WO2011145549A1 - Structure provided with wiring structure, and mems relay - Google Patents

Abstract

A ground conductor comprises: first ground wirings formed on one surface side of a base substrate, and at both sides in the width direction of a signal line; second ground wirings comprised of via-holes formed on the base substrate and electrically connected to each of the first ground wirings; a third ground wiring that electrically connects the second ground wirings with each other at the other surface side of the base substrate (1), and that is parallel to the signal line; a fourth ground wiring that is formed on a cover substrate, at a face opposing the base substrate; and fifth ground wirings that are formed on an intermediate substrate (2) at both sides of a cavity section, and that are comprised of penetrating slit wirings that electrically connect each of the first ground wirings and the fourth ground wiring.

Description

Structure having wiring structure and MEMS relay

The present invention relates to a structure having a wiring structure and a MEMS (micro-electromechanical mechanicals) relay.

Conventionally, a microrelay having a configuration shown in FIGS. 16 and 17 has been proposed as a MEMS relay for high-frequency signal transmission (see Patent Document 1). The microrelay includes a base substrate 1 ′, a movable portion forming substrate 2 ′ disposed on one surface side of the base substrate 1 ′, and a cover substrate 3 disposed on the base substrate 1 ′ side of the movable portion forming substrate 2 ′. 'And features.

Here, the base substrate 1 ′ is provided with a pair of signal lines 13 ′ and 13 ′ at both ends in the longitudinal direction on the one surface side. In addition, the movable part forming substrate 2 ′ includes a rectangular frame-shaped frame part 21 ′ fixed to the one surface side of the base substrate 1 ′, and four support spring parts 224 disposed inside the frame part 21 ′. And a movable portion 24 ′ that is swingably supported by the frame portion 21 ′. Further, the movable part forming substrate 2 ′ has contact holding pieces 226 ′ supported by the movable part 24 ′ via two contact pressure spring parts 225 ′, and the contact holding part 226 ′ has a pair of contact holding pieces 226 ′. Movable contacts (not shown) that are in contact with and away from the fixed contacts 14 ′ and 14 ′ at one end portions of the signal lines 13 ′ and 13 ′ are provided. Further, the peripheral portion of the cover substrate 3 ′ is fixed to the frame portion 21 ′. The base substrate 1 ′ and the cover substrate 3 ′ are formed using a glass substrate, and the movable part forming substrate 2 ′ is formed using a silicon substrate.

In the above-described micro relay, a storage portion 116 ′ for storing the electromagnet device 4 ′ is formed on the base substrate 1 ′. The electromagnet device 4 'generates a magnetic flux in accordance with the excitation current to the coils 42' and 42 'wound around the yoke 40'. On the other hand, an armature (not shown) that is driven to swing freely by the electromagnet device 4 ′ is laminated on the base substrate 1 ′ side of the movable portion 24 ′ in the movable portion forming substrate 2 ′.

By the way, in the above-described micro relay, a structure having a wiring structure including a signal line 13 ′ is shown in FIG. 18 for the purpose of reducing transmission loss of a high frequency signal as compared with a microstrip type line or a coplanar type line. In addition, it is conceivable to employ a wiring structure in which the ground conductor 5 ′ surrounding the signal line 13 ′ is formed across the base substrate 1 ′, the movable part forming substrate 2 ′, and the cover substrate 3 ′.

JP 2005-216541 A

By the way, in the structure having the wiring structure having the configuration shown in FIG. 18, the middle substrate (intermediate substrate) among the three substrates (base substrate 1 ′, movable portion forming substrate 2 ′, and cover substrate 3 ′). A cavity 27 ′ that exposes the signal line 13 ′ on the one surface of the base substrate 1 ′ is formed on a certain movable portion forming substrate 2 ′ by anisotropic etching that enables vertical deep drilling. In addition, the ground conductor 5 ′ is provided on the base substrate 1 ′ and the first ground wirings 51 ′ and 51 ′ disposed on both sides in the width direction of the signal line 13 ′ on the one surface of the base substrate 1 ′. Second ground wirings 52 ′, 52 ′ made of vias electrically connected to the first ground wirings 51 ′, 51 ′, and second ground wirings disposed on the other surface of the base substrate 1 ′. The signal line 13 ′ and the signal line 13 ′ in plan view on the side facing the base substrate 1 ′ in the cover substrate 3 ′ and the third ground wiring 53 ′ that electrically connects 52 ′ and 52 ′. A fourth ground wiring 54 ′ having a width straddling the first ground wirings 51 ′, 51 ′ on both sides, and the wall portions 28 ′, 28 ′ of the cavity 27 ′ on the movable part forming substrate 2 ′ are arranged. First ground wiring 51 ′, 1 'and the fourth ground wiring 54' fifth ground wire 55 for electrically connecting the '55' are constructed out with.

However, in the configuration shown in FIG. 18, in the movable part forming substrate 2 ′, the angle formed between the wall surfaces 28 ′, 28 ′ of the cavity 27 ′ and the one surface of the base substrate 1 ′ is approximately 90 degrees. It was difficult to form the fifth ground wirings 55 ′ and 55 ′. Thus, although it is conceivable that the wall surfaces 28 ′ and 28 ′ are inclined surfaces, there is a problem that the planar size of the structure is increased and the planar size of the MEMS relay is increased.

The present invention has been made in view of the above reasons, and its purpose is to form a grounding conductor that can reduce transmission loss while suppressing an increase in the planar size of the structure and surrounds a signal line. It is an object of the present invention to provide a structure and a MEMS relay having an easy wiring structure.

A structure including a wiring structure according to the present invention includes a base substrate having a signal line formed on one surface side, a cover substrate disposed opposite to the one surface side of the base substrate, and the base substrate and the cover substrate. An intermediate substrate having a hollow portion that is interposed and exposed in the thickness direction, and a ground conductor that is formed across the base substrate, the intermediate substrate, and the cover substrate and surrounds the signal line; A first ground line parallel to the signal line on both sides in the width direction of the signal line on the one surface side of the base substrate, and formed in the base substrate and electrically connected to each first ground line and parallel to the signal line A second ground wiring comprising vias, a third ground wiring electrically connecting the second ground wirings on the other surface side of the base substrate and parallel to the signal lines, and a base substrate in the cover substrate A fourth ground wiring having a width across the signal line and the first ground wiring on both sides of the signal line in plan view on the opposite side, and the first ground formed on both sides of the cavity in the intermediate substrate It is characterized by comprising a fifth ground wiring composed of a through slit wiring that electrically connects the wiring and the fourth ground wiring.

In the structure provided with this wiring structure, it is preferable that the intermediate substrate, the base substrate, and the cover substrate are bonded to each other through metal layers formed on opposing surfaces.

In the structure including this wiring structure, the intermediate substrate, the base substrate, and the cover substrate are preferably formed by surface activation bonding of the metal layers.

It is preferable that an insulating film is provided between the intermediate substrate 2 and the fifth ground wiring.

The MEMS relay of the present invention is a MEMS relay having a structure having the wiring structure, wherein the base substrate has a pair of the signal lines on the one surface side, and the intermediate substrate has an opening portion. In addition, the cavity portion that is provided in parallel with the opening portion and that corresponds to each of the signal lines, and a communication portion that connects the opening portion and the cavity portion are formed, and are interposed between the base substrate and the cover substrate. A frame portion, a movable portion disposed inside the frame portion and supported to be swingable by the frame portion, and a pair of the signal lines extending from the movable portion main body disposed in the opening portion of the movable portions. And a contact holding piece having a movable contact that contacts and separates from the fixed contact, and the structure is provided with drive means for driving the movable portion to be swingable.

In this MEMS relay, the driving means includes an armature made of a magnetic material laminated on the cover substrate side in the movable portion main body, and an electromagnet device that is provided on the cover substrate and drives the armature to be swingable. It is preferable to be made.

In the structure having the wiring structure of the present invention, it is possible to reduce transmission loss while suppressing an increase in the planar size of the structure, and it is easy to form a ground conductor.

