JPH11120884A - Electrostatic micro relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic microrelay to be driven by a low drive voltage so as to obtain a desired contact pressure. SOLUTION: A base 10 is formed with a fixed electrode 12 at a central part of a top surface thereof, and a fixed contact 13 is arranged in the periphery thereof. On the other hand, an anchor 21 as an annular framework for actuator is bonded to the top surface of the base 10 for integration. A movable contact 24 opposite to the fixed contact 13 is provided in a lower surface of a movable electrode 22 of the thin film, extending from an edge of the top surface of the anchor 21 freely contactable and separably with/from the fixed contact 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic micro relay, and more particularly, to an electrostatic micro relay that can be manufactured by a semiconductor process.

[0002]

2. Description of the Related Art Conventionally, as an electrostatic micro relay, for example, as shown in FIG. 7, there is a relay in which an actuator 2 made of a silicon wafer is mounted on a base 1 made of a glass wafer. That is, the base 1 is provided with the fixed electrode 3 at the center of the upper surface, and a pair of fixed contacts 4 and 5 (the fixed contact 5 on the back side is not shown) at one side edge. On the other hand, the actuator 2 has a cantilever-shaped movable electrode 7 extending laterally from an upper surface edge of an anchor 6 erected on the base 1. A movable contact 9 is provided at a free end of an insulating film 8 formed on the lower surface of the movable electrode 7 and faces the fixed contacts 4 and 5 of the base 1 so as to be able to contact and separate therefrom.

[0003]

However, according to the above-mentioned electrostatic micro relay, even if the movable electrode 7 is attracted and attracted by the electrostatic attraction of the fixed electrode 3 with respect to the movable electrode 7, the movable electrode 7 is not moved. The movable contact 9 is arranged on the lower surface of the free end. Therefore, according to the leverage principle, the load applied to the movable contact 9 on the fixed contacts 4 and 5 is small, and the contact pressure is low. As a result, the movable contact 9 is easily separated from the fixed contacts 4 and 5 due to external vibration or impact force, and a malfunction is likely to occur. Further, since the fixed electrode 3 sucks the vicinity of the base of the movable electrode 7 more than the movable contact 9, there is a problem that a high driving voltage is required when the movable electrode 7 is attracted and displaced by electrostatic attraction.

[0004] In view of the above problems, an object of the present invention is to provide an electrostatic microrelay that can be driven with a low drive voltage and that can obtain a desired contact pressure.

[0005]

In order to achieve the above object, an electrostatic micro relay according to the present invention has a voltage between a fixed electrode provided on a base and a movable electrode of an actuator fixed on the upper surface of the base. In the electrostatic micro relay that opens and closes an electric circuit by driving the movable electrode with an electrostatic attraction generated by applying a voltage and applying and separating a movable contact provided on the actuator to a fixed contact provided on the base, A fixed electrode is formed on the upper surface, and a fixed contact is arranged around the fixed electrode. On the other hand, an actuator having a thin-film movable electrode extending from the upper edge of the frame is moved outside the fixed contact on the base upper surface. The movable electrode of the actuator is opposed to the fixed electrode so as to be able to contact and separate from the fixed electrode, and the movable contact provided on the lower surface of the movable electrode is fixed to the fixed electrode. Are constituted was separable therefrom opposite the contacts.

Further, the movable electrode is driven by an electrostatic attraction generated by applying a voltage between a fixed electrode provided on a base and a movable electrode of an actuator fixed on the upper surface of the base, and provided on the base. In an electrostatic microrelay for opening and closing an electric circuit by moving a movable contact provided on the actuator to and away from a fixed contact, an actuator having a thin plate beam having a substantially cross-shaped flat surface is provided with an anchor provided at an end of the thin plate beam. Standing upright on the upper surface of the base, and fixing the movable electrode extending laterally from the edge of the thin plate beam portion to the fixed electrode provided on the upper surface of the base so as to be able to contact and separate therefrom, The movable contact provided at the center of the lower surface of the thin beam portion may be opposed to the fixed contact of the base so as to be able to contact and separate therefrom.

