanical stress distribution upon deflection from a relaxed state
wherein the non-uniform mechanical stress distribution is compensated by a compensating structure of the back plate providing a stress distribution opposite to that of the membrane.
2. The condenser microphone of claim 1 ,
wherein membrane and back plate have similar shapes
wherein the stress in the membrane in a direction that is parallel to a first diameter thereof is higher than the stress along a second diameter thereof different from the first diameter
wherein the compensating structure comprises stress releasing means that release the stress in a direction parallel to the first diameter of the membrane.
3. The condenser microphone of claim 1 ,
wherein membrane and back plate have similar shapes
wherein the intrinsic stress distribution is non-uniform in the membrane such that in a direction that is
parallel to a first diameter thereof is higher than the stress along a direction parallel to a second diameter thereof different from the first diameter,
wherein the compensating structure comprises stress enhancing means that enhance the stress in a direction parallel to the second diameter of the membrane.
4. The condenser microphone of claim 2 ,
wherein the stress releasing means comprises an array of holes within the back plate having a shape according to the shape of membrane and back plate.
5. The condenser microphone of claim 3 ,
wherein the stress enhancing means comprises an array of stiffening structures having a shape according to the shape of membrane and back plate.
6. The condenser microphone of claim 2 ,
wherein
the compensating structure comprises an array of stress releasing means distributed on the back plate such that the density of the means is higher along a direction parallel to the first diameter than parallel to the second diameter.
7. The condenser microphone of claim 1 ,
wherein the first diameter is smaller than the second diameter
wherein the first diameter is arranged normal to the second diameter.
8. The condenser microphone of claim 7 ,
wherein the shape of membrane and back plate is similar and is elliptical.
9. The condenser microphone of claim 7 ,
wherein the shapes of membrane and back plate are similar and are both rectangular having rounded edges.
10. The condenser microphone of claim 6 ,
wherein the stiffening structures are areas wherein the back plate has an enhanced thickness or a coating.
11. The condenser microphone of claim 1 ,
wherein the condenser microphone is microminiaturized MEMS microphone manufactured in and on a body of crystalline silicon.
12. The condenser microphone of claim 1 ,
wherein the stress compensating structure is based on a regular pattern of stress releasing or stress enhancing means that is modified such that neighbored means are combined by an extension to a single combined means.
13. The condenser microphone of claim 3 , wherein
the compensating structure comprises an array of stress enhancing means distributed on the back plate such that the density of the means is higher along a direction parallel to the second diameter than parallel to the first diameter.
14. The condenser microphone of claim 2 ,
wherein the first diameter is smaller than the second diameter
wherein the first diameter is arranged normal to the second diameter.
15. The condenser microphone of claim 3 ,
wherein the first diameter is smaller than the second diameter
wherein the first diameter is arranged normal to the second diameter.
16. The condenser microphone of claim 7 ,
wherein the stiffening structures are areas wherein the back plate has an enhanced thickness or a coating.
17. The condenser microphone of claim 2 ,
wherein the condenser microphone is microminiaturized MEMS microphone manufactured in and on a body of crystalline silicon.
18. The condenser microphone of claim 3 ,
wherein the condenser microphone is microminiaturized MEMS microphone manufactured in and on a body of crystalline silicon.
19. The condenser microphone of claim 6 ,
wherein the condenser microphone is microminiaturized MEMS microphone manufactured in and on a body of crystalline silicon.
20. The condenser microphone of claim 2 ,
wherein the stress compensating structure is based on a regular pattern of stress releasing or stress enhancing means that is modified such that neighbored means are combined by an extension to a single combined means.