JP2011249192A - Mems switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a MEMS switch capable of suppressing the occurrence of stiction in a conducting state and performing stable signal transmission in a conducting state.SOLUTION: In a fixed terminal FT11 and a second fixed terminal FT12 of a MEMS switch 10-1, respective end edges are closest to a movable terminal MT, a portion other than the end edges forms a cross-sectional shape separated from the movable terminal MT more than the end edges, and the movable terminal MT is brought into line contact with the end edges of the first fixed terminal FT11 and the second fixed terminal FT12 in a conducting state.

Description

  The present invention relates to a MEMS (Micro Electro Mechanical Systems) switch.

  Semiconductor switches using diodes, FETs, and the like cause characteristics deterioration such as transmission loss increase and isolation decrease as the frequency increases. However, since the MEMS switch is unlikely to cause such characteristic deterioration, it has been attracting attention as a switching device suitable for use in a high-frequency circuit, for example, a circuit in which a high-frequency signal of several GHz to several hundred GHz flows.

  In general, the MEMS switch has a multilayer structure created by using a known thin film forming method. This MEMS switch has a first fixed terminal composed of the end of the first signal line, a second fixed terminal composed of the end of the second signal line, and a movable terminal composed of a conductive layer formed on the movable lever. In addition, both the signal lines are brought into a conductive state by bringing the movable terminals into contact with both the fixed terminals, and the function of bringing the both signal lines into a non-conductive state by releasing the contact is exhibited.

  First, a known example of a MEMS switch will be described with reference to FIG. In this description, for convenience of description, the front, back, top, bottom, left, and right of FIG. 1A are referred to as top, bottom, front, back, left, and right, respectively, and FIG. The directions corresponding to these in C) are also referred to.

  As shown in FIGS. 1 (A) and 1 (B), the first signal line 101 and the second signal line 102 have a rectangular shape when viewed from above, and the tips of the first signal line 101 and the second signal line 102 have a predetermined interval (no symbol). It is arranged to face each other in parallel. The end of the first signal line 101 is used as the first fixed terminal 101a, and the end of the second signal line 102 is used as the second fixed terminal 102a.

  The movable lever (no symbol) is formed on the lever body 103 having a rectangular shape when viewed from above, an insulating layer 104 formed on the lever body 103, and formed on the insulating layer 104 so that the shape when viewed from above is rectangular. And a movable terminal 105 made of a conductive layer. The movable terminal 105 is arranged so that the upper surface thereof faces the lower surfaces of both the fixed terminals 101a and 102a in parallel with a predetermined distance CL101.

  When both the signal lines 101 and 102 are in a conductive state, as shown in FIG. 1C, a drive actuator (not shown) is operated to displace the movable terminal 105 of the movable lever upward, and the displacement causes the movable terminal to move. The upper surface of 105 is brought into surface contact with the lower surfaces of both fixed terminals 101a and 102a. On the other hand, when both the signal lines 101 and 102 in the conducting state are brought into the non-conducting state, the operation of the driving actuator is stopped and the movable terminal 105 of the movable lever is returned to the initial position as shown in FIG. The surface contact between the upper surface of the movable terminal 105 and the lower surfaces of the fixed terminals 101a and 102a is released.

  This MEMS switch makes both signal lines 101 and 102 conductive by bringing the upper surface of the movable terminal 105 into surface contact with the lower surfaces of both fixed terminals 101a and 102a, so that van der Waals force, meniscus force, etc. As a cause, there is a possibility that a phenomenon that the movable terminal 105 sticks to both the fixed terminals 101a and 102a in a conductive state, that is, so-called stiction occurs. When stiction occurs, it is difficult to release the contact between the upper surface of the movable terminal 105 and the lower surfaces of both the fixed terminals 101a and 102a even if the operation of the drive actuator is stopped.

  Next, another known example of the MEMS switch (see Patent Document 1) will be described with reference to FIG. In this description, for convenience of explanation, the front, back, top, bottom, left, and right of FIG. 2A are referred to as top, bottom, front, back, left, and right, respectively, and FIG. The directions corresponding to these in C) are also referred to.

  As shown in FIGS. 2 (A) and 2 (B), the first signal line 201 and the second signal line 202 have a rectangular shape when viewed from above, and the tips of the first signal line 201 and the second signal line 202 have a predetermined interval (no symbol). It is arranged to face each other in parallel. The end of the first signal line 201 is used as the first fixed terminal 201a, and the end of the second signal line 202 is used as the second fixed terminal 202a. A plurality of hemispherical protrusions 201b and 202b are provided on the lower surfaces of the fixed terminals 201a and 202a so as to face the upper surface of the movable terminal 205 described later.

