Composite sacrificial structure for reliably creating a contact gap in a MEMS switch

1. A method for manufacturing a micro-electromechanical system (MEMS) switch, comprising:

providing a substrate;

providing an actuator plate and a contact pad over the substrate;

providing a first sacrificial layer over the contact pad;

providing a second sacrificial layer over the actuator plate, the contact pad, and the first sacrificial layer,

creating a recess in the second sacrificial layer to expose an area of the first sacrificial layer, wherein the area of the first sacrificial layer exposed by the recess is over the contact pad;

forming an actuation member over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess; and

removing the first and second sacrificial layers, wherein removing the first sacrificial layer comprises creating a contact gap between the actuation member and the contact pad.

2. The method of claim 1 wherein removing the first and second sacrificial layers comprises first removing the second sacrificial layer and then removing the first sacrificial layer.

3. The method of claim 1 for manufacturing the MEMS switch, further comprising forming the first sacrificial layer to be over only the contact pad.

4. The method of claim 1 for manufacturing the MEMS switch, wherein forming the actuation member over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess further comprises forming a contact portion of the actuation member within the recess on the area of the first sacrificial layer exposed by the recess.

5. The method of claim 4 for manufacturing the MEMS switch, wherein forming the actuation member over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess further comprises forming a contact area of the actuation member over and on the area of the first sacrificial layer exposed by the recess.

6. The method of claim 1 for manufacturing the MEMS switch, further comprising wherein the first sacrificial layer is provided so that when the actuation member is formed over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess, the first sacrificial layer is positioned in the contact gap between the actuation member and the contact pad.

7. The method of claim 1 for manufacturing the MEMS switch, further comprising providing an anchor pad over the substrate.

8. The method of claim 7 for manufacturing the MEMS switch, wherein forming the actuation member over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess comprises anchoring an end of the actuation member to the anchor pad.

9. The method of claim 1 for manufacturing the MEMS switch, wherein forming the actuation member over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess further comprises forming an arm of the actuation member over the actuator plate whereby the arm of the actuation member and the actuator plate define an actuator gap.

10. The method of claim 1 for manufacturing the MEMS switch, wherein providing the actuator plate and the contact pad over the substrate, further comprises:

providing a conductive layer over the substrate; and

forming the actuator plate and the contact pad from the conductive layer.

11. The method of claim 10 for manufacturing the MEMS switch, wherein providing the first sacrificial layer over the contact pad further comprises:

providing the first sacrificial layer over the conductive layer; and

removing portions of the first sacrificial layer that extend beyond the contact pad.

12. The method of claim 11 for manufacturing the MEMS switch wherein the first sacrificial layer is provided over the conductive layer prior to forming the actuator plate and the contact pad from the conductive layer.

13. The method of claim 11 for manufacturing the MEMS switch, wherein the actuator plate and the contact pad are formed from the conductive layer prior to providing the first sacrificial layer over the conductive layer.

14. The method of claim 10 for manufacturing the MEMS switch, further comprising:

providing a hard conductive layer between the first sacrificial layer and the conductive layer; and

forming a bump pad under the first sacrificial layer.

15. The method of claim 1 for manufacturing the MEMS switch, wherein forming the actuation member over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess further comprises:

providing a hard conductive layer over at least the area of the first sacrificial layer exposed by the recess; and

attaching the hard conductive layer to a contact portion of the actuation member.

16. The method of claim 1 for manufacturing the MEMS switch, wherein forming the actuation member over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess further comprises:

providing a seed layer over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess; and

electroplating conductive material over the seed layer to form the actuation member.

17. The method of claim 16 for manufacturing the MEMS switch wherein:

providing the seed layer over the second sacrificial layer and within the recess on the area of the first sacrificial layer exposed by the recess comprises:

providing an attachment layer over the area of the first sacrificial layer exposed by the recess and the second sacrificial layer; and

providing a seed film over the attachment layer wherein the seed layer includes the seed film and the attachment layer.

18. The method of claim 17 for manufacturing the MEMS switch, further comprising:

removing a portion of the attachment layer underneath at least a contact portion of the actuation member prior to removing the first and second sacrificial layers.

19. The method of claim 1 for manufacturing the MEMS switch, further comprising:

providing a third sacrificial layer over the actuation member;

providing an enclosure layer over the third sacrificial layer; and

removing the third sacrificial layer wherein the enclosure layer forms a dome over the MEMS switch.

20. The method of claim 1 , wherein the area of the first sacrificial layer exposed by the recess is substantially parallel to a contact area of the contact pad and over the contact area of the contact pad.

21. The method of claim 1 for manufacturing the MEMS switch, wherein the first sacrificial layer comprises a metal sacrificial layer.

22. The method of claim 21 for manufacturing the MEMS switch, wherein the second sacrificial layer comprises a polymer based sacrificial layer.

23. The method of claim 1 for manufacturing the MEMS switch, wherein the second sacrificial layer comprises a polymer based sacrificial layer.

24. A fabrication device for manufacturing a micro-electromechanical system (MEMS) switch, comprising:

a substrate;

an actuator plate and a contact pad over the substrate;

a first sacrificial layer over the contact pad;

a second sacrificial layer over the actuator plate and the contact pad, the second sacrificial layer comprising a recess wherein an area of the first sacrificial layer is exposed by the recess and the area of the first sacrificial layer exposed by the recess is over the contact pad; and

an actuation member formed over the second sacrificial layer and having a contact portion formed within the recess on the area of the first sacrificial layer exposed by the recess, wherein a contact gap between the actuation member and the contact pad is defined by the first sacrificial layer.

25. The fabrication device of claim 24 , wherein the actuation member further comprises a contact portion, wherein the contact portion of the actuation member is within the recess in the second sacrificial layer and on the area of the first sacrificial layer exposed by the recess.

26. The fabrication device of claim 25 , wherein the contact portion further comprises a contact area, wherein the contact area of the contact portion is over and on the area of the first sacrificial layer exposed by the recess.

27. The fabrication device of claim 24 , wherein the first sacrificial layer is positioned in the contact gap between the actuation member and the contact pad.

28. The fabrication device of claim 24 , further comprising an anchor pad over the substrate.

29. The fabrication device of claim 28 , wherein an anchored end of the actuation member is attached to the anchor pad.

30. The fabrication device of claim 24 , wherein the area of the first sacrificial layer exposed by the recess is substantially parallel to a contact area of the contact pad and over the contact area of the contact pad.

31. The fabrication device of claim 24 , wherein the first sacrificial layer comprises a metal sacrificial layer.

32. The fabrication device of claim 31 , wherein the second sacrificial layer comprises a polymer based sacrificial layer.

33. The fabrication device of claim 24 , wherein the second sacrificial layer comprises a polymer based sacrificial layer.