In the MEMS relay of the present invention, it is possible to provide a MEMS relay that can reduce transmission loss while suppressing an increase in planar size and that can easily form a ground conductor surrounding a signal line.

1 shows a structure including a wiring structure according to an embodiment, where (a) is a schematic plan view of a main part, (b) is a schematic cross-sectional view along AA ′ in (a), and (c) is a cross-sectional view along BB in (a). 'It is a schematic sectional view. It is principal process sectional drawing for demonstrating the manufacturing method of the structure provided with the wiring structure same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of the structure provided with the wiring structure same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of the structure provided with the wiring structure same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of the structure provided with the wiring structure same as the above. It is a general | schematic disassembled perspective view of the MEMS relay same as the above. The MEMS relay in the same as above is shown, (a), (b) is a schematic perspective view partly broken. It is a schematic perspective view of the MEMS relay same as the above. The intermediate board of the MEMS relay same as the above is shown, (a) is a schematic plan view, (b) is a schematic bottom view. The other example of a structure of the principal part of a MEMS relay same as the above is shown, (a)-(d) is a schematic sectional drawing of a structure example mutually different. It is principal process sectional drawing for demonstrating the formation method of the other structural example of the principal part of the MEMS relay same as the above. It is principal process sectional drawing for demonstrating the formation method of the other structural example of the principal part of the MEMS relay same as the above. It is principal process sectional drawing for demonstrating the formation method of the other structural example of the principal part of the MEMS relay same as the above. It is principal process sectional drawing for demonstrating the formation method of the other structural example of the principal part of the MEMS relay same as the above. It is principal process sectional drawing for demonstrating the formation method of the other structural example of the principal part of the MEMS relay same as the above. It is a general | schematic disassembled perspective view which shows the MEMS relay in a prior art example. It is a schematic perspective view of the MEMS relay same as the above. It is a schematic sectional drawing of the structural example of the structure provided with the wiring structure.

In the present embodiment, a structure having a wiring structure and a method for forming the structure will be described with reference to FIGS. 1 to 5, and a MEMS relay as an example of a MEMS device having the structure will be described with reference to FIGS. The description will be given with reference.

As shown in FIG. 1, the structure including the wiring structure of the present embodiment is arranged so that a base substrate 1 having a signal line (transmission line) 13 formed on one surface side is opposed to one surface side of the base substrate 1. The cover substrate 3, the intermediate substrate 2 between the base substrate 1 and the cover substrate 3, and the cavity 27 that exposes the signal line 13 is provided in the thickness direction; the base substrate 1 and the intermediate substrate 2; And a grounding conductor 5 formed over the cover substrate 3 and surrounding the signal line 13. In the present embodiment, the outer sizes of the base substrate 1 and the cover substrate 3 are set to the same outer size as that of the intermediate substrate 2.

Further, the base substrate 1, the intermediate substrate 2, and the cover substrate 3 each have a thickness. The thicknesses of the base substrate 1, the intermediate substrate 2, and the cover substrate 3 are the same as the direction in which the base substrate 1, the intermediate substrate 2, and the cover substrate 3 are arranged. Accordingly, the thickness direction of the base substrate 1, the intermediate substrate 2, and the cover substrate 3 is defined as a direction along the thickness of the base substrate 1, intermediate substrate 2, and cover substrate 3.

The base substrate 1, the intermediate substrate 2, and the cover substrate 3 have a length and a width, respectively. The lengths of the base substrate 1, the intermediate substrate 2, and the cover substrate 3 are orthogonal to the thickness direction of the base substrate 1. Therefore, the length direction of the base substrate 1, the intermediate substrate 2, and the cover substrate 3 is defined as a direction along the length of the base substrate 1, intermediate substrate 2, and cover substrate 3. The widths of the base substrate 1, the intermediate substrate 2, and the cover substrate 3 are orthogonal to the thickness direction of the base substrate 1. The widths of the base substrate 1, the intermediate substrate 2, and the cover substrate 3 are orthogonal to the length direction of the base substrate 1. Therefore, the width direction of the base substrate 1, the intermediate substrate 2, and the cover substrate 3 is defined as a direction along the width of the base substrate 1, intermediate substrate 2, and cover substrate 3.

Here, the base substrate 1 is formed using a first substrate 10 made of a glass substrate which is a kind of insulating substrate. The first substrate 10 is not limited to a glass substrate. For example, a silicon substrate having a high resistivity (for example, a resistivity of 100 Ωcm or more) or a low-temperature co-fired ceramic substrate (Low Temperature Co-fired Ceramic Substrate: LTCC substrate) is used. It may be used. The glass material of the glass substrate used as the first substrate 10 may be soda glass, alkali-free glass, quartz glass, or borosilicate glass such as Pyrex (registered trademark) or Tempax (registered trademark). A glass material having a low dielectric constant is preferred.

Further, the signal line 13 is composed of a metal layer (for example, an Au layer) patterned in a straight line. The signal line 13 is made of Au, but is not limited to Au. For example, one type selected from the group of Au, Ni, Cu, Pd, Rh, Pt, Ir, and Os, or an alloy thereof. May be adopted.

The intermediate substrate 2 is formed using the semiconductor substrate 20. Here, the intermediate substrate 2 constitutes a movable part forming substrate of the MEMS relay as will be described later. As the semiconductor substrate 20 according to a desired three-dimensional structure of the movable part forming substrate, for example, silicon substrate and a silicon layer / insulating layer (SiO ₂ layer) / SOI having a three-layer structure of the silicon layer and (silicon On insulator) substrate, a silicon layer / insulating layer (SiO ₂ layer) / silicon layer / insulating layer (SiO ₂ A double SOI substrate having a five-layer structure (double SOI structure) / layer of silicon) may be used.

Further, the cover substrate 3 is formed by using the second substrate 30 made of the second glass substrate, but the second substrate 30 is not limited to the glass substrate, like the first substrate 10, A high resistivity silicon substrate or LTCC substrate may be used.

The ground conductor 5 described above includes first ground wirings 51 and 51 parallel to the signal line 13 on both sides in the width direction of the signal line 13 (left and right direction in FIG. 1A) on the one surface side of the base substrate 1. The second ground wirings 52 and 52 formed in the base substrate 1 and electrically connected to the first ground wirings 51 and 51 and including the vias parallel to the signal line 13, and on the other surface side of the base substrate 1 The second ground wirings 52, 52 are electrically connected to each other, the third ground wiring 53 parallel to the signal line 13, and the signal line 13 and the signal line 13 in plan view on the side of the cover substrate 3 facing the base substrate 1. A fourth ground wiring 54 having a width across the first ground wirings 51, 51 on both sides of the signal line 13, and each first ground wiring formed on both sides of the cavity 27 in the intermediate substrate 2. 51 and and a fifth ground wire 55, 55 of electrically connected to the through slit lines and the fourth ground wiring 54. Thus, the ground conductor 5 surrounds the signal line 13 in a cross section orthogonal to the length direction of the signal line 13.

Here, the first ground lines 51 and 51 are formed on one surface of the first substrate 10, similarly to the signal line 13. Each of the first ground lines 51 and 51 is configured by a metal layer (for example, an Au layer) patterned so as to be parallel to the signal line 13. As the material of the first ground wirings 51, 51, Au is adopted, but not limited to Au, for example, Al, Cu, etc. may be adopted.

Further, the second ground wirings 5, 52 are formed inside via holes 11, 11 penetrating in the thickness direction of the first substrate 10. The material of the second ground wirings 52 and 52 and the third ground wiring 53 is Cu, but is not limited to Cu. For example, Ni, Au, or the like may be employed.

Further, the fourth ground wiring 54 is constituted by a metal layer (for example, Au layer) patterned so as to be parallel to the signal line 13. As the material of the fourth ground wiring 54, Au is adopted. However, the material is not limited to Au, and for example, Al, Cu or the like may be adopted.