  The movable lever (without reference numeral) is formed on the lever body 203 having a rectangular shape when viewed from above, an insulating layer 204 formed on the lever body 203, and on the insulating layer 204 so that the shape when viewed from above is rectangular. And a movable terminal 205 made of a conductive layer. The movable terminal 205 is arranged so that the upper surface thereof faces the lower ends of the plurality of hemispherical protrusions 201b and 202b of the fixed terminals 201a and 202a in parallel with a predetermined distance CL201.

  When both the signal lines 201 and 202 are in a conductive state, as shown in FIG. 2C, a driving actuator (not shown) is operated to displace the movable terminal 205 of the movable lever upward, and the displacement causes the movable terminal to move. The upper surface of 205 is brought into multipoint contact with the lower ends of the plurality of hemispherical protrusions 201b and 202b of both fixed terminals 201a and 202a. On the other hand, when both the signal lines 201 and 202 in the conductive state are brought into the non-conductive state, as shown in FIG. 2B, the operation of the drive actuator is stopped and the movable terminal 205 of the movable lever is returned to the initial position. Then, the multipoint contact between the upper surface of the movable terminal 205 and the lower ends of the plurality of hemispherical protrusions 201b and 202b of the fixed terminals 201a and 202a is released.

  In this MEMS switch, both signal lines 201 and 202 are brought into conduction by bringing the upper surface of the movable terminal 205 into multipoint contact with the lower ends of the plurality of hemispherical protrusions 201b and 202b of the fixed terminals 201a and 202a. Compared with the surface contact type MEMS switch shown in FIG. 1, the contact area between the movable terminal 205 and the fixed terminals 201a and 202a in the conductive state can be reduced, and the occurrence of the stiction is suppressed by reducing the contact area. Is possible.

  By the way, in order to realize the multipoint contact in the MEMS switch shown in FIG. 2, at least the heights of the plurality of hemispherical protrusions 201b on the first fixed terminal 201a side are the same and the second fixed terminal 202a side is provided. The plurality of hemispherical protrusions 202b must have the same height.

  However, since the height of the hemispherical protrusions 201b and 202b is on the order of μm or nm, and the hemispherical protrusions 201b and 202b are formed using a known thin film forming method, The height of the plurality of hemispherical protrusions 201b on the first fixed terminal 201a side is likely to vary, and the height of the plurality of hemispherical protrusions 202b on the second fixed terminal 202a side is also likely to vary.

  This variation in height is a factor that causes variations in the number of contact points in the multipoint contact. Therefore, the contact region between the movable terminal 205 and both signal lines 201 and 202 in the conductive state is likely to vary, and the contact region There is a high possibility that transmission loss will vary due to variations. That is, although the multipoint contact type MEMS switch shown in FIG. 2 can suppress the occurrence of the stiction, it is difficult to perform stable signal transmission in a conductive state.

JP 2007-012558 A

  The objective of this invention is providing the MEMS switch which can suppress generation | occurrence | production of the stiction in a conduction | electrical_connection state, and can perform the stable signal transmission in a conduction | electrical_connection state.

  In order to achieve the above object, the present invention includes a first fixed terminal formed of an end portion of a first signal line, a second fixed terminal formed of an end portion of a second signal line, and a conductive layer provided on a movable lever. And having a movable terminal facing the first fixed terminal and the second fixed terminal at an interval, and bringing the movable terminal into contact with the first fixed terminal and the second fixed terminal. A MEMS switch for bringing a signal line into a conducting state and releasing the contact to bring the first signal line and the second signal line into a non-conducting state, wherein the first fixed terminal and the second fixed terminal have respective edges The portion closest to the movable terminal and excluding the edge has a cross-sectional shape farther from the movable terminal than the edge, and the movable terminal is the edge of the first fixed terminal and the second fixed terminal in the conductive state. Touch the line.

  According to this MEMS switch, since both signal lines are made conductive by bringing the movable terminal into line contact with the edges of both fixed terminals, compared to the conventional surface contact type MEMS switch, The contact area between the movable terminal and both fixed terminals can be reduced. That is, the reduction of the contact area can surely suppress the occurrence of stiction (a phenomenon in which the movable terminal sticks to both fixed terminals in the conductive state).

  In addition, since the line contact can be performed with a predetermined contact area without variation, the contact area between the movable terminal and both fixed terminals in the conductive state may vary as compared with the conventional multipoint contact type MEMS switch. Can be suppressed. That is, by suppressing this variation, it is possible to suppress a variation in transmission loss and perform stable signal transmission in a conductive state.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the stiction in a conduction | electrical_connection state can be suppressed, and the MEMS switch which can perform the stable signal transmission in a conduction | electrical_connection state can be provided.

