KR20090090107A - Mems switch - Google Patents

Abstract

An MEMS(Micro Electro Mechanical System) switch is provided to compensate for the deformation of a cantilever unit due to the change of the ambient temperature by forming a compensation layer in a lower part of the cantilever unit. A cantilever unit(110) is supported by a support unit(100). A piezoelectric capacitor(120) is formed in an upper part of a cantilever unit. A contact electrode(130) is formed in the upper part of the cantilever unit. A compensation layer(150) is formed in the lower part of the cantilever unit to compensate for the deformation of the cantilever unit due to the change of the ambient temperature. The compensation layer is made of the material with a thermal expansion coefficient. Signal lines(200) is conducted by the contact of the contact electrode.

Description

MEMS switch {MEMS switch}

The present invention relates to a MEMS switch capable of correcting deformation due to temperature change.

Recently, due to the rapid development of the IT field, miniaturization, light weight, and high performance of information and communication electronic systems are required, and development of component devices to satisfy this condition is required.

Currently, a semiconductor switch is widely used as a switch of an information communication system.

However, semiconductor switches have many disadvantages such as high power loss, distortion, nonlinearity, high insertion loss and low isolation.

Recently, in order to solve this problem, interest in MEMs (Micro elctro mechanical systems) switches to which micromachining technology is applied is increasing.

MEMS switches have a lower resistance loss, lower power, and less signal distortion and higher isolation than semiconductor switches, and can be applied to various applications such as digitally controlled antennas, satellite systems, and transmission / reception switches for various mobile communications.

It is a component device that short-circuits or opens a circuit in an RF transmission line through mechanical operation.

MEMs switch is divided into electrostatic force switch and piezoelectric switch according to the driving method.

1 is a perspective view showing a schematic configuration of a MEMS switch according to the prior art, the prior art MEMS switch is a cantilever 11 fixed to one side to the support 10, the hinge 12 to the cantilever 11 The contact electrode 13 is connected to each other and the signal transmission lines 21 and 22 are connected to each other by the contact of the contact electrode 13.

In this case, when the cantilever 11 is bent by the driving force of the driving unit, the contact electrode receives the force of the cantilever 11 from the hinge 12 to be in contact with the signal transmission lines 21 and 22.

Therefore, the MEMS switch is connected to the disconnected signal transmission lines (21, 22).

The driving unit of the MEMS switch is operated by the electrostatic force, electromagnetic force, heat and piezoelectric force.

When the driver does not operate, the signal transmission lines 21 and 22 are in an open state.

Figure 2 is a schematic cross-sectional view for explaining that the deformation of the cantilever occurs in accordance with the temperature change in the MEMS switch according to the prior art, the piezoelectric drive type MEMS switch has a support (50); A cantilever portion 51 supported by the support portion 50; A piezoelectric capacitor 52 formed on the cantilever portion 51; A contact electrode 53 formed on an upper end of the cantilever portion 51; The signal lines 55 are connected to each other by the contact electrode 53.

Here, the signal lines 55 are composed of a pair.

Since the piezoelectric driven MEMS switch is formed of various materials, deformation occurs due to a difference in thermal expansion coefficient of each layer material according to a change in environmental temperature.

Therefore, as shown in FIG. 2, even though the piezoelectric capacitor 52 is not driven, the cantilever part 51 is bent so that the gap between the contact electrode 53 and the signal lines 55 is maintained. It changes from 'G1' to 'G2'.

As a result, an unwanted contact is generated between the signal lines and the switch contact electrode or the contact fails.

In addition, even if a contact is made between the signal lines and the switch contact, a problem occurs that the contact force is weakened.

The present invention is to solve the problem of lowering the reliability by the deformation caused by the difference in the coefficient of thermal expansion of the materials constituting the MEMS switch.

According to a preferred aspect of the present invention,

A support;

A cantilever portion supported by the support portion;

A piezoelectric capacitor formed on the cantilever portion;

A contact electrode formed on the cantilever portion;

A compensation layer formed below the cantilever portion to compensate for the bending deformation of the cantilever portion by the ambient temperature change;

There is provided a MEMS switch including signal lines which are conducted by the contact of the contact electrode.