Further, although Cu is adopted as the material of the fifth ground wirings 55, 55, not limited to Cu, for example, Ni, Au, or the like may be adopted. Here, the fifth ground wirings 55 and 55 are formed inside the through slit 20a penetrating in the thickness direction of the semiconductor substrate 20, and the fifth ground wirings 55 and 55 and the through slits 20a and 20a are formed. A part of an insulating film 20b made of a silicon oxide film (thermal oxide film) formed across both surfaces in the thickness direction of the semiconductor substrate 20 and the inner surface of the through slit 20a is interposed therebetween. In short, the fifth ground wirings 55 and 55 are electrically insulated from the semiconductor substrate 20. In addition, the through slits 20 a and 20 a have a uniform opening width in a cross section perpendicular to the direction in which the signal line 13 runs (longitudinal direction of the signal line 13) regardless of the position in the thickness direction of the semiconductor substrate 20. Is formed. In addition, with respect to the cavity 27 of the semiconductor substrate 20, the opening width in a cross section orthogonal to the direction in which the signal line 13 runs (longitudinal direction of the signal line 13) is uniform regardless of the position in the thickness direction of the semiconductor substrate 20. It is formed as follows. In short, the cavity 27 has a rectangular cross section perpendicular to the direction in which the signal line 13 runs.

Further, the fifth ground wirings 55, 55 are formed on the base substrate 1 side of the semiconductor substrate 20 and are connected to the first ground wirings 51, 51 via the connection metal layer 25. 51 is electrically connected. Here, on the base substrate 1 side of the semiconductor substrate 20, bonding metal layers 26 and 26 are formed on the sides of the connecting metal layers 25 and 25, and the bonding metal layers 26 and 26 are formed on the base substrate 1. Are joined to the joining metal layers 16 and 16 formed on the sides of the first ground wirings 51 and 51. The joining metal layers 16 and 16 of the base substrate 1 are formed of the same material as the first ground wirings 51 and 51 and have the same film thickness as the first ground wirings 51 and 51.

The fifth ground wirings 55 and 55 are electrically connected to the fourth ground wiring 54 via a connection metal layer 29 formed on the cover substrate 3 side of the semiconductor substrate 20 and joined to the fourth ground wiring 54. It is connected to the. Here, each of the connecting metal layers 25 and 29 and the bonding metal layer 26 is electrically insulated from the semiconductor substrate 20 by the above-described insulating film 20b. Each of the connecting metal layers 25 and 29 and the bonding metal layer 26 is composed of a laminated film of a Ti film formed on the insulating film 20b and an Au film formed on the Ti film. A connecting metal layer 25 and a bonding metal layer 26 on the base substrate 1 side of the substrate 20 are formed simultaneously. In this embodiment, the thickness of the Ti film on the insulating film 20b is set to 15 to 50 nm, and the thickness of the Au film on the Ti film is set to 500 nm. However, these numerical values are only examples and are particularly limited. Not what you want. Further, although a Ti film is interposed as an adhesion layer for improving adhesion between each Au film and the insulating film 20b, the material of the adhesion layer is not limited to Ti, for example, Cr, Nb, Zr, TiN, TaN or the like may be used. The connecting metal layer 25 and the bonding metal layer 26 may employ an Al film or a Cu film instead of the Au film.

By the way, in the present embodiment, the signal line 13 described above is electrically connected to the via 15 penetrating in the thickness direction of the first substrate 10. Here, the via 15 to which the signal line 13 is bonded is formed inside a via hole 12 having a circular shape in plan view and penetrating in the thickness direction of the first substrate 10, and the other surface of the first substrate 10. On the side, it is electrically connected to the external connection electrode 17 formed on the periphery of the via hole 12. In the present embodiment, the signal line 13 is connected to the via 15 at one end in the longitudinal direction of the signal line 13, but a via connected to the other end may be formed.

Hereinafter, a method for forming a structure having the above-described wiring structure will be described with reference to FIGS. 2 to 5. FIGS. (A) to (d) are cross-sectional views taken along the line BB ′ of FIG. The schematic cross section of the part corresponding to is shown.

First, a first substrate 10 made of a glass substrate as shown in FIG. 2 (a) is prepared, and then via holes 11, 11, 12 penetrating in the thickness direction of the first substrate 10 are formed on the first substrate 10. A structure shown in FIG. 2B is obtained by performing a via hole forming process formed by sandblasting or the like from the other surface side. Here, the formation method of the via holes 11, 11, and 12 is not limited to the sandblast method, and may be laser processing, machining, or etching, for example. In the case where a silicon substrate is used as the first substrate 10, the via holes 11, 11, and 12 may be formed using a photolithography technique and an etching technique.

After the above-described via hole forming step, the second ground wirings 52 and 52, the third ground wiring 53, the via 15 and the metal material (for example, Cu, which closes the via holes 11, 11 and 12 serving as the basis of the external connection electrode 17). By performing a plating step of forming a metal part 170 made of Ni, Au, etc. on the inner surfaces of the via holes 11, 11, 12 of the first substrate 10 and the other surface of the first substrate 10 by a plating method, The structure shown in FIG.

Thereafter, unnecessary portions on the other surface side (back surface side) of the first substrate 10 in the metal portion 170 are removed by etching, whereby second ground wirings 52 and 52 each including a part of the metal portion 170, The structure shown in FIG. 2D is obtained by performing the back surface side patterning process for forming the third ground wiring 53 and the via 15. The via 15 formed by this back surface side patterning process is separated from the second ground wirings 52 and 52 and the third ground wiring 53. The via 15 is formed continuously and integrally with the external connection electrode 17 on the periphery of the via hole 12 on the other surface of the first substrate 10.

After the back side patterning step described above, a metal layer (hereinafter referred to as an Au layer or the like serving as a basis for the first ground wirings 51 and 51 and the bonding metal layers 16 and 16 is formed on the one surface side of the first substrate 10. 3 (a) is performed by performing a metal layer forming step (hereinafter referred to as a first metal layer forming step) for forming 18 by a sputtering method or a vapor deposition method, for example. Get the structure.

Thereafter, unnecessary portions on the one surface side (surface side) of the first substrate 10 in the first metal layer 18 are removed by etching, whereby first grounds each consisting of a part of the first metal layer 18 are obtained. The structure shown in FIG. 3B is obtained by performing a back surface side patterning process for forming the wirings 51 and 51 and the bonding metal layers 16 and 16.

Next, a resist layer 119 having an opening corresponding to a region where the signal line 13 is to be formed is formed on the one surface side of the first substrate 10, and the signal line 13 made of a metal material (for example, Au) is formed. 3 is obtained by plating, and after obtaining the structure shown in FIG. 3C, the resist layer 119 is removed to obtain the base substrate 1 having the structure shown in FIG. The method for forming the signal line 13 is not limited to the plating method, and for example, the signal line 13 may be formed using a lift-off method.

On the other hand, in forming the intermediate substrate 2, first, a semiconductor substrate 20 as shown in FIG. 4A is prepared, and then the semiconductor substrate 20 is penetrated in the thickness direction by using a photolithography technique and an etching technique. By performing the through slit forming step of forming the through slits 20a, 20a, the structure shown in FIG. 4B is obtained. Here, the etching of the semiconductor substrate 20 in the through slit forming step is performed by a dry etching apparatus capable of highly anisotropic etching (perpendicular deep drilling) such as an inductively coupled plasma (ICP) type etching apparatus. Just do it.

After the above-described through slit forming step, an insulating film 20b made of a silicon oxide film (thermal oxide film) straddling one surface and the other surface of the semiconductor substrate 20 and the inner surfaces of the through slits 20a and 20a is formed by a thermal oxidation method. After performing the insulating film forming process, the structure shown in FIG. 4C is obtained by performing the through slit wiring forming process of forming the fifth ground wiring 55, 55 made of the through slit wiring by a plating method. In this through slit wiring forming step, the inside of each through slit 20a, 20a is enriched by a part of the insulating film 20b and the fifth ground wiring 55, 55 made of a metal material (for example, Cu, Ni, Au, etc.). The fifth ground wirings 55 and 55 are formed so as to be blocked.

