Switch and method for manufacturing the same, and relay

Abstract

 To smoothly form the contacting surfaces of the contacts and to reduce the contact resistance between the contacts such that the contacts reliably contact each other. The fixed contact portion (33) has an adhesion layer (43) and a wiring layer (44) stacked on a fixed contact substrate (41) and a contact layer (45) formed thereon. An end face that faces a movable contact portion (34) of a contact layer (45) becomes a fixed contact (46) (contacting surface), and the fixed contact (46) projects out from the wiring layer (44) and the adhesion layer (43), as well as the fixed contact substrate (41). The movable contact portion (34) has the adhesion layer (53) and the wiring layer (54) formed on the movable contact substrate (51) and the contact layer (55) formed thereon. An end face that faces the fixed contact portion (33) of a contact layer (55) becomes a movable contact (56) (contacting surface), and the movable contact (56) projects out from the wiring layer (54) and the adhesion layer (53) as well as the fixed contact substrate (51). The fixed contact and the movable contact are surfaces coming into contact with the side surfaces of the mold portion (A2) in the step of growing the contact layers (45, 55) through vapor deposition, sputtering, and the like.

Description

BACKGROUND OF THE INVENTION

1. TECHNICAL FIELD

[0001] The present invention relates to a switch and a method for manufacturing the same, and a relay. Specifically, the present invention relates to a switch in which a surface perpendicular to a moving direction of a movable contact portion is a contact and a method for manufacturing the same, and to a relay that uses the structure of the switch.

2. RELATED ART

(Japanese Unexamined Patent Publication No. 2006-526267)

[0002] A MEMS (Micro Electrical-Mechanical Systems) switch in which the surface perpendicular to the moving direction of the movable contact portion is the contact (contacting surface) is disclosed in Japanese Unexamined Patent Publication No. 2006-52627. As shown in Fig. 1A, in the switch 11, an insulating layer 13a is formed on an upper surface of a substrate 12a, a conductive layer 14a made of Al, Cu, or the like is formed thereon, and a plated layer 15a of Au or the like is grown from the upper surface to the end face of the conductive layer 14a to form a movable contact portion 17. Similarly, an insulating layer 13b is formed on an upper surface of a substrate 12b, a conductive layer 14b made of Al, Cu, or the like is formed thereon, and a plated layer 15b of Au or the like is grown from the upper surface to the end face of the conductive layer 14b to form a fixed contact portion 18. The switching operation is carried out between the movable contact portion 17 and the fixed contact portion 18 by moving the movable contact portion 17 in the direction of the arrow, and contacting or separating a movable contact 16a that is a projecting region of the plated layer 15a and a fixed contact 16b that is a projecting region of the plated layer 15b, as shown in Fig. 1B.

[0003] In such a switch 11, however, the surface of the movable contact 16a formed on the end face of the conductive layer 14a and the surface of the fixed contact 16b formed on the end face of the conductive layer 14b are brought into contact with or separated from each other, and hence the movable contact 16a and the fixed contact 16b contact with each other at the surface (plated surface) perpendicular to the growing direction of each plated layer 15a, 15b. However, since the surface of the plated layer is rough and includes microscopic bumps, the substantial contacting area in the case where the movable contact 16a and the fixed contact 16b are brought in contact with each other is significantly small, and the contact resistance of the contacts is large.

[0004] When voltage is applied to the conductive layers 14a, 14b for plating process, the growing speed of the plating coating is large in the projecting region (movable contact 16a, fixed contact 16b) since the electric field intensity is high at the end face of the conductive layers 14a, 14b, and hence the gap distance between the contacts is difficult to control. As the surface of the contact is rough and has irregular microscopic bumps, discharge easily occurs between the contacts when the contacts are brought close due to the variation in the gap distance. Thus, it is difficult to narrow the gap distance between the contacts in the switch 11.

(Japanese Unexamined Patent Publication No. 9-251834)

[0005] An electrostatic relay in which the movable contact moves parallel to the base substrate and the movable contacts come into contact with or separate from each other is disclosed in Japanese Unexamined Patent Publication No. 9-251834. As shown in Fig. 2, in an electrostatic relay 21, a lever 24a is elastically bent by applying voltage to a movable comb teeth like electrode 22a and a fixed comb teeth like electrode 23a, and at the same time, a lever 24b is elastically bent by applying voltage to a movable comb teeth like electrode 22b and a fixed comb teeth like electrode 23b, so that a movable contact 25a formed at the distal end of the lever 24a and a movable contact 25b formed at the distal end of the lever 24b are brought in contact with each other thereby closing the movable contacts 25a, 25b. The movable contacts 25a, 25b are opened and separated by releasing the applied voltage between each comb teeth like electrode 22a and 23a and the movable comb teeth like electrode 22b and 23b. In such electrostatic relay 21, the movable contacts 25a, 25b are formed by forming a metal film on the distal ends of the levers 24a, 24b through vapor deposition, sputtering, and the like.

[0006] In the electrostatic relay 21 of Japanese Unexamined Patent Publication No. 9-251834 as well, the surfaces of the movable contacts 25a, 25b formed at the end faces of the levers 24a, 24b are contacted and separated. Therefore, in the electrostatic relay 21 as well, the movable contacts 25a, 25b come into contact with each other at the surfaces perpendicular to the growing direction of the vapor deposition film and the like.

[0007] However, the surfaces (surfaces of contacts) perpendicular to the growing direction of such contacts are considerably rough when viewed microscopically, and have irregular microscopic bumps. The contacting area of the contacts is thus small when seen microscopically, and the contact resistance in the case where the contacts are closed is large, Furthermore, the contact resistance between the contacts tends to become unnecessarily large since the parallelism of the surfaces of the opposing contacts is difficult to obtain.

SUMMARY

[0008] The present invention has been devised to solve the problems described above, and an object thereof is to provide a switch capable of smoothly forming a contacting surface of a contact, and reducing the contact resistance between the contacts so that the contacts are reliably brought into contact with each other and a method for manufacturing the same, as well as, a relay that uses the structure of the switch.

[0009] In accordance with one aspect of the present invention, a switch according to the present invention relates to a switch including a first contact portion in which a plurality of layers including a first contact layer is formed on an upper side of a first substrate; and a second contact portion in which a plurality of layers including a second contact layer is formed on an upper side of a second substrate, wherein an end face parallel to a growing direction when forming the contact layer in the first contact layer is a contact of the first contact portion; an end face parallel to a growing direction when forming the contact layer in the second contact layer is a contact of the second contact portion; the contact of the contact portion projects out than an end face of a layer other than the contact layer in the contact portion and the substrate of the contact portion in at least one of the contact portions of the first contact portion or the second contact portion, and the contact of the first contact portion and the contact of the second contact portion face each other so that the contacts come into contact with or separate from each other.

[0010] In the switch of the present invention, the surface that becomes each contact when forming the first and second contact layers using the MEMS technique can be smoothened and the parallelism between the contacts can be enhanced since the end face parallel in the growing direction of each first and second contact layers becomes the contact of the first contact portion and the contact of the second contact portion. Therefore, the substantial contacting area between the contacts becomes large and the contact resistance between the contacts becomes small. The welding between the contacts is less likely to occur since the contacting surfaces of the contacts become smooth, whereby the open/dose lifespan of the switch becomes longer. Furthermore, since the inter-contact distance can be narrowed, the actuator can be driven at low voltage to open and close the contacts.

[0011] According to the switch of the present invention, in at least one of the contact portion of the first contact portion or the second contact portion, the contact of such contact portion projects out than the end face of the layer other than the contact layer in the contact portion and the substrate of the contact portion, and hence the layers other than the contact layer or the substrates come into contact each other before the contacts of the first contact portion and the second contact portion come into contact each other, and the contact between the contact of the first contact portion and the contact of the second contact portion is not inhibited. Since the contacts come into contact with each other, the contact of the layers other than the contact layer can be prevented, and the fixation of the layers other than the contact layer can be prevented thereby extending the contact lifespan.

