WO2022153697A1 - Mems switch and manufacturing method for mems switch - Google Patents

Mems switch and manufacturing method for mems switch Download PDF

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Publication number
WO2022153697A1
WO2022153697A1 PCT/JP2021/043956 JP2021043956W WO2022153697A1 WO 2022153697 A1 WO2022153697 A1 WO 2022153697A1 JP 2021043956 W JP2021043956 W JP 2021043956W WO 2022153697 A1 WO2022153697 A1 WO 2022153697A1
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WIPO (PCT)
Prior art keywords
insulating layer
layer
base layer
face
mems switch
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PCT/JP2021/043956
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French (fr)
Japanese (ja)
Inventor
理 松島
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ローム株式会社
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Application filed by ローム株式会社 filed Critical ローム株式会社
Priority to JP2022575115A priority Critical patent/JPWO2022153697A1/ja
Publication of WO2022153697A1 publication Critical patent/WO2022153697A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H57/00—Electrostrictive relays; Piezoelectric relays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H59/00—Electrostatic relays; Electro-adhesion relays

Definitions

  • This disclosure relates to a MEMS switch and a method for manufacturing a MEMS switch.
  • Patent Document 1 discloses a MEMS switch.
  • This MEMS switch includes a fixed contact portion and a movable contact portion.
  • the fixed contact portion has a lower surface fixed to the upper surface of the base substrate via an insulating film.
  • the movable contact portion floats from the upper surface of the base substrate.
  • the movable contact portion is moved by the actuator in a direction parallel to the upper surface of the base substrate.
  • An MEMS switch as an example of the present disclosure has a first main surface and a second main surface on the opposite side thereof, and is formed on a substrate in which a cavity is formed and on the first main surface side of the substrate.
  • An actuator unit that converts an electric signal into a mechanical operation
  • a movable contact unit that is formed on the first main surface side of the substrate in a state of floating in the cavity and can be displaced by the mechanical operation of the actuator unit, and the above.
  • a fixed contact portion facing the movable contact portion and capable of contacting and not contacting the movable contact portion due to displacement of the movable contact portion is included, and at least one of the movable contact portion and the fixed contact portion includes the substrate and the fixed contact portion.
  • the first insulating layer formed on the substrate and the first insulating layer formed on the first insulating layer so as to cover the end faces of the first insulating layer along the thickness direction of the substrate are referred to as the first insulating layer. It has a first structure including a second insulating layer containing different materials and a conductive contact layer supported by the first insulating layer.
  • FIG. 1 is a schematic plan view of a MEMS switch according to an embodiment of the present disclosure.
  • FIG. 2 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure.
  • 3A and 3B are schematic views showing the operation of the MEMS switch of FIG. 4A and 4B are schematic views (enlarged views) showing the operation of the MEMS switch of FIG.
  • FIG. 5A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG.
  • FIG. 5B is a diagram showing the next step of FIG. 5A.
  • FIG. 5C is a diagram showing the next step of FIG. 5B.
  • FIG. 5D is a diagram showing the next step of FIG. 5C.
  • FIG. 5E is a diagram showing the next step of FIG. 5D.
  • FIG. 5F is a diagram showing the next step of FIG. 5E.
  • FIG. 5G is a diagram showing the next step of FIG. 5F.
  • FIG. 5H is a diagram showing the next step of FIG. 5G.
  • FIG. 6 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure.
  • FIG. 7A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG.
  • FIG. 7B is a diagram showing the next step of FIG. 7A.
  • FIG. 7C is a diagram showing the next step of FIG. 7B.
  • FIG. 7D is a diagram showing the next step of FIG. 7C.
  • FIG. 7E is a diagram showing the next step of FIG. 7D.
  • FIG. 7F is a diagram showing the next step of FIG. 7E.
  • FIG. 7G is a diagram showing the next step of FIG. 7F.
  • FIG. 7H is a diagram showing the next step of FIG. 7G.
  • FIG. 8 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure.
  • FIG. 9A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG.
  • FIG. 9B is a diagram showing the next step of FIG. 9A.
  • FIG. 9C is a diagram showing the next step of FIG. 9B.
  • FIG. 9D is a diagram showing the next step of FIG. 9C.
  • FIG. 9E is a diagram showing the next step of FIG. 9D.
  • FIG. 9F is a diagram showing the next step of FIG. 9E.
  • FIG. 9G is a diagram showing the next step of FIG.
  • FIG. 9F is a diagram showing the next step of FIG. 9G.
  • FIG. 10 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure.
  • FIG. 11A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG.
  • FIG. 11B is a diagram showing the next step of FIG. 11A.
  • FIG. 11C is a diagram showing the next step of FIG. 11B.
  • FIG. 11D is a diagram showing the next step of FIG. 11C.
  • FIG. 11E is a diagram showing the next step of FIG. 11D.
  • FIG. 11F is a diagram showing the next step of FIG. 11E.
  • FIG. 11G is a diagram showing the next step of FIG. 11F.
  • FIG. 11H is a diagram showing the next step of FIG. 11G.
  • the MEMS switch as the first example of the present disclosure has a first main surface and a second main surface on the opposite side thereof, and is formed on a substrate in which a cavity is formed and on the first main surface side of the substrate.
  • An actuator unit that converts an electric signal into a mechanical operation, and a movable contact portion that is formed in a state of floating in the cavity on the first main surface side of the substrate and can be displaced by the mechanical operation of the actuator unit.
  • a fixed contact portion facing the movable contact portion and capable of contacting and not contacting the movable contact portion due to displacement of the movable contact portion is included, and at least one of the movable contact portion and the fixed contact portion is the substrate.
  • the end face of the first insulating layer of the first structure is covered with the second insulating layer.
  • the substrate is a semiconductor substrate containing impurities
  • the first insulating layer directly under the contact layer is excessively etched, a part of the contact layer may float in the air and come into contact with the semiconductor substrate. This type of contact can lead to poor switching of the MEMS switch.
  • the MEMS switch of the present disclosure such switching failure can be suppressed.
  • the substrate is formed on the first base layer, the first base layer, and the embedded insulating layer containing the same material as the first insulating layer, and the embedded insulation.
  • the cavity is formed between the first base layer and the second base layer, and is partitioned from the side by the embedded insulating layer, including a second base layer formed on the layer.
  • the first insulating layer may be formed on the second base layer.
  • the first insulating layer and the embedded insulating layer contain the same material, but the end face of the first insulating layer is covered with the second insulating layer. Therefore, for example, when a part of the embedded insulating layer is removed by etching to form a cavity between the first base layer and the second base layer, the first insulating layer is prevented from being etched from the end face. be able to.
  • the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the first In the structure, the second insulating layer may cover the end face of the first insulating layer so as to have an end portion at the boundary between the end face of the second base layer and the end face of the first insulating layer.
  • the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the first In the structure, the second insulating layer may further cover the end face of the second base layer in addition to the end face of the first insulating layer.
  • the second base layer of the first structure has an end face. Etching can be suppressed.
  • a part of the first insulating layer is formed between the end face of the second base layer and the end face of the first insulating layer.
  • a step may be formed so as to project from the end face of the base layer.
  • the actuator portion is an electrostatic actuator formed on the second base layer while floating with respect to the cavity, and the fixed electrodes and the fixed electrodes are arranged alternately.
  • the movable electrode includes a comb-tooth type electrostatic actuator that is displaced by an electrostatic force between the movable electrode and the fixed electrode, and the movable contact portion is said to be via a connecting member connected to the movable electrode. It may be provided so as to be displaceable with respect to the electrostatic actuator.
  • At least one of the movable electrode and the fixed electrode has a second structure including the second base layer, the first insulating layer, and the second insulating layer. You may have.
  • the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the second base layer is connected to the end face.
  • the second insulating layer may cover the end face of the first insulating layer so as to have an end portion at the boundary between the end face of the second base layer and the end face of the first insulating layer.
  • the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the second base layer is connected to the end face.
  • the second insulating layer may further cover the end face of the second base layer in addition to the end face of the first insulating layer.
  • the second base layer of the second structure has an end face. Etching can be suppressed. As a result, the distance between the movable electrode and the fixed electrode can be maintained almost as designed.
  • a part of the first insulating layer is formed between the end face of the second base layer and the end face of the first insulating layer.
  • a step may be formed so as to project from the end face of the base layer.
  • the first insulating layer has a main surface intersecting the end surface of the first insulating layer, and the second insulating layer is the first insulating layer.
  • the main surface and the end surface are continuously covered, and the contact layer may face the main surface and the end surface of the first insulating layer via the second insulating layer.
  • the first insulating layer may contain silicon oxide (SiO 2 ), and the second insulating layer may contain aluminum oxide (Al 2 O 3 ).
  • a method for manufacturing a MEMS switch as a second example of the present disclosure includes a first base layer, an embedded insulating layer formed on the first base layer, and a second base layer formed on the embedded insulating layer.
  • the first insulating layer containing a material different from the first insulating layer is provided so as to cover the main surface of the first insulating layer and the end surface of the first insulating layer exposed to the first opening.
  • the second base layer partitioned by the through hole and the first on the second base layer.
  • the first base layer and the second base layer are formed by forming a movable contact portion and a fixed contact portion including the insulating layer and the second insulating layer, and etching the embedded insulating layer through the through hole.
  • the process includes a step of forming a cavity between the two, and a step of forming a contact layer on the first insulating layer by depositing a conductive material in a predetermined pattern after etching the embedded insulating layer.
  • the end face of the first insulating layer is covered with the second insulating layer. This makes it possible to prevent the first insulating layer from being etched from the end face when the embedded insulating layer is etched through the through hole. Therefore, it is possible to prevent the first insulating layer immediately below the contact layer from being removed by etching, so that the contact layer can be stably supported by the first insulating layer.
  • a method for manufacturing a MEMS switch as a third example of the present disclosure includes a first base layer, an embedded insulating layer formed on the first base layer, and a second base layer formed on the embedded insulating layer.
  • the second base layer partitioned by the through hole, a movable contact portion including the first insulating layer on the second base layer, and fixing
  • the step of forming the contact portion, the main surface of the first insulating layer, the end surface of the first insulating layer exposed to the first opening, and the end surface of the second base layer exposed to the through hole are covered.
  • the first insulating layer is formed.
  • a contact layer is formed on the first insulating layer by a step of forming a cavity between the base layer and the second base layer and by depositing a conductive material in a predetermined pattern after etching the embedded insulating layer. Including the process.
  • the end face of the first insulating layer is covered with the second insulating layer. This makes it possible to prevent the first insulating layer from being etched from the end face when the embedded insulating layer is etched through the through hole. Therefore, it is possible to prevent the first insulating layer immediately below the contact layer from being removed by etching, so that the contact layer can be stably supported by the first insulating layer.
  • the end face of the second base layer is also covered and protected by the second insulating layer, it is possible to prevent the second base layer from being etched from the end face.
  • the step of forming the second insulating layer forms the second insulating layer by an atomic layer deposition method (ALD). It may include a step.
  • ALD atomic layer deposition method
  • FIG. 1 is a schematic plan view of the MEMS switch A1 according to the embodiment of the present disclosure.
  • FIG. 2 is a schematic cross-sectional view of the MEMS switch A1 according to the embodiment of the present disclosure.
  • FIG. 2 does not show a cross section of a specific portion of the MEMS switch A1 of FIG.
  • FIG. 2 some configurations of the MEMS switch A1 are extracted and shown in order to clarify the structure of the MEMS switch A1.
  • the MEMS switch A1 is, for example, an electrostatically driven MEMS switch including an electrostatic actuator 2.
  • the MEMS switch A1 generates a driving force along the first direction X by, for example, mechanical operation of the electrostatic actuator 2.
  • the direction orthogonal to the first direction X in the horizontal direction is the second direction Y
  • the direction orthogonal to the first direction X in the vertical direction is the third direction Z.
  • the third direction Z may be defined as the thickness direction of the MEMS switch A1 and the thickness direction of the substrate 3 described later.