  The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

1A is a partial top view of a MEMS switch showing a known example, FIG. 1B is a cross-sectional view taken along line S101-S101 in FIG. 1A, and FIG. It is sectional drawing which shows the state which carried out. 2A is a partial top view of a MEMS switch showing another known example, FIG. 2B is a cross-sectional view taken along line S201-S201 in FIG. 2A, and FIG. It is sectional drawing which shows the state which conducted. FIG. 3 is a top view of the MEMS switch showing the first embodiment of the present invention. 4A is a sectional view taken along line S11-S11 in FIG. 3, FIG. 4B is a sectional view taken along line S12-S12 in FIG. 3, and FIG. 4C is taken along line S13-S13 in FIG. It is sectional drawing which follows. 5 (A) and 5 (B) are diagrams for explaining the operation of the MEMS switch shown in FIG. 1, and FIG. 5 (C) is a diagram showing a contact area of both fixed terminals with respect to the movable terminal. FIG. 6 is a diagram corresponding to FIG. 4 (A) showing a modification of the shape of both the fixed terminals shown in FIG. 4 (A). 7A and 7B are explanatory diagrams of an example of a method for obtaining both the fixed terminals shown in FIG. 4A and the both fixed terminals shown in FIG. FIG. 8A is a partial top view of a MEMS switch showing a second embodiment of the present invention, and FIG. 8B is a diagram showing a contact area of both fixed terminals with respect to a movable terminal. FIG. 9A is a partial top view of a MEMS switch showing a third embodiment of the present invention, and FIG. 9B is a diagram showing a contact area of both fixed terminals with respect to the movable terminal. FIG. 10A is a partial top view of a MEMS switch showing a fourth embodiment of the present invention, and FIG. 10B is a diagram showing a contact area of both fixed terminals with respect to a movable terminal. FIG. 11 is a top view of a MEMS switch showing a fifth embodiment of the present invention.

[First Embodiment]
First, a MEMS switch 10-1 to which the present invention is applied will be described with reference to FIGS. In this description, for convenience of explanation, the front, back, top, bottom, left, and right in FIG. 3 are referred to as top, bottom, front, back, left, and right, and the directions corresponding to these in other drawings are also the same. Called.

  The MEMS 10-1 has a multi-layer structure formed by using a known thin film forming method. In terms of the original size, the front-rear dimension is about 3.0 mm, and the left-right dimension is about 1.5 mm.

As shown in FIGS. 3 and 4 (A) to 4 (C), the base layer 11 is formed using Si or the like as a material so as to form a rectangular shape in top view, and the upper surface of the base layer 11 is formed. An insulating layer 12 made of SiO ₂ or the like is formed over the entire area. Further, the base layer 11 and the insulating layer 12 are formed with through holes 11a and 12a having a U-shape when viewed from above. Inside the through holes 11a and 12a, a part 11b of the base layer 11 and A movable lever ML having a rectangular shape when viewed from the top, which is constituted by a part 12b of the insulating layer 12, is formed.

  A plurality (three in the figure) of through holes 11b1 and 12b1 are formed on the front side of the center of the movable lever ML in the front-rear direction, and the rear part of the movable lever ML from the through holes 11b1 and 12b1 is the main body. The part corresponding to the part MLa corresponds to the movable part MLb in front of the through holes 11b1 and 12b1, and the part in which the through holes 11b1 and 12b1 are formed corresponds to the hinge part MLc.

  The upper surface of the main body MLa of the movable lever ML (the upper surface of the part 12b of the insulating layer 12) extends from the upper surface to the rear side so that the first electrode layer 13 has a rectangular shape when viewed from above. The first electrode layer 13 is integrally provided with an overhanging portion 13a having a rectangular shape in a top view on the right side of the rear portion. The first electrode layer 13 has, for example, a multilayer structure including a Ti layer having a thickness of 5 nm and a Pt layer having a thickness of 200 nm formed thereon. In addition, a piezoelectric layer 14 made of PZT or the like is formed on the upper surface of the first electrode layer 13 (excluding the overhanging portion 13 a) in the same top view shape as the first electrode layer 13. Further, the second electrode layer 15 is formed on the upper surface of the piezoelectric layer 14 in the same top view shape as the piezoelectric layer 14. The second electrode layer 15 has, for example, a multilayer structure including a Ti layer having a thickness of 5 nm and a Pt layer having a thickness of 200 nm formed thereon. The first electrode layer 13, the piezoelectric layer 14, and the second electrode layer 15 constitute a drive actuator (no symbol) for deforming the body portion MLa of the movable lever ML so as to warp.

  A movable terminal MT made of a conductive layer is formed on the upper surface of the movable portion MLb of the movable lever ML (the upper surface of the part 12b of the insulating layer 12) so that the shape of the movable terminal MT when viewed from above is rectangular. The movable terminal MT (conductive layer) has, for example, a multilayer structure including a Ti layer having a thickness of 5 nm and an Au layer having a thickness of 200 nm formed thereon.

