MEMS microphone device and electronics apparatus

1. A MEMS microphone device, comprising:

a substrate;

a MEMS microphone element placed on the substrate;

a cover encapsulating the MEMS microphone element together with the substrate; and

an acoustic port for the MEMS microphone element,

wherein a compliant membrane is provided to seal the acoustic port, and the membrane has a mechanical stiffness lower than that of the diaphragm of the MEMS microphone element,

wherein a support is attached to the substrate via a second die attachment, the MEMS microphone element is attached to the support via a first die attachment, the compliant membrane is sandwiched between the first die attachment and the support to suspend, a suspended length of the compliant membrane is equal to a length of a diaphragm of the MEMS microphone element,

wherein the compliant membrane is pre-buckled in rest position, and has a low initial in-plane tensile stress through compressive,

wherein the compliant membrane does not have a ventilation hole.

2. The MEMS microphone device according to claim 1 , wherein the acoustic port is provided in the substrate or the cover.

3. The MEMS microphone device according to claim 1 , wherein an ASIC for the MEMS microphone element is also sealed by the substrate, the cover and the compliant membrane.

4. The MEMS microphone device according to claim 1 , wherein the compliant membrane is made of at least one of the followings: silicon, polysilicon, silicon nitride, silicon oxide, polymer, plastics, elastomer, metal, alloy, metallic glass, or dielectrics, which have a higher elongation or ultimate strength than that of silicon materials.

5. The MEMS microphone device according to claim 1 , wherein the compliant membrane has a Young's modulus of less than 100 GPa.

6. The MEMS microphone device according to claim 1 , wherein the compliant membrane is air permeable.

7. The MEMS microphone device according to claim 1 , wherein the compliant membrane is water-proofing.

8. The MEMS microphone device according to claim 1 , wherein the substrate is a printed circuitry board or flexible PCB.

9. An electronics apparatus comprising a MEMS microphone device according to claim 1 .