JP2001014998A - Electrostatic relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture the relay easily, inexpensively, and with satisfactory yield by constructing a fixed electrode with a first fixed electrode and a second fixed electrode, and applying voltage with various polarities. SOLUTION: Voltage is applied to pads 6a, 6b to electrify a first fixed electrode 5a to positive charge and a second fixed electrode 5b to negative charge. Therefore, in a movable electrode 11, a part facing to the first fixed electrode 5a is electrified to a negative charge, and a part facing to the second fixed electrode 5b is electrified to a positive charge. Electrostatic attractive force is generated between the movable electrode 11 and both fixed electrodes 5a, 5b, the movable electrode 11 is attracted to the fixed electrodes 5a, 5b, and a movable contact 15 is closed to fixed contacts 7a, 7b. The generated electrostatic attractive force depends on a charge amount applied to the fixed electrodes 5 having small occupied area. However, since the occupied areas of both fixed electrodes 5a, 5b are the same, a settable maximum value can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic relay for driving a movable electrode by electrostatic attraction to open and close a contact.

[0002]

2. Description of the Related Art Conventionally, as an electrostatic relay, for example, FIG.
(See Japanese Patent Application Laid-Open No. 4-58431). This electrostatic relay includes a fixed electrode block 200,
And a movable electrode block 201 disposed thereabove. A fixed electrode 202 is provided on the upper surface of the fixed electrode block 200.
And a fixed contact 203 are formed. In the movable electrode block 201, a movable electrode portion 205 is provided by a slit 204.
And a movable contact portion 206 extending on both sides thereof. A movable electrode 207 is provided on the lower surface of the movable electrode portion 205.
Is provided on the lower surface of the movable contact portion 206.
8 are provided. When a voltage is applied between the two electrodes 202 and 207 to generate an electrostatic attraction, the movable electrode unit 205 is driven and the movable contact 208 is closed to the fixed contact 203.

[0003]

However, in the electrostatic relay, in order to charge the movable electrode 207, a conductive layer 209 composed of a plurality of layers is formed at a joint portion between the blocks 200 and 201, and the conductive layer 209 is formed. It is necessary to make an electrical connection to the fixed electrode block 200 side via the same. Therefore, there is a problem that the number of steps is increased and the cost is increased because the conductive layer 209 must be formed. Further, it is impossible to completely eliminate the variation in the thickness of the conductive layer 209 from the viewpoint of processing. Therefore, the conductive layer 209
In some cases, the electrical connection to the movable electrode 207 or the fixed electrode block 200 side may be insufficient, or the connection with the fixed electrode block 200 may be inappropriate, resulting in a decrease in yield.

Accordingly, an object of the present invention is to provide an electrostatic relay that can be manufactured easily and inexpensively with a high yield.

[0005]

According to the present invention, as a means for solving the above problems, a movable substrate having a movable electrode opposed to a fixed substrate having a fixed electrode is applied by applying a voltage between both electrodes. A fixed contact formed on the fixed substrate, and a movable contact formed on the movable substrate being brought into contact with and separated from the fixed contact formed on the fixed substrate. It is composed of an electrode and a second fixed electrode, and voltages of different polarities are applied to each of them.

With this configuration, when a voltage is applied between the first fixed electrode and the second fixed electrode, the portions of the movable electrode that face each fixed electrode have opposite polarities, and the gap between the movable electrode and both fixed electrodes is reduced. Causes an electrostatic attraction.

It is preferable that the first and second fixed electrodes are arranged evenly with respect to the fixed contacts, since the contacts do not contact one another and a good conduction state can be secured.

It is preferable that the first and second fixed electrodes have the same area because the generated electrostatic attraction can be maximized.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 and 2 show an electrostatic relay according to this embodiment. This electrostatic relay includes a fixed substrate 1 and a movable substrate 2.

The fixed substrate 1 is, as shown in FIG.
On the upper surface of the glass substrate 3, the signal lines 4a, 4b,
The second fixed electrodes 5a, 5b and the pads 6a, 6b, 6c,
6d is formed. The signal lines 4a and 4b are juxtaposed at a predetermined interval, one end of which is fixed contacts 7a and 7b, and the other end of which is pads 6a and 6b. First fixed electrode 5a
Are arranged along the signal lines 4a and 4b, and the second fixed electrode 5b is arranged along the first fixed electrode 5a. The occupied areas of the fixed electrodes 5a and 5b are the same, the first fixed electrode 5a is connected to the pad 6c, and the second fixed electrode 5b is connected to the pad 6d. The surfaces of the fixed electrodes 5a and 5b are covered with an insulating film 8 (see FIG. 2B). Each of the pads 6a, 6b, 6
Lead wires (not shown) are connected to c and 6d.

The movable substrate 2 is, as shown in FIG.
The first thin beam 1 is formed on the anchor 9 from a silicon substrate.
In this configuration, the movable electrode 11 is supported via the “0”.
The anchor 9 is in the form of a frame that stands upright around the upper surface of the fixed substrate 1. The first thin beam portion 10 extends laterally from four locations on the inner edge of the upper surface of the anchor 9. As shown in FIG. 1B, the movable electrode 11 has a second thin plate beam portion 13 formed in the center by a pair of slits 12, and a movable contact 15 provided in the center of the lower surface via an insulating film 14. ing. The movable contact 15 opposes the fixed contacts 7a and 7b so as to be able to come and go.

