Sensor protective coating

1. A microelectromechanical system (MEMS) sensor device comprising:

a substrate;

a support structure supported by the substrate;

a membrane supported by the support structure and spaced from the substrate;

a polymer layer covering the membrane; and

a dielectric layer that laterally surrounds the membrane and the support structure, wherein the dielectric layer establishes a hermetically sealed cavity between the membrane and the substrate.

2. The MEMS sensor device of claim 1 , wherein the polymer layer covers the dielectric layer.

3. The MEMS sensor device of claim 1 , further comprising a reference cell covered by the dielectric layer so that ambient pressure does not deflect a membrane of the reference cell.

4. The MEMS sensor device of claim 1 , wherein the sensor device is not enclosed by a cap.

5. The MEMS sensor device of claim 1 , further comprising a bond pad supported by the substrate, wherein the polymer layer is patterned to not cover the bond pad.

6. The MEMS sensor device of claim 1 , wherein the polymer layer comprises a photoresist material.

7. The MEMS sensor device of claim 1 , wherein the polymer layer comprises a parylene material or a polyimide material.

8. The MEMS sensor device of claim 1 , further comprising a reference cell completely covered by the dielectric layer.

9. The MEMS sensor device of claim 8 , wherein the polymer layer covers the reference cell.

10. A microelectromechanical system (MEMS) sensor device comprising:

a substrate;

a support structure supported by the substrate;

a membrane supported by the support structure and spaced from the substrate, the membrane having a periphery;

a dielectric layer disposed along the periphery of the membrane to define an opening in the dielectric layer over the membrane; and

a polymer layer disposed in the opening and covering the membrane;

wherein the dielectric layer establishes a hermetically sealed cavity between the membrane and the substrate.

11. The MEMS sensor device of claim 10 , wherein the polymer layer covers the dielectric layer.

12. The MEMS sensor device of claim 10 , wherein the dielectric layer laterally surrounds the membrane and the support structure.

13. The MEMS sensor device of claim 10 , further comprising a reference cell covered by the dielectric layer so that ambient pressure does not deflect a membrane of the reference cell.

14. The MEMS sensor device of claim 10 , further comprising a reference cell completely covered by the dielectric layer.

15. A microelectromechanical system (MEMS) sensor device comprising:

a substrate;

a support structure supported by the substrate;

a membrane supported by the support structure and spaced from the substrate by a gap, the membrane having a periphery;

a dielectric layer disposed along the periphery of the membrane to seal the gap, the dielectric layer having an opening over the membrane; and

a polymer layer disposed in the opening;

wherein the polymer layer is in contact with the membrane and the dielectric layer to cover the membrane and the dielectric layer, and

wherein the dielectric layer establishes a hermetically sealed cavity between the membrane and the substrate.

16. The MEMS sensor device of claim 15 , wherein the dielectric layer laterally surrounds the membrane and the support structure.

17. The MEMS sensor device of claim 15 , wherein the polymer layer comprises a photoresist material.

18. The MEMS sensor device of claim 15 , wherein the polymer layer comprises a parylene material or a polyimide material.

19. The MEMS sensor device of claim 15 , further comprising a reference cell completely covered by the dielectric layer.