Micro-device with a cavity

1. A micro-device, comprising a substrate with a cavity, wherein the cavity is covered with a patterned cap layer, the patterned cap layer being covered with a porous layer that is permeable to vapor hydrofluoric acid (HF) etchant, wherein a top surface of the porous layer is at a first level over features of the patterned cap layer and at a second level between the features, the second level being different than the first level, wherein the micro-device comprises a Microelectromechanical Systems (MEMS) device with a component that is moveable in operational use of the MEMS device, wherein the component is arranged within the cavity, wherein the porous layer comprises a non-densified carbon doped oxide.

2. The micro-device of claim 1 , further comprising a release hole extending to the cavity through the cap layer, wherein the porous layer is provided on the cap layer and in the release hole.

3. The micro-device of claim 1 , further comprising a sealing layer deposited over the porous layer.

4. The micro-device of claim 1 , wherein the cavity comprises an air gap in a sacrificial oxide region.

5. The micro-device of claim 4 , wherein the sacrificial oxide region comprises silicon oxide.

6. The micro-device of claim 1 , wherein the porous layer has a thickness less than 700 nm.

7. A micro-device comprising:

a substrate comprising an element that is moveable in operational use of a Microelectromechanical Systems (MEMS) device, the element being positioned within a cavity;

a packaging cap layer including a hole aligned with the cavity; and

a porous layer comprising a porous material, the porous layer covering the cavity such that a top surface of the porous layer is at a first level within the hole and a different level over the packaging cap layer, the porous material being permeable to a vapor hydrofluoric acid (HF) etchant;

wherein the porous layer comprises a non-densified carbon doped oxide.

8. The device of claim 7 , further comprising a release hole in the packaging cap layer over the porous layer.

9. The device of claim 8 , wherein the packaging cap layer includes the release hole directly above the element.

10. The device of claim 8 , further comprising, a sealing layer over the porous layer.

11. The device of claim 8 , wherein the porous layer has a thickness less than 700 nm.

12. The device of claim 8 , wherein the cavity comprises an air gap in a sacrificial oxide region.

13. A micro-device comprising:

a substrate;

a first interconnect layer;

a first porous layer being permeable to a vapor hydrofluroic acid (HF) etchant, the porous layer being disposed over the first interconnect layer, the first interconnect layer and the first porous layer define a first cavity;

a second interconnect layer disposed over the first interconnect layer;

a second porous layer disposed over the second interconnect layer, wherein the second porous layer is permeable to a vapor HF etchant, the second interconnect layer and the second porous layer defining a second cavity wherein the first and second porous layers comprise a non-densified carbon-doped oxide; and

a Microelectromechanical System (MEMS) device disposed within the first and second cavities.

14. The device of claim 13 , further comprising, a sealing layer over the first porous layer.

15. The device of claim 13 , wherein the first porous layer has a thickness less than 700 nm.

16. The device of claim 13 , wherein the first cavity comprises an air gap in a sacrificial oxide region.

17. The device of claim 13 , further comprising a patterned packaging cap layer with a release hole extending to the cavity.

18. The device of claim 17 , wherein the porous layer is provided on the packaging cap layer and in the release hole.

19. The device of claim 13 , wherein the micro-device does not include a packaging cap layer between the porous layer and the cavity.