KR100516167B1 - MEMS actuator using plural beams having lengths different from each other, and a tweezer and a switch adopting the same - Google Patents

Abstract

MEMS actuators are disclosed that are easy to manufacture, reduce manufacturing costs, consume less power, and provide faster driving speeds. MEMS actuators have a pair of beams arranged parallel to the substrate. The beams are made of the same material, have different lengths from one another, and one part is fixed to each other. The change in the position of the fixed beams occurs due to the difference in the degree of expansion of each beam with temperature changes. The fixed site may be one end of each of the pair of beams or may be approximately the center of each of the beams. MEMS actuator according to the present invention can be driven by the indirect heating method can be used as an electrical switch. In addition, the MEMS actuator can be used to manufacture MEMS tweezers and MEMS switches with low power consumption and high driving speed.

Description

MEMS actuator using plural beams having lengths different from each other, and a tweezer and a switch adopting the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro electro mechanical system (MEMS) that implements mechanical components as electrical components on a semiconductor substrate. More specifically, a MEMS actuator driven on a substrate and a MEMES tweezer employing the same It is about MEMS switch.

MEMS (Micro electro mechanical system) is a technology for implementing mechanical components into electrical devices using a semiconductor process. Each device having a mechanical structure and corresponding operation is manufactured on a semiconductor wafer through a semiconductor manufacturing process. In order to implement components such as actuators and switches using MEMS technology, a method of expanding a metal disposed on a substrate by using heat generated electrically is used.

1 is a view showing an example of a conventional MEMS actuator, in particular a view showing an example of a switch implemented using the MEMS actuator. The conventional MEMS switch 10 includes a heater 11 for heating a predetermined space, a plurality of arced beams 15 that are expanded by the heat of the space heated by the heater 11, an arced beam ( 15 is provided with a switching terminal 17 driven by 15 and two contacts 19a and 19b interrupted by the switching terminal 17.

Both ends of the heater 11 are provided with power supply terminals 11a and 11b to which an external power source (not shown) is connected. When power is supplied through the power supply terminals 11a and 11b, the heater 11 starts to generate heat.

Both ends of the arcuate beam 15 are supported by the support 13. Therefore, when the arcuate beam 15 expands by the air heated by the heater 11, the arcuate beam 15 expands in the curved outward direction, that is, above the figure. As a result, the switching terminal 17 fixed to the arcuate beam 15 moves upward.

In the state in which the switching terminal 17 is moved upward, the two contacts 19a and 19b are electrically interconnected through the switching terminal 17. In the state where the switching terminal 17 is moved downward, the two contacts 19a and 19b are electrically disconnected. Therefore, when power is supplied to the heater 11, the two contacts 19a and 19b are turned on, and when the power supply is stopped, the two contacts 19a and 19b are turned off.

However, the conventional MEMS switch 10 as described above has a disadvantage in that power consumption is large because the switch 10 must continuously supply power to the heater 11 in order to maintain the turn-on state. Further, since the arcuate beam 15 is heated by the air heated by the heater 11, the power consumption due to indirect heating is further increased, and the time from the start of power supply to the turn-on of the switch is long. There is this.

2 is a view showing another example of a conventional MEMS actuator. In this example, the MEMS actuator 20 is configured to fix the first beam 21 having a thin thickness, the second beam 22 having a large thickness, and one end of the first beam 21 and the second beam 22 to each other. It is composed of a fixed portion 25 and power supply terminals 21a and 21b for supplying power to each of the first and second beams 21 and 22.

When power is supplied to the first and second beams 21 and 22 through the power supply terminals 21a and 21b, heat is generated in the first and second beams 21 and 22. At this time, since the first beam 21 is manufactured to have a relatively thin thickness compared to the second beam 22, the first beam 21 has a larger resistance value than the second beam 22, and thus the first beam 21 The beam 21 expands more length in its longitudinal direction than the second beam. Accordingly, the first beam 21 and the second beam are bent in the right direction on the drawing due to the difference in the amount of expansion, and the fixing portion 25 is rotated to the right. In this way, by placing the target animal to be driven at a point on the rotation path of the rotating part 25 is rotated, it is possible to control the mechanical operation by the electrical signal.