  • the first direction X and the second direction Y may be defined as directions orthogonal to the thickness direction of the substrate 3, which will be described later.
  • the MEMS switch A1 includes the substrate 3.
  • the substrate 3 may form the outer shape of the MEMS switch A1.
  • the substrate 3 may be a structure formed in a chip shape (rectangular cuboid shape). 1 and 2 show a part of the substrate 3.
  • the substrate 3 may be a semiconductor substrate containing a semiconductor material such as Si.
  • the substrate 3 has a first main surface 4 and a second main surface 5 on the opposite side of the first main surface 4.
  • the first main surface 4 may be the upper surface of the substrate 3, and the second main surface 5 may be the lower surface of the substrate 3.
  • the first main surface 4 may be a processed surface of the substrate 3 on which the MEMS structure is formed, and the second main surface 5 may be a non-processed surface with respect to the processed surface.
  • the substrate 3 includes a first base layer 6, a second base layer 7, and an embedded insulating layer 8 between the first base layer 6 and the second base layer 7.
  • the substrate 3 may be an SOI (Silicon on Insulator) substrate.
  • the first base layer 6 may be a Si substrate
  • the second base layer 7 may be a Si layer
  • the embedded insulating layer 8 may be a BOX (Buried Oxide) layer.
  • the first base layer 6 may be a semiconductor substrate (for example, a Si substrate).
  • the thickness of the first base layer 6 may be, for example, 10 ⁇ m or more and 700 ⁇ m or less.
  • the first base layer 6 has a first main surface 9 and a second main surface 10 on the opposite side of the first main surface 9.
  • the second main surface 10 of the first base layer 6 may be the second main surface 5 of the substrate 3.
  • the second base layer 7 may be a semiconductor layer (for example, a Si layer).
  • the thickness of the second base layer 7 may be, for example, 10 ⁇ m or more and 100 ⁇ m or less.
  • the second base layer 7 has a first main surface 11 and a second main surface 12 on the opposite side of the first main surface 11.
  • the first main surface 11 of the second base layer 7 may be the first main surface 4 of the substrate 3.
  • the embedded insulating layer 8 is in contact with and sandwiched between the first base layer 6 and the second base layer 7.
  • the embedded insulating layer 8 may be an insulating layer containing the first insulating material.
  • the first insulating material may be, for example, an insulating material containing silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or the like.
  • the first insulating material may be, for example, an insulating material that can be etched by an etching gas such as CF 4 , CHF 3 , SF 6 , and an etching solution.
  • the thickness of the embedded insulating layer 8 may be smaller than that of the first base layer 6 and the second base layer 7.
  • the thickness of the embedded insulating layer 8 may be, for example, 0.1 ⁇ m or more and 20 ⁇ m or less.
  • the embedded insulating layer 8 has a first joint surface 13 in contact with the second main surface 12 of the second base layer 7, and a second joint surface 14 in contact with the first main surface 9 of the first base layer 6. ..
  • the embedded insulating layer 8 further has a side surface 15.
  • the side surface 15 of the embedded insulating layer 8 faces the cavity 16 from the side. In other words, the side surface 15 of the embedded insulating layer 8 faces the cavity 16 in the first direction X and the second direction Y.
  • the embedded insulating layer 8 is partially formed between the first base layer 6 and the second base layer 7. In the region between the first base layer 6 and the second base layer 7, the region where the embedded insulating layer 8 is not formed is the cavity 16.
  • the cavity 16 is partitioned by a first main surface 9 of the first base layer 6, a second main surface 12 of the second base layer 7, and a side surface 15 of the embedded insulating layer 8.
  • the bottom surface of the cavity 16 is the first main surface 9 of the first base layer 6,
  • the upper surface of the cavity 16 is the second main surface 12 of the second base layer 7, and
  • the side surface 15 of the cavity 16 is the side surface of the embedded insulating layer 8. It may be 15.
  • the second base layer 7 includes a fixed structure 17 and a movable structure 18 that can be displaced with respect to the fixed structure 17.
  • the fixing structure 17 has a frame portion 19 fixed to the first joint surface 13 of the embedded insulating layer 8 and a first cantilever supported by the frame portion 19 in a floating state with respect to the cavity 16. Includes structure 20 and.
  • the frame portion 19 may include a pair of strip-shaped frame portions 19 extending parallel to each other in the first direction X.
  • the first cantilever structure 20 may include a plurality of first cantilever structures 20 extending parallel to each other in the second direction Y from the frame portion 19. In this embodiment, four first cantilever structures 20 are mechanically connected to the frame portion 19. Since the first cantilever structure 20 is an electrode fixed via the frame portion 19, it may be defined as a fixed electrode 21.
  • the movable structure 18 is formed so as to be entirely floating with respect to the cavity 16. With reference to FIG. 1, the movable structure 18 includes a connecting member 22 and a second cantilever structure 23.
  • the connecting member 22 may include a strip-shaped connecting member 22 extending in the first direction X.
  • the second cantilever structure 23 may include a plurality of second cantilever structures 23 extending parallel to each other in the second direction Y from the connecting member 22. In this embodiment, four second cantilever structures 23 extending from the connecting member 22 toward the frame portion 19 are mechanically connected to the connecting member 22.
  • the second cantilever structure 23 extends between adjacent first cantilever structures 20 toward the frame portion 19.
  • the first cantilever structure 20 and the second cantilever structure 23 extend in parallel with each other with a gap 55 in between. Since the second cantilever structure 23 is an electrode supported by the connecting member 22 while floating with respect to the cavity 16, it may be defined as a movable electrode 24.
  • the integrated structure of the connecting member 22 and the second cantilever structure 23 may be defined as the movable electrode 24. Since the connecting member 22 is a member that presses the movable contact portion 45 against the fixed contact portion 46 described later, it may be defined as a push rod.
  • the first cantilever structure 20 and the second cantilever structure 23 are each formed in a comb-teeth shape and mesh with each other at intervals.
  • the comb-tooth type electrode 25 including the first cantilever structure 20 (fixed electrode 21) and the second cantilever structure 23 (movable electrode 24) is formed.
  • an electrostatic force is generated between the fixed electrode 21 and the movable electrode 24.
  • the comb-toothed electrode 25 may be defined as an electrostatic actuator 2 that converts an electrical signal into a mechanical displacement along the first direction X.
  • the first cantilever structure 20 and the second cantilever structure 23 face each other in the first direction X.
  • the first cantilever structure 20 and the second cantilever structure 23 may be arranged alternately along the first direction X.
  • the second cantilever structure 23 and the first cantilever structure 20 are defined as the first movable electrode 24A, the first fixed electrode 21A, the second movable electrode 24B, and the second fixed electrode 21B in the order of arrangement in the first direction X. You may.
  • the first fixed electrode 21A is sandwiched between the first movable electrode 24A and the second movable electrode 24B at intervals in the first direction X.
  • the second movable electrode 24B is sandwiched between the first fixed electrode 21A and the second fixed electrode 21B at intervals in the first direction X.
  • the distance between one fixed electrode 21 and a pair of movable electrodes 24 adjacent to the fixed electrode 21 may be different from each other.
  • the distance between one movable electrode 24 and a pair of fixed electrodes 21 adjacent to the movable electrode 24 may be different from each other.
  • the distance d1 between the first movable electrode 24A and the first fixed electrode 21A may be smaller than the distance d2 between the second movable electrode 24B and the first fixed electrode 21A.
  • the distance d2 between the second movable electrode 24B and the first fixed electrode 21A may be larger than the distance d3 between the second movable electrode 24B and the second fixed electrode 21B.
  • the asymmetric structure 72 in which the distance between the fixed electrode 21 and the movable electrode 24 varies is provided.
  • This asymmetric structure 72 upsets the balance of the electrostatic force in the comb-tooth type electrode 25.
  • an electrostatic force acting between the second movable electrode 24B and the second fixed electrode 21B acts between the second movable electrode 24B and the first fixed electrode 21A. It can be made larger than the electrostatic force (first electrostatic force F1). Therefore, the movable structure 18 is displaced toward the fixed contact portion 46 by the electrostatic force corresponding to the difference between the first electrostatic force F1 and the second electrostatic force F2 (first electrostatic force F1-second electrostatic force F2). Can be done.
  • the movable structure 18 is mechanically connected to the fixed structure 17 via a beam portion 27 so as to be displaceable.
  • the beam portion 27 is formed by utilizing the second base layer 7 as in the fixed structure 17 and the movable structure 18.
  • the beam portion 27 is formed in a band shape extending from both sides of the connecting member 22 in the second direction Y toward the frame portion 19 along the second direction Y.
  • the first end 28 in the longitudinal direction of the beam 27 and the second end 29 on the opposite side thereof are mechanically connected to the frame 19 and the connecting member 22, respectively.
  • two beam portions 27 may be formed on both sides of the comb tooth type electrode 25 in the first direction X, for a total of four beams.
  • the movable structure 18 is supported at four points by the beam portion 27 in a state of floating with respect to the cavity 16.
  • Each beam portion 27 may be connected perpendicularly to the connecting member 22.
  • the beam portion 27 has flexibility.
  • the beam portion 27 can be elastically bent in the first direction X.
  • the second end portion 29, which is a free end opposite to the fixed end can be displaced in the first direction X with respect to the first end portion 28, which is a fixed end fixed to the frame portion 19.
  • it may have flexibility.
  • the beam portion 27 has a flexible structure for connecting the fixed structure 17 and the movable structure 18, it may be defined as a flexible connection structure.
  • the beam portion 27 may be defined as a spring structure that bends in the first direction X.
  • the beam portion 27 may be defined as a structure included in the movable structure 18.
  • the integrated structure of the connecting member 22, the second cantilever structure 23, and the beam portion 27 may be defined as the movable electrode 24.
  • the MEMS switch A1 includes a movable contact portion 45 and a fixed contact portion 46.
  • the movable contact portion 45 is provided on the connecting member 22 of the movable structure 18.
  • the movable contact portion 45 is provided at the end portion 47 in the longitudinal direction of the connecting member 22.
  • the second beam portion 48 is mechanically connected to the end portion 47 of the connecting member 22.
  • the second beam portion 48 has a linear shape extending in a direction intersecting the longitudinal direction of the connecting member 22.
  • the second beam portion 48 extends from the end portion 47 of the connecting member 22 on both sides in the crossing direction.
  • the movable contact portion 45 is selectively formed on the second side portion 50 of the first side portion 49 and the second side portion 50 in the width direction of the second beam portion 48.
  • the first side portion 49 of the second beam portion 48 is a side portion facing the electrostatic actuator 2 in the first direction X, and the second side portion 50 is the opposite side of the first side portion 49.
  • the movable contact portion 45 has a first structure 51 formed in a floating state with respect to the cavity 16.
  • the first structure 51 includes a second base layer 7, a first insulating layer 36, a second insulating layer 37, and a movable contact layer 52.
  • the first insulating layer 36 is formed on the second base layer 7.
  • the first insulating layer 36 has an end surface 53 along the thickness direction of the substrate 3 (in this embodiment, the third direction Z) and a main surface 54 intersecting the end surface 53.
  • the main surface 54 of the first insulating layer 36 is formed along the first main surface 4 of the substrate 3.
  • the end surface 53 of the first insulating layer 36 of the first structure 51 faces the fixed contact portion 46 via a gap 55 between the first insulating layer 36 and the fixed contact portion 46.
  • the second base layer 7 has an end surface 83 facing the fixed contact portion 46 via a gap 55 so as to be connected to the end surface 53 of the first insulating layer 36.
  • the first insulating layer 36 may contain, for example, the same first insulating material as the embedded insulating layer 8.
  • the first insulating layer 36 may be silicon oxide (SiO 2 ).
  • the first insulating material may be, for example, an insulating material containing silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or the like.
  • the first insulating material may be, for example, an insulating material that can be etched by an etching gas such as CF 4 , CHF 3 , SF 6 , and an etching solution.
  • the first insulating layer 36 may have a thickness of, for example, 0.1 ⁇ m or more and 20 ⁇ m or less.