Further, the movable electrode is driven by an electrostatic attraction generated by applying a voltage between the fixed electrode provided on the base and the movable electrode of the actuator fixed on the upper surface of the base, and provided on the base. In an electrostatic microrelay for opening and closing an electric circuit by moving a movable contact provided on the actuator to and away from a fixed contact, an actuator consisting of a straight thin-beam is used as an anchor provided at an end of the thin-beam. The movable electrode, which is erected on the upper surface of the base member and extends laterally from both side edges of the thin plate beam portion, is opposed to a fixed electrode provided on the upper surface of the base so as to be able to contact and separate from the thin plate beam portion. The movable contact provided at the center of the lower surface of the portion may be configured to face the fixed contact of the base so as to be able to contact and separate therefrom.

The movable electrode may be thinner than the thin beam portion. Further, an insulating film may be formed on at least one of the opposing surfaces of the movable electrode and the fixed electrode.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment according to the present invention will be described with reference to the accompanying drawings of FIGS. As shown in FIGS. 1 to 4, the electrostatic microrelay according to the first embodiment has an actuator 20 integrated with an upper surface of a base 10 made of a glass substrate 11a.

In the base 10, a circular fixed electrode 12 is provided at the center of the upper surface of a glass substrate 11a, and concentric fixed contacts 13 are provided therearound. The fixed electrode 12 and the fixed contact 13 are connected to connection pads (not shown) via printed wiring (not shown).

The actuator 20 includes the base 1
An anchor 21 which is an annular frame body is joined and integrated with the upper surface edge of the "0". A thin-film movable electrode 22 extends from the upper surface edge of the anchor 21. An annular movable contact 24 is formed on the lower surface of the movable electrode 22 via an insulating film 23.
Is formed, and is opposed to the fixed contact 13 so as to be able to contact and separate therefrom. If a silicon oxide film having a relative dielectric constant of 3 to 4 or a silicon nitride film having a relative dielectric constant of 7 to 8 is used as the insulating film 23, a large electrostatic attraction can be obtained and the contact load can be increased.

Next, a method of manufacturing the electrostatic micro relay having the above-described configuration will be described. First, as shown in FIG.
The fixed electrode 12 and the fixed contact 13 are formed by depositing and patterning Au on a glass substrate 11a such as Pyrex serving as the base 10. Further, at the same time, printed wiring and connection pads (not shown) are formed.

On the other hand, as shown in FIG. 3, after oxidizing and patterning a silicon wafer 25 serving as the actuator 20, a cavity 26 having a depth of 5 μm is formed by etching with TMAH. And the cavity 26
A thermal oxide film is formed on the ceiling surface of the semiconductor device and patterned to form an insulating film 23 in the cavity 26. Then, Cr,
An annular movable contact 24 is formed by sequentially depositing and patterning Ni and Au.

Then, the silicon wafer 25 is bonded to the base 10 by anodic bonding at a temperature of 400 ° C. and a voltage of 400 V for one hour to be integrated. Then T
Thin the silicon wafer 25 with MAH to a thickness of 10
The movable electrode 22 having a thickness of μm is formed.

The base 10 is not limited to the single glass substrate 11a, but may be formed of a single crystal silicon substrate having at least an upper surface covered with an insulating film.

According to this embodiment, the actuator 20
Since the whole is formed from a single silicon wafer and the movable electrode 22 is formed symmetrically to the left and right, the movable electrode 22 is hardly deformed. As a result, inoperability,
There is an advantage that variation in operating characteristics can be effectively prevented and smooth operating characteristics can be ensured.

Next, the operation of the electrostatic micro relay having the above configuration will be described. First, when no voltage is applied between the fixed electrode 12 and the movable electrode 22,
And the movable electrode 22 are kept parallel, and the movable contact 24 is separated from the fixed contact 13 (FIG. 1B).

