Micro-electromechanical systems switch and method of fabricating the same

• US 20060086597A1
• Filed: 03/23/2005
• Published: 04/27/2006
• Est. Priority Date: 10/21/2004
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Lee, Jae Woo, Kang, Sung Weon, Je, Chang Han
• Granted Patent: US 7,283,025 B2
• Time in Patent Office: Days
• US Class Current: 200/200
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01H 2059/0072 with stoppers or protrusions for maintaining a gap, reducing the contact area or for preventing stiction between the movable and the fixed electrode in the attracted position
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01P 1/127 Strip line switches
• CPC Class Codes: Y10T 29/49105 Switch making
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49204 Contact or terminal manufacturing
• CPC Class Codes: Y10T 29/49208 by assembling plural parts

Abstract

Provided is a micro-electromechanical systems switch for controlling signal delivery in a high frequency band wireless communication and a radio frequency (RF) system and, comprising: a substrate; a signal line formed on the substrate and having a predetermined opening portion; at least one supporting frame each formed on the substrate at both sides of the signal line; a ground line formed on the substrate between the supporting frame and the signal line; a moving plate fixed to the supporting frame at both sides thereof, the moving plate being movable upward and downward; a switching unit positioned on the moving plate, the switching unit comprising contact means for connecting the opened signal line; and a supporting layer for supporting the moving plate and the switching unit, wherein the supporting layer comprises a support protrusion portion for maintaining a distance from the substrate.

Claims

1. A micro-electromechanical systems switch comprising:

a substrate;

a signal line formed on the substrate and having a predetermined opening portion;

at least one supporting frame each formed on the substrate at both sides of the signal line;

a ground line formed on the substrate between the supporting frame and the signal line;

a moving plate fixed to the supporting frame at both sides thereof, the moving plate being movable upward and downward;

a switching unit positioned on the moving plate, the switching unit comprising contact means for connecting the opened signal line; and

a supporting layer for supporting the moving plate and the switching unit, wherein the supporting layer comprises a support protrusion portion for maintaining a distance from the substrate.

2. The switch according to claim 1, wherein a dielectric layer is formed on a surface of the ground line.

3. The switch according to claim 1, wherein the moving plate is made of material having an elastic restoration force.

4. The switch according to claim 1, wherein the switching unit is formed in a rectangular shape having a center opening.

5. The switch according to claim 1, wherein the support protrusion portion is formed at a height to reach to the substrate when the contact means comes in contact with the signal line.

6. The switch according to claim 1, wherein a wedge-shaped groove is formed in the support protrusion portion.

7. The switch according to claim 1, wherein a dielectric layer having a predetermined thickness is formed on surfaces of the moving plate and the switching unit.

8. The switch according to claim 1, wherein a driving voltage is applied to the ground line and the moving plate to generate an electrostatic force.

9. A method of fabricating a micro-electromechanical systems switch, comprising:

a) forming a signal line having a predetermined opening portion, a supporting frame positioned at both sides of the signal line, and a ground line positioned between the supporting frame and the signal line on a substrate, respectively;

b) forming a sacrificial layer having a predetermined thickness over the surface;

c) forming grooves in the sacrificial layer at portions where ends of the signal line reach, respectively, and then, forming contact portions in the grooves;

d) forming a hole in the sacrificial layer to expose the substrate between the opened signal lines, a support protrusion portion in the hole, and a supporting layer on the sacrificial layer other than the contact portion;

e) forming a moving plate over the supporting frame and the sacrificial layer and over the supporting layer;

f) forming a switching unit over the supporting layer and the contact portion inside the moving plate; and

g) removing the sacrificial layer.

10. The method according to claim 9, further comprising after the step (a), forming a dielectric layer on a surface of the ground line.

11. The method according to claim 9, wherein the signal line, the ground line and the supporting frame are formed by a thin film deposition and patterning process or by an electro plating process.

12. The method according to claim 9, wherein the switching unit is formed in a rectangular shape having a center opening.

13. The method according to claim 9, further comprising after the step (g), forming a dielectric layer on a surface of the exposed supporting layer and the switching unit.

14. The method according to claim 13,

wherein the supporting layer is made of a silicon nitride layer and the dielectric layer is made of polyimide, and

wherein the silicon nitride layer is formed by a plasma enhanced chemical vapor deposition method and the polyimide is formed by a spin coating method.

15. The method according to claim 9, wherein the sacrificial layer is removed by any one of a reactive ion etching method and a wet etching method.