  • the second insulating layer 37 is formed on the first insulating layer 36 so as to cover the end surface 53 of the first insulating layer 36.
  • the second insulating layer 37 may continuously cover the main surface 54 and the end surface 53 of the first insulating layer 36.
  • the second insulating layer 37 has a main surface of the first insulating layer 36 so that the second insulating layer 37 has an end portion 84 at the boundary portion 56 between the end surface 83 of the second base layer 7 and the end surface 53 of the first insulating layer 36.
  • the 54 and the end face 53 are continuously covered.
  • the boundary portion 56 between the end surface 83 of the second base layer 7 and the end surface 53 of the first insulating layer 36 is formed at the boundary portion 85 between the end surface 83 of the second base layer 7 and the end surface 86 of the second insulating layer 37. It is covered.
  • the end surface 86 of the second insulating layer 37 is a surface continuous with the end surface 83 of the second base layer 7, and faces the fixed contact portion 46 via the gap 55.
  • the second insulating layer 37 may have a main surface 87 intersecting the end surface 86.
  • the main surface 87 of the second insulating layer 37 is formed along the first main surface 4 of the substrate 3.
  • the second insulating layer 37 may contain a second insulating material different from that of the first insulating layer 36.
  • the second insulating layer 37 may be a second insulating material having an etching selectivity with respect to the first insulating layer 36.
  • the second insulating layer 37 may be a second insulating material having an etching selectivity with respect to the first insulating layer 36 and the embedded insulating layer 8.
  • the second insulating layer 37 may be a second insulating material having etching resistance against an etching gas and an etching solution that can be used for etching the first insulating layer 36.
  • the second insulating layer 37 has etching resistance, for example, when the etching gas for the first insulating layer 36 is used, the etching selectivity of the first insulating layer 36 and the second insulating layer 37 (the first insulating layer 36).
  • the average etching rate of the second insulating layer 37) may be 10 to 1000. Therefore, the second insulating layer 37 may be defined as an etching protective layer that protects the first insulating layer 36 from etching when the embedded insulating layer 8 made of the same material as the first insulating layer 36 is etched.
  • the second insulating material may be an insulating material containing aluminum oxide (Al 2 O 3 ), tantalum oxide (TaO 2 ) and the like.
  • the second insulating material may be, for example, an insulating material that can be etched by an etching gas such as CF 4 , CHF 3 , SF 6 , and an etching solution.
  • the second insulating layer 37 may be thinner than the first insulating layer 36.
  • the second insulating layer 37 may have a thickness of, for example, 0.01 ⁇ m or more and 10 ⁇ m or less.
  • the movable contact layer 52 is supported by the first insulating layer 36 via the second insulating layer 37.
  • the movable contact layer 52 covers the main surface 87 and the end surface 86 of the second insulating layer 37.
  • the movable contact layer 52 faces the main surface 54 and the end surface 53 of the first insulating layer 36 via the second insulating layer 37.
  • the portion of the end surface 86 close to the main surface 87 is covered with the movable contact layer 52, and the remaining portion of the end surface 86 is exposed toward the gap 55. May be good.
  • the boundary portion 85 between the second insulating layer 37 and the second base layer 7 of the first structure 51 may face the gap 55.
  • the movable contact layer 52 includes a base portion 57 formed on the main surface 87 of the second insulating layer 37, and a protruding portion 58 protruding from the base portion 57 toward the fixed contact portion 46 with respect to the end surface 86 of the second insulating layer 37. May be included integrally.
  • the protruding portion 58 may be a portion that covers the end face 86 of the second insulating layer 37.
  • the movable contact layer 52 may be made of a conductive material such as gold (Au) or aluminum (Al). The movable contact layer 52 is electrically connected to the first signal line 59.
  • the fixed contact portion 46 is provided in the frame portion 19 of the fixed structure 17.
  • the frame portion 19 includes a first frame portion 60 and a second frame portion 61 that are mechanically separated from each other.
  • the first frame portion 60 and the second frame portion 61 are formed with a second signal line 62 that conducts by contact between the movable contact portion 45 and the fixed contact portion 46.
  • the fixed contact portion 46 has a second structure 63 supported by the embedded insulating layer 8.
  • the second structure 63 includes a second base layer 7, a first insulating layer 36, a second insulating layer 37, and a fixed contact layer 64.
  • the first insulating layer 36 is formed on the second base layer 7.
  • the first insulating layer 36 has an end surface 65 along the thickness direction of the substrate 3 (in this embodiment, the third direction Z) and a main surface 66 intersecting the end surface 65.
  • the main surface 66 of the first insulating layer 36 is formed along the first main surface 4 of the substrate 3.
  • the end surface 65 of the first insulating layer 36 of the second structure 63 faces the movable contact portion 45 via a gap 55 between the first insulating layer 36 and the movable contact portion 45.
  • the second base layer 7 has an end face 88 facing the fixed contact portion 46 via a gap 55 so as to be connected to the end face 65 of the first insulating layer 36.
  • the second insulating layer 37 is formed on the first insulating layer 36 so as to cover the end face 65 of the first insulating layer 36.
  • the second insulating layer 37 may continuously cover the main surface 66 and the end surface 65 of the first insulating layer 36.
  • the second insulating layer 37 has a main surface of the first insulating layer 36 so that the second insulating layer 37 has an end portion 89 at a boundary portion 67 between the end surface 88 of the second base layer 7 and the end surface 65 of the first insulating layer 36.
  • the 66 and the end face 65 are continuously covered.
  • the boundary portion 67 between the end face 88 of the second base layer 7 and the end face 65 of the first insulating layer 36 is formed at the boundary portion 90 between the end face 88 of the second base layer 7 and the end face 91 of the second insulating layer 37. It is covered.
  • the end surface 91 of the second insulating layer 37 is a surface continuous with the end surface 88 of the second base layer 7, and faces the movable contact portion 45 via the gap 55.
  • the second insulating layer 37 may have a main surface 92 that intersects the end surface 91.
  • the main surface 92 of the second insulating layer 37 is formed along the first main surface 4 of the substrate 3.
  • the fixed contact layer 64 is supported by the first insulating layer 36 via the second insulating layer 37.
  • the fixed contact layer 64 covers the main surface 92 and the end surface 91 of the second insulating layer 37.
  • the fixed contact layer 64 faces the main surface 66 and the end surface 65 of the first insulating layer 36 via the second insulating layer 37.
  • the portion of the end surface 91 near the main surface 92 is covered with the fixed contact layer 64, and the remaining portion of the end surface 91 is exposed toward the gap 55. May be good.
  • the boundary portion 90 between the second insulating layer 37 and the second base layer 7 of the second structure 63 may face the gap 55.
  • the fixed contact layer 64 includes a base portion 68 formed on the main surface 92 of the second insulating layer 37 and a protruding portion 69 protruding from the base portion 68 toward the movable contact portion 45 side of the end surface 91 of the second insulating layer 37. May be included integrally.
  • the protruding portion 69 may be a portion that covers the end face 91 of the second insulating layer 37.
  • the fixed contact layer 64 may be, for example, a conductive material such as gold (Au) or aluminum (Al).
  • the fixed contact layer 64 is electrically connected to the second signal line 62.
  • 3A and 3B are schematic views showing the operation of the MEMS switch A1 of FIG. 4A and 4B are schematic views (enlarged views) showing the operation of the MEMS switch A1 of FIG.
  • the MEMS switch A1 To drive the MEMS switch A1, for example, a voltage is applied so that a potential difference is formed between the movable electrode 24 and the fixed electrode 21 of the electrostatic actuator 2. As a result, as shown in FIGS. 3B and 4B, the beam portion 27 is deformed and the connecting member 22 is displaced. Due to the displacement of the connecting member 22, the movable contact portion 45 approaches the fixed contact portion 46, and the movable contact portion 45 can be brought into contact with the fixed contact portion 46. By this contact, the MEMS switch A1 is turned on, the first signal line 59 and the second signal line 62 are made conductive, and a conduction circuit is formed.
  • the second base layer 7 of the movable contact portion 45 may selectively project toward the fixed contact portion 46 with respect to the second beam portion 48. Further, the second base layer 7 of the fixed contact portion 46 may selectively project toward the movable contact portion 45 with respect to the first frame portion 60.
  • 5A to 5H are diagrams showing a part of the manufacturing process of the MEMS switch A1 of FIG. 1 in the order of processes.
  • a wafer 73 forming the substrate 3 of the MEMS switch A1 is prepared with reference to FIG. 5A.
  • the wafer 73 has a first wafer main surface 74 and a second wafer main surface 75 on the opposite side of the first wafer main surface 74.
  • the first wafer main surface 74 is the first main surface 11 of the second base layer 7, and the second wafer main surface 75 is the second main surface 10 of the first base layer 6.
  • the wafer 73 is an SOI wafer in this embodiment.
  • the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73.
  • the first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
  • the unnecessary portion of the first insulating layer 36 is removed.
  • the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
  • the second insulating layer 37 is formed on the first insulating layer 36.
  • the second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD).
  • ALD atomic layer deposition method
  • a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8.
  • the trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching).
  • an etching gas capable of etching the embedded insulating layer 8 is supplied.
  • a fluorine-based gas for example, HF or the like
  • the embedded insulating layer 8 is selectively removed.
  • a cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed.
  • the fixed structure 17 and the movable structure 18 are separately formed.
  • a part of the embedded insulating layer 8 remains in contact with and sandwiched between the first base layer 6 and the second base layer 7.
  • the movable contact layer 52 and the fixed contact layer 64 are formed.
  • the movable contact layer 52 and the fixed contact layer 64 are formed by depositing these conductive materials (metal materials).
  • the movable contact layer 52 and the fixed contact layer 64 may be deposited by, for example, a CVD (Chemical Vapor Deposition) method, a PVD (Physical Vapor Deposition) method, or the like.
  • a part of the conductive material may not be deposited on the first insulating layer 36, but may be deposited as a residue 77 on the end faces 83, 88, the cavity 16 and the like of the second base layer 7.
  • the residue 77 is physically and electrically separated from the movable contact layer 52 and the fixed contact layer 64.
  • the end faces 53 and 65 of the first insulating layer 36 are covered with the second insulating layer 37.
  • FIG. 6 is a schematic cross-sectional view of the MEMS switch B1 according to the embodiment of the present disclosure.
  • the same reference numerals will be given to the structures corresponding to the structures described for the MEMS switch A1 according to the above-described embodiment, and the description thereof will be omitted.
  • the movable electrode 24, the fixed electrode 21, and the beam portion 27 each have a third structure 94 formed in a floating state with respect to the cavity 16.
  • the third structure 94 includes a second base layer 7, a first insulating layer 36, and a second insulating layer 37.
  • the first insulating layer 36 is formed on the second base layer 7.
  • the first insulating layer 36 has an end surface 95 along the thickness direction of the substrate 3 (in this embodiment, the third direction Z) and a main surface 96 intersecting the end surface 95.
  • the main surface 96 of the first insulating layer 36 is formed along the first main surface 4 of the substrate 3.
  • the second base layer 7 has an end face 97 so as to be connected to the end face 95 of the first insulating layer 36.
  • the second insulating layer 37 is formed on the first insulating layer 36 so as to cover the end face 95 of the first insulating layer 36.
  • the second insulating layer 37 may continuously cover the main surface 96 and the end surface 95 of the first insulating layer 36.
  • the second insulating layer 37 has a main surface of the first insulating layer 36 so that the second insulating layer 37 has an end portion 98 at a boundary portion 99 between the end surface 97 of the second base layer 7 and the end surface 95 of the first insulating layer 36.
  • 96 and end face 95 are continuously covered.
  • the boundary portion 99 between the end face 97 of the second base layer 7 and the end face 95 of the first insulating layer 36 is the boundary portion 100 between the end face 97 of the second base layer 7 and the end face 101 of the second insulating layer 37. It is covered.
  • the end surface 101 of the second insulating layer 37 is a surface continuous with the end surface 97 of the second base layer 7. Further, the second insulating layer 37 may have a main surface 102 that intersects the end surface 101.
