MEMS DEVICE AND METHOD OF MANUFACTURING

• US 20150191345A1
• Filed: 02/13/2015
• Published: 07/09/2015
• Est. Priority Date: 07/08/2013
• Status: Active Grant

• Current Assignee: Motion Engine inc
• Original Assignee: Motion Engine inc
• Inventors: Boysel, Robert Mark, Ross, Louis
• Granted Patent: US 9,309,106 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2207/095 through the lid
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/94 at wafer-level, i.e. with connecting carried out on a wafer comprising a plurality of undiced individual devices

Abstract

A MEMS device is provided. The device includes a MEMS wafer, a top cap wafer and a bottom cap wafer. The top and bottom cap wafers are respectively bonded to first and second sides of the MEMS wafer, the MEMS and cap wafers being electrically conductive. The outer side of the top cap wafer is provided with electrical contacts. The MEMS wafer, the top cap wafer and the bottom cap wafer define a cavity for housing a MEMS structure. The device includes insulated conducting pathways extending from within the bottom cap wafer, through the MEMS wafer and through the top cap wafer. The pathways are connected to the respective electrical contacts on the top cap wafer, for routing electrical signals from the bottom cap wafer to the electrical contacts on the top cap wafer. A method of manufacturing the MEMS device is also provided.

Claims

1. A MEMS device comprising:

an electrically conductive MEMS wafer including a MEMS structure, the MEMS wafer having a first side and a second side;

an electrically conductive top cap wafer having an inner top cap side and an outer top cap sides, the inner top cap side being bonded to the first side of the MEMS wafer, the outer top cap side having electrical contacts;

an electrically conductive bottom cap wafer having an inner bottom cap side and an outer bottom cap side, the inner bottom cap side being bonded to the second side of the MEMS wafer such that the MEMS wafer, the top cap wafer and the bottom cap wafer define a cavity for housing the MEMS structure; and

insulated conducting pathways extending from the bottom cap wafer, through the MEMS wafer and through the top cap wafer, to respective electrical contacts such that the insulated conducting pathways are operative to conduct electrical signals from the bottom cap wafer to the electrical contacts on the top cap wafer.

2. The MEMS device according to claim 1, wherein at least one of the insulated conducting pathways comprises a portion formed by a channel extending through the entire thickness of at least the corresponding top cap wafer or the MEMS wafer or the bottom cap wafer.

3. The MEMS device according to claim 1, wherein at least one of the conducting pathways comprises a portion formed by a trench surrounding a conductive wafer plug.

4. The MEMS device according to claim 3, wherein the trench is filled with an insulating material.

5. The MEMS device according to claim 2, wherein the channel has a sidewall coated with an insulating material, the inside of the channel being filled with a conducting material.

6. The MEMS device according to claim 1, wherein said insulated conducting pathways each comprises a top cap wafer channel, a MEMS wafer channel and a bottom cap channel, said channels being aligned at a first wafer interfaces between the top cap wafer and the MEMS wafer and a second wafer interface between the MEMS wafer and the bottom cap wafer.

7. The MEMS device according to claim 6, wherein for at least one of the insulated conducting pathways, the top cap wafer channel and the bottom cap wafer channel respectively comprises a through silicon via (TSV).

8. The MEMS device according to claim 1, wherein at least one of the electrical contacts on the top cap wafer is connectable to an external potential, the corresponding insulated conducting pathway being a case pathway located at the periphery of the device.

9. The MEMS device according to claim 1, wherein the outer side of the bottom cap wafer has electrical contacts, at least one of the insulated conducting pathways being a device feedthrough extending from one of the electrical contacts on the top cap wafer to one of the electrical contacts on the bottom cap wafer.

10. The MEMS device according to claim 1, wherein the bottom cap wafer comprises bottom cap electrodes, some of the insulated conducting pathways being respectively connected to the bottom cap electrodes, for transmitting electrical signals between the bottom cap electrodes and corresponding electrical contacts on the top cap wafer.

11. The MEMS device according to claim 1, comprising at least one additional insulated conducting pathway extending through the MEMS wafer and through the top cap wafer, said at least one additional insulated conducting pathway connecting the MEMS structure to one of the electrical contacts on the top cap wafer such that the at least one additional insulated conducting pathway transmits electrical signals between the MEMS structure and said one electrical contact.

12. The MEMS device according to claim 1, wherein the MEMS wafer is a SOI wafer with an insulating layer separating a device layer from a handle layer, the insulated conducting pathways comprising respective SOI conducting shunts, electrically connecting the device and handle layers

13. The MEMS device according to claim 12, wherein the MEMS structure is patterned in both the device layer and the handle layers.

14. The MEMS device according to claim 1, wherein the top cap wafer comprises top cap electrodes, the MEMS device comprising other additional insulated conducting pathways respectively extending through the top cap wafer between said top cap electrodes and corresponding electrical contacts on the top cap wafer, for transmitting electrical signals between the top cap electrodes and the corresponding electrical contacts on the top cap wafer.

15. The MEMS device according claim 1, comprising a cap insulating layer deposited on the outer side of at least one of the top cap wafer and the bottom cap wafers.