Thereafter, a metal layer (hereinafter, referred to as a second metal layer) 290 formed of a laminated film of a Ti film and an Au film serving as a base of the connection metal layer 29 is applied to the entire surface of the semiconductor substrate 20 on the one surface side by a sputtering method. And a lamination of a Ti film and an Au film serving as a basis for the connection metal layers 25 and 25 and the bonding metal layers 26 and 26 over the entire surface of the semiconductor substrate 20 on the other surface side. A structure shown in FIG. 4D is obtained by performing a second metal layer forming step of forming a metal layer (hereinafter referred to as a third metal layer) 250 made of a film by sputtering, vapor deposition, CVD, or the like. Get.

Thereafter, the second metal layer using the photolithography technique and the etching technique is left so that portions corresponding to the connection metal layers 29 and 29 of the second metal layer 290 on the one surface side of the semiconductor substrate 20 remain. 290 is patterned, and the photolithography technique is performed so that portions corresponding to the connection metal layers 25 and 25 and the bonding metal layers 26 and 26 remain in the third metal layer 250 on the other surface side of the semiconductor substrate 20. And the structure shown in FIG. 5A is obtained by performing a second metal layer patterning step of patterning the third metal layer 250 using an etching technique.

Thereafter, the cavity 27 is formed by etching the semiconductor substrate 20 from the one surface side using the mask layer 270 formed for forming the cavity using the photolithography technique on the one surface side of the semiconductor substrate 20 as a mask. The cavity portion forming step is performed, and the mask layer 270 is removed to obtain the structure shown in FIG. Here, the etching of the semiconductor substrate 20 in the cavity forming step is performed by a dry etching apparatus capable of highly anisotropic etching (perpendicular deep drilling) such as an inductively coupled plasma (ICP) type etching apparatus. Just do it.

After the cavity forming step described above, the first intermediate substrate 2 is bonded to the cover substrate 3 on which the fourth ground wiring 54 is formed on one surface side (the intermediate substrate 2 side) of the second substrate 30. By performing the bonding step, the structure shown in FIG. 5C is obtained. Here, in the first bonding step, the connection metal layer 29 of the intermediate substrate 2 and the fourth ground wiring 54 of the cover substrate 3 are bonded and electrically connected.

After the first bonding step described above, a second bonding step for bonding the intermediate substrate 2 and the base substrate 1 is performed to obtain a structure having the wiring structure shown in FIG. Here, in the second bonding step, the bonding metal layer 26 of the intermediate substrate 2 and the bonding metal layer 16 of the base substrate 1 are bonded, and the connection metal layer 25 of the intermediate substrate 2 and the base substrate 1 are bonded. The first ground wiring 51 is joined and electrically connected.

In the first bonding step and the second bonding step described above, each bonding surface is cleaned and activated by irradiating the bonding surfaces with argon plasma, ion beam or atomic beam in vacuum before bonding. Then, the bonding surfaces are brought into contact with each other, and a room temperature bonding method in which the bonding surfaces are directly bonded at a normal temperature (for example, 25 ° C.) is employed. Stress and the like can be greatly reduced. Note that the first bonding step and the second bonding step are not limited to the normal temperature bonding method, and after normalizing and activating each of the bonding surfaces described above, the bonding surfaces are brought into contact with each other and a specified temperature (normal temperature higher than normal temperature) ( For example, you may make it join directly at 80 degreeC.

By the way, in the manufacturing method of the MEMS relay having the structure provided with the wiring structure in the present embodiment, all the processes until the second bonding process is completed are performed for each of the intermediate substrate 2, the base substrate 1 and the cover substrate 3 at the wafer level. In this way, a wafer level package structure including a plurality of MEMS relays is formed, and a dividing step of dividing the wafer level package structure into individual MEMS relays is performed. Thus, the outer sizes of the base substrate 1 and the cover substrate 3 can be easily adjusted to the outer size of the intermediate substrate 2, and mass productivity can be improved.

In the structure including the wiring structure of the present embodiment described above, the ground conductor 5 surrounding the signal line 13 is parallel to the signal line 13 on both sides in the width direction of the signal line 13 on the one surface side of the base substrate 1. First ground wirings 51, 51, and second ground wirings 52, 52 formed on the base substrate 1 and electrically connected to the first ground wirings 51, 51 and made of vias parallel to the signal lines 13, The second ground wirings 52, 52 are electrically connected to each other on the other surface side of the base substrate 1, and the third ground wiring 53 parallel to the signal line 13 is opposed to the base substrate 1 in the cover substrate 3. And a fourth ground wiring 54 having a width across the signal line 13 and the first ground wirings 51, 51 on both sides of the signal line 13 in plan view, and a cavity in the intermediate substrate 2. 27, and is formed of fifth ground wirings 55 and 55 formed of through slit wirings that are formed on both sides of the first wiring 27 and electrically connect the first ground wirings 51 and 51 to the fourth ground wiring 54, Since the fifth ground wirings 55 and 55 can be easily formed as compared to the case where the fifth ground wirings 55 and 55 are formed on the wall surfaces 28 and 28 of the cavity portion 27 having an angle of about 90 degrees with the one surface. Transmission loss can be reduced while suppressing an increase in the planar size of the structure, and formation of the ground conductor 5 surrounding the signal line 13 is facilitated.

That is, the structure includes a base substrate 1, a cover substrate 3, an intermediate substrate 2, and a ground conductor. The base substrate 1 is provided with a signal line 13 on one surface side thereof. The cover substrate 3 is disposed at a position facing the one surface side of the base substrate 1. The intermediate substrate 2 is disposed so as to be interposed between the base substrate 1 and the cover substrate 3. The intermediate substrate 2 has a thickness. The intermediate substrate 2 is provided with a cavity 27 formed so as to penetrate in the thickness direction.

The hollow portion 27 is provided to expose the signal line 13. In other words, the intermediate substrate 2 is disposed between the base substrate 1 and the cover substrate 3 so that the signal line 13 is located in the cavity 27.

The ground conductor is formed over the base substrate 1, the intermediate substrate 2, and the cover substrate 3 so as to surround the signal line 13. The ground conductor has a first ground wiring 51, a second ground wiring 52, a third ground wiring 53, a fourth ground wiring 54, and a fifth ground wiring 55.

The first ground wiring 51 is parallel to the signal line 13 on both sides in the width direction of the signal line 13 on the one surface side of the base substrate 1.

The second ground wiring 52 is formed on the base substrate 1 and is electrically connected to each first ground wiring 51 and includes a via parallel to the signal line 13. In other words, the second ground wiring 52 is formed on the base substrate 1 so as to be located in the via hole parallel to the signal line 13 and is electrically connected to each first ground wiring 51.

The third ground wiring 53 is electrically connected to the second ground wirings 52 on the other surface side of the base substrate 1 and is parallel to the signal line 13.

The fourth ground wiring 54 has a width dimension straddling the signal line 13 and the first ground wiring 51 on both sides of the signal line 13 in a plan view on the side of the cover substrate 3 facing the base substrate 1.

The fifth ground wiring 55 is formed of a through-slit wiring that is formed on both sides of the cavity 27 in the intermediate substrate 2 and electrically connects the first ground wiring 51 and the fourth ground wiring 54. In other words, the fifth ground wiring 55 is configured by a through slit wiring arranged in the through slit 20 a provided so as to be located on both sides of the cavity portion 27 in the intermediate substrate 2. The through slit wiring electrically connects the first ground wiring 51 and the fourth ground wiring 54.

Thereby, it is possible to obtain a structure having a wiring structure that can reduce transmission loss while suppressing an increase in the planar size of the structure and can easily form a ground conductor surrounding the signal line 13.