Next, when a voltage is applied between the fixed electrode 12 and the movable electrode 22, the movable electrode 22 is attracted to the fixed electrode 12 by an electrostatic attraction generated between the electrodes 12 and 22. Therefore, the center of the movable electrode 22 sinks, and the movable electrode 22 approaches the fixed electrode 12. As a result, the gap is narrowed, so that the movable electrode 22 is attracted by the fixed electrode 12 with a stronger electrostatic attraction, and after the movable contact 24 contacts the fixed contact 13, the movable electrode 22 is fixed via the insulating film 23. Adsorb to 12

When the application of the voltage is stopped,
After the movable electrode 22 is separated from the fixed electrode 12 by the spring force of the movable electrode 22, the movable contact 24 is separated from the fixed contact 13, and the movable electrode 22 returns to the original state.

As shown in FIG. 5, the electrostatic micro relay according to the second embodiment includes a base 10 made of a glass wafer 11a and an actuator 20, as in the first embodiment. The actuator 20 has a substantially cross-shaped thin plate beam portion 2 on an anchor 21 which is a flat rectangular frame.
7 is spanned. Furthermore, this thin plate beam portion 27
Is a substantially rectangular movable electrode 28 from one edge in the same direction.
Are respectively extended. The movable contact 24 is located at the center of the lower surface of the thin beam 27 via an insulating film (not shown).
Is provided. The movable electrode 28 is thinner than the thin beam 27.

On the other hand, the base 10 made of the glass wafer 11a has a fixed electrode 12 and a fixed contact (not shown) formed at positions corresponding to the movable electrode 28 and the movable contact 24. Further, the fixed electrode 12 and the fixed contact are respectively electrically connected to connection pads via a printed wiring (not shown).

Next, a method of manufacturing the electrostatic micro relay according to the second embodiment will be described. The base 10 forms four fixed electrodes 12 and fixed contacts by depositing and patterning Au on a glass substrate 11a such as Pyrex. At the same time, printed wiring and connection pads (not shown) are formed and electrically connected.

On the other hand, after oxidizing and patterning the lower surface of the SOI silicon wafer serving as the actuator 20,
A cavity is formed by etching with TMAH. Then, a thermal oxide film is formed and patterned on the ceiling surface of the cavity, and an insulating film is formed in the cavity. Subsequently, the movable contact 24 is formed by sequentially depositing and patterning Cr, Ni, and Au.

Then, the SOI silicon wafer is bonded and integrated to the base 10 by anodic bonding. Then, TM
The silicon wafer is etched to an oxide film with AH and thinned. Furthermore, after removing the oxide film with a fluorine-based etchant, the mold is etched by dry etching using RIE or the like, and a bent slit is formed to cut out the thin plate beam portion 27 and the movable electrode 28, thereby completing the actuator 20. I do.

Next, the operation of the second embodiment will be described. First, when no voltage is applied between the fixed electrode 12 and the movable electrode 28, the fixed electrode 12 and the movable electrode 28 are parallel, and the movable contact 24 is separated from the fixed contact.

Next, when a voltage is applied between the fixed electrode 12 and the movable electrode 28, the movable electrode 28 is attracted to the fixed electrode 12 by the electrostatic attraction generated between the electrodes 12 and 28. For this reason, the free end of the movable electrode 28 approaches the fixed electrode 12, the electrostatic attraction further increases, and the movable electrode 28 is sucked with a stronger suction force. As a result, the movable electrode 28 is attracted to the fixed electrode 12 via the insulating film after the thin beam portion 27 bends and the movable contact 24 contacts the fixed contact.

When the application of the voltage is stopped,
After the movable electrode 28 is separated from the fixed electrode 12 by the spring force of the thin beam 27, the movable contact 24 is separated from the fixed contact, and the movable electrode 28 returns to its original state by its own spring force.

In the third embodiment, as shown in FIG. 6, an actuator 20 made of a silicon wafer is joined and integrated with a base 10 made of a silicon wafer 11b. That is, the base 10 is
An insulating film 14 is formed on the upper surface of b, and a pair of fixed contacts 13 and 15 (the rear fixed contact 15 is not shown) are disposed on the upper surface of the insulating film 14. Further, a pair of fixed electrodes 12, 12 are provided with the fixed contacts 13, 15 therebetween.