  • the main surface 102 of the second insulating layer 37 is formed along the first main surface 4 of the substrate 3.
  • 7A to 7H are diagrams showing a part of the manufacturing process of the MEMS switch B1 of FIG. 6 in the order of the processes.
  • a wafer 73 forming the substrate 3 of the MEMS switch B1 is prepared with reference to FIG. 7A.
  • the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73.
  • the first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
  • the unnecessary portion of the first insulating layer 36 is removed.
  • the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
  • the second insulating layer 37 is formed on the first insulating layer 36.
  • the second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD).
  • ALD atomic layer deposition method
  • the main surfaces 54, 66, 96 of the first insulating layer 36 and the end faces 53, 65, 95 of the first insulating layer 36 exposed to the first opening 93 are covered with the second insulating layer 37.
  • a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8.
  • the trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching).
  • an etching gas capable of etching the embedded insulating layer 8 is supplied.
  • a fluorine-based gas for example, HF or the like
  • the embedded insulating layer 8 is selectively removed.
  • a cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed.
  • the movable contact layer 52 and the fixed contact layer 64 are formed.
  • the end face 95 of the first insulating layer 36 is covered with the second insulating layer 37. This makes it possible to prevent the first insulating layer 36 from being etched from the end face 95 when the embedded insulating layer 8 is etched through the trench 76 (FIG. 7G). Therefore, the first main surface 11 of the movable electrode 24 and the fixed electrode 21 can be reliably covered with the first insulating layer 36, so that the insulation reliability of the movable electrode 24 and the fixed electrode 21 can be improved.
  • FIG. 8 is a schematic cross-sectional view of the MEMS switch C1 according to the embodiment of the present disclosure.
  • the same reference numerals will be given to the structures corresponding to the structures described for the MEMS switches A1 and B1 according to the above-described embodiment, and the description thereof will be omitted.
  • the second insulating layer 37 is a second base layer 7 in addition to the end faces 53, 65, 95 of the first insulating layer 36. It covers the end faces 83, 88, 97.
  • the second insulating layer 37 is a first insulating layer so as to cross the boundary portions 56, 67, 99 between the end faces 83, 88, 97 of the second base layer 7 and the end faces 53, 65, 95 of the first insulating layer 36.
  • the end faces 53, 65, 95 of 36 and the end faces 83, 88, 97 of the second base layer 7 are integrally covered.
  • the second main surface 12 of the second base layer 7 is not covered with the second insulating layer 37 and is exposed to the cavity 16. ..
  • 9A to 9H are diagrams showing a part of the manufacturing process of the MEMS switch C1 of FIG. 8 in the order of the processes.
  • a wafer 73 forming the substrate 3 of the MEMS switch C1 is prepared with reference to FIG. 9A.
  • the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73.
  • the first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
  • the unnecessary portion of the first insulating layer 36 is removed.
  • the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
  • a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8.
  • the trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching).
  • the second insulating layer 37 is formed on the first insulating layer 36.
  • the second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD).
  • ALD atomic layer deposition method
  • the main surfaces 54, 66, 96 of the first insulating layer 36, the end faces 53, 65, 95 of the first insulating layer 36 exposed to the first opening 93, and the end faces 83 of the second base layer 7 exposed to the trench 76, 88 and 97 are covered with the second insulating layer 37.
  • an etching gas capable of etching the embedded insulating layer 8 is supplied.
  • a fluorine-based gas for example, HF or the like
  • the embedded insulating layer 8 is selectively removed.
  • a cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed.
  • the movable contact layer 52 and the fixed contact layer 64 are formed.
  • the MEMS switch C1 for example, when a part of the embedded insulating layer 8 is removed by etching to form a cavity 16 between the first base layer 6 and the second base layer 7, a third structure is formed. It is possible to prevent the second base layer 7 of 94 from being etched from the end face 97. Thereby, for example, the distances d1 to d3 between the movable electrode 24 and the fixed electrode 21 can be maintained substantially as designed.
  • FIG. 10 is a schematic cross-sectional view of the MEMS switch D1 according to the embodiment of the present disclosure.
  • the same reference numerals will be given to the structures corresponding to the structures described for the MEMS switches A1 to C1 according to the above-described embodiment, and the description thereof will be omitted.
  • the MEMS switch D1 in the first structure 51, the second structure 63, and the third structure 94, between the end faces 83, 88, 97 of the second base layer 7 and the end faces 53, 65, 95 of the first insulating layer 36. Is formed with a step 103 so that a part of the first insulating layer 36 projects from the end faces 83, 88, 97 of the second base layer 7.
  • 11A to 11H are diagrams showing a part of the manufacturing process of the MEMS switch D1 of FIG. 10 in the order of processes.
  • a wafer 73 forming the substrate 3 of the MEMS switch D1 is prepared with reference to FIG. 11A.
  • the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73.
  • the first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
  • the unnecessary portion of the first insulating layer 36 is removed.
  • the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
  • a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8.
  • the trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching). As a result, the step 103 is formed.
  • the second insulating layer 37 is formed on the first insulating layer 36.
  • the second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD).
  • ALD atomic layer deposition method
  • the main surfaces 54, 66, 96 of the first insulating layer 36, the end faces 53, 65, 95 of the first insulating layer 36 exposed to the first opening 93, and the end faces 83 of the second insulating layer 37 exposed to the trench 76, 88 and 97 are covered with the second insulating layer 37.
  • an etching gas capable of etching the embedded insulating layer 8 is supplied.
  • a fluorine-based gas for example, HF or the like
  • the embedded insulating layer 8 is selectively removed.
  • a cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed.
  • the movable contact layer 52 and the fixed contact layer 64 are formed.
  • FIGS. 11A to 11H According to the methods of FIGS. 11A to 11H, the same effects as the methods of FIGS. 5A to 5H, the methods of FIGS. 7A to 7H, and the methods of FIGS. 9A to 9H can be obtained.
  • MEMS switches A1, B1, C1, and D1 of the present disclosure can also be implemented in other embodiments.
  • the movable structure 18 is displaced by the electrostatic drive of the electrostatic actuator 2, but it may be displaced by the piezoelectric drive of the piezoelectric actuator including the piezoelectric element. Further, the movable structure 18 may be displaced by a combination of electrostatic drive and piezoelectric drive.
  • Electrostatic actuator 3 Substrate 4: First main surface 5: Second main surface 6: First base layer 7: Second base layer 8: Embedded insulating layer 9: First main surface 10: Second main surface 11 : 1st main surface 12: 2nd main surface 13: 1st joint surface 14: 2nd joint surface 15: Side surface 16: Cavity 17: Fixed structure 18: Movable structure 19: Frame portion 20: 1st cantilever structure 21: Fixed Electrode 21A: 1st fixed electrode 21B: 2nd fixed electrode 22: Connecting member 23: 2nd cantilever structure 24: Movable electrode 24A: 1st movable electrode 24B: 2nd movable electrode 25: Comb tooth type electrode 27: Beam portion 28 : 1st end 29: 2nd end 36: 1st insulating layer 37: 2nd insulating layer 45: Movable contact part 46: Fixed contact part 47: End part 48: 2nd beam part 49: 1st side part 50 : Second side portion 51: First structure 52: Movable contact layer 53

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Abstract

This MEMS switch comprises: a substrate that has a first main surface and a second main surface on the opposite side thereof, and also has a cavity formed therein; an actuator unit that is formed on the first main surface side of the substrate and converts an electric signal to a mechanical action; a movable contact part that is formed, in a floating state in the cavity, on the first main surface side of the substrate, and can be displaced by the mechanical action of the actuator unit; and a fixed contact part that faces the movable contact part, and can be set to be in contact with or non-contact with the movable contact part by the displacement of the movable contact part, wherein at least one of the movable contact part and the fixed contact part has a first structure in which are included the substrate, a first insulating layer that is formed on the substrate, a second insulating layer that is formed on the first insulating layer so as to cover an end surface of the first insulating layer along the thickness direction of the substrate, and that contains a material different from that of the first insulating layer, and a conductive contact layer that is supported by the first insulating layer.

Description

ＭＥＭＳスイッチおよびＭＥＭＳスイッチの製造方法MEMS switch and manufacturing method of MEMS switch
　本開示は、ＭＥＭＳスイッチおよびＭＥＭＳスイッチの製造方法に関する。 This disclosure relates to a MEMS switch and a method for manufacturing a MEMS switch.
　たとえば、特許文献１は、ＭＥＭＳスイッチを開示している。このＭＥＭＳスイッチは、固定接点部と可動接点部とを備えている。固定接点部は、絶縁膜を介してベース基板の上面に固定された下面を有している。可動接点部は、ベース基板の上面から浮いている。可動接点部は、アクチュエータによってベース基板の上面と平行な方向に移動する。 For example, Patent Document 1 discloses a MEMS switch. This MEMS switch includes a fixed contact portion and a movable contact portion. The fixed contact portion has a lower surface fixed to the upper surface of the base substrate via an insulating film. The movable contact portion floats from the upper surface of the base substrate. The movable contact portion is moved by the actuator in a direction parallel to the upper surface of the base substrate.
欧州特許出願公開第２３６５４９９明細書European Patent Application Publication No. 2365499
　本開示の一例としてのＭＥＭＳスイッチは、第１主面およびその反対側の第２主面を有し、空洞が内部に形成された基板と、前記基板の前記第１主面側に形成され、電気信号を機械的動作に変換するアクチュエータ部と、前記基板の前記第１主面側に前記空洞に浮いた状態で形成され、前記アクチュエータ部の機械的動作によって変位可能な可動接点部と、前記可動接点部と対向し、前記可動接点部の変位によって前記可動接点部と接触および非接触可能な固定接点部とを含み、前記可動接点部および前記固定接点部の少なくとも一方は、前記基板と、前記基板上に形成された第１絶縁層と、前記基板の厚さ方向に沿う前記第１絶縁層の端面を被覆するように前記第１絶縁層上に形成され、前記第１絶縁層とは異なる材料を含む第２絶縁層と、前記第１絶縁層に支持された導電性の接点層とを含む第１構造を有している。 An MEMS switch as an example of the present disclosure has a first main surface and a second main surface on the opposite side thereof, and is formed on a substrate in which a cavity is formed and on the first main surface side of the substrate. An actuator unit that converts an electric signal into a mechanical operation, a movable contact unit that is formed on the first main surface side of the substrate in a state of floating in the cavity and can be displaced by the mechanical operation of the actuator unit, and the above. A fixed contact portion facing the movable contact portion and capable of contacting and not contacting the movable contact portion due to displacement of the movable contact portion is included, and at least one of the movable contact portion and the fixed contact portion includes the substrate and the fixed contact portion. The first insulating layer formed on the substrate and the first insulating layer formed on the first insulating layer so as to cover the end faces of the first insulating layer along the thickness direction of the substrate are referred to as the first insulating layer. It has a first structure including a second insulating layer containing different materials and a conductive contact layer supported by the first insulating layer.