In the present embodiment, the intermediate substrate 2, the base substrate 1, and the cover substrate 3 are formed on the metal layers formed on the opposing surfaces (in the intermediate substrate 2, the connection metal layers 25 and 29, the bonding metal layer 26. Each of them constitutes a metal layer. In the base substrate 1, the first ground wiring 51 and the bonding metal layer 16 each constitute a metal layer, and in the cover substrate 3, the fourth ground wiring 54 constitutes a metal layer. The fifth ground wirings 55 and 55 of the intermediate substrate 2, the first ground wirings 51 and 51 of the base substrate 1, and the fourth ground wiring 54 of the cover substrate 3. Can be easily electrically connected.

In the present embodiment, the intermediate substrate 2, the base substrate 1, and the cover substrate 3 are directly bonded after the metal layers activate each other's bonding surfaces (that is, surface activated bonding). Therefore, it is possible to bond the intermediate substrate 2 to the base substrate 1 and the cover substrate 3 at room temperature, and the stress caused by thermal expansion at the time of bonding is a line between the intermediate substrate 2, the base substrate 1 and the cover substrate 3. Stress generated at the time of joining due to the difference in expansion coefficient can be reduced.

In addition, an electrical insulating film having electrical insulation is provided between the intermediate substrate 2 and the fifth ground wiring 55.

Hereinafter, the specific structure of the MEMS relay will be described with reference to FIGS. 6 to 9, but the above-described ground conductor 5 and the like are not illustrated, and only the basic structure of the MEMS relay is illustrated.

The base substrate 1 is formed in a rectangular plate shape, and a pair of signal lines 13 and 13 are formed at both ends in the longitudinal direction on the one surface side. Here, the pair of signal lines 13 and 13 have the length direction aligned with the short direction of the base substrate 1 and are aligned on a straight line. The base substrate 1 has a pair of signal lines 13 and 13 at one end and is electrically connected to vias 15 and 15 that overlap in the thickness direction, and fixed contacts 14 and 14 are provided at the other end. Yes. In addition, the base substrate 1 is electrically connected to a pair of signal lines 13 and 13 via external vias 15 and 15 and external connection electrodes 17 and 17 formed on the other surface side of the base substrate 1. .

Each fixed contact 14 is a metal film made of a metal material having good conductivity such as Cu or Au, and is formed using a sputtering method, an electroplating method, a vacuum deposition method, or the like. Each fixed contact 14 is not limited to a single layer structure, and may have a multilayer structure. Further, the material of the fixed contact 14 is not limited to Cu or Au, and for example, Cu, Au, Ag, Cr, Ti, Pt, Ru, Rh, Co, Ni, and alloys thereof may be employed.

In addition, the via hole 12 in which the above-described via 15 is provided inside the base substrate 1 is formed in a tapered shape in which the opening area gradually increases as it approaches the other surface from the one surface of the base substrate 1. Here, the via 15 is formed along the inner surface of the via hole 12 and closes the via hole 12 on the one surface side of the base substrate 1.

Further, the intermediate substrate 2 (hereinafter also referred to as the movable portion forming substrate 2) is provided with an opening 22 formed in the central portion of the semiconductor substrate 20 and a pair of signal lines 13 and 13 arranged in parallel to the opening 22 respectively. The corresponding cavity portions 27, 27 and the communication portions 23, 23 for communicating the openings 22 with the respective cavity portions 27, 27 are formed, and the frame portion 21 interposed between the base substrate 1 and the cover substrate 3, and the frame A movable portion 24 disposed inside the portion 21 and supported by the frame portion 21 in a swingable manner, and both ends in the longitudinal direction of a rectangular plate-shaped movable portion main body 24 a disposed in the opening 22 of the movable portion 24. A contact holding piece 24b having a movable contact 214 (see FIG. 9B) extending from the portion along the longitudinal direction and contacting and leaving the fixed contacts 14 and 14 provided on the pair of signal lines 13 and 13, respectively. And with That. Here, in the intermediate substrate 2, the frame portion 21 is fixed to the base substrate 1 and the cover substrate 3, and the movable contact 214 is opposed to the pair of fixed contacts 14, 14, and between the pair of fixed contacts 14, 14. Can be displaced between a position for short-circuiting and a position for opening. The movable contact 214 is a metal film made of a metal material having good conductivity such as Cu or Au, like the fixed contact 14, and uses a sputtering method, an electroplating method, a vacuum deposition method, or the like. Is formed. The movable contact 214 is not limited to a single layer structure, and may be a multilayer structure, for example, a laminated film of a Ti film and an Au film. The material of the movable contact 214 is not limited to Cu or Au, and for example, Cu, Au, Ag, Cr, Ti, Pt, Ru, Rh, Co, Ni, or an alloy thereof may be employed.

Further, the movable part forming substrate 2 has a fulcrum projecting piece 24c projecting at the center of each of both ends in the short direction of the movable part main body 24a, and the fulcrum projecting piece 24c is opposed to the cover substrate 3. Further, a fulcrum protrusion 24d is provided so as to function as a fulcrum for the swinging operation (seesaw operation) of the movable portion 24. In short, the fulcrum protrusion 24d is interposed between the fulcrum protrusion 24c and the cover substrate 3, and the movable portion 24 is supported by the cover substrate 3 via the fulcrum protrusion 24d. In the movable portion forming substrate 2, the portion of the frame 21 between the opening 22 and the cavities 27 and 27 regulates the movement of the movable portion 24 in the direction along the longitudinal direction of the movable portion forming substrate 2. A movement restricting unit 231 is configured.

In the movable part forming substrate 2 described above, the movable part 24 is supported by the frame part 21 via four support spring parts 224 so as to be swingable. The support springs 224 are formed at two locations spaced apart in the longitudinal direction of the movable part main body 24a on both side surfaces in the short side direction of the movable part main body 24a. Here, one end of each support spring portion 224 is continuously and integrally connected to the movable portion main body 24 a, and the other end portion is continuously and integrally connected to the inner peripheral surface of the frame portion 21. In addition, the support spring part 224 is lengthened by forming the part between the said one end part and the said other end part in the planar shape in the meandering shape in the same plane. Thus, the stress generated in the support spring portion 224 when the movable portion 24 swings can be dispersed, and the support spring portions 224 can be prevented from being damaged.

By the way, the MEMS relay according to the present embodiment includes an armature 6 made of a magnetic material laminated on the cover substrate 3 side of the movable portion main body 24a as a driving means for driving the movable portion 24, and an armature 6 provided on the cover substrate 3. An electromagnetic drive type driving means is provided which is composed of an electromagnet device 4 which is driven to swing. The drive means is not limited to the electromagnetic drive type that drives the movable part 24 by electromagnetic force, but may be an electrostatic drive type that drives the movable part 24 by electrostatic force, or the movable part 24 by a piezoelectric element (electromechanical element). It may be a piezoelectric drive type.

The armature 6 is formed into a rectangular plate by machining a magnetic material such as electromagnetic soft iron, electromagnetic stainless steel, and permalloy, and is fixed to the movable portion main body 24a by a method such as adhesion, welding, hot welding, or brazing. Has been. In addition, a reciprocal 60 is provided on the side of the movable portion main body 24a facing the base substrate 1.

Here, the movable part main body 24 a is thinner than the frame part 21, and the thickness dimension of the armature 6 is appropriately set between the armature 6 and the cover substrate 3 in a state where the movable part forming substrate 2 and the cover substrate 3 are fixed. It is set so that a void is formed. Further, the thickness dimension of the sequential 60 is set so that an appropriate gap is formed between the movable portion 24 and the base substrate 1. Here, if the above-described double SOI substrate is used as the semiconductor substrate 20 serving as the basis of the movable portion forming substrate 2, the distance between the movable portion main body 24a and the base substrate 1 is defined by the thickness of the silicon layer on the base substrate 1 side. Thus, the distance (insulating distance) between the fixed contact 14 and the movable contact 214 in a state where the fixed contact 14 and the movable contacts 214 and 214 are open can be set with high accuracy. In addition, the distance between the movable part main body 24a and the cover substrate 3 can be defined by the thickness of the silicon layer on the cover substrate 3 side, and the distance (magnetic gap length) between the armature 6 and the electromagnet device 4 can be set with high accuracy. It becomes possible to do.

