KR970004214B1 - Micro relay structure using electrostatic charge - Google Patents

Abstract

The micro relay for operating with low voltage less than 10 V has rapid response speed less than 100 micro second. The relay has a cantilever shape thin metal electrode on SiO2 insulator. The gap between electrodes is less than 2 micro meter to be driven with low voltage. It also uses liquified mercury as upper cover plate to maintain low contact resistance and prolong operation time.

Description

Cantilever type constant power driving micro relay structure and manufacturing method

1 is the overall structure of the relay system of the present invention.

2 is a working principle diagram of the relay of the present invention.

(A) is the contact state,

(B) is disconnected state.

3 is an electrode layout of the relay of the present invention.

4 is a form of cantilever due to residual stress before and after bonding the substrate.

(A) is a cantilever

(B) The cantilever is deformed in the direction of the driving electrode.

5 is a process flowchart.

* Description of the symbols for the main parts of the drawings *

101,102,110,501,509,514: Substrate

103,201,304,401,404,506: cantilever moving electrode

301,404,504,507: cantilever oxide layer

104,203,306,403,502: Floor driving electrode

103,304: upper driving electrode 106: mercury reservoir

107: micro-channel 109,308: mercury contact hole

105,202,305,307,402,512: Relay contact pole

503: epitaxy layer 515: mercury

508,511: etching area 505,510: metal thin film

513: adhesive interface

The present invention relates to a structure and a manufacturing method of a high speed cantilever type constant power driving micro relay capable of operating at a low voltage of 10V or less and having a response speed of 100usec or less.

Recently, it has been applied to the fabrication of mechanical structures of several micrometers to hundreds of micrometers using semiconductor processing technology, that is, micron-sized sensors and actuators. Electronic relays currently used as communication components are several tens of millimeters in size.

Therefore, by reducing the size of the existing tens of millimeters of relay to a size of several hundred micrometers or less by utilizing micromachining technology can bring a significant improvement in the function of the relay.

In addition, when the semiconductor micromachining technology is used, the production cost is locally reduced due to excellent mass productivity.

The working voltage of the micro relay currently being studied requires a high voltage of 60-100V or more and a large contact resistance, which causes problems in practical use.

In order for the micro relay to be put into practical use, it must be operated with a low voltage of 10V or less, and a low resistance contact characteristic of 50 kV is required.

In order to meet the demand, the present invention provides a structure and a manufacturing method of a cantilever type constant power driving micro relay having low voltage (less than 10V) and fast response (less than 100usec) using micromachining technology. The purpose is.

In order to achieve the above object, in the present invention, the micro relay structure has a cantilever shape in which an electrode metal thin film is formed on a Sio2 insulator, and has a distance between electrodes of about 2 μm for driving at a low voltage of 10 V or less, The upper cover plate has the advantage of maximizing the driving force by deforming the cantilever in the downward direction.

Also, it is a structure that solves the problem of (Cantilever) bending caused when manufacturing (Cantilever), and is suitable for "Normally-ON" relay. In addition, this structure is characterized by the use of mercury, which is a liquid metal, on the upper cover plate to maintain the low resistance of the relay contacts and increase the operating level.

Hereinafter will be described in detail with reference to the accompanying drawings. The overall structure of the relay system is shown in FIG. As shown in FIG. 1, the relay system includes a silicon substrate 101 on which a cantilever type moving electrode 103 is implemented, a silicon substrate on which an upper driving electrode 105, and a mercury reservoir 106 are implemented. 102, and a substrate 110 for sealing the mercury reservoir.

When the micron size relay having the above structure is manufactured, the contact force between the moving electrode 103 and the fixed electrode 105 is about 0.1 uN.

With this magnitude of contact force, the contact resistance is 50 kPa or more, and the contact state becomes unstable.

Therefore, in order to solve this problem, the resistance is lowered by placing mercury in the portion where the contact is formed.

Mercury reservoir 106 is fabricated on a silicon substrate using bulk micromachining techniques. Normally, the hole 109 of the mercury microchannel is blocked by the cantilever 103 by the elastic force caused by the change of the cantilever.

Mercury in the reservoir 106 forms a thin film of mercury between the fixed electrode 105 and the moving electrode 103 through the microchannel 107 by surface tension.

Even when the moving electrode Cantilever 103 moves toward the bottom driving electrode 104, mercury is limited to only the microchannel 107 due to the surface tension in the mercury microchannel 105. The relay having such a basic structure and characteristics is a 'Noramly-ON' type switch in which a relay contact is formed in a state where a voltage is not applied to the driving electrodes 203 and 201.