Another preferable aspect of this invention is that

A first cantilever structure including a first support portion, a first cantilever portion supported on the first support portion, a first piezoelectric capacitor formed on the first cantilever portion, and a contact electrode formed on the first cantilever portion;

A second support portion, a second cantilever portion supported by the second support portion, a second piezoelectric capacitor formed on the second cantilever portion, and a lower portion of the second cantilever portion, and are electrically conductive by contact with the contact electrode. There is provided a MEMS switch comprising a second cantilever structure composed of signal lines.

Another preferred embodiment of the present invention,

A first cantilever structure composed of a first support portion, a first cantilever portion supported on the first support portion, and a first piezoelectric capacitor formed on the first cantilever portion;

MEMS switch comprising a second support portion, a second cantilever portion supported by the second support portion, signal lines formed under the first cantilever portion, and a second cantilever structure including a contact electrode formed on the first cantilever portion. Is provided.

According to the present invention, a compensation layer is formed under the cantilever portion in which the contact electrode is formed, and thus the bending deformation of the cantilever portion can be compensated for by the ambient temperature change.

In addition, the present invention constitutes a MEMS switch with the first cantilever structure in which the contact electrode is formed and the second cantilever structure in which the signal lines are formed, so that the distance between the contact electrode and the signal lines is changed linearly even when the ambient temperature is changed. Since it can contact smoothly, there exists an effect which can improve the reliability of an element.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

3 is a schematic cross-sectional view for explaining a MEMs switch according to a first embodiment of the present invention, including a support part 100; A cantilever part 110 supported by the support part 100; A piezoelectric capacitor 120 formed on the cantilever unit 110; A contact electrode 130 formed on the cantilever unit 110; A compensation layer (150) formed under the cantilever portion (110) to compensate for the bending deformation of the cantilever portion (110) by the ambient temperature change; The signal lines 200 are connected to each other by the contact electrode 130.

Here, the MEMS switch is a thermal expansion coefficient of the materials of the piezoelectric capacitor 120 and the contact electrode 130 on the cantilever portion 110 and the cantilever portion 110 by the cantilever portion 110 floating below. Since is different, the floating region of the MEMS switch is bent due to the change in the ambient temperature.

Therefore, the MEMS switch according to the first embodiment of the present invention forms a compensation layer 150 under the cantilever portion 110, and can compensate for the bending deformation of the cantilever portion 110 due to a change in ambient temperature. There is an advantage.

The compensation layer 150 is made of a material having a coefficient of thermal expansion, and is formed of a material capable of reducing deformation of the cantilever part 110 according to a temperature change.

That is, as shown in Table 1 below, when the cantilever without the compensation layer caused a deformation of 1 nm due to a temperature change of 1 ° C., the cantilever with the compensation layer applied to the first embodiment of the present invention was bent. The deformation is zero.

Temperature change transform Cantilever without compensation layer 1 ℃ 1 nm Cantilever with Compensation Layer 1 ℃ 0

As a result, the MEMS switch according to the first embodiment of the present invention forms a layer under the cantilever portion 110 that can compensate for the deformation of the floating region due to the change in ambient temperature to approach zero.

Meanwhile, the material of the compensation layer 150 is preferably metal.

In addition, the piezoelectric capacitor 120 includes a lower electrode, a piezoelectric film, and an upper electrode.

4 is a schematic plan view for explaining a MEMs switch according to a second embodiment of the present invention. The MEMS switch according to the second embodiment of the present invention includes a first support unit 210 and the first support unit 210. The first cantilever structure 200 includes a first cantilever portion 220 supported by the first cantilever 220, a first piezoelectric capacitor formed on the first cantilever portion 220, and a contact electrode formed on the first cantilever portion 220. )and; A second support part 310, a second cantilever part 320 supported by the second support part 310, a second piezoelectric capacitor formed on the second cantilever part 320, and the second cantilever part ( A second cantilever structure 300 is formed below the second cantilever structure 300 and includes signal lines that are connected to the contact electrode.