By the way, the MEMS actuator 20 as described above, there is a problem that the speed reduction problem, which is a problem of the MEMS actuator 10 as shown in Figure 1 does not occur, but the power consumption is still a lot. That is, since the direct heating method is adopted, the power consumption is reduced compared to the MEMS actuator of FIG. During this time, the beams (21, 22) must be powered continuously.

In addition, the MEMS actuator 20 as described above has a disadvantage that it does not operate by the indirect heating method as shown in FIG. Because the operation is caused by the difference in the amount of heat generated by the difference in resistance between the beams 21 and 22, an indirect heating method such as heating the surrounding air may bring about a difference in the expansion ratio of the beams 21 and 22. Because you can't.

In addition, the MEMS actuator 20 as described above has a current flowing through a portion for performing the actuation operation, that is, the beams 21 and 22 and the fixing portion 25, and thus is not used as a switch for switching the electrical connection state. There is a problem that is inappropriate. This is because the current flowing through the beams 21 and 22 and the fixing part 25 may be supplied to the object to be switched, which may cause serious malfunction in the operation of the circuit of the object.

3 is a view showing another embodiment of a conventional MEMS actuator. In this embodiment, the MEMS actuator 30 includes a first beam 31, a second beam 32, and a heater 37 installed in the chamber 35. have. The second beam 32 is made of a material having a greater coefficient of thermal expansion than the first beam 32. The second beam 32 is fixed by the fixing part 39. When power is supplied to the heater 37 and the chamber 35 is heated, since the second beam 32 having a large thermal expansion rate expands more than the first beam 31, the first beam 31 and the second beam are expanded. The right end of the beam 32 is curved to move upward. Accordingly, the first beam 31 drives the driven mold.

However, the conventional MEMS actuator 30 as shown in FIG. 3 has a problem in that the power consumption is high and the speed is slow as described above by the indirect heating method. In addition, the process of forming the chamber 35 and manufacturing the heater 37 and the process of forming the first beam and the second beam made of two different materials are very complicated, which makes the manufacturing difficult and expensive. have.

The present invention has been made to solve the above problems, an object of the present invention is to provide a MEMS actuator with low power consumption, high operating speed, and easy to manufacture.

Another object of the present invention is to provide other MEMS parts implemented using the MEMS actuator as described above.

Still another object of the present invention is to provide a method of manufacturing a MEMS actuator as described above.

MEMS actuator according to the present invention for achieving the above object, the substrate; And a plurality of beams formed on the substrate, made of the same material, having different lengths, and having one portion fixed to each other and each other portion fixed on the substrate. The change in the position of the beams fixed to each other by the difference in the degree of expansion of each of the plurality of beams according to the temperature change occurs.

Preferably the pair of beams are arranged parallel to each other. The fixed portion may be one end of each of the pair of beams, or may be approximately the central portion of each of the beams. In the case where the center portion is fixed to the central portion, the central portion is preferably thinner than other portions. According to this, the bending of the beams upon heating of the beams is quick and easy.

At the end of each beam, a power supply terminal is formed integrally with the beam. This power supply terminal has a larger area than the beam. This facilitates the manufacture of the actuator.

According to the present invention, it is easy to manufacture and the manufacturing cost is reduced, there is provided a MEMS actuator with low power consumption and high driving speed. In addition, since the MEMS actuator according to the present invention can be driven by an indirect heating method, it can be used as an electrical switch.

On the other hand, according to the present invention, by using such a MEMS actuator, it is possible to manufacture a MEMS tweezer, a MEMS switch and the like with low power consumption and fast driving speed.

In addition, the MEMS actuator manufacturing method according to the present invention comprises the steps of oxidizing the substrate to form an insulating film; Depositing a metal sheath layer on the insulating film; Forming an actuator-shaped mold having a plurality of beams having different lengths and fixed to each other on the seed layer; Forming a metal layer in the mold by conducting metal plating by energizing the seed layer; Cleaning the mold; Removing an externally exposed portion of the seed layer; And removing the insulating layer such that a portion of the metal layer corresponding to the beam floats on the substrate.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

4 is a view showing a MEMS actuator according to the present invention. In the description of the present embodiment, only the respective components of the MEMS actuator are shown and described, and the other parts such as the substrate on which the respective parts are disposed will be described in detail later in the description of the manufacturing process of the MEMS actuator.