[0012] In the one aspect of the switch according to the present invention, the first and second contact layers are formed from one of a noble metal, an alloy, an Si material having conductivity, or a conductive oxide. According to such aspect, the first and second contact layers can be formed from a material having high hardness and relatively small specific resistance.

[0013] In another aspect of the switch according to the present invention, the first contact portion has a first wiring layer formed on the upper side of the first substrate and the first contact layer formed on the upper surface of the first wiring layer; and the second contact portion has a second wiring layer formed on the upper side of the second substrate and the second contact layer formed on the upper surface of the second wiring layer. According to such aspect, the most suitable material can be selected for the wiring layer and the contact layer, respectively, since the wiring layer for wiring and the contact layer including the contact for opening and closing can be separately provided.

[0014] In another aspect of the switch according to the present invention, an end face of the wiring layer of the contact portion is an inclined surface gradually retreating in a direction of approaching the substrate of the contact portion from an end on the side contacting the contact layer of the contact portion in at least one of the contact portions in which the contact projects out than the end faces of the layer other than the contact layer and the substrate. According to such aspect, the projecting portion of the contact layer can be supported by the wiring layer while avoiding the wiring layers from coming into contact with each other.

[0015] In another further aspect of the switch according to the present invention, the first and second wiring layers are formed from one of a noble metal, an alloy, an Si material having conductivity, or a conductive oxide. According to such aspect, the first and second wiring layers can be formed from a material having small specific resistance and relatively high hardness.

[0016] In accordance with another aspect of the present invention, a first method for manufacturing a switch according to the present invention includes the steps of growing a plurality of layers including a contact layer in a thickness direction of a substrate at an upper side of the substrate to form a plurality of layers including the contact layer on the upper side of the substrate, and forming a mold portion of a predetermined pattern at an uppermost surface; etching the plurality of layers including the contact layer with the mold portion as a mask to divide the plurality of layers including the contact layer to a plurality of regions and forming a surface to become a contact from the etched surface of the contact layer; performing isotropic etching on a surface of the substrate between the divided regions of a plurality of layers including the contact layer to form a recess at the surface of the substrate; performing anisotropic etching on the substrate between the divided regions of the plurality of layers including the contact layer to divide the substrate into plurals in accordance with the divided region of the plurality of layers including the contact layer; and etching a layer other than the contact layer in at least one region of the divided regions to retreat an end face of the layer other than the contact layer than a surface to become the contact of the contact layer, The contact layer is formed through a deposition method such as vapor deposition, sputtering, MBE, CVD, plating, spraying method, sol-gel method, inkjet method, or screen printing.

[0017] According to the first method for manufacturing the switch according to the present invention, the surface that becomes each contact can be smoothened and the parallelism between the contacts can be enhanced since the surface that is etched when dividing the contact layer through etching becomes the contact. Therefore, the substantial contacting area between the contacts becomes large and the contact resistance between the contacts becomes small. The welding between the contacts is less likely to occur since the contacting surfaces of the contacts become smooth, whereby the open/lose lifespan of the switch becomes longer. Furthermore, since the inter-contact distance can be narrowed, the actuator can be driven at low voltage to open and close the contacts.

[0018] According to the above manufacturing method, each contact projects out than the end face of the layer other than the contact layer and the substrate of the contact portion, and hence the layers other than the contact layer or the substrates come into contact with each other before the contacts of each contact portion come into contact with each other, and the contact between the contacts is not inhibited. Since the contacts come into contact with each other, the contact of the layers other than the contact layer can be prevented, and the fixation of the layers other than the contact layer can be prevented thereby extending the contact lifespan.

[0019] In accordance with another further aspect of the present invention, a second method for manufacturing a switch according to the present invention includes the steps of forming a mold portion of a predetermined pattern on an upper side of a substrate and growing a plurality of layers including a contact layer in a thickness direction of a substrate in a plurality of regions excluding a region where the mold portion is formed at the upper side of the substrate to form a plurality of layers including the contact layer on the upper side of the substrate; removing the mold portion and forming a surface to become a contact from a surface contacting a side surface of the mold portion of the contact layer; performing isotropic etching on a surface of the substrate between the separated regions of the plurality of layers including the contact layer to form a recess at the surface of the substrate; performing anisotropic etching on the substrate between the separated regions of the plurality of layers including the contact layer to divide the substrate into plurals in accordance with the separated region of the plurality of layers including the contact layer; and etching a layer other than the contact layer in at least one region of the separated regions to retreat an end face of the layer other than the contact layer than a surface to become the contact of the contact layer. The contact layer is formed through a deposition method vapor deposition, sputtering, PLD, MBE, ALD, MOCVD, thermal CVD, plating, spraying method, sol-gel method, inkjet method, or screen printing.

[0020] According to the second method for manufacturing the switch according to the present invention, the surface that becomes each contact can be smoothened and the parallelism between the contacts can be enhanced since the surface contacting the mold portion of the contact layer becomes the contact. Therefore, the substantial contacting area between the contacts becomes large and the contact resistance between the contacts becomes small. The welding between the contacts is less likely to occur since the contacting surfaces of the contacts become smooth, whereby the open/dose lifespan of the switch becomes longer. Furthermore, since the inter-contact distance can be narrowed, the actuator can be driven at low voltage to open and close the contacts.

[0021] According to the above manufacturing method, each contact projects out than the end face of the layer other than the contact layer and the substrate of the contact portion, and hence the layers other than the contact layer or the substrates come into contact with each other before the contacts of each contact portion come into contact with each other, and the contact between the contacts is not inhibited. Since the contacts come into contact with each other, the contact of the layers other than the contact layer can be prevented, and the fixation of the layers other than the contact layer can be prevented thereby extending the contact lifespan.

[0022] In another aspect of the first or second method for manufacturing the switch according to the present invention, the plurality of layers including the contact layer has the contact layer formed on the upper surface of the wiring layer formed on the upper side of the substrate. According to such aspect, the most suitable material can be selected for the wiring layer and the contact layer, respectively, since the wiring layer for wiring and the contact layer including the contact for opening and closing can be separately provided. The wiring layer is formed through a deposition method such as vapor deposition, sputtering, MBE, CVD, plating, spraying method, sol-gel method, inkjet method, or screen printing.

[0023] In such aspect, the step of retreating the end face of the layer other than the contact layer than the surface to become the contact of the contact layer includes inclining the end face of the wiring layer so as to greatly retreat towards the substrate from the contact layer side. According to such aspect, the projecting portion of the contact layer can be supported by the wiring layer while avoiding the wiring layers from coming into contact with each other.

[0024] In accordance with another further aspect of the present invention, a relay according to the present invention includes the switch according to the present invention, and an actuator for moving at least one of the first contact portion and the second contact portion in a direction perpendicular to contacting surfaces of a contact of the first contact portion and a contact of the second contact portion so that the contacts come into contact with or separate from each other.. In such a relay, the contact resistance in the case where the contacts come into contact with each other becomes small since the contacting surfaces of the contacts of the first contact portion and the second contact portion can be smoothly formed. Furthermore, discharge is less likely to occur when the contacts are brought close to each other and the welding between the contacts is also less likely to occur as the contacting surfaces of the contacts are smooth. As a result, the lifespan of the relay becomes longer. Since the contact projects out than the end faces of other layers and the end face of the substrate, the layers other than the contact layer and the substrates contact each other before the contacts come into contact with each other, whereby the contact between the contact of the first contact portion and the contact of the second contact portion is not inhibited.