Therefore, the MEMS switch according to the second embodiment of the present invention is designed such that the first cantilever structure in which the contact electrode is formed and the second cantilever structure in which the signal lines are formed have the same deformation according to the change of ambient temperature. The interval of is to change linearly and consistently with temperature change.

For example, the first cantilever structure and the second cantilever structure are designed so that 1 nm of deformation occurs at a temperature change of 1 ° C. of the MEMs switch.

In this way, the MEMS switch is composed of the first cantilever structure in which the contact electrode is formed and the second cantilever structure in which the signal lines are formed. Since it is possible to contact, there is an advantage that can improve the reliability of the device.

FIG. 5 is a schematic cross-sectional view illustrating another structure of the MEMs switch according to the second exemplary embodiment of the present invention, wherein the MEMS switch of FIG. 5 is substantially the same as the first cantilever structure 200 and the second cantilever structure 300. To configure.

As such, when the first and second cantilever structures 200 and 300 are configured in almost the same manner, the first and second cantilever structures 200 and 300 may have the same deformation according to a change in ambient temperature, so that the contact electrode and the signal lines are smoothly contacted even when the ambient temperature changes.

That is, first material layers 250 that are the same as the signal lines 350 of the second cantilever structure 300 are formed below the first cantilever structure 200 of the first cantilever structure 200.

A second material layer 340 is formed on the second cantilever part 300 of the second cantilever structure 300, the same as the contact electrode 240 of the first cantilever structure 200.

The contact electrode and the signal lines may be made of metal, and the first and second material layers 250 and 340 may be made of metal.

As a result, the first and second cantilever structures 200 and 300 are configured in almost the same manner.

For reference, '230' of FIG. 5 is a first piezoelectric capacitor, and '330' is a second piezoelectric capacitor.

FIG. 6 is a view illustrating a state where deformation occurs in accordance with a temperature change of a MEMs switch according to a second embodiment of the present invention. As described above, the MEMs switch according to the second embodiment of the present invention has an ambient temperature. The contact electrode is formed on the first cantilever structure 200 and the signal lines are formed on the second cantilever structure 300 so as to have the same deformation according to the change.

Therefore, the deformation D1 of the first cantilever part 220 of the first cantilever structure 200 and the deformation of the second cantilever part 320 of the second cantilever structure 300 with respect to the change amount of the ambient temperature of the MEMs switch. (D1) becomes substantially the same.

Therefore, the gap G between the contact electrode 240 and the signal lines 350 is changed to be linear and constant according to the temperature change.

In this case, the first piezoelectric capacitor 230 of the first cantilever structure 200 and the second piezoelectric capacitor 330 of the second cantilever structure 300 may be used to conduct the contact electrode 240 and the signal lines 350. ) To bend the first cantilever part 220 of the first cantilever structure 200 and the first cantilever part 320 of the second cantilever structure 300 to bend the contact electrode 240. The signal lines 350 are in contact with each other.

For reference, the dotted line in FIG. 6 is a line extending from the bottom surface of the first and second cantilever portions 220 and 320 before deformation.

FIG. 7 is a schematic cross-sectional view for describing a MEMs switch according to a third embodiment of the present invention. In the MEMs switch according to the third embodiment of the present invention, the distance between the contact electrode and the signal lines is linear with a change in temperature. The first cantilever structure in which the contact electrode is formed so as to be constantly changed, and the second cantilever structure in which the signal lines are formed.

In this case, unlike the MEMS switch of the second embodiment of the present invention, the second cantilever structure is not provided with a piezoelectric capacitor.

That is, as shown in FIG. 7, the first cantilever structure 500 of the MEMS switch includes a first support part 510, a first cantilever part 520 supported by the first support part 510, and the first cantilever structure 500. The first piezoelectric capacitor 530 is formed on the first cantilever 520 and the contact electrode 540 is formed on the first cantilever 530.