The contact is formed by the protruding upper fixed electrode 202 of the cover substrate 102 and the relay contact electrode 201 of the cantilever. As shown in FIG. 2A, in a state where no voltage is applied to the bottom driving electrode 203, the protruding upper fixed electrode 202 of the cover substrate presses the moving electrode 201 of the cantilever downward. The contact is formed.

As shown in (b) of FIG. 2, when the voltage is applied to the bottom driving electrode 203, the cantilever moving electrode 201 is attracted to the bottom driving electrode 203 by the electrostatic force, thereby the electrode 202 and the electrode 201. The contact formed in the is released.

When the voltage applied to the driving electrode 203 is released again, the cantilever moving electrode 201 returns to its original state to form a contact.

3 schematically shows the shape of the electrode. 3A and 3B show a driving electrode 304 and a relay contact electrode 305 implemented in the cantilever.

When the cantilever 301 is deformed by the voltage applied to the driving electrode 304 and the bottom driving electrode 306, the relay contact electrode 305 is deformed together to form or release the contact.

3 (c) shows the relay contact electrode 307 and the mercury contact hole 308.

4 shows in the form of a cantilever due to residual stress before and after bonding the substrate.

A phenomenon in which the cantilever 401 bends upward due to the residual stress interposed in the insulating oxide film of the cantilever occurs.

The cantilever 404 is also deformed in the direction of the bottom driving electrode 403 by the protruding push electrode 402, so that the distance between the moving electrode 404 and the bottom driving electrode 403 is kept to a minimum, so that driving by a low voltage is possible. It becomes possible.

5 schematically shows a process for producing such a structure.

That is, as shown in (a), the bottom driving electrode 502 is formed on the substrate 501, and the silicon thin film 503, the oxide film 504, and the metal thin film 505 are sequentially formed as shown in (b).

Next, as shown in (c), the metal thin film 505 is formed into the upper driving electrode and the relay contact electrode form 506, and the oxide film 504 is formed into the cantilever shape 507 as shown in (d).

Next, as shown in (e), the silicon thin film 503 is etched by etching to prepare a substrate on which the cantilever electrode and the bottom driving electrode are implemented.

As shown in (f), a metal thin film 510 is formed on the substrate 509 having a crystal direction in order to fabricate a substrate on which a mercury reservoir and a relay contact electrode are formed.

Next, as shown in (g), the backside of the substrate 509 is anisotropically etched to form a pyramid 511 having a side in the <111> direction, and as shown in (h), a relay contact electrode having a mercury microchannel formed of a metal thin film. Make it to 512.

The substrates produced in the above steps (e) and (h) are bonded together, and mercury is filled in a mercury reservoir 515 and the mercury reservoir is sealed with the substrate 514. The final structure is implemented.

Such a relay of the present invention is a "Noramlly-on type switch in which a relay contact is formed in a state in which a voltage is not applied to a driving electrode. The contact is formed by a protruding upper fixed electrode and a cantilever relay contact electrode of a cover substrate. In addition, when no voltage is applied to the bottom driving electrode, the protruding upper fixed electrode of the cover substrate is formed to press the moving electrode of the cantilever downward.

In particular, since the cantilever is bent upward by the residual stress interposed in the insulating oxide film of the cantilever, the cantilever is also deformed in the direction of the bottom driving electrode by the protruding push electrode, so that the distance between the moving electrode and the bottom driving electrode is kept to a minimum. The cantilever type constant power drive micro relay which can be driven by this is made.

Claims (2)

As a relay formed of three substrate parts, the cantilever moving electrode 103 having a flat shape is loaded to the relay contact electrode 105, which is a fixed electrode, as a projecting part, thereby reducing the driving voltage and reducing the contact resistance between the contacts by reducing the distance between the electrodes. Cantilever-type constant-power drive micro relay structure, characterized in that for injecting a liquid mercury (515) to the contact portion. As a relay formed of three substrate parts, the cantilever moving electrode 103 having a flat shape is loaded to the relay contact electrode 105, which is a fixed electrode, as a projecting part, thereby reducing the driving voltage and reducing the contact resistance between the contacts by reducing the distance between the electrodes. In order to inject and store the liquid mercury (515) in the contact portion for manufacturing a cantilever type constant power drive micro relay.