  A power input terminal 16 made of a conductive layer is formed on the rear upper surface of the second electrode layer 15 so that the shape of the upper surface view is rectangular. The power input terminal 16 (conductive layer) has, for example, a multilayer structure including a Ti layer having a thickness of 5 nm and an Au layer having a thickness of 200 nm formed thereon.

  A ground terminal 17 made of a conductive layer is formed on the upper surface of the overhanging portion 13a of the first electrode layer 13 so that the shape of the top view is rectangular. The ground terminal 17 (conductive layer) has, for example, a multilayer structure composed of a Ti layer having a thickness of 5 nm and an Au layer having a thickness of 200 nm formed thereon.

On the upper surface of the front portion of the insulating layer 12, a first signal line SL11 having a predetermined width made of a conductive layer and a second signal line SL12 made of a conductive layer and having the same width as the first signal line SL11 are arranged on the left and right sides of the movable terminal MT. It is formed so as to be symmetrical with respect to the center in the direction. The first signal line SL11 (conductive layer) and the second signal line SL12 (conductive layer) are, for example, (1) a Ti layer having a thickness of 5 nm, an Au layer having a thickness of 200 nm formed thereon, and an upper layer thereof. A multi-layer structure (four-layer structure) composed of a 3 μm thick Au layer formed thereon and a 200 nm thick SiO ₂ layer formed thereon, and (2) a 5 nm thick Ti layer and formed thereon. And a multilayer structure (three-layer structure) composed of an Au layer having a thickness of 200 nm and an Au layer having a thickness of 3 μm formed thereon.

  As can be seen from FIG. 4A, the first signal line SL11 has a portion joined to the insulating layer 12 and a non-joined portion continuous with the portion, and an end portion of the non-joined portion (right end portion in the figure). Has a cross-sectional shape inclined toward the movable terminal MT, and the end portion is used as the first fixed terminal FT11. Similarly, the second signal line SL12 has a portion joined to the insulating layer 12 and a non-joined portion continuous with the portion, and an end portion (left end portion in the figure) of the non-joined portion is connected to the movable terminal MT. The end portion is used as the second fixed terminal FT12. The tips of the fixed terminals FT11 and FT12 face each other in parallel in the left-right direction with a predetermined interval (no symbol), and the edges of the fixed terminals FT11 and FT12 are spaced from the upper surface of the movable terminal MT by a predetermined interval CL11. And face each other in parallel. In FIG. 4A, θ represents an inclination angle of both the fixed terminals FT11 and FT12, and the inclination angle θ is 1 to 45 degrees, preferably 3 to 5 degrees.

  In the MEMS switch 10-1, when both the signal lines SL11 and SL12 are brought into conduction, the power input terminal 16 and the ground terminal 17 are connected to a variable DC power supply (not shown), and the power input terminal 16 is connected to the variable DC power supply. A drive voltage is applied to. By applying this drive voltage, the piezoelectric layer 14 of the drive actuator contracts due to the piezoelectric effect, and the contraction causes the main body portion MLa of the movable lever ML to be warped up, and in accordance with the deformation, the movable portion MLc moves on the movable portion MLc. The terminal MT is displaced upward, and due to the displacement, the upper surface of the movable terminal MT comes into contact so as to slightly push up the edges of the fixed terminals FT11 and FT12, and the upper surface of the movable terminal MT is in contact with the fixed terminals FT11 and FT12. Line contact is made with the edge under a predetermined contact pressure (see FIGS. 5A and 5B).

  The movable portion MLb warps together with the main end portion MLa, but since there is a hinge portion MLc which is more flexible than the movable portion MLb, the movable terminal MT contacts the edges of the fixed terminals FT11 and FT12. When it starts, the movable part MLb tilts by utilizing the flexibility of the hinge part MLc, and the tilting causes the upper surface of the movable terminal MT to be in line contact with the edges of the fixed terminals FT11 and FT12. Further, since the upper surface of the movable terminal MT is in contact so as to slightly push up the edges of the fixed terminals FT11 and FT12, even if the edges of the fixed terminals FT11 and FT12 are displaced in the vertical direction, this push-up action is performed. This offsets the displacement, and the upper surface of the movable terminal MT is surely in line contact with the end edges of the fixed terminals FT11 and FT12. That is, the line contact between the movable terminal MT and both the fixed terminals FT11 and FT12 has a predetermined contact area CR11 and CR12 according to the width of the edge of the both fixed terminals FT11 and FT12, as shown in FIG. And it is performed without variation.