[0025] The means for solving the problems in the present invention have characteristics in which the configuring elements described above are appropriately combined, where the present invention includes a great number of variations obtained by combining the configuring elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 

Figs. 1 and 1B are cross-sectional views showing a MEMS switch disclosed in Japanese Unexamined Patent Publication No. 2006-526267;

Fig. 2 is a perspective view of an electrostatic relay disclosed in Japanese Unexamined Patent Publication No. 9-251834;

Figs. 3A and 3B are cross-sectional views showing a structure of a switch according to a first embodiment of the present invention;

Figs. 4A to 4D are schematic cross-sectional views describing a first method for manufacturing the switch of the first embodiment;

Figs. 5A to 5D are schematic cross-sectional views showing the steps following Fig. 4D;

Figs. 6A to 6D are schematic cross-sectional views describing a second method for manufacturing the switch of the first embodiment;

Figs. 7A to 7D are schematic cross-sectional views showing the steps following Fig. 6D;

Figs. 8A to 8D are schematic cross-sectional views describing a third method for manufacturing the switch of the first embodiment;

Fig. 9 is a cross-sectional view showing a structure of a switch according to a second embodiment of the present invention;

Figs. 10A to 10D are schematic cross-sectional views describing a first method for manufacturing the switch of the second embodiment;

Figs. 11A to 11C are schematic cross-sectional views showing the steps following Fig. 10D;

Figs. 12A to 12D are schematic cross-sectional views describing a second method for manufacturing the switch of the second embodiment;

Figs. 13A to 13C are schematic cross-sectional views showing the steps following Fig. 12D;

Fig. 14 is a plan view showing an electrostatic relay according to a third embodiment of the present invention;

Fig. 15 is a perspective view showing an area A of Fig. 14 in an enlarged manner; and

Fig. 16 is a schematic cross-sectional view taken along line B-B of Fig. 14.

DETAILED DESCRIPTION

[0027] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and various design changes can be made within a scope not departing from the gist of the invention.

[First embodiment]

(Structure)

[0028] Fig. 3A is a cross-sectional view showing a structure of a switch according to a first embodiment of the present invention. The switch 31 includes a fixed contact portion 33 and a movable contact portion 34. The fixed contact portion 33 has the lower surface fixed to the upper surface of the base substrate 32 through the insulating film 42, and the movable contact portion 34 is floated from the upper surface of the base substrate 32 and can move in a direction (direction indicated with outlined arrow) parallel to the upper surface of the base substrate 32 by an actuator. For instance, the switch of the present invention can be used in the MEMS switch having the structure disclosed in Japanese Unexamined Patent Publication No. 2006-526267.

[0029] The fixed contact portion 33 includes a wiring pattern 48 formed on the upper surface of the fixed contact substrate 41. The wiring pattern 48 includes an adhesion layer 43 positioned on the upper surface of the fixed contact substrate 41, and a wiring layer 44 and a contact layer 45 stacked thereon. The movable contact portion 34 includes a wiring pattern 58 formed on the upper surface of the movable contact substrate 51. The wiring pattern 58 includes an adhesion layer 53 positioned on the upper surface of the movable contact substrate 51, and a wiring layer 54 and a contact layer 55 stacked thereon.

[0030] The adhesion layer 43 is a layer for enhancing the adhesion strength (stripping strength) of the wiring layer 44 and the fixed contact substrate 41. The adhesion layer 53 is a layer for enhancing the adhesion strength (stripping strength) of the wiring layer 54 and the fixed contact substrate 51. The adhesion layers 43, 53 have a two-layer structure including a lower layer Cr / an upper layer Au, and are formed through methods such as CVD, vapor deposition, sputtering, electrolytic plating, non-electrolytic plating, and the like. The wiring layers 44, 54 are preferably made of material having small specific resistance and high hardness, and is configured by a noble metal or an alloy such as Pt, Rh, Pd, and Au, Si material such as polysilicon (Poly-Si), doped silicon (doped Si) and doped polysilicon doped with impurities, and conductive oxide such as AgO and SrRuO₃. The contact layers 45, 55 are also preferably made of material having small specific resistance and high hardness, and is configured by noble metal such as Pt, Rh, Pd, and Au, Si material such as polysilicon, doped silicon and doped polysilicon, and conductive oxide such as AgO and SrRuO₃. The wiring layers 44, 54 and the contact layers 45, 55 are formed through the deposition method such as vapor deposition, sputtering, MBE, CVD, plating, spraying method, sol-gel method, inkjet method, screen printing, and the like.

[0031] The contact layers 45, 55 are layers for forming the fixed contact and the movable contact that contact and separate to and from each other, where the sticking (fixing) is less likely to occur when the contacts come into contact with each other and the lifespan of the switch 31 is longer the higher the hardness of the material, and hence the material of high hardness is desirably preferentially selected for the material of the contact layers 45, 55. The wiring layers 44, 54, on the other hand, are layers for transmitting signals and do not directly come into contact with each other, where the effect of alleviating the impact when the contacts come into contact with each other can be expected even if the layers are soft, and hence the material of low resistance is desirably preferentially selected rather than the material of high hardness for the material of the wiring layers 44, 54. Therefore, the material of low resistance and high hardness is preferable for the wiring layers 44, 54 and the contact layers 45, 55 as well, but the wiring layers 44, 54 are typically formed from a material of smaller specific resistance than the contact layers 45, 55, and the contact layers 45, 55 are formed from a material of higher hardness than the wiring layers 44, 54.

[0032] The adhesion layers 43, 53, the wiring layers 44, 54, and the contact layers 45, 55 are formed by growing the respective material in the thickness direction (direction a of the arrow in Fig. 3). The opposing end face of the contact layer 45 of the respective opposing end faces of the contact layer 45 and the contact layer 55 becomes the fixed contact 46 (electrical contacting surface), and the opposing end face of the contact layer 55 becomes the movable contact 56 (electrical contacting surface). Therefore, the fixed contact 46 is an end face parallel to the growing direction a of the contact layer 45, or a surface perpendicular to the surface of the contact layer 45. The movable contact 56 is also an end face parallel to the growing direction α of the contact layer 55, or a surface perpendicular to the surface of the contact layer 55. The fixed contact 46 and the movable contact 56 are parallel to each other and are both smoothly formed. However, the fixed contact 46 and the movable contact 56 may not necessarily be a plane and may be a curved surface.

[0033] The fixed contact 46 projects out in the horizontal direction than the end face of the fixed contact substrate 41 and the end face of the adhesion layer 43 at the surface facing the movable contact portion 34. The end at the upper surface of the wiring layer 44 is aligned with the fixed contact 46 or is retreated than the fixed contact 46, and the end face 49 of the wiring layer 44 is retreated so as to move away from the movable contact portion 34 as the end face 49 approaches the fixed contact substrate 41 side. Similarly, the movable contact 56 projects out in the horizontal direction than the end face of the movable contact substrate 51 and the end face of the adhesion layer 53 at the surface facing the fixed contact portion 33. The end at the upper surface of the wiring layer 54 is aligned with the movable contact 56 or is retreated than the movable contact 56, and the end face 59 of the wiring layer 54 is retreated so as to move away from the fixed contact portion 33 as the end face 59 approaches the movable contact substrate 51 side.

[0034] In the fixed contact portion 33 and the movable contact portion 34, an insulating layer may be formed between the adhesion layer 43, 53 and each substrate 41, 51.

[0035] In the switch 31, when the movable contact portion 34 is moved in a direction parallel to the upper surface of the base substrate 32 by an actuator, and the like, the fixed contact 46 of the fixed contact portion 33 and the movable contact 56 of the movable contact portion 34 come into contact with each other, and the fixed contact 46 and the moveable contact 56 are electrically closed, as shown in Fig. 3B. Furthermore, since the contact layers 45, 55 project out in the horizontal direction than the end faces of the wiring layers 44, 54 and the adhesion layers 43, 53 and the end faces of each substrates 41, 51, respectively, the wiring layers 44, 54 do not come into contact with each other, the adhesion layers 43, 53 do not come into contact with each other, or the substrates 41, 51 do not come into contact with each other, thereby inhibiting the contact of the fixed contact 46 and the movable contact 56 before the fixed contact 46 and the movable contact 56 come into contact with each other. When the fixed contact 46 and the movable contact 56 come into contact with each other, the contact of the wiring layers 44, 54 and the adhesion layers 43, 53 is prevented, and hence the wiring layers 44, 54 and the adhesion layers 43, 53 do not stick to each other thus affecting the lifespan of the contact even if a material of low hardness is used for the wiring layers 44, 54 and the adhesion layers 43, 53.

[0036] As the end faces 49, 59 of the wiring layers 44, 54 are inclined to project out towards the upper side, the projecting portions of the contact layers 45, 55 can be supported by the wiring layers 44, 54 while avoiding the wiring layers 44, 54 from coming into contact with each other.