図１は、本開示の一実施形態に係るＭＥＭＳスイッチの模式的な平面図である。FIG. 1 is a schematic plan view of a MEMS switch according to an embodiment of the present disclosure. 図２は、本開示の一実施形態に係るＭＥＭＳスイッチの模式的な断面図である。FIG. 2 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure. 図３Ａおよび図３Ｂは、図１のＭＥＭＳスイッチの動作を示す模式図である。3A and 3B are schematic views showing the operation of the MEMS switch of FIG. 図４Ａおよび図４Ｂは、図１のＭＥＭＳスイッチの動作を示す模式図（拡大図）である。4A and 4B are schematic views (enlarged views) showing the operation of the MEMS switch of FIG. 図５Ａは、図１のＭＥＭＳスイッチの製造工程の一部を示す図である。FIG. 5A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG. 図５Ｂは、図５Ａの次の工程を示す図である。FIG. 5B is a diagram showing the next step of FIG. 5A. 図５Ｃは、図５Ｂの次の工程を示す図である。FIG. 5C is a diagram showing the next step of FIG. 5B. 図５Ｄは、図５Ｃの次の工程を示す図である。FIG. 5D is a diagram showing the next step of FIG. 5C. 図５Ｅは、図５Ｄの次の工程を示す図である。FIG. 5E is a diagram showing the next step of FIG. 5D. 図５Ｆは、図５Ｅの次の工程を示す図である。FIG. 5F is a diagram showing the next step of FIG. 5E. 図５Ｇは、図５Ｆの次の工程を示す図である。FIG. 5G is a diagram showing the next step of FIG. 5F. 図５Ｈは、図５Ｇの次の工程を示す図である。FIG. 5H is a diagram showing the next step of FIG. 5G. 図６は、本開示の一実施形態に係るＭＥＭＳスイッチの模式的な断面図である。FIG. 6 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure. 図７Ａは、図６のＭＥＭＳスイッチの製造工程の一部を示す図である。FIG. 7A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG. 図７Ｂは、図７Ａの次の工程を示す図である。FIG. 7B is a diagram showing the next step of FIG. 7A. 図７Ｃは、図７Ｂの次の工程を示す図である。FIG. 7C is a diagram showing the next step of FIG. 7B. 図７Ｄは、図７Ｃの次の工程を示す図である。FIG. 7D is a diagram showing the next step of FIG. 7C. 図７Ｅは、図７Ｄの次の工程を示す図である。FIG. 7E is a diagram showing the next step of FIG. 7D. 図７Ｆは、図７Ｅの次の工程を示す図である。FIG. 7F is a diagram showing the next step of FIG. 7E. 図７Ｇは、図７Ｆの次の工程を示す図である。FIG. 7G is a diagram showing the next step of FIG. 7F. 図７Ｈは、図７Ｇの次の工程を示す図である。FIG. 7H is a diagram showing the next step of FIG. 7G. 図８は、本開示の一実施形態に係るＭＥＭＳスイッチの模式的な断面図である。FIG. 8 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure. 図９Ａは、図８のＭＥＭＳスイッチの製造工程の一部を示す図である。FIG. 9A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG. 図９Ｂは、図９Ａの次の工程を示す図である。FIG. 9B is a diagram showing the next step of FIG. 9A. 図９Ｃは、図９Ｂの次の工程を示す図である。FIG. 9C is a diagram showing the next step of FIG. 9B. 図９Ｄは、図９Ｃの次の工程を示す図である。FIG. 9D is a diagram showing the next step of FIG. 9C. 図９Ｅは、図９Ｄの次の工程を示す図である。FIG. 9E is a diagram showing the next step of FIG. 9D. 図９Ｆは、図９Ｅの次の工程を示す図である。FIG. 9F is a diagram showing the next step of FIG. 9E. 図９Ｇは、図９Ｆの次の工程を示す図である。FIG. 9G is a diagram showing the next step of FIG. 9F. 図９Ｈは、図９Ｇの次の工程を示す図である。FIG. 9H is a diagram showing the next step of FIG. 9G. 図１０は、本開示の一実施形態に係るＭＥＭＳスイッチの模式的な断面図である。FIG. 10 is a schematic cross-sectional view of the MEMS switch according to the embodiment of the present disclosure. 図１１Ａは、図１０のＭＥＭＳスイッチの製造工程の一部を示す図である。FIG. 11A is a diagram showing a part of the manufacturing process of the MEMS switch of FIG. 図１１Ｂは、図１１Ａの次の工程を示す図である。FIG. 11B is a diagram showing the next step of FIG. 11A. 図１１Ｃは、図１１Ｂの次の工程を示す図である。FIG. 11C is a diagram showing the next step of FIG. 11B. 図１１Ｄは、図１１Ｃの次の工程を示す図である。FIG. 11D is a diagram showing the next step of FIG. 11C. 図１１Ｅは、図１１Ｄの次の工程を示す図である。FIG. 11E is a diagram showing the next step of FIG. 11D. 図１１Ｆは、図１１Ｅの次の工程を示す図である。FIG. 11F is a diagram showing the next step of FIG. 11E. 図１１Ｇは、図１１Ｆの次の工程を示す図である。FIG. 11G is a diagram showing the next step of FIG. 11F. 図１１Ｈは、図１１Ｇの次の工程を示す図である。FIG. 11H is a diagram showing the next step of FIG. 11G.
＜本開示の実施形態＞
　まず、本開示の実施形態を列記して説明する。 <Embodiment of the present disclosure>
First, the embodiments of the present disclosure will be listed and described.
　本開示の第１例としてのＭＥＭＳスイッチは、第１主面およびその反対側の第２主面を有し、空洞が内部に形成された基板と、前記基板の前記第１主面側に形成され、電気信号を機械的動作に変換するアクチュエータ部と、前記基板の前記第１主面側に前記空洞に浮いた状態で形成され、前記アクチュエータ部の機械的動作によって変位可能な可動接点部と、前記可動接点部と対向し、前記可動接点部の変位によって前記可動接点部と接触および非接触可能な固定接点部とを含み、前記可動接点部および前記固定接点部の少なくとも一方は、前記基板と、前記基板上に形成された第１絶縁層と、前記基板の厚さ方向に沿う前記第１絶縁層の端面を被覆するように前記第１絶縁層上に形成され、前記第１絶縁層とは異なる材料を含む第２絶縁層と、前記第１絶縁層に支持された導電性の接点層とを含む第１構造を有している。 The MEMS switch as the first example of the present disclosure has a first main surface and a second main surface on the opposite side thereof, and is formed on a substrate in which a cavity is formed and on the first main surface side of the substrate. An actuator unit that converts an electric signal into a mechanical operation, and a movable contact portion that is formed in a state of floating in the cavity on the first main surface side of the substrate and can be displaced by the mechanical operation of the actuator unit. A fixed contact portion facing the movable contact portion and capable of contacting and not contacting the movable contact portion due to displacement of the movable contact portion is included, and at least one of the movable contact portion and the fixed contact portion is the substrate. The first insulating layer formed on the substrate and the first insulating layer formed on the first insulating layer so as to cover the end faces of the first insulating layer along the thickness direction of the substrate. It has a first structure including a second insulating layer containing a material different from the above, and a conductive contact layer supported by the first insulating layer.
　この構成によれば、第１構造の第１絶縁層の端面が第２絶縁層で被覆されている。これにより、たとえば、基板に空洞を形成する際に第１絶縁層をエッチングし得るエッチングガスやエッチング液が使用されても、第１絶縁層が端面からエッチングされることを抑制することができる。そのため、接点層の直下の第１絶縁層がエッチングにより除去されることを防止できるので、接点層を第１絶縁層によって安定的に支持することができる。その結果、可動接点部と固定接点部との接触信頼性を向上することができる。 According to this configuration, the end face of the first insulating layer of the first structure is covered with the second insulating layer. Thereby, for example, even if an etching gas or an etching solution capable of etching the first insulating layer is used when forming a cavity in the substrate, it is possible to prevent the first insulating layer from being etched from the end face. Therefore, it is possible to prevent the first insulating layer immediately below the contact layer from being removed by etching, so that the contact layer can be stably supported by the first insulating layer. As a result, the contact reliability between the movable contact portion and the fixed contact portion can be improved.
　また、基板が不純物を含む半導体基板である場合、接点層の直下の第１絶縁層が過度にエッチングされると、接点層の一部が宙に浮いて半導体基板と接触する場合がある。この種の接触は、ＭＥＭＳスイッチのスイッチング不良を起こすおそれがある。これに対し、本開示のＭＥＭＳスイッチでは、そのようなスイッチング不良を抑制することができる。 Further, when the substrate is a semiconductor substrate containing impurities, if the first insulating layer directly under the contact layer is excessively etched, a part of the contact layer may float in the air and come into contact with the semiconductor substrate. This type of contact can lead to poor switching of the MEMS switch. On the other hand, in the MEMS switch of the present disclosure, such switching failure can be suppressed.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記基板は、第１ベース層と、前記第１ベース層上に形成され、前記第１絶縁層と同じ材料を含む埋め込み絶縁層と、前記埋め込み絶縁層上に形成された第２ベース層とを含み、前記空洞は、前記第１ベース層と前記第２ベース層との間に形成され、前記埋め込み絶縁層によって側方から区画されており、前記第１構造において前記第１絶縁層は、前記第２ベース層上に形成されていてもよい。 In the MEMS switch as the first example of the present disclosure, the substrate is formed on the first base layer, the first base layer, and the embedded insulating layer containing the same material as the first insulating layer, and the embedded insulation. The cavity is formed between the first base layer and the second base layer, and is partitioned from the side by the embedded insulating layer, including a second base layer formed on the layer. In the first structure, the first insulating layer may be formed on the second base layer.
　この構成によれば、第１絶縁層と埋め込み絶縁層とが同じ材料を含むが、第１絶縁層の端面が第２絶縁層で被覆されている。そのため、たとえば、埋め込み絶縁層の一部をエッチングによって除去して第１ベース層と第２ベース層との間に空洞を形成する際に、第１絶縁層が端面からエッチングされることを抑制することができる。 According to this configuration, the first insulating layer and the embedded insulating layer contain the same material, but the end face of the first insulating layer is covered with the second insulating layer. Therefore, for example, when a part of the embedded insulating layer is removed by etching to form a cavity between the first base layer and the second base layer, the first insulating layer is prevented from being etched from the end face. be able to.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第１構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、前記第１構造において前記第２絶縁層は、前記第２ベース層の端面と前記第１絶縁層の端面との境界部に端部を有するように前記第１絶縁層の端面を被覆していてもよい。 In the MEMS switch as the first example of the present disclosure, in the first structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the first In the structure, the second insulating layer may cover the end face of the first insulating layer so as to have an end portion at the boundary between the end face of the second base layer and the end face of the first insulating layer.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第１構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、前記第１構造において前記第２絶縁層は、前記第１絶縁層の端面に加えてさらに、前記第２ベース層の端面を被覆していてもよい。 In the MEMS switch as the first example of the present disclosure, in the first structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the first In the structure, the second insulating layer may further cover the end face of the second base layer in addition to the end face of the first insulating layer.
　この構成によれば、たとえば、埋め込み絶縁層の一部をエッチングによって除去して第１ベース層と第２ベース層との間に空洞を形成する際に、第１構造の第２ベース層が端面からエッチングされることを抑制することができる。 According to this configuration, for example, when a part of the embedded insulating layer is removed by etching to form a cavity between the first base layer and the second base layer, the second base layer of the first structure has an end face. Etching can be suppressed.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第１構造において前記第２ベース層の端面と前記第１絶縁層の端面との間には、前記第１絶縁層の一部が前記第２ベース層の端面に対して突出するように、段差が形成されていてもよい。 In the MEMS switch as the first example of the present disclosure, in the first structure, a part of the first insulating layer is formed between the end face of the second base layer and the end face of the first insulating layer. A step may be formed so as to project from the end face of the base layer.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記アクチュエータ部は、前記空洞に対して浮いた状態で前記第２ベース層に形成された静電アクチュエータであって、交互に配列された固定電極および可動電極を含み、前記可動電極と前記固定電極との間の静電気力によって変位する櫛歯型の静電アクチュエータを含み、前記可動接点部は、前記可動電極に連結された連結部材を介して前記静電アクチュエータに対して変位可能に設けられていてもよい。 In the MEMS switch as the first example of the present disclosure, the actuator portion is an electrostatic actuator formed on the second base layer while floating with respect to the cavity, and the fixed electrodes and the fixed electrodes are arranged alternately. The movable electrode includes a comb-tooth type electrostatic actuator that is displaced by an electrostatic force between the movable electrode and the fixed electrode, and the movable contact portion is said to be via a connecting member connected to the movable electrode. It may be provided so as to be displaceable with respect to the electrostatic actuator.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記可動電極および前記固定電極の少なくとも一方は、前記第２ベース層と、前記第１絶縁層と、前記第２絶縁層とを含む第２構造を有していてもよい。 In a MEMS switch as a first example of the present disclosure, at least one of the movable electrode and the fixed electrode has a second structure including the second base layer, the first insulating layer, and the second insulating layer. You may have.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第２構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、前記第２構造において前記第２絶縁層は、前記第２ベース層の端面と前記第１絶縁層の端面との境界部に端部を有するように前記第１絶縁層の端面を被覆していてもよい。 In the MEMS switch as the first example of the present disclosure, in the second structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the second base layer is connected to the end face. In the structure, the second insulating layer may cover the end face of the first insulating layer so as to have an end portion at the boundary between the end face of the second base layer and the end face of the first insulating layer.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第２構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、前記第２構造において前記第２絶縁層は、前記第１絶縁層の端面に加えてさらに、前記第２ベース層の端面を被覆していてもよい。 In the MEMS switch as the first example of the present disclosure, in the second structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate, and the second base layer is connected to the end face. In the structure, the second insulating layer may further cover the end face of the second base layer in addition to the end face of the first insulating layer.