  In the contact process, the upper surface of the movable terminal MT contacts the fixed terminals FT11 and FT12 by slightly pushing up the edges of the fixed terminals FT11 and FT12. The fixed terminals FT11 and FT12 have an appropriate rigidity and have an inclination angle θ. Is appropriately set based on the rigidity, push-up force and the like, the line contact can be performed without any trouble with the contact areas CR11 and CR12 shown in FIG. In other words, even if the upper surface of the movable terminal MT contacts with the upper edges of the fixed terminals FT11 and FT12 pushed up, the line contact can be ensured without any problem, and the line contact does not become a surface contact.

  On the other hand, when the signal lines SL11 and SL12 in the conductive state are brought into the non-conductive state, the application of the drive voltage to the power input terminal 16 may be canceled. By releasing the application of the drive voltage, the operation of the drive actuator is stopped, the movable lever ML is restored, the movable terminal MT is returned to the initial position, and the upper surface of the movable terminal MT and the edges of the fixed terminals FT11 and FT12 are connected. The line contact is released (see FIG. 4A).

  In FIG. 4A, the two fixed terminals FT11 and FT12 have cross-sectional shapes inclined toward the movable terminal MT. However, as shown in FIG. 6, the fixed terminals FT11 ′ and FT12 ′ are movable terminals. Even when a cross-sectional shape curved toward the MT is employed, the same line contact and release as described above can be performed. The cross-sectional shapes of the two fixed terminals are not limited to those shown in FIGS. 4A and 6. In short, the edges of the two fixed terminals are closest to the movable terminal MT and the edges are excluded. Even if a portion having a cross-sectional shape that is farther from the movable terminal MT than the end edge is used as both the fixed terminals, the same line contact and release as described above can be performed.

  By the way, both signal lines SL11 and SL12 including both fixed terminals FT11 and FT12 shown in FIG. 4A and both signal lines SL11 and SL12 including both fixed terminals FT11 ′ and FT12 ′ shown in FIG. Therefore, it is practically difficult to obtain a cross-sectional shape shown in FIG. 4A or a cross-sectional shape shown in FIG. But no.

  Therefore, in order to make both the fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′) have the cross-sectional shape shown in FIG. 4A and the cross-sectional shape shown in FIG. 6, both signal lines SL11 and SL12 are formed. In the process, it is necessary to devise such that both fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′) can be inclined or curved. Below, the suitable example of a method clarified through various experiments is demonstrated.

(First method example)
The first example method is
・ In the process of forming both signal lines SL11 and SL12 including both fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′), internal stresses (compression stress, tensile stress, etc.) at least in the part corresponding to both fixed terminals The basic idea is to cause the same part to be inclined or bend by the internal stress.

Here, both signal lines SL11 and SL12 are “formed on the 5 nm thick Ti layer, the 200 nm thick Au layer formed thereon, and the 3 μm thick Au layer formed thereon. A case of having a “multi-layer structure (four-layer structure) composed of a SiO ₂ layer having a thickness of 200 nm” will be described as an example, and a first method example will be specifically described with reference to FIG. 7A corresponds to a Ti layer having a thickness of 5 nm, LA12 corresponds to an Au layer having a thickness of 200 nm, LA13 corresponds to an Au layer having a thickness of 3 μm, and LA14 corresponds to an SiO ₂ layer having a thickness of 200 nm.

In this case, both signal lines SL11 and SL12 are
-A Ti layer LA11 is formed by DC sputtering on a patterned resist (not shown), an Au layer LA12 is formed by DC sputtering on this Ti layer LA11, and plating comprising the Ti layer LA11 and the Au layer L12 is performed. Step of forming seed layer (no symbol) Step of forming Au layer LA13 by electrolytic plating on plating seed layer Step of forming SiO ₂ layer LA14 by plasma CVD or RF sputtering on Au layer LA12 It is created through a step of removing the resist used when forming the layer. In the step of forming the SiO ₂ layer LA14, the substrate temperature is set to 300 ° C., which is higher than room temperature, and the SiO ₂ layer LA14 is formed. The temperature is lowered to 20 ° C.

Since the linear expansion coefficient of the SiO ₂ layer LA14 is smaller than the linear expansion coefficient of the Au layer LA13, the lower Au layer LA13 contracts more greatly than the upper SiO ₂ layer LA14 during the temperature drop process (FIG. 7A). ), The SiO ₂ layer LA14 and the Au layer LA13 are inclined or curved downward due to the compressive stress based on the difference in contraction amount, and accordingly, a thin plating seed layer (Ti layer LA11 + Au layer) LA12) is also inclined or curved downward, and both fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′) have the cross-sectional shape shown in FIG. 4A and the cross-sectional shape shown in FIG.

  According to experiments, when the specific method was carried out with the lengths of both fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′) being 90 μm, the edges of the fixed terminals were approximately 1. It could be lowered by 2 μm. Further, even when the ambient temperature in which both the fixed terminals were created was changed within the room temperature (20 ± 15 ° C.), no significant change was observed in the numerical value of 1.2 μm.