[0037] According to such structure of the switch 31, various manufacturing methods as will be described below can be adopted.

(First manufacturing method)

[0038] The switch 31 is manufactured using the MEMS technique. Figs. 4A to 4D and Figs. 5A to 5D show one example of the manufacturing steps of the switch 31.

[0039] Fig. 4A shows a state in which an adhesion layer A3 is formed on the upper surface of a substrate A1 made of Si by a method such as vapor deposition and sputtering. The adhesion layer A3 uses a material of high adhesiveness for the lower layer or a material such as Cr and Ti, and forms a material of low resistance or a material such as Au, Cu, and Al thereon. After forming the adhesion layer A3 on the upper surface of the substrate A1, a photoresist is applied on the upper surface of the adhesion layer A3, the photoresist is patterned through a photolithography technique, and a mold portion A2 is arranged in a region other than the region to form the wiring patterns 48, 58 at the upper surface of the adhesion layer A3, as shown in Fig. 4B.

[0040] Then, as shown in Fig. 4C, the material of the wiring layer is deposited on the adhesion layer A3 through the method such as vapor deposition, sputtering, and electrolytic planting, and a wiring layer A4 is stacked in a region to form the wiring patterns 48 and 58. The material of the contact layer is thereafter deposited on the wiring layer A4 through the method such as vapor deposition, sputtering, and electrolytic plating, and a contact layer A5 is stacked in a region to form the wiring patterns 48 and 58.

[0041] Subsequently, the resultant is immersed in a stripping solution to strip the mold portion A2, whereby the wiring layers 44, 54 and the contact layers 45, 55 are formed in the region to form the wiring patterns 48 and 48, as shown in Fig. 4D. The end faces of the contact layers 45, 55 contacting the mold portion A2 are smoothly formed and parallel to each other, and respectively become the fixed contact 46 and the movable contact 56.

[0042] The adhesion layer A3 is then selectively etched using the etchant, to which the wiring layers 44, 54, the contact layers 45, 55 and the substrate A1 have resistance, to remove the region exposed from the contact layers 45, 55 of the adhesion layer A3 and over-etch the adhesion layer A3 to retreat the edge of the adhesion layer A3 from the edge of the wiring layers 44, 54 and pattern the adhesion layers 43, 53, as shown in Fig. 5A.

[0043] Thereafter, the substrate A1 is subjected to isotropic etching with the contact layers 45, 55 as the mask in the intermediate region A6 of the contact layer 45 and the contact layer 55. In this case, as shown in Fig. 5B, the substrate A1 is over-etched so that the upper surface of the substrate A1 is etched to a width wider than the opening width between the adhesion layers 43, 53 using the etching method, to which the contact layers 45, 55, the wiring layers 44, 54, and the adhesion layers 43, 53 have corrosion resistance, thereby forming a recess A7 at the upper surface of the substrate A1. In the method of isotropic etching the substrate A1, RIE (Reactive Ion Etching) is carried out (e.g., condition of pressure at 10 to 100 Pa, high frequency power at 50 to and 200W) with sulfur hexafluoride and perfluorocyclobutane as the gaseous species. The method of performing the isotropic etching also includes a method of performing dry etching using xenon gas for the gaseous species and a method of performing wet etching using fluoro nitric acid.

[0044] After the recess A7 is formed at the upper surface of the substrate A1 as shown in Fig. 5B, the substrate A1 is further subjected to anisotropic etching from the recess A7 side with the contact layers 45, 55 as the mask, the substrate A1 is divided to the fixed contact substrate 41 and the movable contact substrate 51 through the anisotropic etching so that the end face of the fixed contact substrate 41 is retreated than the fixed contact 46 and the end face of the movable contact substrate 51 is retreated than the movable contact 56 as shown in Fig. 5C. In the method of anisotropic etching, DRIE (Deep Reactive Ion Etching) is carried out (e.g., condition of pressure at 3 to 10 Pa, high frequency power at 200 to and 800W) with sulfur hexafluoride as the gaseous species. The method of performing the anisotropic etching also includes methods of performing ion milling, and wet etching using KOH aqueous solution and TMAH solution. The distance of the fixed contact substrate 41 and the movable contact substrate 51 after anisotropic etching (or extent of retreating the end faces of the fixed contact substrate 41, movable contact substrate 51) can be controlled by the width of the recess A7 of Fig. 5B.

[0045] The end faces of the wiring layers 44, 54 are then etched (etch backed) to incline the end faces 49, 59 of the wiring layers 44, 54. In Fig. 5D, the ends of the upper surfaces of the wiring layers 44, 54 are aligned with the fixed contact 46 and the movable contact 56, but may be retreated from the fixed contact 46 and the movable contact 56. The end faces 49, 59 of the wiring layers 44, 54 may not be inclined surfaces, and may be perpendicular surfaces parallel to the contacts 46, 56 as long as the end faces are retreated from the fixed contact 46 and the movable contact 56.

[0046] One of the blocks thereby becomes the fixed contact portion 33 in which the fixed contact substrate 41, the adhesion layer 43, the wiring layer 44, and the contact layer 45 are stacked. The fixed contact portion 33 is fixed to the upper surface of the base substrate 32 through the insulating film 42. The other block becomes the movable contact portion 34 in which the movable contact substrate 51, the adhesion layer 53, the wiring layer 54, and the contact layer 55 are stacked. The movable contact portion 34 is ultimately separate from the base substrate 32 by removing the insulating film at the lower surface through etching. The switch 31 (MEMS switch) is formed as a result.

[0047] In regards to the switch 31 formed in such manner, the surfaces that become the fixed contact 46 and the movable contact 56 are the surfaces parallel to the growing direction of the contact layers 45, 55 and are molded by both side surfaces of the mold portion A2, and hence such surfaces can be smoothly formed compared to the surfaces of the contact layers 45, 55, and the parallelism can also be enhanced. The contacts 46, 56 thus can be reliably brought into contact with each other, and the contact resistance between the contacts can be reduced. As the contacting surfaces of the contacts 46, 56 become smooth, discharge is less likely to occur when the contacts are brought close, welding of the fixed contact 46 and the movable contact 56 is also less likely to occur, and the open/lose lifespan of the switch 31 becomes longer.

[0048] Furthermore, according to such manufacturing method, the inter-contact distance between the fixed contact 46 and the movable contact 56 can be accurately determined by the width of the mold portion A2, and discharge is less likely to occur between the contacts, whereby the inter-contact distance between the fixed contact 46 and the movable contact 56 can be narrowed and the actuator can be driven at low voltage to open and close the contacts.

(Second manufacturing method)

[0049] The switch 31 may be formed through steps shown in Figs. 6A to 6D and Figs. 7A to 7D. The second manufacturing method will be described below.

[0050] First, as shown in Fig. 6A, the adhesion layer A3 is formed on the upper surface of the substrate A1 made of Si through vapor deposition, sputtering, and the like, and the wiring layer A4 and the contact layer A5 are stacked on the upper surface thereof.

[0051] The photoresist is then applied on the contact layer A5 and patterned to form the mold portion A2 in the region to form the wiring patterns 48 and 58, as shown in Fig. 6B. After the mold portion A2 is patterned, the exposed region of the contact layer A5 is selectively etched with the mold portion A2 as the mask to pattern the contact layers 45, 55 at the upper surface of the wiring layer A4 and form the fixed contact 46 and the movable contact 56 at the end faces of the contact layers 45, 55, respectively, as shown in Fig. 6C. The etchant is then changed, and the exposed region of the wiring layer A4 is selectively etched with the mold portion A2 as the mask to pattern the wiring layers 44, 54 on the adhesion layer A3, as shown in Fig. 6D.

[0052] Furthermore, the adhesion layer A3 is selectively etched using the etchant, to which the contact layers 45, 55 and the substrate A1 have resistance, to remove the region exposed from the contact layers 45, 55 of the adhesion layer A3 and over-etch the adhesion layer A3 to retreat the edge of the adhesion layer A3 from the edges of the wiring layers 44, 54 and pattern the adhesion layers 43, 53, as shown in Fig. 7A. It is then immersed in the stripping solution to strip the mold portion A2.