As shown in FIG. 4, the MEMS actustor 100 has a pair of beams 110, 120 formed on a substrate. Each beam 110, 120 is made of the same material and has a different length from each other. The number of beams 110 and 120 may be three or more, but is preferably composed of two as shown in FIG. In addition, the angle between the beams 110 and 120 can be arbitrarily set, but is preferably arranged in parallel with each other as shown in FIG. The beams 110 and 120 are made of metal having a predetermined coefficient of thermal expansion, and preferably made of copper.

Upper ends of the beams 110 and 120 are fixed to each other by the fixing part 130. The fixing part 130 may be made of the same material as the beams 110 and 120 and may be made of different materials. Preferably, the fixing part 130 is made of the same material as the beams 110 and 120 and also made of the beams 110 and 120. It is formed integrally with

In addition, power supply terminals 111 and 121 are formed at lower ends of the beams 110 and 120. The power supply terminals 111 and 121 are formed to have a relatively larger area than the beams 110 and 120 to facilitate the connection of external power, and the power supply terminals 111 and 121 are each beam 110. And 120). In addition, forming the power supply terminals 111 and 121 to have a larger area than the beam, as described later, the power supply terminals 111 and 121 are fixed on the substrate and the beams 110 and 120 are spaced apart from the substrate. The advantage is that it is as easy to produce as floating as possible.

Based on the experimental results, a preferred physical configuration for the good operation of the MEMS actuator according to the present invention will be described as follows.

Material: Copper

Density: 8920 Kg / m ³

Young's Modulus: 130 Gpa

Poisson Ratio: 0.34

Thermal expansion coefficient: 16.5 e-6 / K

Width of each beam: 10㎛

Long beam length: 500㎛

Short beam length: 250㎛

Spacing between beams: 10㎛

Beam Thickness: 10㎛

When power is connected to the power supply terminals 111 and 121 and power is supplied to each of the beams 110 and 120, heat is generated in the beams 110 and 120 by the resistances of the beams 110 and 120. Since the beams 110 and 120 are formed of the same material and have the same cross-sectional area, the calorific value per unit length is the same. As a result, the length of the long beam 120 expands as compared to the short beam 110 as a whole, so that each beam 110, 120 is rotated to the left side of the drawing as shown by the dotted line in FIG.

The fixed part 130 is rotated by the beams 110 and 120 rotated as described above, and by placing the target animal to be driven at a point on the rotation path of the fixed part 130, It is possible to control the mechanical operation.

According to the present invention, since the beams 110 and 120 as well as the fixing part 130 and the power supply terminals 111 and 121 are manufactured in an integrated shape by the same material, the manufacturing process is simple, and directly Driven by the heating method has the advantage that the driving speed is fast.

In addition, although the embodiment shown in Figure 4 used a method for supplying power to each beam (110, 120), MEMS actuator 100 according to the present invention is to heat the surrounding air without directly supplying power, etc. It can also be driven by the same indirect heating method. Accordingly, even when the MEMS actuator 100 is to be used as an electrical switch, the MEMS actuator 100 according to the present invention may be used to prevent adverse effects on other circuits caused by the current flowing through the MEMS actuator 100 itself. Can be.

5 and 6 illustrate an example of an application of the MEMS actuator 100 according to the present invention as illustrated in FIG. 4, as a MEMS tweeter 200. In the following description, the same parts as those shown in FIG. 4 are referred to with the same reference numerals.

MEMS tweezers 200 according to the present invention is configured using two MEMS actuators 100 as shown in FIG. That is, as shown in FIG. 5, the MEMS tweezers 200 are manufactured by symmetrically disposing two MEMS actuators 100.

As power is supplied to each of the power supply terminals 111 and 121, heat is generated in the beams 110 and 120 of each actuator 100, whereby the driving units 130 are spaced apart from each other as shown in FIG. 6. Curved in the direction. In addition, when power supply to the power supply terminals 111 and 121 is stopped, the beams 110 and 120 of the respective actuators 100 are cooled, whereby the driving unit 130 approaches each other as shown in FIG. 5. Is restored.