(Second method example)
The second example method is
-In the process of forming both signal lines SL11 and SL12 including both fixed terminals (FT11 and FT12, FT11 'and FT12'), plastic deformation is caused at least in a portion corresponding to both fixed terminals, and the plastic deformation The basic idea is to incline or bend the same part.

  Here, both signal lines SL11 and SL12 are “a multilayer structure (3 nm comprising a Ti layer having a thickness of 5 nm, an Au layer having a thickness of 200 nm formed thereon, and an Au layer having a thickness of 3 μm formed thereon. The case of having a “layer structure” ”will be taken as an example, and a second method example will be specifically described with reference to FIG. 7B corresponds to a Ti layer having a thickness of 5 nm, LA 22 corresponds to an Au layer having a thickness of 200 nm, and LA 23 corresponds to an Au layer having a thickness of 3 μm.

In this case, both signal lines SL11 and SL12 are
A Ti layer LA21 is formed on the patterned resist RE by DC sputtering, an Au layer LA22 is formed on the Ti layer LA21 by DC sputtering, and a plating seed layer composed of the Ti layer LA21 and the Au layer L22 ( It is created through a step of forming an Au layer LA23 by electrolytic plating on a step / plating seed layer that has no reference number) and a step of removing the resist RE used in forming the plating seed layer. As the resist RE used for forming the layer, a heat-shrinkable resist, for example, a novolac positive resist is used, and as a step before removing the resist RE, the resist RE is heated and held at a temperature of 180 ° C. for 1 hour. Perform the steps.

  Since the resist RE can be heated and shrunk, the resist RE shrunk during the heating process (see the arrow in FIG. 7B), and the plating seed layer (Ti layer LA21 + Au layer thereon) accompanying the shrinkage. LA22) and Au layer LA23 are plastically deformed downward and inclined or curved downward, and both fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′) are shown in the cross-sectional shape shown in FIG. The cross-sectional shape is as shown.

  According to experiments, when the above-mentioned specific method was carried out with the length of both fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′) being 40 μm, the edges of the two fixed terminals were approximately 2. It could be lowered by 0 μm.

In addition, the specific method is described as follows: “Ti layer having a thickness of 5 nm, Au layer having a thickness of 200 nm formed thereon, Au layer having a thickness of 3 μm formed thereon, and a thickness of 200 nm formed thereon. Even when applied to the production of both signal lines SL11 and SL12 having a “multilayer structure (four-layer structure) made of SiO ₂ layers”, both fixed terminals (FT11 and FT12, FT11 ′ and FT12 ′) are used in the same manner as described above. The cross-sectional shape shown in FIG. 4A and the cross-sectional shape shown in FIG. 6 could be obtained.

  According to the MEMS switch 10-1 described above, the following effects (1) and (2) can be obtained.

  (1) Since the signal lines SL11 and SL12 are brought into conduction by bringing the upper surface of the movable terminal MT into line contact with the end edges of the fixed terminals FT11 and FT12, the surface contact type MEMS shown in FIG. Compared with the switch, the contact area between the movable terminal MT and the fixed terminals FT11 and FT12 in the conductive state can be reduced. That is, the reduction of the contact area can surely suppress the occurrence of stiction (a phenomenon in which the movable terminal MT sticks to both the fixed terminals FT11 and FT12 in the conductive state).

  (2) Since the line contact can be performed with the predetermined contact areas CR11 and CR12 without variations, the movable terminal MT and the fixed terminals FT11 in the conductive state and the fixed terminals FT11 and FT11 in the conductive state can be compared with the multipoint contact type MEMS switch shown in FIG. It is possible to suppress variation in the contact area with the FT12. That is, by suppressing this variation, it is possible to suppress a variation in transmission loss and perform stable signal transmission in a conductive state.

[Second Embodiment]
Next, a MEMS switch 10-2 to which the present invention is applied will be described with reference to FIG. In this description, for convenience of explanation, the front, back, top, bottom, left, and right of FIG. 8A are respectively referred to as top, bottom, front, back, left, and right, and those of FIG. The direction corresponding to is also referred to similarly.

The difference between the MEMS switch 10-2 and the MEMS switch 10-1 described in the first embodiment is that, as shown in FIG.
The width W12 of the tips (edges) of the fixed terminals FT21 and FT22 is smaller than the width W11 of the signal lines SL21 and SL22.

  In this case, the line contact between the movable terminal MT and the fixed terminals FT21 and FT22 is, as shown in FIG. 8B, a predetermined contact area CR21 according to the width W12 of the edges of the fixed terminals FT21 and FT21. With CR22, it is performed without variation.