[0053] Thereafter, the recess A7 is formed at the upper surface of the substrate A1 through isotropic etching (Fig. 7B), the substrate A1 is subjected to anisotropic etching to be divided to the fixed contact substrate 41 and the movable contact substrate 51 (Fig. 7C), and the end faces 49, 59 of the wiring layers 44, 54 are etch backed (Fig. 7D) to form the switch 31 through the steps similar to Figs. 5B to 5D in the first manufacturing method.

[0054] In such method as well, the fixed contact 46 and the movable contact 56 can be formed by etching the contact layer A5 with the mold portion A2 as the mask, and hence the fixed contact 46 and the movable contact 56 can be formed so as to be smooth and so as to be parallel to each other. The inter-contact distance of the fixed contact 46 and the movable contact 56 can also be sized at high accuracy.

(Third manufacturing method)

[0055] The switch 31 may be formed through steps shown in Figs. 4A to 4D and Figs. 8A to 8D. In the third manufacturing method as well, the adhesion layer A3 is first formed on the upper surface of the substrate A1, the mold portion A2 is formed in the region other than the region to form the wiring patterns 48, 58, the wiring layer A4 and the contact layer A5 are stacked on the adhesion layer A3 in the region to form the wiring patterns 48, 58 and then the mold portion A2 is stripped with the stripping solution through the steps of Figs. 4A to 4D. The steps of Figs. 4A to 4D are already described, and thus will be omitted.

[0056] In the third manufacturing method, after the wiring layers 44, 54 and the contact layers 45, 55 are formed on the adhesion layer A3 through the steps of Figs. 4A to 4D, the adhesion layer A3 is selectively etched using the etchant, to which the contact layers 45, 55 and the substrate A1 have resistance, as shown in Fig. 8A. As a result, the region exposed from the contact layers 45, 55 of the adhesion layer A3 is removed, and the adhesion layer A3 is over-etched so that the edge of the adhesion layer A3 is retreated than the edges of the wring layers 44, 54.

[0057] Thereafter, the substrate A1 is subjected to anisotropic etching from the upper surface side with the contact layers 45, 55 as the mask in the intermediate region A6 of the contact layer 45 and the contact layer 55 to divide the substrate A1 into the fixed contact substrate 41 and the movable contact substrate 51 as shown in Fig. 8B. In the method of anisotropic etching, DRIE is carried out with sulfur hexafluoride as the gaseous species. The method of performing the anisotropic etching also includes methods of performing ion milling, and wet etching using KOH aqueous solution and TMAH solution.

[0058] The fixed contact substrate 41 and the movable contact substrate 51 are then subjected to isotropic etching from the upper side with the contact layers 45, 55 as the mask, and the recess A7 is formed at the corners on the upper surfaces of the fixed contact substrate 41 and the movable contact substrate 51, as shown in Fig. 8C. In this case, the substrate A1 is over-etched so that the upper surface of the substrate A1 is etched to a width wider than the opening width between the adhesion layers 43, 53 using the etching method, to which the contact layers 45, 55, the wiring layers 44, 54, and the adhesion layers 43, 53 have corrosion resistance. In the method of isotropic etching the fixed contact substrate 41 and the movable contact substrate 51, RIE is carried out with sulfur hexafluoride and perfluorocyclobutane as the gaseous species. The method of performing the isotropic etching also includes a method of performing dry etching using xenon gas for the gaseous species and a method of performing wet etching using fluoro nitric acid.

[0059] Moreover, the end faces of the wiring layers 44, 54 are etched (etch backed) to incline the end faces 49, 59 of the wiring layers 44, 54, as shown in Fig. 8D. In Fig. 5D, the ends at the upper surfaces of the wiring layers 44, 54 are aligned with the fixed contact 46 and the movable contact 56, but may be retreated from the fixed contact 46 and the movable contact 56. When etching back the end faces 49, 59 of the wiring layers 44, 54, the fixed contact substrate 41 and the movable contact substrate 51 are further etched at the same time to desirably retreat the end face of the fixed contact substrate 41 from the end face of the adhesion layer 43 and retreat the end face of the movable contact substrate 51 from the end face of the adhesion layer 53.

[Second embodiment]

(Structure)

[0060] Fig. 9 is a cross-sectional view showing a structure of a switch 31A according to a second embodiment of the present invention. In the switch 31A, the contact layer 45 is directly formed on the adhesion layer 43 formed on the upper surface of the fixed contact substrate 41 to form the fixed contact portion 33, and the contact layer 55 is directly formed on the adhesion layer 53 formed on the upper surface of the movable contact substrate 51 to form the movable contact portion 34. The second embodiment is the same as the first embodiment in that the end faces of the contact layers 45, 55 that face each other become the fixed contact 46 and the movable contact 56. Therefore, compared to the switch 31 of the first embodiment, the switch 31A does not include the wiring layers 44, 54, the wiring pattern 48 has a two-layer structure of the adhesion layer 43 and the contact layer 45, the wiring pattern 58 has a two-layer structure of the adhesion layer 53 and the contact layer 55, and the contact layers 45, 55 have both a function of bringing the contacts into contact with each other and a function (function of wiring layer) of transmitting signals.

(First manufacturing method)

[0061] Figs. 10A to 10D and Figs. 11A to 11C show one example of the manufacturing steps of the switch 31A.

[0062] Fig. 10A shows a state in which the adhesion layer A3 is formed on the upper surface of the substrate A1 made of Si through methods such as vapor deposition and sputtering. The adhesion layer A3 uses a material of high adhesiveness for the lower layer or a material such as Cr and Ti, and forms a material of low resistance or a material such as Au, Cu, and Al thereon. After the adhesion layer A3 is formed on the upper surface of the substrate A1, the photoresist is applied on the upper surface of the adhesion layer A3, the photoresist is patterned through the photolithography technique, and the mold portion A2 is arranged in a region other than the region to form the wiring patterns 48, 58 at the upper surface of the adhesion layer A3, as shown in Fig. 10B.

[0063] Then, as shown in Fig. 10C. the material of the contact layer is deposited on the adhesion layer A3 through the method such as vapor deposition, sputtering, and electrolytic plating, and the contact layer A5 is stacked in a region to form the wiring patterns 48 and 58.

[0064] Thereafter, the mold portion A2 is removed, and the contact layers 45, 55 are formed in the region to form the wiring patterns 48, 58, as shown in Fig. 10D. As a result, the end faces of the contact layers 45, 55 contacting the mold portion A2 are smoothly formed and parallel to each other, and become the fixed contact 46 and the movable contact 56, respectively.

[0065] The adhesion layer A3 is then selectively etched using the etchant, to which the contact layers 45, 55 and the substrate A1 have resistance, to remove the region exposed from the contact layers 45, 55 of the adhesion layer A3 and over-etch the adhesion layer A3 to retreat the edge of the adhesion layer A3 from the edges of the contact layers 45, 55 and pattern the adhesion layers 43, 53, as shown in Fig. 11A.

[0066] Thereafter, the substrate A1 is subjected to isotropic etching with the contact layers 45, 55 as the mask in the intermediate region A6 of the contact layer 45 and the contact layer 55. In this case, as shown in Fig. 11B, the substrate A1 is over-etched so that the upper surface of the substrate A1 is etched to a width wider than the opening width between the adhesion layers 43, 53 using the etching method, to which the contact layers 45, 55 and the adhesion layers 43, 53 have resistance, thereby forming the recess A7 at the upper surface of the substrate A1. In the method of isotropic etching the substrate A1, RIE is carried out (e.g., condition of pressure at 10 to 100 Pa, high frequency power at 50 to and 200W) with sulfur hexafluoride and perfluorocyclobutane as the gaseous species. The method of performing the isotropic etching also includes a method of performing dry etching using xenon gas for the gaseous species and a method of performing wet etching using fluoro nitric acid.