In this way, since the positions of the driving unit 130 are changed to be spaced apart and approach each other by the temperature change according to the supply and interruption of the power supply, the object placed near the driving unit 130 by the control of the electrical signal is held or The gripping state can be released. In addition, as described above, the MEMS tweezers 200 may be driven by an indirect heating method.

7 is a view showing another embodiment of a MEMS actuator according to the present invention and a MEMS switch manufactured using the MEMS actuator.

MEMS actuator 300 according to another embodiment of the present invention (hereinafter referred to as 'second actuator') is a pair of beams (310, 320) placed in parallel to each other, both ends of each of the beams (310, 320) Power supply terminals 311 and 321 formed at the respective ends, and switching terminals 310 arranged in the horizontal direction in the longitudinal direction of the beams 310 and 320, respectively. The beams 310 and 320 are different in length from each other, and the switching terminals 310 are fixed to the beams 310 and 320 at substantially center portions of the beams 310 and 320.

When power is supplied to each of the beams 310 and 320 through the power supply terminals 311 and 321, the beams 310 and 320 are expanded by the heat generation operation of the beams 310 and 320. In this case, as described above with reference to FIG. 4, each of the beams 310 and 320 is bent to the left by a difference in the amount of expansion due to the difference in length of each of the beams 310 and 320, whereby the switching terminal ( 350 is moved to the left. The other part on the substrate is driven by the switching terminal 350 moved as described above.

On the other hand, the center portion of each of the beams 310 and 320, that is, the portion where each of the beams 310 and 320 and the swiss terminal 350 intersect, is thinner than other portions as shown in FIG. have. As a result of the thinly formed central portion, the curved portion of the central portion of each of the beams 310 and 320 may be more easily and quickly generated when the beams 310 and 320 are heated. At this time, the center portion of each of the beams 310 and 320 is curved so that the right side is recessed, which serves to guide each of the beams 310 and 320 to be curved to the left when inflated by heat generation.

On the left side of the second actuator 300, a tweezer 200 'having a structure similar to the tweezer shown in FIG. 5 is installed. As described above, the tweezers 200 is constituted by a pair of actuators 100 (hereinafter, referred to as a 'first actuator'), and the operation thereof is as described above.

Meanwhile, a stopper 250 is formed at an end of the first actuator 100, and a locking part 351 corresponding to the stopper 250 is formed at an end of the switching terminal 350 of the second actuator 300. have. The stopper 250 and the engaging portion 351 are formed to be inclined to the surface in contact with each other in the direction in which they are coupled in order to facilitate engagement at the time of mutual access movement. In addition, the stopper 250 and the engaging portion 351 are to be in contact with each other in the direction away from each other in order to make it difficult to disengage during mutual movement.

8A to 8E sequentially illustrate the operation of the MEMS switch shown in FIG. 7.

In the initial state, as shown in FIG. 8A, both the tweezers 200 ′ and the second actuator 300 are in an unactivated state, and thus, they are not electrically connected.

When power is supplied to the second actuator 300, each of the beams 310 and 320 of the second actuator 300 is bent to the left, so that the switching terminal 350 is moved to the left, and as shown in FIG. 8B. Likewise, the switching terminal 350 is inserted into the first actuators 100 and held by the tweezers 200 '. Thereby they are electrically connected to each other.

Then, when the power supply to the second actuator 300 is cut off, the beams 310 and 320 of the second actuator 300 are cooled to generate a force to move the swiveling terminal 350 to the right, but is shown in FIG. 8C. As described above, the stopper 250 and the catching part 351 are mutually caught to maintain the state in which they are coupled to each other. Therefore, even when the power supply to the second actuator 300 is cut off, the first actuators 100 and the second actuators 300 remain electrically connected.

On the other hand, when power is supplied to the first actuators 100 in the state as shown in Figure 8c, as shown in Figure 8d, the first actuators 100 are spaced apart from each other and the tweezers 200 'release the gripping state, Accordingly, the switch window 350 is moved to the right side by the restoring force of the second actuator 300. As a result, the electrical connection between the first actuator 100 and the second actuator 300 is disconnected. Thereafter, when the power supply to the first actuator 100 is cut off, the first actuators 100 in the tweezers 200 are restored to the mutually accessed state as shown in FIG. 8E.