By the way, the movable part formation board | substrate 2 is joining metal layer 238 (refer FIG. 6 and FIG. 9A) for joining to the cover board | substrate 3 over the perimeter of the frame part 21 in the said one surface side. ) And a bonding metal layer 218 (see FIG. 9B) for bonding to the base substrate 1 is formed over the entire circumference of the frame portion 21 on the other surface side. On the other hand, a bonding metal layer (not shown) to be bonded to the bonding metal layer 238 is formed over the entire circumference of the cover substrate 3 on the side facing the movable portion forming substrate 2. A joining metal layer 118 (see FIG. 6) to be joined to the joining metal layer 218 is formed over the entire circumference of the base substrate 1 on the side facing the movable portion forming substrate 2. In addition, the joining method of the movable part forming substrate 2, the base substrate 1, and the cover substrate 3 is not limited to the above-described room temperature joining method, and for example, an anodic joining method may be employed.

The cover substrate 3 is formed with a storage portion 36 for storing the above-described electromagnet device 4 in the center. Here, in the cover substrate 3, a storage portion opening 34 through which the electromagnet device 4 is inserted is formed in the central portion of the second substrate 30. In the cover substrate 3, a closing plate 32 that closes the storage portion opening 34 is fixed to one surface side of the second substrate 2 on the movable portion forming substrate 2 side. In short, in the cover substrate 3, a space surrounded by the inner peripheral surface of the storage portion opening 34 and the closing plate 32 forms a storage portion 36. Thus, the space surrounded by the base substrate 1, the frame portion 21 of the movable portion forming substrate 2, and the cover substrate 3 is an airtight space.

The storage portion opening 34 has a tapered shape in which the opening area gradually increases as it approaches the other surface from the one surface of the second substrate 30. Thus, the cover substrate 3 is easy to insert the electromagnet device 4 from the side opposite to the movable portion forming substrate 2 side, and the opening area of the storage portion opening 34 on the one surface of the second substrate 30 is compared. Can be made smaller. Note that the storage portion opening 34 described above may be formed by, for example, a sandblasting method or an etching method. The closing plate 32 is made of a thin plate such as a silicon plate or a glass plate having a thickness of about 5 to 50 μm (preferably about 20 μm). Such a blocking plate 32 is formed, for example, by thinning a silicon substrate or a glass substrate by polishing or etching.

The electromagnet device 4 includes a yoke 40 and two coils 42 and 42 wound around the yoke 40. The yoke 40 extends in the direction of approaching the closing plate 32 from each of the elongated rectangular plate-shaped coil winding portion 40a around which both the coils 42 and 42 are directly wound, and both ends in the longitudinal direction of the coil winding portion 40a. The length of the coil winding portion 40a between the pair of leg pieces 40b and 40b whose tip surfaces are excited with different polarities in response to the excitation current to the coils 42 and 42 and the leg pieces 40b and 40b of the yoke 40 And a rectangular plate-like permanent magnet 41 disposed so as to overlap the central portion of the direction. Thus, the movement of the coil winding portion 40a in the longitudinal direction of each of the coils 42 and 42 is restricted by the permanent magnet 41 and the leg pieces 40b and 40b of the yoke 40, respectively. The yoke 40 is formed by processing an iron plate such as electromagnetic soft iron by bending, casting, pressing, or the like, and the cross sections of both leg pieces 40b, 40b are formed in a rectangular shape.

The above-described electromagnet device 4 generates an electromagnetic force when an excitation current is applied to the two coils 42 and 42, and the armature 6 fixed to the movable portion 24 can be attracted by the electromagnetic force. it can.

In the permanent magnet 41, the magnetic pole surfaces on both sides in the overlapping direction (thickness direction) with the coil winding portion 40a are magnetized with different polarities, and one magnetic pole surface abuts on the coil winding portion 40a of the yoke 40. The thickness dimension is set so that the other magnetic pole surface is located on the same plane as the tip surfaces of the leg pieces 40b, 40b of the yoke 40. Here, the above-described electromagnet device 4 is housed in the housing portion 36 in such a manner that the front end surfaces of both leg pieces 40b, 40b of the yoke 40 described later and the other magnetic pole surface of the permanent magnet 41 abut against the closing plate 32. Yes. Thus, the other magnetic pole surface of the permanent magnet 41 in the electromagnet device 4 and the tip surfaces of the leg pieces 40b, 40b of the yoke 40 can be positioned on the same plane, so that there is a gap between the electromagnet device 4 and the armature 6. The accuracy of the gap length can be increased.

In addition, the electromagnet device 4 includes a terminal block 46 in which a pair of coil terminals 45 and 45 protrude from both leg pieces 44b and 44b of a terminal holding portion 44 made of an insulating resin and having a U-shaped cross section. The central piece 44a of the terminal holding portion 44 is disposed on the opposite side of the coil winding portion 40a from the permanent magnet 41 side so as to be orthogonal to the coil winding portion 40a of the yoke 40. Here, the terminals of the coils 42, 42 are connected to the coil terminals 45, 45, and a current flows through both the coils 42, 42 by applying a voltage between the pair of coil terminals 45, 45.

Further, the cover substrate 3 has wiring patterns (conductor patterns) 37, 37 made of a metal film to which the coil terminals 45, 45 are electrically connected on the surface opposite to the movable part forming substrate 2 side. In addition, coil terminals 45 and 45 are joined and electrically connected to one end portions of the wiring patterns 37 and 37 by soldering or the like. On the other hand, the other end portions of the wiring patterns 37 and 37 are electrically connected to driving external connection electrodes 19 and 19 (see FIG. 7A) provided on the other surface side of the base substrate 1. Yes. Here, the wiring patterns 37 and 37 and the driving external connection electrodes 19 and 19 are energized vias 315, 215 and 115 formed in the cover substrate 3, the movable portion forming substrate 2 and the base substrate 1, respectively. It is electrically connected via. Note that the via 315 of the cover substrate 3 and the via 215 of the movable part forming substrate 2 are connection metal layers (not shown) formed on the opposing surfaces of the cover substrate 3 and the movable part forming substrate 2. They are electrically connected by joining them together. Similarly, the via 215 of the movable part forming substrate 2 and the via 115 of the base substrate 1 are a connection metal layer (not shown) formed on the mutually facing surface side of the movable part forming substrate 2 and the base substrate 1. ) Are electrically connected by joining each other.

Next, the operation of the MEMS relay of this embodiment will be described.

In the microrelay of this embodiment, when the coils 42 are energized, one end in the longitudinal direction of the armature 6 is attracted to one leg piece 40b of the yoke 40 according to the direction of magnetization, and the movable part main body The movable contact 214 fixed to the contact holding piece 24b on one end side of the contact 24a contacts the pair of fixed contacts 14 and 14 facing the movable contact 214 with a predetermined contact pressure (that is, a pair of fixed contacts). 14 and 14 are short-circuited via the movable contact 214). Even if energization of the coils 42 and 42 is stopped in this state, the attractive force is maintained by the magnetic flux generated by the permanent magnet 41, and the state is maintained as it is.

When the energizing direction of the coils 42 is reversed, the other end portion of the armature 6 in the longitudinal direction is attracted to the other leg piece 40b of the yoke 40, and the contact holding piece on the other end side of the movable portion main body 24a. The movable contact 214 fixed to the contact 24b comes into contact with the pair of fixed contacts 14 and 14 facing the movable contact 214 with a predetermined contact pressure. Even if energization is stopped in this state, the attractive force is maintained by the magnetic flux generated by the permanent magnet 41, and the state is maintained as it is.

Note that the MEMS relay of the present embodiment is a polar type electromagnet device in which the electromagnet device 4 that drives the armature 6 includes a permanent magnet 41, and constitutes a latching type relay. As the electromagnet device 4, a non-polar electromagnet device that does not include the permanent magnet 41 may be used.

