MEMS ELEMENT AND METHOD OF MANUFACTURING THE SAME

• US 20100213039A1
• Filed: 02/12/2010
• Published: 08/26/2010
• Est. Priority Date: 02/24/2009
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: SAITO, Tomohiro
• Granted Patent: US 8,686,816 B2
• Time in Patent Office: Days
• US Class Current: 200/181
• CPC Class Codes: B81B 2201/016 having a bridge fixed on two ends and connected to one or more dimples
• CPC Class Codes: B81B 2203/0109 Bridges
• CPC Class Codes: B81B 3/007 For controlling stiffness, e.g. ribs
• CPC Class Codes: H01H 2001/0084 with perpendicular movement of the movable contact relative to the substrate
• CPC Class Codes: H01H 2059/0036 Movable armature with higher resonant frequency for faster switching
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A MEMS element of an aspect of the present invention including a first electrode provided on a substrate, a second electrode which is provided above the first electrode and which is driven toward the first electrode, an anchor provided on the substrate, a beam which supports the second electrode in midair, one end of the beam being connected to the anchor and the beam including a sidewall part provided at its end in the width direction, the sidewall part having a downward-facing protrusion.

Claims

1. A MEMS element comprising:

a first electrode provided on a substrate;

a second electrode which is provided above the first electrode and which is driven toward the first electrode;

an anchor provided on the substrate;

a beam which supports the second electrode in midair, one end of the beam being connected to the anchor and the beam including a sidewall part provided at its end in the width direction, the sidewall part having a downward-facing protrusion.

2. The element of claim 1, wherein the other end of the beam is connected to the second electrode with a joining part, and

the width of the joining part is less than the width of the beam.

3. The element of claim 1, wherein the second electrode has at its end a first protrusion protruding in a direction perpendicular to the surface of the substrate.

4. The element of claim 1, wherein the second electrode has a first concave part which sinks toward the first electrode between one and the other ends of the second electrode.

5. The element of claim 4, wherein the first electrode has a first slit or a first groove in a position facing the first concave part.

6. The element of claim 5, wherein the width of the first slit or groove is greater than twice the film thickness of the first electrode in a direction perpendicular to the substrate.

7. The element of claim 1, wherein the side of the sidewall part is provided with a second protrusion protruding in a direction parallel to the surface of the substrate.

8. The element of claim 1, wherein the substrate below the beam is provided with a dummy layer, the width of the dummy layer being less than the width of the beam.

9. The element of claim 8, wherein the underside of the beam is provided with a third protrusion protruding in a direction perpendicular to the surface of the substrate.

10. The element of claim 9, wherein the dummy layer has a second slit in a position facing the third protrusion.

11. The element of claim 1, wherein the second electrode has on its underside a fourth protrusion protruding toward the substrate.

12. The element of claim 11, wherein the first electrode has a third slit or a third groove in a position facing the fourth protrusion.

13. The element of claim 12, wherein the width of the third slit or groove is less than twice the thickness of the first electrode in a direction perpendicular to the substrate.

14. The element of claim 1, wherein the thickness of the sidewall part in a direction parallel to the surface of the substrate is not greater than the thickness of the beam in a direction perpendicular to the surface of the substrate.

15. A MEMS element manufacturing method comprising:

forming a first electrode and a dummy layer on a substrate;

forming a sacrificial layer with an upward-facing convex part on the first electrode and the dummy layer;

forming a second electrode above the first electrode and forming a beam with a sidewall part based on the convex part of the sacrificial layer above the dummy layer; and

removing the sacrificial layer and forming a cavity between the dummy layer and the beam, between the dummy layer and the sidewall part, and between the first electrode and the second electrode.

16. The method of claim 15, wherein the thickness of the sidewall part in a direction parallel to the surface of the substrate is not greater than the thickness of the second electrode in a direction perpendicular to the surface of the substrate.

17. The method of claim 15, further comprising:

when forming the second electrode, forming at the ends of the second electrode a first protrusion protruding in a direction perpendicular to the surface of the substrate on the basis of a step between the first electrode and sacrificial layer.

18. The method of claim 15, further comprising:

when forming the beam and the sidewall part, covering not only the beam and the sidewall part with a mask but also a part protruding from the end of the sidewall part in a direction parallel to the surface of the substrate with the mask; and

processing the beam and the sidewall part by use of the mask and at the same time, forming at the end of the sidewall part a second protrusion protruding in a direction parallel to the surface of the substrate.

19. The method of claim 15, further comprising:

forming a slit or a groove in the first electrode before forming the sacrificial layer; and

forming a member for forming the second electrode in the slit or groove and forming a part protruding toward the first electrode in the second electrode.

20. The method of claim 19, wherein the dimensions of the slit or groove are greater than twice the thickness of the second electrode in a direction perpendicular to the substrate.