According to the MEMS switch 400 as described above, when the power is supplied to the second actuator 300, the switch is turned on, and the MEMS switch 400 is stopped even after the power supply to the second actuator 300 is stopped. It remains turned on. In addition, when the power is supplied to the second actuator 300, the switch difference is turned off, and the MEMS switch 400 is maintained in the turned off state even after the power supply to the first actuator 300 is stopped. . Therefore, since the switching state is switched only by temporarily supplying power to the first actuator 100 or the second actuator 300, power is not consumed to maintain the switched state. Therefore, there is an advantage that the overall power consumption is reduced.

9 is a view showing another embodiment of FIG. 8.

In the present embodiment, the configuration of the second actuator 300 ′ of the MEMS switch 400 shown in FIG. 8 is different from that of FIG. 8. In the present embodiment, the second actuator 300 ′ has the same structure as the conventional MEMS actuator 10 as shown in FIG. 1, and the tweezers 200 ′ are the same as those shown in FIG. 6. As such, only a part of the MEMS switch 400 may be manufactured using the MEMS actuator according to the present invention.

Hereinafter, a manufacturing process of the MEMS actuator 100 according to the present invention as shown in FIG. 4 will be described with reference to FIGS. 10A to 10D.

As shown in FIG. 10A, an insulating film OL is formed on a substrate SB made of high resistive silicon, and a seed layer SL is deposited. The insulating layer OL is formed by oxidizing the substrate SB, and the seed layer SL is formed of metal.

Then, a photoresist (PR) or a photosensitive polymer is laminated on the seed layer SL and photographed to etch the pair of beams 110 and 120 and the power supply terminals 111 and 121 and the fixing part. A mold having a shape of 130 is formed (Modl forming). After the mold is formed, the metal layer ME is formed by energizing the seed layer SL to perform metal plating, and the metal layer ME is formed on the etched portion to be in a state as shown in FIG. 10B.

After cleaning the photoresist PR, the exposed portion of the sheath layer SL is removed using acetic acid and the like, and also exposed to the outside of the insulating layer OL using hydrofluoric acid (HF). Removal of the site results in a state as shown in FIG. 10C. In this state, isotropic etching is performed to obtain a state as shown in FIG. 10D.

At this time, since the two portions on the left side of the left metal layer ME are narrow, the two portions on the left side are etched to the lower portion of the metal layer ME so that the lower portion is hollow, and the right portion is wider, so only the peripheral portion of the lower portion thereof is wide. Is etched. The wide part on the right side is used as the power supply terminals 111 and 121 as described above, and the narrow part on the left side is used as the beams 110 and 120. The portion used as the beams 110 and 120 is etched in the lower portion thereof and thus remains in a hollow state, so that the portion is floated on the substrate SB to facilitate movement by thermal expansion.

According to the present invention, since each beam of the MEMS actuator is made of the same material, the production is easy and the production cost is reduced. In addition, since it is driven by the direct heating method has the advantage of low power consumption and fast driving speed.

In addition, since the MEMS actuator according to the present invention can be driven by an indirect heating method, it can be used as an electrical switch.

In addition, the MEMS actuator can be used to manufacture MEMS tweezers and MEMS switches with low power consumption and high driving speed.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as claimed in the claims. Anyone skilled in the art can make various modifications, as well as such modifications are within the scope of the claims.

1 to 3 show examples of a conventional MEMS actuator,

4 is a view showing a MEMS actuator according to the present invention,

5 and 6 are views illustrating a MEMS tweezer using the MEMS actuator shown in FIG. 4;

7 is a view showing an embodiment of a MEMS switch using a MEMS actuator according to the present invention;

8A through 8E sequentially illustrate on / off operations of the MEMS switch illustrated in FIG. 7;

9 is a view showing another embodiment of a MEMS switch according to the present invention, and

10A to 10D are views sequentially illustrating a manufacturing process of a MEMS actuator according to the present invention.