[0067] After the recess A7 is formed at the upper surface of the substrate A1 as shown in Fig. 11B, the substrate A1 is further subjected to anisotropic etching from the recess A7 side with the contact layers 45, 55 as the mask, the substrate A1 is divided to the fixed contact substrate 41 and the movable contact substrate 51 through the anisotropic etching and etched until the end face of the fixed contact substrate 41 and the end face of the movable contact substrate 51 are retreated than the ends of the adhesion layers, 43, 53, respectively as shown in Fig. 11C. In the method of anisotropic etching, DRIE (Deep Reactive Ion Etching) is carried out (e.g., condition of pressure at 3 to 10 Pa, high frequency power at 200 to and 800W) with sulfur hexafluoride as the gaseous species. The method of performing the anisotropic etching also includes methods of performing ion milling, and wet etching using KOH aqueous solution and TMAH solution. The distance of the fixed contact substrate 41 and the movable contact substrate 51 after anisotropic etching (or extent of retreating the end faces of the fixed contact substrate 41, movable contact substrate 51) can be controlled by the width of the recess A7 of Fig. 11B.

[0068] One of the blocks thereby becomes the fixed contact portion 33 in which the fixed contact substrate 41, the adhesion layer 43, and the contact layer 45 are sacked. The fixed contact portion 33 is fixed to the upper surface of the base substrate 32 through the insulating film 42. The block becomes the movable contact portion 34 in which the movable contact substrate 51, the adhesion layer 53, and the contact layer 55 are stacked. The movable contact portion 34 is ultimately separated from the base substrate 32 by removing the insulating film at the lower surface through etching. The switch 31A (MEMS switch) is thereby formed.

[0069] In regards to the switch 31A formed in such manner, the surfaces that become the fixed contact 46 and the movable contact 56 is molded by both side surfaces of the mold portion A2, and hence can be smoothly formed compared to the surfaces of the contact layers 45, 55 and the parallelism is also enhanced. The contacts 46, 56 thus can be reliably contacted, and the contact resistance between the contacts can be reduced. As the contacting surfaces of the contacts 46, 56 become smooth, discharge is less likely to occur when the contacts are brought close, welding of the fixed contact 46 and the movable contact 56 is also less likely to occur, and the open/close lifespan of the switch 31A becomes longer.

[0070] Furthermore, according to such a manufacturing method, the distance between the fixed contact 46 and the movable contact 56 can be accurately determined without variation by the width of the mold portion A2, and discharge is less likely to occur between the contacts, whereby the distance between the fixed contact 46 and the movable contact 56 can be narrowed and the actuator can be driven at low voltage to open and close the contacts.

(Second manufacturing method)

[0071] The switch 31A may be formed through steps shown in Figs. 12A to 12D and Figs. 13A to 13C. The second manufacturing method will be described below.

[0072] First, as shown in Fig. 12A, the adhesion layer A3 is formed on the upper surface of the substrate A1 made of Si through vapor deposition, sputtering, and the like, and the contact layer A5 is formed on the upper surface thereof.

[0073] The photoresist is then applied on the contact layer A5 and patterned to form the mold portion A2 in the region to form the wiring patterns 48 and 58, as shown in Fig. 12B. After the mold portion A2 is patterned, the exposed region of the contact layer A5 is selectively etched with the mold portion A2 as the mask to pattern the contact layers 45, 55 and form the fixed contact 46 and the movable contact 56 at the end faces of the contact layers 45, 55, respectively, as shown in Fig. 12C.

[0074] Furthermore, the adhesion layer A3 is selectively etched using the etchant, to which the contact layers 45, 55 and the substrate A1 have resistance, to remove the region exposed from the contact layers 45, 55 of the adhesion layer A3 and over-etch the adhesion layer A3 to retreat the edge of the adhesion layer A3 from the edges of the contact layers 45, 55 and pattern the adhesion layers 43, 53, as shown in Fig. 12D.

[0075] Thereafter, the substrate A1 is subjected to isotropic etching with the mold portion A2 as the mask in the intermediate region A6 of the contact layer 45 and the contact layer 55. In this case, as shown in Fig. 13A, the substrate A1 is over-etched so that the upper surface of the substrate A1 is etched to a width wider than the opening width between the adhesion layers 43, 53 using the etching method, to which the contact layers 45, 55 and the adhesion layers 43, 53 have resistance, thereby forming the recess A7 at the upper surface of the substrate A1.

[0076] After the recess A7 is formed at the upper surface of the substrate A1 as shown in Fig. 13B, the substrate A1 is further subjected to anisotropic etching from the recess A7 side with the mold portion A2 as the mask, the substrate A1 is divided to the fixed contact substrate 41 and the movable contact substrate 51 through the anisotropic etching so that the end face of the fixed contact substrate 41 and the end face of the movable contact substrate 51 are respectively retreated than the ends of the adhesion layers 43, 53 as shown in Fig. 13B.

[0077] The mold portion A2 on the wiring layers 44, 54 is then stripped by the stripping solution, thereby forming the switch 31A.

[0078] In the switch 31A formed in such manner, the surfaces that become the fixed contact 46 and the movable contact 56 are molded through etching, and thus can be smoothly formed compared to the surfaces of the contact layers 45, 55, and the parallelism is also enhanced. The contacts 46, 56 thus can be reliably brought into contact with each other, and the contact resistance between the contacts can be reduced. As the contacting surfaces of the contacts 46, 56 become smooth, discharge is less likely to occur when the contacts are brought close, welding of the fixed contact 46 and the movable contact 56 is also less likely to occur, and the open/close lifespan of the switch 31A becomes longer. The distance between the fixed contact 46 and the movable contact 56 thus can be narrowed, and the actuator can be driven at low voltage to open and close the contacts.

[0079] The fixed contact 46 and the movable contact 56 both project out from the end faces of each substrate 41, 51, the adhesion layers 43, 53, and the wiring layers 44, 54 in the switch 31, and the fixed contact 46 and the movable contact 56 both project out from the end faces of each substrate 41, 51, and the adhesion layers 43, 53 in the switch 31A, but only one of the contacts of the fixed contact 46 or the movable contact 56 may project out, and the other contact may be aligned with the ends of the substrate, the adhesion layers, and the like.

[Third embodiment]

[0080] A structure of a high frequency electrostatic relay 31B according to a third embodiment of the present invention will be described below. Fig. 14 is a plan view showing a structure of the electrostatic relay 31 B. Fig. 15 is a perspective view showing area A of Fig. 14 in an enlarged manner, and Fig. 16 is a schematic cross-sectional view taken along line B-B of Fig. 14.

[0081] The electrostatic relay 31B has the fixed contact portion 33, the movable contact portion 34, a fixed electrode portion 35, a movable electrode portion 36 for supporting the movable contact portion 34, an elastic spring 37, and a supporting portion 38 for supporting the elastic spring 37 on the upper surface of the base substrate 32 including the Si substrate, the glass substrate, or the like.

[0082] As shown in Fig. 16, the fixed contact portion 33 has the lower surface of the fixed contact substrate 41 made of Si fixed to the upper surface of the base substrate 32 by the insulating film 42 (SiO₂). As shown in Fig. 15, the adhesion layers 43a, 43b having a two-layer structure in which the material of high adhesiveness (e.g., material of Cr, Ti, etc.) is used for the lower layer and the low resistance material (e.g., material of Au, Cu, Al, etc.) is formed thereon are formed on the upper surface of the fixed contact substrate 41, and the wiring layers 44a, 44b of Pt and the like and the contact layers 45a, 45b are stacked on the adhesion layers 43a, 43b.

[0083] As shown in Fig. 14 and Fig. 15, the fixed contact substrate 41 extends in the width direction (X direction) at the end on the upper surface of the base substrate 32, where a bulging-out portion 41 a projecting out towards the movable contact portion 34 side is formed at the central part and pad supporting portions 41 b, 41 b are formed at both ends. The wiring patterns 48a, 48b are wired along the upper surface of the fixed contact substrate 41, where one of the ends of the wiring patterns 48a, 48b are arranged parallel to each other on the upper surface of the bulging-out portion 41 a, and the distal end faces of the contact layers 45a, 45b projecting out from the end face of the bulging-out portion 41 a are positioned within the same plane to become the fixed contacts 46a, 46b (electrical contacting surface), respectively. The other ends of the wiring patterns 48a, 48b have metal pad portions 47a, 47b formed on the upper surface of the pad supporting portions 41b, 41b. If the wiring pattern 48 has a three-layer structure of the adhesion layer 43a, 43b, the wiring layer 44a, 44b, and the contact layer 45a, 45b as in the switch 31 of Fig. 3, the contact layers 45a, 45b may not necessarily be arranged over the entire wiring patterns 48a, 48b, and merely need to be arranged at least near the bulging-out portion 41a including the fixed contact 46 and the movable contact 56.

