Micro-switching element fabrication method and micro-switching element

• US 20050190023A1
• Filed: 06/29/2004
• Published: 09/01/2005
• Est. Priority Date: 02/27/2004
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Nakatani, Tadashi, Miyashita, Tsutomu
• Granted Patent: US 7,312,677 B2
• Time in Patent Office: Days
• US Class Current: 335/78
• CPC Class Codes: B81B 2201/016 having a bridge fixed on two ends and connected to one or more dimples
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81C 1/00142 Bridges deformable micromirrors G02B26/0841
• CPC Class Codes: B81C 2201/0109 Sacrificial layers not provided for in B81C2201/0107 - B81C2201/0108
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A method is provided for making a micro-switching element. The switching element includes a substrate, two supporting members fixed to the substrate, and a movable beam bridging between the supporting members. The beam includes a membrane, a movable contact electrode and a movable driving electrode, both disposed on the membrane. The switching element also includes a pair of stationary contact electrodes facing the movable contact electrode, and a stationary driving electrode cooperating with the movable driving electrode for generation of electrostatic force. The method includes the steps of making a sacrifice layer on the substrate, making the membrane on the sacrifice layer, and subjecting the sacrifice layer to etching with the membrane intervening, so that the supporting members are formed as remaining portions of the sacrifice layer between the substrate and the membrane.

Claims

1. A method of making a micro-switching element, the switching element comprising:

a first substrate;

a pair of supporting members spaced from each other and fixed to the substrate;

a movable beam that includes a membrane bridging between the supporting members, a movable contact electrode disposed on the membrane and a movable driving electrode disposed on the membrane;

a pair of stationary contact electrodes arranged to face the movable contact electrode; and

a stationary driving electrode cooperating with the movable driving electrode for generation of electrostatic force;

the method comprising;

a sacrifice layer forming step for making a sacrifice layer on the substrate;

a membrane forming step for making the membrane on the sacrifice layer; and

a supporting member forming step for subjecting the sacrifice layer to etching with the membrane intervening, so that the supporting members are formed as remaining portions of the sacrifice layer between the substrate and the membrane.

2. The method according to claim 1, further comprising:

a first additional step performed before the sacrifice layer forming step; and

a second additional step performed after the membrane forming step but before the supporting member forming step;

wherein the first additional step is performed for forming the stationary driving electrode and the stationary contact electrodes on the substrate, the second additional step being performed for forming the movable contact electrode and the movable driving electrode on the membrane;

wherein in the membrane forming step, an opening corresponding in position to the stationary contact electrodes is formed in the membrane, the movable contact electrode including a portion extending through the opening to face a relevant one of the stationary contact electrodes.

3. The method according to claim 1, further comprising the steps of:

forming the stationary driving electrode and the stationary contact electrodes on a second substrate; and

combining the first substrate and the second substrate via a bonding wall in a manner such that the movable contact electrode faces the stationary contact electrodes, and that the movable driving electrode faces the stationary driving electrode.

4. The method according to claim 3, wherein the first substrate, the second substrate and the bonding wall separate the movable contact electrode, the stationary contact electrodes, the movable driving electrode and the stationary driving electrode from an exterior of the micro-switching element.

5. The method according to claim 1, wherein the sacrifice layer is made of silicon, the membrane being made of silicon dioxide or silicon nitride.

6. The method according to claim 1, wherein the sacrifice layer is made of silicon dioxide, the membrane being made of silicon.

7. The method according to claim 1, wherein the membrane has a thickness no smaller than 1.5 μ

m.

8. A micro-switching element comprising:

a substrate;

a pair of supporting members spaced from each other and fixed to the substrate;

a movable beam that includes a membrane bridging between the supporting members, a movable contact electrode on the membrane and a movable driving electrode on the membrane;

a pair of stationary contact electrodes formed on the substrate and arranged to face the movable contact electrode; and

a stationary driving electrode formed on the substrate and cooperating with the movable driving electrode for generation of electrostatic force;

wherein the supporting members are formed as remaining portions of the sacrifice layer by removing part of the sacrifice layer disposed between the substrate and the membrane.

9. A micro-switching element comprising:

a first substrate and a second substrate facing the first substrate;

a pair of supporting members spaced from each other and fixed to the first substrate;

a movable beam that includes a membrane bridging between the supporting members, a movable contact electrode on the membrane and a movable driving electrode on the membrane, the beam being disposed between the first substrate and the second substrate;

a pair of stationary contact electrodes formed on the second substrate and arranged to face the movable contact electrode;

a stationary driving electrode formed on the second substrate and cooperating with the movable driving electrode for generation of electrostatic force; and

a bonding wall disposed between the first substrate and the second substrate;

wherein the first substrate, the second substrate and the bonding wall separate the movable contact electrode, the stationary contact electrodes, the movable driving electrode and the stationary driving electrode from an exterior of the micro-switching element.

10. The micro-switching element according to claim 9, wherein the supporting members are formed as remaining portions of the sacrifice layer by removing part of the sacrifice layer disposed between the first substrate and the movable beam.