In addition, the second cantilever structure 600 may include a second support part 610, a second cantilever part 620 supported by the second support part 620, and signal lines formed under the first cantilever part 520. It consists of 650.

In this case, the second cantilever part 620 may be configured of at least one thin film.

As a result, in the MEMS switch according to the third exemplary embodiment of the present invention, the second cantilever structure 600 may have the same deformation as the second cantilever structure 600 according to the temperature change of the first cantilever structure 500. Thin film and signal lines 650 constituting the appropriately designed and configured.

8A and 8B are schematic cross-sectional views for explaining the cantilever structure of the MEMS switch according to the present invention. First, in FIG. 6, a lower part of the first cantilever part 220 in the floating region of the first cantilever structure 200 is illustrated. Although metal layers 250 are formed on the metal layers 250, the metal layers may be formed on most of the lower front surface of the first cantilever portion 720 as illustrated in FIG. 8A.

For reference, '730' of FIG. 8A is a piezoelectric capacitor, and '740' is a contact electrode.

In FIG. 7, signal lines 250 are formed at a lower portion of the second cantilever portion 620 in the floating region of the first cantilever structure 600, but as shown in FIG. 8B, the second cantilever portion 620 is formed. Signal lines 250 may be formed on most of the lower front surface.

As described above, the present invention may configure the MEMS switch with the optimum structure as described above in order to compensate for the deformation of the MEMS switch according to the change of ambient temperature, but the design change according to the spirit of the present invention belongs to the right scope. Will be done.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

1 is a perspective view showing a schematic configuration of a MEMS switch according to the prior art

Figure 2 is a schematic cross-sectional view for explaining that the deformation of the cantilever occurs in accordance with the temperature change in the MEMS switch according to the prior art

3 is a schematic cross-sectional view for explaining a MEMs switch according to a first embodiment of the present invention;

4 is a schematic plan view for explaining a MEMs switch according to a second embodiment of the present invention;

5 is a schematic cross-sectional view for explaining another structure of the MEMs switch according to the second embodiment of the present invention.

6 is a view illustrating a state in which deformation occurs in accordance with a temperature change of a MEMS switch according to a second embodiment of the present invention;

7 is a schematic cross-sectional view for explaining a MEMs switch according to a third embodiment of the present invention.

8A and 8B are schematic cross-sectional views for explaining the cantilever structure of a MEMS switch according to the present invention.

Claims (7)

A support; A cantilever portion supported by the support portion; A piezoelectric capacitor formed on the cantilever portion; A contact electrode formed on the cantilever portion; A compensation layer formed below the cantilever portion to compensate for the bending deformation of the cantilever portion by the ambient temperature change; MEMS switch comprising a signal line is conducted in contact with the contact electrode. The method according to claim 1, MEMS switch, characterized in that the material of the compensation layer is a metal. A first cantilever structure including a first support portion, a first cantilever portion supported on the first support portion, a first piezoelectric capacitor formed on the first cantilever portion, and a contact electrode formed on the first cantilever portion; A second support portion, a second cantilever portion supported by the second support portion, a second piezoelectric capacitor formed on the second cantilever portion, and a lower portion of the second cantilever portion, and formed to be in contact with the contact electrode. MEMS switch comprising a second cantilever structure consisting of signal lines. The method according to claim 3, First material layers identical to signal lines of the second cantilever structure are formed under the first cantilever part of the first cantilever structure; MEMS switch, wherein a second layer of material is formed on the second cantilever portion of the second cantilever structure, the same as the contact electrode of the first cantilever structure. The method according to claim 4, And the contact electrode, the signal lines, and the first and second material layers are made of metal. A first cantilever structure composed of a first support portion, a first cantilever portion supported on the first support portion, and a first piezoelectric capacitor formed on the first cantilever portion; MEMS switch comprising a second support portion, a second cantilever portion supported by the second support portion, signal lines formed under the first cantilever portion, and a second cantilever structure including a contact electrode formed on the first cantilever portion. . The method according to claim 6, The second cantilever portion, MEMS switch comprising at least one thin film.

Images