Stress release mechanism in MEMS device and method of making same

• US 20070024156A1
• Filed: 07/28/2005
• Published: 02/01/2007
• Est. Priority Date: 07/28/2005
• Status: Active Grant

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Koury, Daniel, Hammond, Jonathan, Li, Gary
• Granted Patent: US 7,268,463 B2
• Time in Patent Office: Days
• US Class Current: 310/309
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type

Abstract

MEMS devices (100) and methods for forming the devices have now been provided. In one exemplary embodiment, the MEMS device (100) comprises a substrate (106) having a surface, an electrode (128) having a first portion coupled to the substrate surface, and a second portion movably suspended above the substrate surface, and a stress-release mechanism (204) disposed on the electrode second portion, the stress-release mechanism (204) including a first slot (208) integrally formed in the electrode. In another exemplary embodiment, the substrate (106) includes an anchor (134, 136) and the stress-release mechanism 222 is formed adjacent the anchor (134, 136).

Claims

1. A MEMS device comprising:

a substrate having a surface;

an electrode having a first portion coupled to the substrate surface, and a second portion movably suspended above the substrate surface; and

a stress-release mechanism disposed on the electrode second portion, the stress-release mechanism including a first slot integrally formed in the electrode.

2. The MEMS device of claim 1, wherein the electrode includes a first side and a second side and the first slot extends from the electrode first side at least partially to the electrode second side.

3. The MEMS device of claim 2, wherein the stress-release mechanism comprises a second slot integrally formed in the electrode.

4. The MEMS device of claim 3, wherein the second slot extends from the electrode second side at least partially to the electrode first side.

5. The MEMS device of claim 1, wherein:

the substrate comprises an insulating layer and an active layer disposed over the insulating layer; and

the electrode is formed in the active layer.

6. The MEMS device of claim 1, wherein:

the electrode includes a third portion coupled to the substrate surface; and

the electrode second portion is disposed between the first and third portions.

7. The MEMS device of claim 1, wherein the stress-release mechanism is formed adjacent to the electrode first portion.

9. The MEMS device of claim 1, wherein:

the substrate comprises an insulating layer and an active layer disposed over the insulating layer; and

at least a portion of the anchor is formed in the active layer.

8. A MEMS device comprising:

a substrate having a surface;

an anchor at least partially coupled to the substrate surface; and

a stress-release mechanism coupled to the anchor, the stress-release mechanism including a first slot formed adjacent the anchor.

10. The MEMS device of claim 8, wherein:

the anchor includes a first side and a second side opposite the first side; and

the first slot is formed proximate the anchor first side.

11. The MEMS device of claim 10, wherein:

the stress release mechanism includes a second slot, the second slot formed proximate the anchor second side.

12. A method of forming a micro-electromechanical (“

MEMS”

) device from a substrate comprising an insulating layer and an active layer overlying the insulating layer, the method comprising the steps of;

forming a protective layer over the active layer in a pattern, the pattern having at least a first electrode section having a corner, a second electrode section adjacent the first electrode section and having an corner disposed diagonally from the first electrode section corner, and a strip connecting the first and second electrode section corners; and

removing material from portions of the active layer and the insulating layer over which the protective layer is not formed to thereby form an electrode having a slot formed therein.

13. The method of claim 12, wherein the first electrode section has a side and the second electrode section has a side substantially parallel to the first electrode section side and at least a portion of the strip is substantially parallel to the first and second electrode section sides.

14. The method of claim 12, wherein the step of forming comprises placing a shadowmask having an outline of the pattern over the active layer.

15. The method of claim 12, wherein the step of forming comprises:

depositing the protective material over the surface of the active layer; and

etching the pattern into the deposited protective material.

16. The method of claim 12, further comprising etching a portion of the insulating layer beneath the first electrode portion to thereby release at least a portion of the first electrode from the substrate.

17. A method of forming a micro-electromechanical (“

MEMS”

) device from a substrate comprising an insulating layer and an active layer overlying the insulating layer, the method comprising the steps of;

forming a protective layer over the active layer in a pattern, the pattern having at least an anchor section having a first corner and a strip extending from the anchor section first corner; and

removing material from portions of the active layer and the insulating layer over which the protective layer is not formed to thereby form an anchor having a slot formed adjacent thereto.

18. The method of claim 17, wherein the step of forming comprises:

depositing the protective material over the surface of the active layer; and

etching the pattern into the deposited protective material.

19. The method of claim 17, wherein the anchor section further comprises a second corner adjacent the first corner and the pattern further comprises a second strip extending from the anchor section second corner.

20. The method of claim 17, wherein the step of forming comprises placing a shadowmask having an outline of the pattern over the active layer.