Next, a method of manufacturing the electrostatic relay having the above-described configuration will be described.

First, as shown in FIG. 3B, first and second glass substrates 3 such as Pyrex shown in FIG.
The fixed electrodes 5a and 5b and the fixed contacts 7a and 7b are formed.
At the same time, the signal lines 4a and 4b and the connection pads 6
a, 6b, 6c and 6d are respectively formed. Then, an insulating film 8 is formed on each of the first and second fixed electrodes 5a and 5b to complete the fixed substrate 1 shown in FIG. 3C.

The insulating film 8 has a relative dielectric constant of 3-4.
If a silicon oxide film or a silicon nitride film having a relative dielectric constant of 7 to 8 is used, a large electrostatic attraction can be obtained, and the contact load can be increased.

On the other hand, as shown in FIG. 3D, a contact gap is formed on the lower surface of the SOI wafer 100 including the silicon layer 101, the silicon oxide layer 102, and the silicon layer 103 from the upper surface side. For example, wet etching with TMAH using a silicon oxide film as a mask is performed to form an anchor 9 projecting downward as shown in FIG. Then, as shown in FIG.
Is provided, the movable contact 15 is formed.

Next, as shown in FIG. 3G, the SOI wafer 100 is integrated with the fixed substrate 1 by anodic bonding. Then, as shown in FIG. 3 (h), the upper surface of the SOI wafer 100 is thinned to a silicon oxide layer 102 as an oxide film with an alkali etching solution such as TMAH or KOH. Further, the silicon oxide layer 102 is removed with a fluorine-based etchant to expose the silicon layer 103, that is, the movable electrode 11, as shown in FIG. Then, die cutting etching is performed by dry etching using a reactive ion etching method (RIE) or the like, and the notch 2a is formed.
And a slit 12 to form the first and second thin beam portions 10,
13 is cut out to complete the movable substrate 2.

The fixed substrate 1 is not limited to the glass substrate 3 but may be formed of a single-crystal silicon substrate having at least an upper surface covered with an insulating film 8.

Next, the operation of the electrostatic micro relay having the above configuration will be described.

If no voltage is applied, as shown in FIG. 2B, the first and second fixed electrodes 5a and 5b and the movable electrode 11 are maintained in a parallel state, and the movable contact 15 is
a, 7b.

Here, a voltage is applied to the pads 6a and 6b to charge the first fixed electrode 5a to a positive charge and charge the second fixed electrode 5b to a negative charge as shown in FIG. Let it. As a result, the movable electrode 11 is
As shown in (a), the portion facing the first fixed electrode 5a is charged to a negative charge, and the portion facing the second fixed electrode 5b is charged to a positive charge. As a result, an electrostatic attraction is generated between the movable electrode 11 and the fixed electrodes 5a and 5b, and the movable electrode 11 is attracted to the fixed electrodes 5a and 5b.
The movable contact 15 is closed by the fixed contacts 7a and 7b. Although the generated electrostatic attraction is dominated by the amount of charge applied to the fixed electrode 5 having a small occupied area, in the present embodiment, since the occupied areas of the two fixed electrodes 5a and 5b are the same, the set value is This is the maximum possible value.

[0022]

As is apparent from the above description, according to the electrostatic relay according to the present invention, the fixed electrode is constituted by the first fixed electrode and the second fixed electrode, and voltages having different polarities are applied to the respective fixed electrodes. This eliminates the need to apply a voltage to the movable electrode and eliminates the need for a step for forming a conductive layer at the joint of the movable substrate. In addition, since there is no problem associated with the formation of the conductive layer, it is possible to easily and inexpensively manufacture the semiconductor device with high yield.

Further, since the first and second fixed electrodes are arranged evenly with respect to the fixed contact, the contact does not hit one side and the contact reliability of the contact can be improved.

Further, since the areas of the first and second fixed electrodes are the same, it is possible to maximize the generated electrostatic attraction and improve the responsiveness.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electrostatic relay according to an embodiment.

FIG. 2A is a plan view of an electrostatic relay according to the embodiment (a).
And a sectional view (b) of FIG.

FIG. 3 is a cross-sectional view showing a manufacturing process of the electrostatic relay shown in FIGS. 1 and 2.

FIG. 4 is a plan view (a) and a sectional view (b) of an electrostatic relay according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fixed board 2 ... Movable board 4a, 4b ... Signal line 5a ... 1st fixed electrode 5b ... 2nd fixed electrode 7a, 7b ... Fixed contact 10 ... 1st thin plate beam part 11 ... Movable electrode 13 ... 2nd thin plate beam part 15 movable contacts

Claims (3)

[Claims] 1. A movable substrate having a movable electrode opposed to a fixed substrate having a fixed electrode is driven by applying a voltage between the two electrodes to generate an electrostatic attraction, and formed on the fixed substrate. In an electrostatic relay in which a movable contact formed on the movable substrate is brought into contact with and separated from a fixed contact, the fixed electrode is constituted by a first fixed electrode and a second fixed electrode, and voltages of different polarities are applied to each of the fixed electrodes. An electrostatic relay characterized by: 2. The electrostatic relay according to claim 1, wherein the first and second fixed electrodes are arranged evenly with respect to the fixed contacts. 3. The electrostatic relay according to claim 1, wherein the first and second fixed electrodes have the same area.