　この構成によれば、たとえば、埋め込み絶縁層の一部をエッチングによって除去して第１ベース層と第２ベース層との間に空洞を形成する際に、第２構造の第２ベース層が端面からエッチングされることを抑制することができる。これにより、可動電極と固定電極との間の距離を、ほぼ設計通りに維持することができる。 According to this configuration, for example, when a part of the embedded insulating layer is removed by etching to form a cavity between the first base layer and the second base layer, the second base layer of the second structure has an end face. Etching can be suppressed. As a result, the distance between the movable electrode and the fixed electrode can be maintained almost as designed.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第２構造において前記第２ベース層の端面と前記第１絶縁層の端面との間には、前記第１絶縁層の一部が前記第２ベース層の端面に対して突出するように、段差が形成されていてもよい。 In the MEMS switch as the first example of the present disclosure, in the second structure, a part of the first insulating layer is formed between the end face of the second base layer and the end face of the first insulating layer. A step may be formed so as to project from the end face of the base layer.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第１絶縁層は、前記第１絶縁層の端面に交差する主面を有しており、前記第２絶縁層は、前記第１絶縁層の前記主面および前記端面を連続して被覆しており、前記接点層は、前記第２絶縁層を介して前記第１絶縁層の前記主面および前記端面に対向していてもよい。 In the MEMS switch as the first example of the present disclosure, the first insulating layer has a main surface intersecting the end surface of the first insulating layer, and the second insulating layer is the first insulating layer. The main surface and the end surface are continuously covered, and the contact layer may face the main surface and the end surface of the first insulating layer via the second insulating layer.
　本開示の第１例としてのＭＥＭＳスイッチでは、前記第１絶縁層は、酸化シリコン（ＳｉＯ２）を含み、前記第２絶縁層は、酸化アルミニウム（Ａｌ２Ｏ３）を含んでいてもよい。 In the MEMS switch as the first example of the present disclosure, the first insulating layer may contain silicon oxide (SiO 2 ), and the second insulating layer may contain aluminum oxide (Al 2 O 3 ).
　本開示の第２例としてのＭＥＭＳスイッチの製造方法は、第１ベース層と、前記第１ベース層上に形成された埋め込み絶縁層と、前記埋め込み絶縁層上に形成された第２ベース層とを含む基板の前記第２ベース層上に、前記埋め込み絶縁層と同じ材料を含む第１絶縁層を形成する工程と、前記第１絶縁層に選択的に第１開孔を形成する工程と、前記第１絶縁層の主面、および前記第１開孔に露出する前記第１絶縁層の端面を被覆するように、前記第１絶縁層とは異なる材料を含む第２絶縁層を前記第１絶縁層上に形成する工程と、前記第２ベース層に所定パターンを有する貫通孔を形成することによって、前記貫通孔によって区画された前記第２ベース層、当該第２ベース層上の前記第１絶縁層および前記第２絶縁層を含む可動接点部および固定接点部を形成する工程と、前記貫通孔を介して前記埋め込み絶縁層をエッチングすることによって、前記第１ベース層と前記第２ベース層との間に空洞を形成する工程と、前記埋め込み絶縁層のエッチング後、導電材料を所定パターンで堆積することによって、前記第１絶縁層上に接点層を形成する工程とを含む。 A method for manufacturing a MEMS switch as a second example of the present disclosure includes a first base layer, an embedded insulating layer formed on the first base layer, and a second base layer formed on the embedded insulating layer. A step of forming a first insulating layer containing the same material as the embedded insulating layer on the second base layer of the substrate containing the above, and a step of selectively forming a first opening in the first insulating layer. The first insulating layer containing a material different from the first insulating layer is provided so as to cover the main surface of the first insulating layer and the end surface of the first insulating layer exposed to the first opening. By forming a step of forming on the insulating layer and forming a through hole having a predetermined pattern in the second base layer, the second base layer partitioned by the through hole and the first on the second base layer. The first base layer and the second base layer are formed by forming a movable contact portion and a fixed contact portion including the insulating layer and the second insulating layer, and etching the embedded insulating layer through the through hole. The process includes a step of forming a cavity between the two, and a step of forming a contact layer on the first insulating layer by depositing a conductive material in a predetermined pattern after etching the embedded insulating layer.
　この方法によれば、第１絶縁層の端面が第２絶縁層で被覆されている。これにより、貫通孔を介して埋め込み絶縁層をエッチングする際に、第１絶縁層が端面からエッチングされることを抑制することができる。そのため、接点層の直下の第１絶縁層がエッチングにより除去されることを防止できるので、接点層を第１絶縁層によって安定的に支持することができる。 According to this method, the end face of the first insulating layer is covered with the second insulating layer. This makes it possible to prevent the first insulating layer from being etched from the end face when the embedded insulating layer is etched through the through hole. Therefore, it is possible to prevent the first insulating layer immediately below the contact layer from being removed by etching, so that the contact layer can be stably supported by the first insulating layer.
　本開示の第３例としてのＭＥＭＳスイッチの製造方法は、第１ベース層と、前記第１ベース層上に形成された埋め込み絶縁層と、前記埋め込み絶縁層上に形成された第２ベース層とを含む基板の前記第２ベース層上に、前記埋め込み絶縁層と同じ材料を含む第１絶縁層を形成する工程と、前記第１絶縁層に選択的に第１開孔を形成する工程と、前記第２ベース層に所定パターンを有する貫通孔を形成することによって、前記貫通孔によって区画された前記第２ベース層、当該第２ベース層上の前記第１絶縁層を含む可動接点部および固定接点部を形成する工程と、前記第１絶縁層の主面、前記第１開孔に露出する前記第１絶縁層の端面、および前記貫通孔に露出する前記第２ベース層の端面を被覆するように、前記第１絶縁層とは異なる材料を含む第２絶縁層を前記第１絶縁層上に形成する工程と、前記貫通孔を介して前記埋め込み絶縁層をエッチングすることによって、前記第１ベース層と前記第２ベース層との間に空洞を形成する工程と、前記埋め込み絶縁層のエッチング後、導電材料を所定パターンで堆積することによって、前記第１絶縁層上に接点層を形成する工程とを含む。 A method for manufacturing a MEMS switch as a third example of the present disclosure includes a first base layer, an embedded insulating layer formed on the first base layer, and a second base layer formed on the embedded insulating layer. A step of forming a first insulating layer containing the same material as the embedded insulating layer on the second base layer of the substrate containing the above, and a step of selectively forming a first opening in the first insulating layer. By forming a through hole having a predetermined pattern in the second base layer, the second base layer partitioned by the through hole, a movable contact portion including the first insulating layer on the second base layer, and fixing The step of forming the contact portion, the main surface of the first insulating layer, the end surface of the first insulating layer exposed to the first opening, and the end surface of the second base layer exposed to the through hole are covered. As described above, by forming a second insulating layer containing a material different from the first insulating layer on the first insulating layer and etching the embedded insulating layer through the through hole, the first insulating layer is formed. A contact layer is formed on the first insulating layer by a step of forming a cavity between the base layer and the second base layer and by depositing a conductive material in a predetermined pattern after etching the embedded insulating layer. Including the process.
　この方法によれば、第１絶縁層の端面が第２絶縁層で被覆されている。これにより、貫通孔を介して埋め込み絶縁層をエッチングする際に、第１絶縁層が端面からエッチングされることを抑制することができる。そのため、接点層の直下の第１絶縁層がエッチングにより除去されることを防止できるので、接点層を第１絶縁層によって安定的に支持することができる。 According to this method, the end face of the first insulating layer is covered with the second insulating layer. This makes it possible to prevent the first insulating layer from being etched from the end face when the embedded insulating layer is etched through the through hole. Therefore, it is possible to prevent the first insulating layer immediately below the contact layer from being removed by etching, so that the contact layer can be stably supported by the first insulating layer.
　また、第２ベース層の端面も第２絶縁層で被覆されて保護されているので、第２ベース層が端面からエッチングされることを抑制することもできる。 Further, since the end face of the second base layer is also covered and protected by the second insulating layer, it is possible to prevent the second base layer from being etched from the end face.
　本開示の第２例および第３例としてのＭＥＭＳスイッチの製造方法では、前記第２絶縁層を形成する工程は、原子層堆積法（ALD：Atomic Layer Deposition）によって前記第２絶縁層を形成する工程を含んでいてもよい。
＜本開示の実施形態の詳細な説明＞
　次に、本開示の実施形態を、添付図面を参照して詳細に説明する。以下の詳細な説明において、序数が付された名称の構成要素および方向が複数存在するが、当該序数と、請求項に記載の構成要素および方向の序数とは、必ずしも一致するものではない。 In the method for manufacturing a MEMS switch as the second example and the third example of the present disclosure, the step of forming the second insulating layer forms the second insulating layer by an atomic layer deposition method (ALD). It may include a step.
<Detailed description of the embodiments of the present disclosure>
Next, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following detailed description, there are a plurality of components and directions with ordinal numbers, but the ordinal numbers and the ordinal numbers of the components and directions described in the claims do not always match.
　図１は、本開示の一実施形態に係るＭＥＭＳスイッチＡ１の模式的な平面図である。図２は、本開示の一実施形態に係るＭＥＭＳスイッチＡ１の模式的な断面図である。図２は、図１のＭＥＭＳスイッチＡ１の特定部分の断面を示すものではない。図２では、ＭＥＭＳスイッチＡ１の構造の明瞭化のために、ＭＥＭＳスイッチＡ１のいくつかの構成が抽出して示されている。 FIG. 1 is a schematic plan view of the MEMS switch A1 according to the embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view of the MEMS switch A1 according to the embodiment of the present disclosure. FIG. 2 does not show a cross section of a specific portion of the MEMS switch A1 of FIG. In FIG. 2, some configurations of the MEMS switch A1 are extracted and shown in order to clarify the structure of the MEMS switch A1.
　ＭＥＭＳスイッチＡ１は、たとえば、静電アクチュエータ２を備える静電駆動ＭＥＭＳスイッチである。ＭＥＭＳスイッチＡ１は、たとえば、静電アクチュエータ２の機械的動作によって、第１方向Ｘに沿う駆動力を発生する。この実施形態では、第１方向Ｘに対して水平方向に直交する方向が第２方向Ｙであり、第１方向Ｘに対して鉛直方向に直交する方向が第３方向Ｚである。第３方向Ｚは、ＭＥＭＳスイッチＡ１の厚さ方向、後述する基板３の厚さ方向と定義してもよい。第１方向Ｘおよび第２方向Ｙは、後述する基板３の厚さ方向に直交する方向と定義してもよい。 The MEMS switch A1 is, for example, an electrostatically driven MEMS switch including an electrostatic actuator 2. The MEMS switch A1 generates a driving force along the first direction X by, for example, mechanical operation of the electrostatic actuator 2. In this embodiment, the direction orthogonal to the first direction X in the horizontal direction is the second direction Y, and the direction orthogonal to the first direction X in the vertical direction is the third direction Z. The third direction Z may be defined as the thickness direction of the MEMS switch A1 and the thickness direction of the substrate 3 described later. The first direction X and the second direction Y may be defined as directions orthogonal to the thickness direction of the substrate 3, which will be described later.