16. The MEMS device according to claim 1, wherein the top cap wafer, the MEMS wafer and the bottom cap wafer are made of a silicon-based semiconductor and wherein the top cap wafer, the MEMS wafer and optionally, the bottom cap wafer are bonded with a conductive bond.

17. The MEMS device according to claim 1, wherein the cavity is hermetically sealed and wherein the cavity is under vacuum or contains fluid.

18. A method for manufacturing a MEMS device, the method comprising the steps of:

a) providing top and bottom cap wafers having respective inner and outer sides, and forming insulated conducting cap wafer channels on the inner sides of said cap wafers;

b) providing a MEMS wafer having first and second sides, and patterning portions of a MEMS structure and portions of insulated conducting MEMS wafer channels in one of the first and second sides;

c) bonding the side of the MEMS wafer patterned in step b) to the inner side of the top or bottom cap wafer by aligning the insulated conducting cap channels of said cap wafer with the portions of the insulated conducting MEMS channels;

d) patterning the remaining portions of the MEMS structure and the remaining portions of the insulated conducting MEMS wafer channels on the other side of the MEMS wafer;

e) bonding the side of the MEMS wafer patterned in step d) to the inner side of the other top or bottom cap wafer, by aligning the insulated conducting cap channels of said other cap wafer with the remaining portions of the insulated conducting MEMS channels, thereby creating insulated conducting pathways extending from the bottom cap wafer, through the MEMS wafer and through the top cap wafer; and

f) removing a portion of the outer sides of the top and bottom cap wafers to expose and isolate the insulated conducting pathways.

19. The method for manufacturing a MEMS device according to claim 18, wherein step a) comprises patterning trenches on the inner sides of the bottom and top cap wafers, the trenches (28) extending only partially through the cap wafers;

and filling the trenches of the top and bottom cap wafers with an insulating material.

20. The method for manufacturing a MEMS device according to claim 18, wherein step a) comprises patterning a recess in at least the top cap wafer to from part of a cavity for housing the MEMS structure.

21. The method for manufacturing a MEMS device according to claim 18, wherein step a) comprises patterning trenches and filling the trenches for forming top cap electrodes and/or leads.

22. The method for manufacturing a MEMS device according to claim 18, the MEMS wafer being an SOI wafer with an insulating layer separating a device layer from a handle layer, wherein step b) comprises forming SOI conducting shunts through the device layer and the insulating layer, and wherein step b) comprises etching trenches surrounding some of the SOI conducting shunts, for forming said portions of insulated conducting MEMS wafer channels.

23. The method for manufacturing a MEMS device according to claim 18, wherein step b) comprises etching trenches for forming MEMS electrodes and/or leads.

24. The method for manufacturing a MEMS device according to claims 18, wherein step c) comprises bonding the top cap wafer to the first side of the MEMS wafer with a conductive bond and wherein step e) comprises bonding the bottom cap wafer to the second side of the MEMS wafer with a conductive bond, the conductive bond comprising a bonding layer or a fusion bond

25. The method for manufacturing a MEMS device according to claim 18, wherein step d) comprises etching trenches to form the remaining portion of the MEMS structure to and to form conductive wafer plugs part of the insulated conducting MEMS wafer channels.

26. The method for manufacturing a MEMS device according to claim 18, wherein step f) comprises grinding and polishing the outer sides of the top and bottom cap wafers and wherein step f) comprises electrically passivating the outer sides of the top and bottom cap wafers with cap insulating layers.

27. The method for manufacturing a MEMS device according to claim 18, comprising a step g) of forming electrical contacts on the outer side of the top cap wafer connected with the insulated conducting pathways, allowing conducting of electrical signals from the bottom cap wafer to said electrical contacts on the top cap wafer.

28. The method for manufacturing a MEMS device according to claim 28, wherein step g) further comprises forming electrical contacts on the outer side of the bottom cap wafer connected to some of the insulated conducting pathways, allowing routing of electrical signals to the electrical contacts on the bottom cap wafer.

29. The method for manufacturing a MEMS device according to claim 28, wherein step g) comprises creating openings in the cap insulating layer on the outer side of cap wafer(s), in line with the insulated conducting wafer cap channels;

applying a metallic layer on said cap insulating layer and patterning the metallic layer to form electrical leads and bond pads; and

applying a passivating film over the electrical leads and the bond pads, and creating openings in said passivating film over the bond pads.

30. A method of operating a MEMS device comprising:

operating a MEMS structure within a cavity, the cavity defined by a conductive top cap wafer having an inner top cap side bonded to a first side of a conductive MEMS wafer that includes the MEMS structure, the cavity being further defined by a conductive bottom cap wafer having an inner bottom cap side bonded to a second side of the MEMS wafer; and

conducting electrical signals between the bottom cap wafer through the MEMS wafer to electrical contacts on an outer top cap wafer side of the conductive top cap wafer with insulated conducting pathways that extend from the bottom cap wafer through the MEMS wafer and the top cap wafer, the insulated conducting pathways being in conductive contact with corresponding electrical contacts on the outer top cap wafer side.