  According to the MEMS switch 10-2, in addition to the effects (1) and (2) described in the first embodiment, the following effect (3) can be obtained.

  (3) By changing the width W12 of the edges of the fixed terminals FT21 and FT22, the contact area of the fixed terminals FT21 and FT22 with respect to the movable terminal MT can be easily adjusted.

[Third Embodiment]
Next, a MEMS switch 10-3 to which the present invention is applied will be described with reference to FIG. In this description, for convenience of explanation, the front, back, top, bottom, left, and right in FIG. 9A are referred to as top, bottom, front, back, left, and right, respectively, and those in FIG. The direction corresponding to is also referred to similarly.

The difference between the MEMS switch 10-3 and the MEMS switch 10-1 described in the first embodiment is that, as shown in FIG.
Two protrusions FT31a having a substantially semicircular shape when viewed from above are integrally formed at the tip of the first fixed terminal FT31, and the shape when viewed from above is substantially semicircular at the tip of the second fixed terminal FT31. The point is that the individual protrusions 32a are integrally formed so as to be symmetrical with the protrusion FT31a. In short, the same number of convex portions FT31a and 32a are integrally formed at the tips of both fixed terminals FT31 and FT32.

  In this case, the line contact between the movable terminal MT and the fixed terminals FT31 and FT32 is, as shown in FIG. 9B, a predetermined contact area corresponding to the shape (arc) of the edge of each convex portion FT31a and FT32a. It is performed without variation with CR31 and CR32.

  According to the MEMS switch 10-3, in addition to the effects (1) and (2) described in the [first embodiment], the following effect (4) can be obtained.

  (4) By changing the size and number of the convex portions FT31a and FT32a, the contact area of the fixed terminals FT31 and FT32 with respect to the movable terminal MT can be easily adjusted. This effect can be similarly obtained even when one convex portion FT31a and FT32a are integrally formed at the tips of both fixed terminals FT31 and FT32, or when three or more convex portions FT31a and FT32a are integrally formed. Even when the top-view shape of each of the convex portions FT31a and FT32a is a U-shape or a rectangle, the same can be obtained.

[Fourth Embodiment]
Next, a MEMS switch 10-4 to which the present invention is applied will be described with reference to FIG. In this description, for convenience of explanation, the front, back, top, bottom, left, and right of FIG. 10A are respectively referred to as top, bottom, front, back, left, and right, and those of FIG. The direction corresponding to is also referred to similarly.

The difference between the MEMS switch 10-4 and the MEMS switch 10-1 described in the first embodiment is that, as shown in FIG.
Two protrusions FT41a having a substantially semicircular shape when viewed from the top are integrally formed at the tip of the first fixed terminal FT41, and the shape when viewed from the top is approximately semicircular at the tip of the second fixed terminal FT41. The point is that the convex portions 42a are integrally formed. In short, a different number of convex portions FT41a and 42a are integrally formed at the tips of both fixed terminals FT41 and FT42.

  In this case, as shown in FIG. 10B, the line contact between the movable terminal MT and the fixed terminals FT41 and FT42 is a predetermined contact area corresponding to the shape (arc) of the edge of each convex portion FT41a and FT42a. It is performed without variation with CR41 and CR42.

  According to the MEMS switch 10-4, in addition to the effects (1) and (2) described in the first embodiment, the following effects (5) and (6) can be obtained.

  (5) The contact area of the fixed terminals FT41 and FT42 with respect to the movable terminal MT can be easily adjusted by changing the size and number of the convex portions FT41a and FT42a. This effect is similarly obtained even when three or more convex portions FT41a are integrally formed at the tip of the first fixed terminal FT41 and two or more convex portions FT42a are integrally formed at the tip of the second fixed terminal FT42. The same can be obtained even when the top-view shape of each of the convex portions FT41a and FT42a is a U-shape or a rectangle.

  (6) If each convex part FT41a and FT42a are arrange | positioned so that the other convex part FT42a may face between one two convex part FT41a as shown to FIG. 10 (A), both fixed terminal FT41 and FT42. Therefore, it is possible to reduce the signal transmission distance between the fixed terminals FT41 and FT42, thereby contributing to the reduction of transmission loss.

[Fifth Embodiment]
Next, a MEMS switch 10-5 to which the present invention is applied will be described with reference to FIG. In this description, for convenience of description, the front, back, top, bottom, left, and right of FIG. 11 are referred to as top, bottom, front, back, left, and right, respectively.