　ＭＥＭＳスイッチＡ１は、基板３を含む。基板３は、ＭＥＭＳスイッチＡ１の外形を形成していてもよい。たとえば、基板３は、チップ状（直方体形状）に形成された構造体であってもよい。図１および図２は、基板３の一部を示している。基板３は、Ｓｉ等の半導体材料を含む半導体基板であってもよい。基板３は、第１主面４と、第１主面４の反対側の第２主面５とを有している。第１主面４が基板３の上面であり、第２主面５が基板３の下面であってもよい。第１主面４は、ＭＥＭＳ構造が形成された基板３の加工面であり、第２主面５は、加工面に対して非加工面であってもよい。 The MEMS switch A1 includes the substrate 3. The substrate 3 may form the outer shape of the MEMS switch A1. For example, the substrate 3 may be a structure formed in a chip shape (rectangular cuboid shape). 1 and 2 show a part of the substrate 3. The substrate 3 may be a semiconductor substrate containing a semiconductor material such as Si. The substrate 3 has a first main surface 4 and a second main surface 5 on the opposite side of the first main surface 4. The first main surface 4 may be the upper surface of the substrate 3, and the second main surface 5 may be the lower surface of the substrate 3. The first main surface 4 may be a processed surface of the substrate 3 on which the MEMS structure is formed, and the second main surface 5 may be a non-processed surface with respect to the processed surface.
　基板３は、この実施形態では、第１ベース層６と、第２ベース層７と、第１ベース層６および第２ベース層７の間の埋め込み絶縁層８とを含む。基板３は、ＳＯＩ（Silicon on Insulator）基板であってもよい。基板３がＳＯＩ基板である場合、第１ベース層６はＳｉ基板であり、第２ベース層７はＳｉ層であり、埋め込み絶縁層８はＢＯＸ（Buried Oxide）層であってもよい。 In this embodiment, the substrate 3 includes a first base layer 6, a second base layer 7, and an embedded insulating layer 8 between the first base layer 6 and the second base layer 7. The substrate 3 may be an SOI (Silicon on Insulator) substrate. When the substrate 3 is an SOI substrate, the first base layer 6 may be a Si substrate, the second base layer 7 may be a Si layer, and the embedded insulating layer 8 may be a BOX (Buried Oxide) layer.
　第１ベース層６は、この実施形態では、半導体基板（たとえば、Ｓｉ基板）であってもよい。第１ベース層６の厚さは、たとえば、１０μｍ以上７００μｍ以下であってもよい。第１ベース層６は、第１主面９と、第１主面９の反対側の第２主面１０とを有している。第１ベース層６の第２主面１０は、基板３の第２主面５であってもよい。 In this embodiment, the first base layer 6 may be a semiconductor substrate (for example, a Si substrate). The thickness of the first base layer 6 may be, for example, 10 μm or more and 700 μm or less. The first base layer 6 has a first main surface 9 and a second main surface 10 on the opposite side of the first main surface 9. The second main surface 10 of the first base layer 6 may be the second main surface 5 of the substrate 3.
　第２ベース層７は、この実施形態では、半導体層（たとえば、Ｓｉ層）であってもよい。第２ベース層７の厚さは、たとえば、１０μｍ以上１００μｍ以下であってもよい。第２ベース層７は、第１主面１１と、第１主面１１の反対側の第２主面１２とを有している。第２ベース層７の第１主面１１は、基板３の第１主面４であってもよい。 In this embodiment, the second base layer 7 may be a semiconductor layer (for example, a Si layer). The thickness of the second base layer 7 may be, for example, 10 μm or more and 100 μm or less. The second base layer 7 has a first main surface 11 and a second main surface 12 on the opposite side of the first main surface 11. The first main surface 11 of the second base layer 7 may be the first main surface 4 of the substrate 3.
　埋め込み絶縁層８は、第１ベース層６と第２ベース層７との間に接触して挟まれている。埋め込み絶縁層８は、この実施形態では、第１絶縁材料を含む絶縁層であってもよい。第１絶縁材料は、たとえば、酸化シリコン（ＳｉＯ２）、窒化シリコン（Ｓｉ３Ｎ４）等を含む絶縁材料であってもよい。第１絶縁材料は、たとえば、ＣＦ４、ＣＨＦ３、ＳＦ６等のエッチングガスおよびエッチング液によってエッチング可能な絶縁材料であってもよい。埋め込み絶縁層８の厚さは、第１ベース層６および第２ベース層７よりも小さくてもよい。埋め込み絶縁層８の厚さは、たとえば、０．１μｍ以上２０μｍ以下であってもよい。 The embedded insulating layer 8 is in contact with and sandwiched between the first base layer 6 and the second base layer 7. In this embodiment, the embedded insulating layer 8 may be an insulating layer containing the first insulating material. The first insulating material may be, for example, an insulating material containing silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or the like. The first insulating material may be, for example, an insulating material that can be etched by an etching gas such as CF 4 , CHF 3 , SF 6 , and an etching solution. The thickness of the embedded insulating layer 8 may be smaller than that of the first base layer 6 and the second base layer 7. The thickness of the embedded insulating layer 8 may be, for example, 0.1 μm or more and 20 μm or less.
　埋め込み絶縁層８は、第２ベース層７の第２主面１２に接する第１接合面１３と、第１ベース層６の第１主面９に接する第２接合面１４とを有している。埋め込み絶縁層８は、さらに、側面１５を有している。埋め込み絶縁層８の側面１５は、空洞１６に対して横側から面している。他の言い方では、埋め込み絶縁層８の側面１５は、第１方向Ｘおよび第２方向Ｙにおいて、空洞１６に対して面している。埋め込み絶縁層８は、第１ベース層６と第２ベース層７との間に部分的に形成されている。第１ベース層６と第２ベース層７との間の領域において、埋め込み絶縁層８が形成されていない領域が空洞１６である。空洞１６は、第１ベース層６の第１主面９、第２ベース層７の第２主面１２および埋め込み絶縁層８の側面１５によって区画されている。空洞１６の底面が第１ベース層６の第１主面９であり、空洞１６の上面が第２ベース層７の第２主面１２であり、空洞１６の側面１５が埋め込み絶縁層８の側面１５であってもよい。 The embedded insulating layer 8 has a first joint surface 13 in contact with the second main surface 12 of the second base layer 7, and a second joint surface 14 in contact with the first main surface 9 of the first base layer 6. .. The embedded insulating layer 8 further has a side surface 15. The side surface 15 of the embedded insulating layer 8 faces the cavity 16 from the side. In other words, the side surface 15 of the embedded insulating layer 8 faces the cavity 16 in the first direction X and the second direction Y. The embedded insulating layer 8 is partially formed between the first base layer 6 and the second base layer 7. In the region between the first base layer 6 and the second base layer 7, the region where the embedded insulating layer 8 is not formed is the cavity 16. The cavity 16 is partitioned by a first main surface 9 of the first base layer 6, a second main surface 12 of the second base layer 7, and a side surface 15 of the embedded insulating layer 8. The bottom surface of the cavity 16 is the first main surface 9 of the first base layer 6, the upper surface of the cavity 16 is the second main surface 12 of the second base layer 7, and the side surface 15 of the cavity 16 is the side surface of the embedded insulating layer 8. It may be 15.
　第２ベース層７は、固定構造１７と、固定構造１７に対して変位可能な可動構造１８とを含む。 The second base layer 7 includes a fixed structure 17 and a movable structure 18 that can be displaced with respect to the fixed structure 17.
　固定構造１７は、少なくとも一部が埋め込み絶縁層８上に形成されている。図２を参照して、固定構造１７は、埋め込み絶縁層８の第１接合面１３に固定されたフレーム部１９と、フレーム部１９によって空洞１６に対して浮いた状態で支持された第１カンチレバー構造２０とを含む。 At least a part of the fixed structure 17 is formed on the embedded insulating layer 8. With reference to FIG. 2, the fixing structure 17 has a frame portion 19 fixed to the first joint surface 13 of the embedded insulating layer 8 and a first cantilever supported by the frame portion 19 in a floating state with respect to the cavity 16. Includes structure 20 and.
　図１を参照して、フレーム部１９は、第１方向Ｘにおいて互いに平行に延びる一対の帯状のフレーム部１９を含んでいてもよい。第１カンチレバー構造２０は、フレーム部１９から第２方向Ｙに互いに平行に延びる複数の第１カンチレバー構造２０を含んでいてもよい。この実施形態では、フレーム部１９に対して４本の第１カンチレバー構造２０が機械的に接続されている。第１カンチレバー構造２０は、フレーム部１９を介して固定された電極であるため、固定電極２１と定義してもよい。 With reference to FIG. 1, the frame portion 19 may include a pair of strip-shaped frame portions 19 extending parallel to each other in the first direction X. The first cantilever structure 20 may include a plurality of first cantilever structures 20 extending parallel to each other in the second direction Y from the frame portion 19. In this embodiment, four first cantilever structures 20 are mechanically connected to the frame portion 19. Since the first cantilever structure 20 is an electrode fixed via the frame portion 19, it may be defined as a fixed electrode 21.
　可動構造１８は、全体が空洞１６に対して浮いた状態で形成されている。図１を参照して、可動構造１８は、連結部材２２と、第２カンチレバー構造２３とを含む。 The movable structure 18 is formed so as to be entirely floating with respect to the cavity 16. With reference to FIG. 1, the movable structure 18 includes a connecting member 22 and a second cantilever structure 23.
　連結部材２２は、第１方向Ｘに延びる帯状の連結部材２２を含んでいてもよい。第２カンチレバー構造２３は、連結部材２２から第２方向Ｙに互いに平行に延びる複数の第２カンチレバー構造２３を含んでいてもよい。この実施形態では、フレーム部１９に向かって連結部材２２から延びる４本の第２カンチレバー構造２３が、連結部材２２に機械的に連結されている。第２カンチレバー構造２３は、隣り合う第１カンチレバー構造２０の間をフレーム部１９に向かって延びている。第１カンチレバー構造２０および第２カンチレバー構造２３は、互いに隙間５５を挟んで平行に延びている。第２カンチレバー構造２３は、空洞１６に対して浮いた状態で連結部材２２に支持された電極であるため、可動電極２４と定義してもよい。連結部材２２および第２カンチレバー構造２３の一体構造物を可動電極２４と定義してもよい。連結部材２２は、後述する固定接点部４６に可動接点部４５を押し付ける部材であるため、プッシュロッドと定義してもよい。 The connecting member 22 may include a strip-shaped connecting member 22 extending in the first direction X. The second cantilever structure 23 may include a plurality of second cantilever structures 23 extending parallel to each other in the second direction Y from the connecting member 22. In this embodiment, four second cantilever structures 23 extending from the connecting member 22 toward the frame portion 19 are mechanically connected to the connecting member 22. The second cantilever structure 23 extends between adjacent first cantilever structures 20 toward the frame portion 19. The first cantilever structure 20 and the second cantilever structure 23 extend in parallel with each other with a gap 55 in between. Since the second cantilever structure 23 is an electrode supported by the connecting member 22 while floating with respect to the cavity 16, it may be defined as a movable electrode 24. The integrated structure of the connecting member 22 and the second cantilever structure 23 may be defined as the movable electrode 24. Since the connecting member 22 is a member that presses the movable contact portion 45 against the fixed contact portion 46 described later, it may be defined as a push rod.
