MEMS device

1. A micro-electro-mechanical system (MEMS) device comprising:

a semiconductor die including integrated circuitry;

a structure mounted on the semiconductor die and covering at least a portion of the circuitry, the structure defining a space between the structure and the at least a portion of the circuitry; and

a transducer including a membrane, the transducer located outside of the space, wherein the MEMS device defines a volume containing the structure and the transducer, and wherein the space thermally insulates the membrane from the at least a portion of the integrated circuitry.

2. The MEMS device of claim 1 , wherein the structure includes side walls mounted on the semiconductor die and a first layer, wherein side walls and the first layer define the space.

3. The MEMS device of claim 2 , wherein the structure includes at least one additional layer formed on the first layer.

4. The MEMS device of claim 1 , wherein the transducer includes a transducer backplate layer adjacent to and spaced apart from the membrane, the transducer backplate layer and the membrane forming a capacitive transducer.

5. The MEMS device of claim 4 , wherein the transducer backplate layer and at least part of the structure comprise the same material, comprise a continuous layer, and/or are formed in the same formation step.

6. The MEMS device of claim 4 , wherein the structure includes a back layer spaced apart from the at least a portion of the circuitry, and wherein the back layer is thicker than the transducer backplate layer.

7. The MEMS device of claim 1 , wherein the transducer is integrated on the semiconductor die.

8. The MEMS device of claim 7 , further comprising a second membrane within the space.

9. The MEMS device of claim 8 , wherein the membrane and the second membrane comprise the same material, comprise a continuous layer, and/or are formed in the same formation step.

10. The MEMS device of claim 1 , further comprising a package that defines a volume that contains the integrated circuitry, the structure and the transducer, the package including at least one port for allowing sound or pressure waves to interact with the membrane.

11. The MEMS device of claim 1 , wherein the structure includes at least one hole.

12. The MEMS device of claim 1 , wherein the space contains air, a gas, a solid material or a vacuum.

13. The MEMS device of claim 1 , wherein at least part of the structure is formed of silicon nitride.

14. A MEMS microphone packaged device comprising:

a MEMS transducer die comprising a membrane; and

a second die comprising integrated circuitry operatively coupled to the MEMS transducer, wherein the second die comprises a thermal impedance structure mounted above at least part of the integrated circuitry for reducing the effect of change in temperature of the integrated circuitry on the membrane, and wherein the MEMS microphone packaged device further comprises a lid defining a volume containing the MEMS transducer die and the thermal impedance structure.

15. The MEMS device of claim 14 , wherein said space is bounded by said structure so as to be substantially not in acoustic communication with said membrane.

16. A monolithic semiconductor die comprising:

circuitry provided in a first region of the die;

a MEMS transducer provided in a second region of the die; and

an enclosure provided on a thermal flow path between the first region and the second region.

17. A monolithic semiconductor die as claimed in claim 16 , wherein the enclosure is provided so as to overlie at least a part of the circuitry.

18. A monolithic semiconductor die as claimed in claim 16 , wherein the enclosure is at least partly defined by a structure which is formed above the first region.

19. A monolithic semiconductor die as claimed in claim 16 , wherein the enclosure is at least partly defined by a cavity formed within the first region.

20. A monolithic semiconductor die as claimed in claim 16 , wherein the enclosure comprises a thermal low pass filter.