Explanation of symbols on the main parts of the drawings

100: MEMS actuator 110, 120: beam

11, 121: power supply terminal 200: MEMS tweezers

250: stopper 300: MEMS actuator

310, 320: beam 311, 321: power supply terminal

350: switching terminal 351: engaging portion

400: MEMS switch SB: substrate

OL: Insulation SL: Seeder

PR: Photoresist ME: Metal Layer

Claims (24)

 Board; A plurality of beams formed on the substrate, made of the same material, and having different lengths; And Includes; the fixing portion for fixing a predetermined portion of each of the plurality of beams, The fixed part, the MEMS actuator, characterized in that the movement in one direction according to the difference in the degree of expansion of each of the plurality of beams.  The method of claim 1, The plurality of beams, Memes actuator, characterized in that a pair of beams.  The method of claim 2, And the pair of beams are arranged in parallel to each other.  The method of claim 3, wherein The fixing unit, the MEMS actuator, characterized in that for fixing the one end of each of the pair of beams.  The method of claim 3, wherein The fixing unit, the MEMS actuator, characterized in that for fixing the central portion of each of the pair of beams.  The method of claim 5, Each of the pair of beams MEMS actuator, characterized in that the central portion is formed thinner than the other portion.  The method of claim 1, The MEMS actuator further comprises a power supply terminal formed integrally with the beam at one end of each of the plurality of beams and connected to an external power source.  The method of claim 7, wherein MEMS actuator, characterized in that the power supply terminal has a larger area than the beam.  Board; A first actuator having a plurality of first beams manufactured to have different lengths from the same material on the substrate and a first fixing part for fixing a portion of each of the plurality of first beams to each other; And And a second actuator having a plurality of second beams manufactured to have different lengths from the same material on the substrate and a second fixing portion for fixing one portion of each of the plurality of second beams to each other. And the first and second actuators are driven such that the first fixing part and the second fixing part are approached or spaced apart from each other according to a temperature change.  The method of claim 9, The plurality of first beams and the plurality of second beams each of the Memes tweezers characterized in that a pair of beams.  The method of claim 10, And the pair of beams are arranged in parallel to each other.  The method of claim 11, Mess tweezers characterized in that one end of each of the pair of beams are fixed to each other.  The method of claim 9, The MEMS tweezers of claim 1, further comprising a power supply terminal formed integrally with the beam at each end of each of the first and second beams and connected to an external power source.  The method of claim 13, The power supply terminal of the MEMS tweezers, characterized in that having a larger area than the beam.  Board; And a pair of first actuators formed on the substrate and deformed so that a portion of each of the first actuators may be approached / separated from each other in a region on the substrate by a temperature change caused by power supply / disconnection. ; A second actuator having a switching terminal and deformed so that the switching terminal approaches / separates the one region by a temperature change during power supply / supply interruption; And And a stopper formed in the first actuator, the stopper for preventing a spaced movement of the switching terminal from the one region when the switching terminal of the second actuator is close to the one region. The pair of first actuators each have a plurality of beams made of the same material to have a different length from each other on the substrate and a fixing portion for fixing a portion of each of the plurality of beams mutually switch.  The method of claim 15, The second actuator has a plurality of beams made of the same material to have different lengths on the substrate, and a predetermined portion of each of the plurality of beams provided in the second actuator is fixed to each other. MEMS switch.  The method of claim 16, The first switch and the second actuator each of the MEMS switch, characterized in that it comprises a pair of beams.  The method of claim 17, MEMS switch, characterized in that the pair of beams in each of the first and second actuators are arranged in parallel to each other.  The method of claim 18, MEMS switch, characterized in that one end of each of the pair of beams in the first actuator is fixed to each other.  The method of claim 18, MEMS switch, characterized in that the central portion of each of the pair of beams of the second actuator is fixed to each other.  The method of claim 20, Each of the beams in the second actuator is the MEMS switch, characterized in that the central portion is formed thinner than the other portion.  The method of claim 15, MEMS switch further comprises a power supply terminal formed integrally with the beam at the end of each beam.  The method of claim 22, MEMS switch, characterized in that the power supply terminal has a larger area than the beam.  Oxidizing the substrate to form an insulating film; Depositing a metal sheath layer on the insulating film; Forming an actuator-shaped frame having a plurality of beams having mutually different lengths and each predetermined portion fixed to each other on the seed layer; Forming a metal layer in the mold by conducting metal plating by energizing the seed layer; Cleaning the mold; Removing an externally exposed portion of the seed layer; And And removing the insulating layer so that a portion of the metal layer corresponding to the beam floats on the substrate.