[0084] The movable contact portion 34 is arranged at a position facing the bulging-out portion 41 a. As shown in Fig. 15, the movable contact portion 34 has the adhesion layer 53 including the lower layer Cr / the upper layer Au formed on the upper surface of the movable contact substrate 51 made of Si, where the wiring layer 54 of Pt and the like and the contact layer 55 are stacked on the adhesion layer 53. As shown in Fig. 16, the end face of the contact layer 55 facing the contact layers 45a, 45b projects out from the front surface of the movable contact substrate 51, and is also formed parallel to the fixed contacts 46a, 46b, whereby the relevant end face becomes the movable contact 56 (electrical contacting surface). The movable contact 56 has a width substantially equal to the distance from the edge on the outer side of the fixed contact 46a to the edge on the outer side of the fixed contact 46b.

[0085] The movable contact substrate 51 is supported in a cantilever manner by a supporting beam 57 projecting out from the movable electrode portion 36. The lower surfaces of the movable contact substrate 51 and the supporting beam 57 are floating from the upper surface of the base substrate 32, and can move parallel to the length direction (Y direction) of the base substrate 32 with the movable electrode portion 36.

[0086] In the electrostatic relay 31B, a main circuit (not shown) is connected to the metal pad portions 47a, 47b of the fixed contact portion 33, where the main circuit can be closed by contacting the movable contact 56 to the fixed contacts 46a, 46b, and the main circuit can be opened by separating the movable contact 56 from the fixed contacts 46a, 46b. The end faces of the wiring layers 44a, 44b, 54 are inclined to retreat towards the lower side, and the end faces of the bulging-out portion 41 a and the movable contact substrate are also retreated from the fixed contacts 46a, 46b and the movable contact 56, and hence the wiring layers 44a, 44b and the wiring layer 54 do not contact when closing the contacts thereby preventing the movable contact 56 and the fixed contacts 46a, 46b from causing contact failure.

[0087] The actuator for moving the movable contact portion 34 is configured by the fixed electrode portion 35, the movable electrode portion 36, the elastic spring 37. and the supporting portion 38.

[0088] As shown in Fig. 14, a plurality of fixed electrode portions 35 is arranged in parallel to each other on the upper surface of the base substrate 32. In plan view, the fixed electrode portion 35 has a branch-like electrode part 67 of a branch-shape extending in the Y direction from both surfaces of a rectangular pad portion 66. The branch-like electrode part 67 has a branch portion 68 projecting out so as to be symmetrical to each other, which branch portion 68 is lined at a constant pitch in the Y-direction.

[0089] As shown in Fig. 16, the lower surface of the fixed electrode substrate 61 is fixed to the upper surface of the base substrate 32 by the insulating film 62 in the fixed electrode portion 35. Furthermore, in the pad portion 66. the fixed electrode 63 is formed by Cu, Al, and the like on the upper surface of the fixed electrode substrate 61, and the electrode pad layer 65 is arranged on the fixed electrode 63.

[0090] As shown in Fig. 14, the movable electrode portion 36 is formed to surround each fixed electrode portion 35. The movable electrode portion 36 includes a comb teeth like electrode portion 74 formed so as to sandwich each fixed electrode portion 35 from both sides (branch-shape by a pair of comb teeth like electrode portions 74 between the fixed electrode portions 35). The comb teeth like electrode portion 74 is symmetric with each fixed electrode portion 35 as the center, where a comb teeth part 75 extends from each comb teeth like electrode portion 74 to a clearance between the branch portions 68. Furthermore, each comb teeth part 75 has the distance with the branch portion 68 positioned on the side close to the movable contact portion 34 adjacent to the comb teeth part 75 shorter than the distance with the branch portion 68 positioned on the side distant from the movable contact portion 34 adjacent to the comb teeth part 75.

[0091] The movable electrode portion 36 includes a movable electrode substrate 71 of Si, where the lower surface of the movable electrode substrate 71 is floating from the upper surface of the base substrate 32. The supporting beam 57 is arranged in a projecting manner at the center of the end face on the movable contact side of the movable electrode portion 36, and the movable contact portion 34 is held at the distal end of the supporting beam 57.

[0092] The supporting portion 38 is made of Si, and extends long in the X direction at the other end of the base substrate 32. The lower surface of the supporting portion 38 is fixed to the upper surface of the base substrate 32 by the insulating film 39. Both ends of the supporting portion 38 and the movable electrode portion 36 (movable electrode substrate 71) are connected by a pair of elastic springs 37 formed symmetrical by Si, where the movable electrode portion 36 is horizontally supported by the supporting portion 38 by way of the elastic spring 37. The movable electrode portion 36 is movable in the Y direction by elastically deforming the elastic spring 37.

[0093] In the electrostatic relay 31 B having the above structure, a DC voltage source is connected between the fixed electrode portion 35 and the movable electrode portion 36, and the DC voltage is turned ON and OFF by the control circuit and the like. In the fixed electrode portion 35, one terminal of the DC voltage source is connected to the electrode pad layer 65. The other terminal of the DC voltage source is connected to the supporting portion 38. The supporting portion 38 and the elastic spring 37 have conductivity, and the supporting portion 38, the elastic spring 37, and the movable electrode portion 36 are electrically conducted, and hence the voltage applied to the supporting portion 38 will be applied to the movable electrode portion 36.

[0094] When the DC voltage is applied between the fixed electrode portion 35 and the movable electrode portion 36 by the DC voltage source, an electrostatic attractive force is generated between the branch portion of the branch like electrode part 67 and the comb teeth part 75 of the comb teeth like electrode portion 74. However, the electrostatic attractive force in the X direction acting on the movable electrode portion 36 becomes balanced since the structure of the fixed electrode portion 35 and the movable electrode portion 36 is formed symmetric with respect to the center line of each fixed electrode portion 35, whereby the movable electrode portion 36 does not move in the X direction. Since the distance with the branch portion 68 positioned on the side close to the movable contact portion 34 adjacent to the comb teeth part 75 is shorter than the distance with the branch portion 68 positioned on the side distant from the movable contact portion 34 adjacent to the comb teeth part 75, each comb teeth part 75 is attracted to the movable contact portion side, and the movable electrode portion 36 moves in the Y direction white bending the elastic spring 37. As a result, the movable contact portion 34 moves to the fixed contact portion 33 side, and the movable contact 56 comes into contact with the fixed contacts 46a, 46b thereby electrically closing the fixed contact 46a and the fixed contact 46b (main circuit).

[0095] When the DC voltage applied between the fixed electrode portion 35 and the movable electrode portion 36 is released, the electrostatic attractive force between the branch portion 68 and the comb teeth part 75 disappears, whereby the movable electrode portion 36 moves backward in the Y direction by the elastic returning force of the elastic spring 37 thereby separating the movable contact 56 from the fixed contacts 46a, 46b and opening the fixed contact 46a and the fixed contact 46b (main circuit).

[0096] The electrostatic relay 31 B is formed through the following steps. First, the Si substrate 32 (another Si wafer having conductivity) is joined to the upper surface of the base substrate (Si wafer, SOI wafer, etc.) having the entire surface covered with the insulating film, and the metal material is vapor deposited on the upper surface of the Si substrate to form the electrode film. The electrode film is then patterned by the photolithography technique, and the fixed electrode 63 is formed on the upper surface of the fixed electrode substrate 61 at the pad portion 66 by the electrode film.

[0097] Then, the adhesion layer is formed on the upper surface of the Si substrate from above the electrode film, and then the wiring layer and the contact layer are stacked thereon. The contact layer, the wiring layer, and the adhesion layer are then patterned to form the wiring pattern 48 of the fixed contact portion 33 and the wiring pattern 58 of the movable contact portion 34. The electrode pad layer 65 is formed on the fixed electrode 63 at the pad portion 66.