The actuator 20 is composed of a thin plate beam portion 27 having both ends laid over the upper surface edges of a pair of anchors 21 and 21 erected on the upper surface of the base 10, and a movable contact 24 is provided at the center of the lower surface. I have. Further, the movable electrodes 28 extend laterally from both side edges of the thin plate beam portion 27 and face the fixed electrode 12 so as to be able to contact and separate therefrom. The movable electrode 28 is thinner than the thin beam 27.

A method for manufacturing the electrostatic micro relay according to the third embodiment will be described. First, the insulating film 14 is formed by oxidizing and patterning the silicon wafer 11b serving as the base 10. And Cr, Ni, Au
Are sequentially deposited and patterned to form the fixed electrodes 12 and the fixed contacts 13 and 15, and at the same time, to form printed wiring and connection pads (not shown).

On the other hand, after oxidizing and patterning a silicon wafer to be the actuator 20, a cavity is formed by TMAH. Next, a thermal oxide film is formed and patterned, and an insulating film 23 is formed on the ceiling surface of the cavity. Then, Cr, Ni, and Au are sequentially deposited and patterned to form the movable contact 24.

Next, a low-temperature glass is applied to the bonding surface of the silicon wafer serving as the base 10 and the actuator 20 and heated at a temperature of 400 ° C. for one hour.
Join and integrate. Then, the actuator 20 is
The actuator 20 is completed by thinning the silicon wafer to be thinned and further cutting out the thin plate beam portion 27 and the movable electrode 28.

Next, the operation of the third embodiment will be described. First, when no voltage is applied between the fixed electrode 12 and the movable electrode 28, the fixed electrode 12 and the movable electrode 28 face in parallel, and the movable contact 24 is separated from the fixed contacts 13 and 15.

Then, the fixed electrode 12 and the movable electrode 28
When a voltage is applied therebetween, the movable electrode 28 is attracted to the fixed electrode 12 by the electrostatic attraction generated between the electrodes 12 and 28. For this reason, the free end of the movable electrode 28 approaches the fixed electrode 12, the electrostatic attraction further increases, and the movable electrode 28 is sucked with a stronger suction force. As a result,
The movable contact 24 is fixed to the fixed contact 13,
After the contact with the fixed electrode 15, the entire movable electrode 28 is attracted to the fixed electrode 12 via the insulating film 23.

When the application of the voltage is stopped,
After the movable electrode 28 is separated from the fixed electrode 12 by the spring force of the thin plate beam portion 27, the movable contact 24 is moved to the fixed contacts 13 and 15.
, And the movable electrode 28 returns to its original state by its own spring force.

[0036]

As is apparent from the above description, according to the electrostatic micro relay according to the first aspect of the present invention, when a voltage is applied between the fixed electrode and the movable electrode, the center of the thin film movable electrode is changed. Is attracted to the fixed electrode by electrostatic attraction, and the movable contact provided near the base of the movable electrode contacts the fixed contact. Therefore, since the central portion of the movable electrode, which is most easily deformed, is attracted by the electrostatic attraction, an electrostatic micro relay that can open and close the contact with a low driving voltage can be obtained. In addition, since the movable contact is disposed at the base of the movable electrode, the electrostatic attraction can be effectively utilized by the leverage principle. For this reason, an electrostatic micro relay having a large contact load and less likely to malfunction can be obtained.

According to the second and third aspects, when a voltage is applied between the fixed electrode and the movable electrode, an electrostatic attraction is generated and the movable electrode is bent. For this reason, the free end of the movable electrode approaches the fixed electrode, and the movable electrode is attracted by a larger electrostatic attraction. As a result, the movable contact comes into contact with the fixed contact by bending the thin beam portion, so that an electrostatic micro relay that can be driven at a low drive voltage is obtained. According to claims 2 and 3,
In each case, a movable contact is arranged at the center of the thin beam portion and near the base of the movable electrode. For this reason, the electrostatic attraction can be effectively used, and an electrostatic micro relay having a large contact pressure can be obtained.

