MEMS DEVICES AND FABRICATION THEREOF

• US 20110260267A1
• Filed: 05/06/2009
• Published: 10/27/2011
• Est. Priority Date: 05/12/2008
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Van Schaijk, Robertus T. F.
• Granted Patent: US 8,853,797 B2
• Time in Patent Office: Days
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/016 having a bridge fixed on two ends and connected to one or more dimples
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 3/0078 Constitution or structural means for improving mechanical properties not provided for in B81B3/007 - B81B3/0075
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage

Abstract

A MEMS device and method, comprising: a substrate; a beam; and a cavity located therebetween; the beam comprising a first beam layer and a second beam layer, the first beam layer being directly adjacent to the cavity, the second beam layer being directly adjacent to the first beam layer; the first beam layer comprising a metal or a metal alloy containing silicon; and the second beam layer comprising a metal or a metal alloy substantially not containing silicon. Preferably the second beam layer is thicker than the first beam layer e.g. at least five times thicker, and the first beam layer comprises a metal or alloy containing between 1% and 2% of silicon. The second beam layer provides desired mechanical and/or optical properties whilst the first beam layer prevents spiking.

Claims

1. A MEMS device, comprising:

a substrate;

a beam; and

a cavity;

the cavity being located between the substrate and the beam;

wherein

the beam comprises a first beam layer and a second beam layer, the first beam layer being directly adjacent to the cavity, the second beam layer being directly adjacent to the first beam layer;

the first beam layer comprising a metal containing silicon or a metal alloy containing silicon; and

the second beam layer comprising a metal substantially not containing silicon or a metal alloy substantially not containing silicon.

2. A MEMS device according to claim 1, wherein the second beam layer is thicker than the first beam layer.

3. A MEMS device according to claim 1, wherein the second beam layer is at least five times thicker than the first beam layer.

4. A MEMS device according to claim 1, wherein the first beam layer has a thickness in the range 100-500 nm.

5. A MEMS device according to claim 1, wherein the second beam layer has a thickness in the range 500 nm-5 μ

m.

6. A MEMS device according to claim 1, wherein the first beam layer comprises a metal or alloy containing between 1% and 2% of silicon.

7. A MEMS device according to claim 1, wherein the second beam layer comprises one of the alloys selected from aluminium alloy with Cu, Ti or Mn to substantially provide mechanical and/or optical properties of the beam.

8. A method of fabricating a MEMS beam, comprising:

providing a substrate;

depositing a sacrificial layer onto the substrate;

depositing a first beam layer onto the sacrificial layer;

depositing a second beam layer onto the first beam layer; and

removing the sacrificial layer thereby providing a cavity between the substrate and the first beam layer.

9. A method according to claim 8, wherein the second beam layer is thicker than the first beam layer.

10. A method according to claim 8, wherein the second beam layer is at least five times thicker than the first beam layer.

11. A method according to claim 8, wherein the first beam layer has a thickness in the range 100-500 nm.

12. A method according to claim 8, wherein the second beam layer has a thickness in the range 500 nm-5 μ

m.

13. A method according to claim 8, wherein the first beam layer comprises a metal or alloy containing between 1% and 2% of silicon.

14. A method according to claim 8, wherein the second beam layer comprises one of the alloys selected from aluminium alloy with Cu, Ti or Mn to provide mechanical and/or optical properties of the MEMS beam.

15. A method according to claim 8, wherein the sacrificial layer comprises amorphous silicon.