Hybrid MEMS RF switch and method of fabricating same

• US 8,445,306 B2
• Filed: 12/24/2008
• Issued: 05/21/2013
• Est. Priority Date: 12/24/2008
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Lindgren, Peter J., Stamper, Anthony K.
• Primary Examiner(s): Garber, Charles
• Assistant Examiner(s): CHOI, CALVIN Y
• Application Number:
  US12/343,533
• Publication Number:
  US 20120098136A1
• Time in Patent Office: 1,609 Days
• Field of Search: 438/22, 438/24, 438/48, 438/57, 438/73, 438 50- 53, 257/415, 257/418, 296/22
• US Class Current: 438/52
• CPC Class Codes: B81B 3/0097 Devices comprising flexible or deformable elements not provided for in groups B81B3/0002 - B81B3/0094
• CPC Class Codes: B81C 1/0015 Cantilevers switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

Structures having a hybrid MEMS RF switch and method of fabricating such structures using existing wiring layers of a device is provided. The method of manufacturing a MEMS switch includes forming a forcing electrode from a lower wiring layer of a device and forming a lower electrode from an upper wiring layer of the device. The method further includes forming a flexible cantilever arm over the forcing electrode and the lower electrode such that upon application of a voltage to the forcing electrode, the flexible cantilever arm will contact the lower electrode to close the MEMS switch.

Claims

1. A method of manufacturing a MEMS switch, comprising:

forming a forcing electrode from a lower wiring layer of a device;

forming a lower electrode from an upper wiring layer of the device;

depositing a gold layer on a conductive material forming the lower electrode prior to patterning the conductive material;

depositing a refractory material between the conductive material forming the lower electrode and the gold layer prior to the patterning; and

forming a flexible cantilever arm over the forcing electrode and over the lower electrode such that upon application of a voltage to the forcing electrode, the flexible cantilever arm will contact the lower electrode to close the MEMS switch.

2. The method of claim 1, wherein the forcing electrode and the lower electrode are copper wiring levels of the device.

3. The method of claim 1, wherein the forcing electrode is embedded in a dielectric layer formed by a damascene process.

4. The method of claim 1, wherein the lower electrode is formed by performing the patterning of a deposited layer of the conductive material on a dielectric layer.

5. The method of claim 1, wherein the flexible cantilever arm is formed by:

depositing a sacrificial material over a dielectric material and the lower electrode; and

depositing a conductive material on the sacrificial material.

6. The method of claim 5, wherein the conductive material is at least one of Cu, Au, TiN, and Al and the sacrificial material is one of polymer and silicon.

7. The method of claim 1, further comprising hermetically sealing the flexible cantilever arm comprising:

depositing a sacrificial layer on the flexible cantilever arm and on a sacrificial material used in the formation of the flexible cantilever arm;

capping the sacrificial layer with a deposited hard cap material;

opening holes in the hard cap material;

stripping the sacrificial layer and the sacrificial material; and

sealing the holes.

8. A MEMS switch, comprising:

a lower wiring layer of a device acting as forcing electrode;

an upper wiring layer of the device acting as a lower electrode contact, the lower electrode contact comprising a conductive material;

a refractory material formed on the conductive material;

a gold layer formed on the refractory material such that the refractory material is between the conductive material forming the lower electrode and the gold layer; and

a cantilever arm positioned above the forcing electrode and the lower electrode contact such that upon application of a voltage to the forcing electrode, the cantilever arm contacts the lower electrode contact to complete a circuit for the MEMS switch,

wherein the refractory material and the gold layer are formed prior to patterning of the conductive material to form the upper wiring layer.

9. The MEMS switch of claim 8, wherein the MEMS switch is hermetically sealed.

10. The MEMS switch of claim 9, wherein the hermetic seal is a SiN cap layer that has sealed openings.

11. The MEMS switch of claim 8, wherein the cantilever arm is at least one of Al, Cu, AlCu and Au and TiN.

12. The MEMS switch of claim 8, wherein the cantilever arm is about 10 microns thick and spaced from the lower electrode contact at a distance of about 5 microns and the forcing electrode at a distance of about 8 microns.

13. A method of manufacturing a MEMS switch, comprising:

forming a forcing electrode from a lower wiring layer of a device;

forming a lower electrode from an upper wiring layer of the device;

forming another patterned wiring from the upper wiring layer;

depositing a gold layer on the another patterned wiring and the lower electrode of the upper wiring layer;

depositing a refractory material between the gold layer and the lower electrode;

forming a flexible cantilever arm over the forcing electrode and over the lower electrode such that upon application of a voltage to the forcing electrode, the flexible cantilever arm will contact the lower electrode to close the MEMS switch; and

depositing another gold layer on an underside surface of the flexible cantilever arm.

14. The method of claim 13, wherein the flexible cantilever arm is formed in contact with the another patterned wiring of the upper wiring layer of the device.

15. The method of claim 14, wherein the flexible cantilever arm extends past the lower electrode.

16. The method of claim 15, wherein the flexible cantilever arm is spaced from the lower electrode.

17. The method of claim 16, wherein the lower electrode and the upper wiring layer of the device are completely buried in a dielectric layer.