According to the fourth aspect, the movable electrode is thinner than the thin beam portion. Therefore, when a voltage is applied between the fixed electrode and the movable electrode, the movable electrode bends due to electrostatic attraction. As a result, the free end of the movable electrode approaches the fixed electrode, the movable electrode is attracted by a stronger electrostatic attraction, and the movable contact contacts the fixed contact. Therefore, an electrostatic micro relay that can be driven with a lower driving voltage than the conventional example can be obtained. Claim 5
According to this, an insulating film is formed on at least one of the opposing surfaces of the fixed electrode and the movable electrode.
For this reason, the fixed electrode and the movable electrode do not come into direct contact with each other, and they are attracted by a large electrostatic attraction while leaving the thickness of the insulating film, so that an electrostatic micro relay having a desired contact load can be obtained. effective.

[Brief description of the drawings]

1A and 1B show an electrostatic micro relay according to a first embodiment of the present invention, wherein FIG. 1A is a plan view of a base and FIG.
Is a sectional view.

FIG. 2 is a base process flow according to the first embodiment.

FIG. 3 is a process flow of the actuator according to the first embodiment.

FIG. 4 is a process flow showing joining of a base and an actuator.

FIG. 5 is a plan view showing an electrostatic micro relay according to a second embodiment of the present invention.

6A and 6B show an electrostatic micro relay according to a third embodiment of the present invention, wherein FIG. 6A is a plan view of a base and FIG.
Is a sectional view.

FIG. 7 is a cross-sectional view of an electrostatic micro relay according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Base, 12 ... Fixed electrode, 13, 15 ... Fixed contact, 14 ... Insulating film, 20 ... Actuator, 21 ... Anchor, 22 ... Movable electrode, 23 ... Insulating film, 24 ... Movable contact,
27: thin beam, 28: movable electrode.

Claims (5)

[Claims] 1. A movable electrode is driven by electrostatic attraction generated by applying a voltage between a fixed electrode provided on a base and a movable electrode of an actuator fixed on an upper surface of the base,
An electrostatic micro relay that opens and closes an electric circuit by moving a movable contact provided on the actuator to a fixed contact provided on the base to open and close an electric circuit. A fixed electrode is formed on an upper surface of the base, and a fixed contact is arranged around the fixed electrode. On the other hand, an actuator having a thin-film movable electrode extending from the upper surface edge of the frame body is fixed by joining and integrating the frame body to outside of the fixed contact on the base upper surface, and the movable electrode of the actuator is fixed electrode And a movable contact provided on a lower surface of the movable electrode is detachably opposed to the fixed contact. 2. A movable electrode is driven by electrostatic attraction generated by applying a voltage between a fixed electrode provided on a base and a movable electrode of an actuator fixed on an upper surface of the base,
An electrostatic micro relay that opens and closes an electric circuit by moving a movable contact provided on the actuator to a fixed contact provided on the base to open and close an electric circuit, comprising:
An anchor provided at an end of the thin beam portion is erected and fixed on the upper surface of the base, and a movable electrode extending laterally from an edge of the thin beam portion is provided on the upper surface of the base. An electrostatic microrelay, wherein the movable microcontact is provided so as to be able to contact and separate from the fixed electrode, and a movable contact provided at the center of the lower surface of the thin plate beam is made to be able to contact and separate from the fixed contact of the base. 3. The movable electrode is driven by electrostatic attraction generated by applying a voltage between a fixed electrode provided on a base and a movable electrode of an actuator fixed on an upper surface of the base,
In an electrostatic microrelay for opening and closing an electric circuit by moving a movable contact provided on the actuator to a fixed contact provided on the base, an actuator comprising a straight thin beam is provided at an end of the thin beam. The anchor is erected on the upper surface of the base and fixed, and the movable electrode extending laterally from both side edges of the thin beam portion is opposed to the fixed electrode provided on the upper surface of the base so as to be able to contact and separate therefrom. And a movable contact provided at the center of the lower surface of the thin beam portion is opposed to the fixed contact of the base so as to be able to contact and separate therefrom. 4. The electrostatic micro relay according to claim 2, wherein the movable electrode is thinner than the thin beam portion. 5. The electrostatic microrelay according to claim 1, wherein an insulating film is formed on at least one of the opposing surfaces of the movable electrode and the fixed electrode. .