[0098] Thereafter, the Si substrate is etched with the photoresist, and the like as the etching mask, and the fixed contact substrate 41 of the fixed contact portion 33, the movable contact substrate 51 of the movable contact portion 34, the fixed electrode substrate 61 of the fixed electrode portion 35, the movable electrode substrate 71 of the movable electrode portion 36, the elastic spring 37, and the supporting portion 38 are formed from the Si substrate remaining in each region.

[0099] Lastly, the insulating film of the region exposed from the Si substrate and the insulating film at the lower surfaces of the moveable contact portion 34 and the movable electrode portion 36 are removed through etching, and then cut to individual electrostatic relay 31B.

[0100] The movable contact portion 34 and the fixed electrode portion 35 are formed through steps similar to the steps described in relation to the switch 31 of the first embodiment in the manufacturing steps of the electrostatic relay 31B, and hence the fixed contacts 46a, 46b of the fixed contact portion 33 and the movable contact 56 of the movable contact portion 34 become side surfaces parallel to the growing direction of the contact layer, and a contact having satisfactory smoothness and parallelism can be obtained without performing grinding and the like. Effects similar to the switch 31 of the first embodiment thus can be obtained in the electrostatic relay 31B as well.

Claims

1. A switch (31, 31A) comprising a first contact portion in which a plurality of layers including a first contact layer (45, 45a. 45b, 55, A5) is formed on the upper side of a first substrate; and a second contact portion in which a plurality of layers inducing a second contact layer (45, 45a, 45b, 55, A5) is formed on an upper side of a second substrate, wherein
an end face parallel to a growing direction when forming the contact layer (45, 45a, 45b, 55, A5) in the first contact layer (45, 45a, 45b, 55, A5) is a contact of the first contact portion;
an end face parallel to a growing direction when forming the contact layer (45, 45a, 45b, 55, A5) in the second contact layer (45, 45a, 45b, 55, A5) is a contact of the second contact portion; the contact of the contact portion projects out than an end face of a layer other than the contact layer (45, 45a, 45b, 55, A5) in the contact portion and the substrate of the contact portion in at least one of the contact portions of the first contact portion or the second contact portion; and
the contact of the first contact portion and the contact of the second contact portion face each other so that the contacts come into contact with or separate from each other.

2. The switch (31, 31A) according to claim 1, wherein the first and second contact layers (45, 45a, 45b, 55, A5) are formed from one of a noble mental, an alloy, an Si material having conductivity, and a conductive oxide.

3. The switch (31, 31A) according to claim 1, wherein the first contact portion has a first wiring layer (45, 45a, 45b, 55, A5) formed on the upper side of the first substrate and the first contact layer (45, 45a, 45b, 55, A5) formed on the upper surface of the first wiring layer(45, 45a, 45b, 55, A5); and the second contact portion has a second wiring layer (45, 45a, 45b, 55, A5) formed on the upper side of the second substrate and the second contact layer (45, 45a, 45b, 55, A5) formed on the upper surface of the second wiring layer (45, 45a, 45b, 55, A5).

4. The switch (31, 31A) according to claim 3, wherein an end face of the wiring layer (45, 45a, 45b, 55, A5) of the contact portion is an incline surface gradually retreating in a direction of approaching the substrate of the contact portion from an end on the side contacting the contact layer (45, 45a, 45b, 55, A5) of the contact portion in at least one of the contact portions in which the contact projects out than the end faces of the layer other than the contact layer (45, 45a, 45b, 55, A5) and the substrate.

5. The switch (31, 31A) according to claim 3, wherein the first and second wiring layers (45, 45a, 45b, 55, A5) are formed from one of a noble metal, an alloy, an Si material having conductivity, or a conductive oxide.

6. A method for manufacturing a switch (31, 31A) comprising: the steps of
growing a plurality of layers including a contact layer (45, 45a, 45b, 55, A5) in a thickness direction of a substrate at an upper side of the substrate to form a plurality of layers including the contact layer (45, 45a, 45b, 55, A5) on the upper side of the substrate, and forming a mold portion (A2) of a predetermined pattern at an uppermost surface;
etching the plurality of layers including the contact layer (45, 45a, 45b, 55, A5) with the mold portion (A2) as a mask to divide the plurality of layers including the contact layer (45, 45a, 45b, 55, A5) to a plurality of regions and forming a surface to become a contact from the etched surface of the contact layer(45, 45a, 45b, 55, A5);
performing isotropic etching on a surface of the substrate between the divided regions of a plurality of layers including the contact layer (45, 45a, 45b, 55, A5) to form a recess (A7) at the surface of the substrate;
performing anisotropic etching on the substrate between the divided regions of the plurality of layers including the contact layer (45, 45a, 45b, 55, A5) to divide the substrate into plurals in accordance with the divided region of the plurality of layers including the contact layer (45, 45a, 45b, 55, A5); and
etching a layer other than the contact layer (45, 45a, 45b, 55, A5) in at least one region of the divided regions to retreat an end face of the layer other than the contact layer (45, 45a, 45b, 55, A5) than a surface to become the contact of the contact layer (45, 45a, 45b, 55, A5).

7. A method for manufacturing a switch (31, 31 A) comprising the steps of:

forming a mold portion (A2) of a predetermined pattern on an upper side of a substrate;

growing a plurality of layers including a contact layer (45, 45a, 45b, 55, A5) in a thickness direction of the substrate in a plurality of regions excluding a region where the mold portion is formed at the upper side of the substrate to form a plurality of layers including the contact layer (45, 45a, 45b, 55, A5) on the upper side of the substrate;

removing the mold portion (A2) and forming a surface to become a contact from a surface contacting a side surface of the mold portion (A2) of the contact layer (45, 45a, 45b, 55, A5);

performing isotropic etching on a surface of the substrate between the separated regions of the plurality of layers including the contact layer (45, 45a, 45b, 55, A5) to form a recess (A7) at the surface of the substrate; performing anisotropic etching on the substrate between the separated regions of the plurality of layers including the contact layer (45, 45a, 45b, 55, A5) to divide the substrate into plurals in accordance with the separated region of the plurality of layers including the contact layer (45, 45a, 45b, 55, A5); and

etching a layer other than the contact layer (45, 45a, 45b, 55, A5) in at least one region of the separated regions to retreat an end face of the layer other than the contact layer than a surface to become the contact of the contact layer (45, 45a, 45b, 55, A5).

8. The method for manufacturing the switch (31, 31A) according to claim 6 or 7, wherein the contact layer (45, 45a, 45b, 55, A5) is formed through a deposition method such as vapor deposition, sputtering, MBE, CVD, plating, spraying method, sol-gel method, inkjet method, and screen printing.

9. The method for manufacturing the switch (31, 31A) according to claim 6 or 7, wherein the plurality of layers including the contact layer (45, 45a, 45b, 55, A5) has a contact layer (45, 45a, 45b, 55, A5) formed on an upper surface of a wiring layer (45, 45a, 45b, 55, A5) formed on the upper side of the substrate.

10. The method for manufacturing the switch (31, 31A) according to claim 9, wherein the step of retreating the end face of the layer other than the contact layer (45, 45a, 45b, 55, A5) than the surface to become the contact of the contact layer (45, 45a, 45b, 55, A5) includes inclining the end face of the wiring layer (45, 45a, 45b, 55, A5) so as to greatly retreat towards the substrate from the contact layer side.

11. The method for manufacturing the switch (31, 31A) according to claim 9, wherein the wiring layer (45, 45a, 45b, 55, A5) is formed through a deposition method such as vapor deposition, sputtering, MBE, CVD, plating, spraying method, sol-gel method, inkjet method, and screen printing.

12. A relay comprising the switch (31, 31A) according to claim 1, and an actuator for moving at least one of the first contact portion and the second contact portion in a direction perpendicular to contacting surfaces of a contact of the first contact portion and a contact of the second contact portion to contact or separate the contacts to and from each other.

Drawing