This MEMS switch 10-5 is different from the MEMS switch 10-1 described in the first embodiment as shown in FIG.
-Longitudinal dimensions of the base layer 11 'and the insulating layer 12'-Two through holes 11a 'and 12a' forming a rectangle in the base layer 11 'and the insulating layer 12' are formed in parallel to form the base layer The movable lever ML composed of a part 11b ′ of the eleventh part and a part 12b ′ of the insulating layer 12 has a longer front / rear dimension. The movable lever ML ′ has two main parts MLa, one movable part MLb, and two parts. Point constructed with hinge part MLc (point changed from cantilever structure to double-sided structure)
The point that the first electrode layer 13, the piezoelectric layer 14 and the second electrode layer constituting the drive actuator are formed on the upper surface of each main body MLa. Corresponding to the drive actuator provided on the upper surface of the front main body MLa. The power source input terminal 16 and the ground terminal 17 are added.

  In the MEMS switch 10-5, when both the signal lines SL11 and SL12 are brought into conduction, two power input terminals 16 and two ground terminals 17 are connected to a variable DC power supply (not shown), and the variable DC power supply is connected to the MEMS switch 10-5. A drive voltage having the same value is applied to the two power input terminals 16. By applying this drive voltage, the piezoelectric layer 14 of the two drive actuators contracts due to the piezoelectric effect, and the contraction causes the two main body portions MLa of the movable lever ML ′ to warp and move along with the deformation. The movable terminal MT on the part MLc is displaced upward, and due to the displacement, the upper surface of the movable terminal MT comes into contact so as to slightly push up the edges of the fixed terminals FT11 and FT12. Line contact is made under a predetermined contact pressure with the edges of the terminals FT11 and FT12 (see FIGS. 5A and 5B).

  On the other hand, when the signal lines SL11 and SL12 in the conductive state are brought into the non-conductive state, the application of the drive voltage to the two power input terminals 16 may be canceled. By releasing the application of the drive voltage, the operation of the two drive actuators is stopped, the movable lever ML ′ is restored, the movable terminal MT is returned to the initial position, and the upper surface of the movable terminal MT and the ends of the fixed terminals FT11 and FT12 are restored. The line contact with the edge is released (see FIG. 4A).

  According to the MEMS switch 10-5, the effects (1) and (2) described in the first embodiment can be obtained, although the configuration of the movable lever ML 'and the like is different. In addition, the features described in [Second Embodiment], [Third Embodiment], and [Fourth Embodiment] can be appropriately adopted for the MEMS switch 10-5. The effect (3) described in the embodiment, the effect (4) described in the third embodiment, and the effects (5) and (6) described in the fourth embodiment can be appropriately obtained.

  10-1, 10-2, 10-3, 10-4, 10-5 ... MEMS switch, SL11, SL21, SL31, SL41 ... first signal line, FT11, FT11 ', FT21, FT31, FT41 ... first fixed Terminal, FT31a, FT41a ... convex portion, SL12, SL22, SL32, SL42 ... second signal line, FT12, FT12 ', FT22, FT32, FT42 ... second fixed terminal, FT32a, FT42a ... convex portion, CR11, CR12, CR21 , CR22, CR31, CR32, CR41, CR42 ... contact area, ML, ML '... movable lever, MT ... movable terminal.

Claims (7)

The first fixed terminal including the end portion of the first signal line, the second fixed terminal including the end portion of the second signal line, the conductive layer provided on the movable lever, and including the first fixed terminal and the second fixed terminal. A movable terminal facing the fixed terminal at an interval, and bringing the first signal line and the second signal line into a conductive state by bringing the movable terminal into contact with the first fixed terminal and the second fixed terminal; A MEMS switch that uncouples the first signal line and the second signal line by unwinding,
Each of the first fixed terminal and the second fixed terminal has a cross-sectional shape in which each edge is closest to the movable terminal, and a portion excluding the edge is further away from the movable terminal than in the conductive state. The movable terminal makes line contact with the edges of the first fixed terminal and the second fixed terminal. The MEMS switch according to claim 1, wherein
The first fixed terminal and the second fixed terminal have a cross-sectional shape inclined toward the movable terminal. The MEMS switch according to claim 1, wherein
The first fixed terminal and the second fixed terminal have a cross-sectional shape curved toward the movable terminal. The MEMS switch according to any one of claims 1 to 3,
The widths of the edges of the first fixed terminal and the second fixed terminal are smaller than the widths of the first signal line and the second signal line. The MEMS switch according to any one of claims 1 to 3,
One or more convex portions are integrally formed at the tips of the first fixed terminal and the second fixed terminal, and the movable terminal is connected to the edges of the convex portions of the first fixed terminal and the second fixed terminal in the conductive state. Contact. The MEMS switch according to claim 5, wherein
The number of convex portions integrally formed at the tip of the first fixed terminal and the number of convex portions integrally formed at the tip of the second fixed terminal are the same. The MEMS switch according to claim 5, wherein
The number of convex portions integrally formed at the tip of the first fixed terminal is different from the number of convex portions integrally formed at the tip of the second fixed terminal.

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