By the way, the via hole 12 in which the via 15 described above is formed is formed in a tapered shape in which the opening area gradually increases from the one surface of the first substrate 10 toward the other surface. As compared with the case of forming a vertical hole in a uniform case, it can be easily formed. Further, when the via hole 12 is formed in a vertical hole shape, there is a concern that the via 15 cannot be formed inside the via hole 12. On the other hand, if the via hole 12 is formed in a tapered shape, the via 15 is formed by a manufacturing process in which the seed layer for plating is formed by sputtering or the like and then the via 15 is formed by electroplating. be able to. The thickness of the first substrate 10 is not particularly limited, but may be set as appropriate within a range of about 200 μm to 1000 μm, for example.

However, when the tapered via hole 12 is formed in the first substrate 10, the area occupied by the via hole 12 in a plan view becomes large, and the miniaturization of the MEMS relay is limited.

On the other hand, as shown in FIGS. 10A to 10D, if the via hole 12 has a shape in which the opening area gradually decreases from the both sides in the thickness direction of the first substrate 10 toward the specified intermediate position. The area occupied by the via hole 12 can be reduced, and the MEMS relay can be reduced in size. 10 (a) and FIGS. 10 (b), (c), and (d) are different in the shape of the via hole 12, and FIG. 10 (b), FIG. 10 (c), and FIG. Are different in the shape of the via 15. In addition, the via hole 12 of FIGS. 10A to 10D has a circular opening shape, and the minimum diameter is set in a range of about 20 μm to 150 μm, and the maximum diameter is set in a range of about 150 μm to 500 μm. It does not specifically limit to these numerical values.

In the via hole 12 of FIG. 10A described above, the specified intermediate position having the minimum diameter is biased to one side in the thickness direction of the first substrate 10, whereas FIGS. In the via hole 12 of (d), the specified intermediate position that is the minimum diameter is substantially the center in the thickness direction of the first substrate 10, and therefore the maximum diameter is made smaller than in the case of FIG. Can do. Further, in FIG. 10C, since the via hole 12 is filled with the via 15, airtightness can be ensured. On the other hand, in FIG. 10D, since the via hole 12 is closed only in the vicinity of a prescribed intermediate position that is the minimum diameter of the via hole 12, the inner peripheral surface of the via hole 12 and the via 15 are caused by thermal stress. It is possible to suppress the formation of a gap between them, and to improve the heat stress resistance.

In order to form the via 15 as shown in FIG. 10 (b), first, sandblasting is performed on the first substrate 10 from the one surface side and the other surface side of the first substrate 10, respectively. A via hole 12 is formed (see FIG. 11A). Thereafter, a metal layer 171 made of a metal material (for example, Cu, Au, etc.) used as a seed layer for electroplating is sputtered on the one surface and the other surface of the first substrate 10 and the inner surface of the via hole 12. It forms by a vapor deposition method, an electroless plating method, etc. (refer FIG.11 (b)). Subsequently, the via 15 may be formed by electroplating using the metal layer 171 as a seed layer (see FIG. 11C). Note that the thickness of the metal layer 171 may be set as appropriate within a range of about 0.01 μm to 1 μm. When a silicon substrate is used as the first substrate 10 instead of a glass substrate, via holes 12 are formed by dry etching, and then a silicon oxide film is formed on both surfaces of the silicon substrate and the inner surfaces of the via holes 12 by a thermal oxidation method or the like. After that, an insulating film made of a metal layer 171 may be formed.

In order to form the via 15 as shown in FIG. 12E, first, the first substrate 10 is subjected to sandblasting from the one surface side and the other surface side of the first substrate 10. A via hole 12 is formed (see FIG. 12A). Thereafter, a metal layer 171 serving as a seed layer for electroplating is formed on the one surface and other surface of the first substrate 10 and the inner surface of the via hole 12 by sputtering, vapor deposition, electroless plating, or the like. A fourth substrate 173 is prepared in which a metal layer 172 serving as a seed layer for electroplating is formed by sputtering, vapor deposition, electroless plating, or the like (see FIG. 12B). Subsequently, the fourth substrate 173 is bonded to the first substrate 10 (see FIG. 12C). Thereafter, the via 15 is formed by electroplating using the metal layers 171 and 172 as seed layers (see FIG. 12D), and then the fourth substrate 173 is peeled off from the first substrate 10 (FIG. 12). (See (e)). Also in this example, when a silicon substrate is used as the first substrate 10, a via hole 12 is formed by dry etching, and then both sides of the silicon substrate and the via hole 12 are formed by a thermal oxidation method or the like. An insulating film made of a silicon oxide film is formed on the inner surface, and then the metal layer 171 is formed.

Next, an example of a method for forming the via 15 as shown in FIG. 10D will be described with reference to FIG.

First, via holes 12 are formed in the first substrate 10 by performing sandblasting from the one surface side and the other surface side of the first substrate 10 (see FIG. 13A). Thereafter, a metal layer 171 serving as a seed layer for electroplating is formed on the one surface of the first substrate 10 and the inner surface of the tapered portion on the one surface side of the via hole 12 by a sputtering method, a vapor deposition method, or the like. It is formed by an electrolytic plating method or the like (see FIG. 13B). Subsequently, a conductor portion 15a constituting a part of the via 15 is formed by a first electroplating step in which electroplating is performed using the metal layer 171 as a seed layer (see FIG. 13C). Thereafter, a metal layer 181 serving as a seed layer for electroplating is formed on the other surface of the first substrate 10 and the inner surface of the tapered portion on the other surface side of the via hole 12 by a sputtering method, a vapor deposition method, or the like. It is formed by an electrolytic plating method or the like (see FIG. 13D). Subsequently, a conductor portion 15b constituting a part of the via 15 is formed by a second electroplating process in which electroplating is performed using the metal layer 181 as a seed layer (see FIG. 13E). Subsequently, by a third electroplating step in which electroplating is performed, a conductor portion 15c that forms the via 15 together with the conductor portions 15a and 15b on the inner surface of the via hole 12 and closes the via hole 12 is formed (see FIG. 13F). . Also in this example, when a silicon substrate is used as the first substrate 10, a via hole 12 is formed by dry etching, and then both sides of the silicon substrate and the via hole 12 are formed by a thermal oxidation method or the like. An insulating film made of a silicon oxide film is formed on the inner surface, and then the metal layer 171 is formed.

When performing the above electroplating, a copper plating solution for via filling in which a plating accelerator and a plating inhibitor are added to a copper sulfate plating solution is used. Here, the plating accelerator has a function of adhering to the surfaces of the metal layers 171 and 181 inside the via hole 12 to promote plating, and the plating inhibitor is the one surface side of the first substrate 10. On the other surface side, it has a function of adhering to the surfaces of the metal layers 171 and 181 and suppressing plating. Therefore, by adding a plating accelerator and a plating inhibitor as additives in the plating solution, the thickness of the conductor portions 15a, 15b, 15c formed inside the via hole 12 by the action of these additives is increased. This makes it easier to close the via hole 12 with the via 15. For example, bis (3-sulfopropyl) disulfide (SPS) is used as the plating accelerator, and polyethylene glycol (PEG) having a molecular weight of 3000 to 8000 is used as the plating accelerator. However, these materials are particularly limited. Not what you want. In addition, the effect by a plating accelerator and a plating inhibitor can be heightened by speeding up the speed which stirs the copper plating solution for via filling.

Next, another example of a method for forming the via 15 as shown in FIG. 10D will be described with reference to FIG.

First, via holes 12 are formed in the first substrate 10 by performing sandblasting from the one surface side and the other surface side of the first substrate 10 (see FIG. 14A). Thereafter, a metal layer 171 serving as a seed layer for electroplating is formed on the one surface and other surface of the first substrate 10 and the inner surface of the via hole 12 by sputtering, vapor deposition, electroless plating, or the like ( (Refer FIG.14 (b)). Subsequently, by performing an electroplating process using a copper plating solution for via filling, conductor portions 15a and 15b constituting a part of the via 15 are formed (see FIG. 14C), and subsequently, electroplating is performed. As a result, the via 15 is formed together with the conductors 15a and 15b on the inner surface of the via hole 12, and the conductor 15c for closing the via hole 12 is formed (see FIG. 14D). In the examples shown in FIGS. 13 and 14, the minimum diameter of the via hole 12 can be reduced in order to shorten the electroplating time and to close the via hole 12 with a smaller amount of copper plating. preferable. Also in this example, when a silicon substrate is used as the first substrate 10, the via holes 12 are formed by dry etching, and then both sides of the silicon substrate and the via holes 12 are formed by a thermal oxidation method or the like. An insulating film made of a silicon oxide film is formed on the inner surface, and then the metal layer 171 is formed.

Next, another example of a method of forming the via 15 as shown in FIG. 10D will be described with reference to FIG.

First, a bottomed hole (concave portion) 12a is formed in the first substrate 10 by performing sandblasting from the one surface side of the first substrate 10 to a predetermined depth corresponding to the prescribed intermediate position (see FIG. 15 (a)). Thereafter, a metal layer 172 serving as a seed layer for electroplating is formed on the one surface of the first substrate 10 and the inner surface of the bottomed hole 12a by sputtering, vapor deposition, electroless plating, or the like (FIG. 15B). )reference). Subsequently, a conductor portion 15f constituting a part of the via 15 is formed by a first electroplating step in which electroplating is performed using the metal layer 172 as a seed layer (see FIG. 15C). Subsequently, a portion of the first substrate 10 that overlaps the bottomed hole 12a on the other surface is sandblasted until the conductor portion 15f is exposed from the other surface, thereby forming the via hole 12 together with the bottomed hole 12a. 12b is formed on the first substrate 10 (see FIG. 15D). Thereafter, a metal layer 182 serving as a seed layer for electroplating is formed on the other surface of the first substrate 10 and the inner surface of the tapered portion on the other surface side of the via hole 12 by sputtering, vapor deposition, It is formed by an electrolytic plating method or the like (see FIG. 15 (e)). Subsequently, a conductor portion 15g constituting the via 15 is formed together with the above-described conductor portion 15f by a second electroplating step in which electroplating is performed using the metal layer 182 as a seed layer (see FIG. 15F).

According to the MEMS relay of the present embodiment described above, a pair of signal lines 13 and 13 are provided at both ends in the longitudinal direction on the one surface side of the base substrate 1, and the intermediate substrate (movable portion forming substrate) 2 is provided. , The opening portion 22 and the cavity portions 27, 27 arranged in parallel to the opening portion 22 and corresponding to the pair of signal lines 13, 13, respectively, and the communication portion for communicating the opening portion 22 with the cavity portions 27, 27. A frame portion 21 formed between the base substrate 1 and the cover substrate 3; a movable portion 24 disposed inside the frame portion 21 and supported by the frame portion 21 so as to be swingable; Contact holding having a movable contact 214 extending from a movable portion main body 24 a disposed in the opening 22 of the portion 24 and contacting and separating from fixed contacts 14 and 14 provided on the pair of signal lines 13 and 13, respectively. 24b, and the above-described structure is provided with drive means for swingably driving the movable portion 24. Therefore, it is possible to reduce transmission loss while suppressing an increase in planar size and A MEMS relay in which the ground conductor 5 surrounding the signal line 13 can be easily formed can be provided.

Further, in the MEMS relay of this embodiment, since the housing portion 36 for housing the electromagnet device 4 is formed on the cover substrate 3, the electromagnet device is mounted on the base substrate 1 'as in the conventional example shown in FIGS. Since the distance between the electromagnet device 4 and the signal lines 13 and 13 can be increased as compared with the case where the housing portion 116 ′ for housing 4 ′ is provided, transmission loss occurs due to the magnetic flux generated by the electromagnet device 4. Can be suppressed.

Further, according to the MEMS relay of the present embodiment, the thickness dimension of the base substrate 1 is reduced as compared with the case where the electromagnet device 4 ′ is accommodated in the base substrate 1 ′ as in the configuration shown in FIGS. Therefore, the length of the via 15 that electrically connects the signal line 13 and the external connection electrode 17 (see FIG. 1C) can be shortened, and the high-frequency characteristics can be improved.

Further, if a high resistivity silicon substrate is used as the first substrate 10 instead of the glass substrate, the via holes 11, 11, and 12 can be reduced in size as compared with the case where the glass substrate is used. The planar size of the body and the MEMS relay can be reduced, and the high frequency characteristics can be improved. Further, if an LTCC substrate is used as the first substrate 10, desired wirings ( first ground wirings 51 and 51, second ground wirings 52 and 52, third ground wirings 53 and 53, The vias 15) can be formed at the same time, and the manufacturing process can be simplified.

DESCRIPTION OF SYMBOLS 1 Base substrate 2 Intermediate substrate 3 Cover substrate 4 Electromagnet device 5 Ground conductor 6 Armature 13 Signal line 14 Fixed contact 16 Metal layer for joining (metal layer)
21 Frame part 22 Opening part 23 Communication part 24 Movable part 24a Movable part main body 24b Contact holding piece 25 Metal layer for connection (metal layer)
26 Metal layer for bonding (metal layer)
27 Cavity 28 Wall 29 Metal layer for connection (metal layer)
51 First ground wiring (metal layer)
52 Second ground wiring 53 Third ground wiring 54 Fourth ground wiring (metal layer)
55 Fifth ground wiring

Claims (6)

1. A base substrate with a signal line formed on one surface side, a cover substrate opposed to the one surface side of the base substrate, and a cavity that is interposed between the base substrate and the cover substrate to expose the signal line is in the thickness direction And a ground conductor that is formed across the base substrate, the intermediate substrate, and the cover substrate and surrounds the signal line, and the ground conductor has a width of the signal line on the one surface side of the base substrate. A first ground wiring parallel to the signal lines on both sides of the direction, a second ground wiring formed on the base substrate and electrically connected to each first ground wiring and made of vias parallel to the signal lines, and a base The second ground lines are electrically connected to each other on the other surface side of the substrate, and the third ground lines parallel to the signal lines and the signal lines and the relevant lines in plan view on the side of the cover substrate facing the base substrate A fourth ground wiring having a width across the first ground wiring on both sides of the signal line, and the first ground wiring and the fourth ground wiring formed on both sides of the cavity in the intermediate substrate A structure provided with a wiring structure, characterized by comprising a fifth ground wiring composed of through slit wiring to be connected.
   
2. 2. The structure having a wiring structure according to claim 1, wherein the intermediate substrate, the base substrate, and the cover substrate are bonded to each other through metal layers formed on opposing surfaces.
   
3. 3. The structure having a wiring structure according to claim 2, wherein the intermediate substrate, the base substrate, and the cover substrate are formed by surface activation bonding of the metal layers.
   
4. The structure according to any one of claims 1 to 3, wherein an insulating film is provided between the intermediate substrate and the fifth ground wiring.
   
5. 5. The MEMS relay having a structure including the wiring structure according to claim 1, wherein the base substrate includes a pair of the signal lines on the one surface side, The intermediate substrate is formed with an opening and a communication portion that is arranged in parallel with the opening and corresponds to each of the signal lines, and a communication portion that connects the opening and the cavity, and the base substrate and the cover. A frame portion interposed between the substrate, a movable portion disposed inside the frame portion and supported by the frame portion in a swingable manner, and a movable portion main body disposed in the opening portion of the movable portion. And a contact holding piece having a movable contact that contacts and separates from a fixed contact provided on each of the pair of signal lines, and the structure is provided with a driving means for driving the movable portion to be swingable. MEM characterized by Relay.
   
6. The driving means is composed of an armature made of a magnetic material laminated on the cover substrate side in the movable part main body and an electromagnet device provided on the cover substrate to drive the armature so as to be swingable. The MEMS relay according to claim 5, wherein:

Images