　このように、第１カンチレバー構造２０および第２カンチレバー構造２３は、それぞれ櫛歯状に形成されており、互いに間隔を空けてかみ合っている。これにより、第１カンチレバー構造２０（固定電極２１）および第２カンチレバー構造２３（可動電極２４）を含む櫛歯型電極２５が形成されている。固定電極２１および可動電極２４に電気信号が入力されることによって、固定電極２１と可動電極２４との間に静電気力が発生する。この静電気力によって、第１方向Ｘにおいて可動電極２４を固定電極２１に近づけたり、可動電極２４を固定電極２１から遠ざけたりする機械的動作を行うことができる。したがって、櫛歯型電極２５は、電気信号を第１方向Ｘに沿う機械的変位に変換する静電アクチュエータ２と定義してもよい。 As described above, the first cantilever structure 20 and the second cantilever structure 23 are each formed in a comb-teeth shape and mesh with each other at intervals. As a result, the comb-tooth type electrode 25 including the first cantilever structure 20 (fixed electrode 21) and the second cantilever structure 23 (movable electrode 24) is formed. When an electric signal is input to the fixed electrode 21 and the movable electrode 24, an electrostatic force is generated between the fixed electrode 21 and the movable electrode 24. By this electrostatic force, it is possible to perform a mechanical operation such as bringing the movable electrode 24 closer to the fixed electrode 21 or moving the movable electrode 24 away from the fixed electrode 21 in the first direction X. Therefore, the comb-toothed electrode 25 may be defined as an electrostatic actuator 2 that converts an electrical signal into a mechanical displacement along the first direction X.
　第１カンチレバー構造２０および第２カンチレバー構造２３は、第１方向Ｘにおいて対向している。たとえば、図１に示すように、第１カンチレバー構造２０および第２カンチレバー構造２３が、第１方向Ｘに沿って交互に配置されていてもよい。たとえば、第２カンチレバー構造２３および第１カンチレバー構造２０は、第１方向Ｘの配列順に、第１可動電極２４Ａ、第１固定電極２１Ａ、第２可動電極２４Ｂ、および第２固定電極２１Ｂと定義してもよい。第１固定電極２１Ａは、第１方向Ｘにおいて、第１可動電極２４Ａおよび第２可動電極２４Ｂに間隔を空けて挟まれている。第２可動電極２４Ｂは、第１方向Ｘにおいて、第１固定電極２１Ａおよび第２固定電極２１Ｂに間隔を空けて挟まれている。 The first cantilever structure 20 and the second cantilever structure 23 face each other in the first direction X. For example, as shown in FIG. 1, the first cantilever structure 20 and the second cantilever structure 23 may be arranged alternately along the first direction X. For example, the second cantilever structure 23 and the first cantilever structure 20 are defined as the first movable electrode 24A, the first fixed electrode 21A, the second movable electrode 24B, and the second fixed electrode 21B in the order of arrangement in the first direction X. You may. The first fixed electrode 21A is sandwiched between the first movable electrode 24A and the second movable electrode 24B at intervals in the first direction X. The second movable electrode 24B is sandwiched between the first fixed electrode 21A and the second fixed electrode 21B at intervals in the first direction X.
　第１方向Ｘにおいて、１つの固定電極２１と、当該固定電極２１に隣り合う１対の可動電極２４との距離は、互いに異なっていてもよい。第１方向Ｘにおいて、１つの可動電極２４と、当該可動電極２４に隣り合う１対の固定電極２１との距離は、互いに異なっていてもよい。たとえば、第１可動電極２４Ａと第１固定電極２１Ａとの距離ｄ１は、第２可動電極２４Ｂと第１固定電極２１Ａとの距離ｄ２よりも小さくてもよい。また、第２可動電極２４Ｂと第１固定電極２１Ａとの距離ｄ２は、第２可動電極２４Ｂと第２固定電極２１Ｂとの距離ｄ３よりも大きくてもよい。 In the first direction X, the distance between one fixed electrode 21 and a pair of movable electrodes 24 adjacent to the fixed electrode 21 may be different from each other. In the first direction X, the distance between one movable electrode 24 and a pair of fixed electrodes 21 adjacent to the movable electrode 24 may be different from each other. For example, the distance d1 between the first movable electrode 24A and the first fixed electrode 21A may be smaller than the distance d2 between the second movable electrode 24B and the first fixed electrode 21A. Further, the distance d2 between the second movable electrode 24B and the first fixed electrode 21A may be larger than the distance d3 between the second movable electrode 24B and the second fixed electrode 21B.
　このように、櫛歯型電極２５において固定電極２１と可動電極２４との距離にばらつきがある非対称構造７２が提供される。この非対称構造７２は、櫛歯型電極２５における静電気力の釣り合いを崩す。その結果、たとえば、第２可動電極２４Ｂと第２固定電極２１Ｂとの間に作用する静電気力（第２静電気力Ｆ２）を、第２可動電極２４Ｂと第１固定電極２１Ａとの間に作用する静電気力（第１静電気力Ｆ１）に比べて大きくすることができる。したがって、第１静電気力Ｆ１と第２静電気力Ｆ２との差（第１静電気力Ｆ１－第２静電気力Ｆ２）に相当する静電気力によって、可動構造１８を固定接点部４６に向かって変位させることができる。 As described above, in the comb-tooth type electrode 25, the asymmetric structure 72 in which the distance between the fixed electrode 21 and the movable electrode 24 varies is provided. This asymmetric structure 72 upsets the balance of the electrostatic force in the comb-tooth type electrode 25. As a result, for example, an electrostatic force acting between the second movable electrode 24B and the second fixed electrode 21B (second electrostatic force F2) acts between the second movable electrode 24B and the first fixed electrode 21A. It can be made larger than the electrostatic force (first electrostatic force F1). Therefore, the movable structure 18 is displaced toward the fixed contact portion 46 by the electrostatic force corresponding to the difference between the first electrostatic force F1 and the second electrostatic force F2 (first electrostatic force F1-second electrostatic force F2). Can be done.
　可動構造１８は、ビーム部２７を介して、固定構造１７に対して変位可能に機械的に接続されている。ビーム部２７は、固定構造１７および可動構造１８と同様に第２ベース層７を利用して形成されている。ビーム部２７は、連結部材２２の第２方向Ｙの両側からフレーム部１９に向かって第２方向Ｙに沿って延びる帯状に形成されている。ビーム部２７の長手方向の第１端部２８およびその反対側の第２端部２９は、それぞれ、フレーム部１９および連結部材２２に機械的に接続されている。ビーム部２７は、図１に示すように、櫛歯型電極２５の第１方向Ｘの両側に２本ずつ、合計４本形成されていてもよい。これにより、可動構造１８は、空洞１６に対して浮いた状態で、ビーム部２７によって４点で支持されている。各ビーム部２７は、連結部材２２に対して垂直に接続されていてもよい。 The movable structure 18 is mechanically connected to the fixed structure 17 via a beam portion 27 so as to be displaceable. The beam portion 27 is formed by utilizing the second base layer 7 as in the fixed structure 17 and the movable structure 18. The beam portion 27 is formed in a band shape extending from both sides of the connecting member 22 in the second direction Y toward the frame portion 19 along the second direction Y. The first end 28 in the longitudinal direction of the beam 27 and the second end 29 on the opposite side thereof are mechanically connected to the frame 19 and the connecting member 22, respectively. As shown in FIG. 1, two beam portions 27 may be formed on both sides of the comb tooth type electrode 25 in the first direction X, for a total of four beams. As a result, the movable structure 18 is supported at four points by the beam portion 27 in a state of floating with respect to the cavity 16. Each beam portion 27 may be connected perpendicularly to the connecting member 22.
　ビーム部２７は、可撓性を有している。たとえば、ビーム部２７は、第１方向Ｘにおいて弾性的に折り曲げ可能である。ビーム部２７は、たとえば、フレーム部１９に固定された固定端である第１端部２８に対して、固定端の反対側の自由端である第２端部２９が第１方向Ｘにおいて変位可能なように、可撓性を有していてもよい。ビーム部２７は、固定構造１７と可動構造１８とを接続する可撓性を有する構造であるため、フレキシブル接続構造と定義してもよい。ビーム部２７は、第１方向Ｘに撓むスプリング構造と定義してもよい。また、ビーム部２７は、可動構造１８に含まれる構造と定義してもよい。この場合、連結部材２２、第２カンチレバー構造２３およびビーム部２７の一体構造物を可動電極２４と定義してもよい。 The beam portion 27 has flexibility. For example, the beam portion 27 can be elastically bent in the first direction X. In the beam portion 27, for example, the second end portion 29, which is a free end opposite to the fixed end, can be displaced in the first direction X with respect to the first end portion 28, which is a fixed end fixed to the frame portion 19. As such, it may have flexibility. Since the beam portion 27 has a flexible structure for connecting the fixed structure 17 and the movable structure 18, it may be defined as a flexible connection structure. The beam portion 27 may be defined as a spring structure that bends in the first direction X. Further, the beam portion 27 may be defined as a structure included in the movable structure 18. In this case, the integrated structure of the connecting member 22, the second cantilever structure 23, and the beam portion 27 may be defined as the movable electrode 24.
　ＭＥＭＳスイッチＡ１は、可動接点部４５と、固定接点部４６とを含む。 The MEMS switch A1 includes a movable contact portion 45 and a fixed contact portion 46.
　図１を参照して、可動接点部４５は、可動構造１８の連結部材２２に設けられている。たとえば、可動接点部４５は、連結部材２２の長手方向の端部４７に設けられている。この実施形態では、連結部材２２の端部４７に第２ビーム部４８が機械的に接続されている。第２ビーム部４８は、連結部材２２の長手方向に交差する方向に延びる直線状である。第２ビーム部４８は、連結部材２２の端部４７から当該交差方向の両側に延びている。可動接点部４５は、第２ビーム部４８の幅方向における第１側部４９および第２側部５０のうち、第２側部５０に選択的に形成されている。第２ビーム部４８の第１側部４９は、第１方向Ｘにおいて静電アクチュエータ２に対向する側部であり、第２側部５０は第１側部４９の反対側である。 With reference to FIG. 1, the movable contact portion 45 is provided on the connecting member 22 of the movable structure 18. For example, the movable contact portion 45 is provided at the end portion 47 in the longitudinal direction of the connecting member 22. In this embodiment, the second beam portion 48 is mechanically connected to the end portion 47 of the connecting member 22. The second beam portion 48 has a linear shape extending in a direction intersecting the longitudinal direction of the connecting member 22. The second beam portion 48 extends from the end portion 47 of the connecting member 22 on both sides in the crossing direction. The movable contact portion 45 is selectively formed on the second side portion 50 of the first side portion 49 and the second side portion 50 in the width direction of the second beam portion 48. The first side portion 49 of the second beam portion 48 is a side portion facing the electrostatic actuator 2 in the first direction X, and the second side portion 50 is the opposite side of the first side portion 49.
　図２を参照して、可動接点部４５は、空洞１６に対して浮いた状態で形成された第１構造５１を有している。第１構造５１は、第２ベース層７と、第１絶縁層３６と、第２絶縁層３７と、可動接点層５２とを含む。 With reference to FIG. 2, the movable contact portion 45 has a first structure 51 formed in a floating state with respect to the cavity 16. The first structure 51 includes a second base layer 7, a first insulating layer 36, a second insulating layer 37, and a movable contact layer 52.
　第１構造５１において第１絶縁層３６は、第２ベース層７上に形成されている。第１絶縁層３６は、基板３の厚さ方向（この実施形態では、第３方向Ｚ）に沿う端面５３と、当該端面５３に交差する主面５４を有している。第１絶縁層３６の主面５４は、基板３の第１主面４に沿って形成されている。第１構造５１の第１絶縁層３６の端面５３は、固定接点部４６との間の隙間５５を介して固定接点部４６に対向している。第１絶縁層３６の端面５３に連なるように、第２ベース層７は、隙間５５を介して固定接点部４６に対向する端面８３を有している。 In the first structure 51, the first insulating layer 36 is formed on the second base layer 7. The first insulating layer 36 has an end surface 53 along the thickness direction of the substrate 3 (in this embodiment, the third direction Z) and a main surface 54 intersecting the end surface 53. The main surface 54 of the first insulating layer 36 is formed along the first main surface 4 of the substrate 3. The end surface 53 of the first insulating layer 36 of the first structure 51 faces the fixed contact portion 46 via a gap 55 between the first insulating layer 36 and the fixed contact portion 46. The second base layer 7 has an end surface 83 facing the fixed contact portion 46 via a gap 55 so as to be connected to the end surface 53 of the first insulating layer 36.
　第１絶縁層３６は、たとえば、埋め込み絶縁層８と同じ第１絶縁材料を含んでいてもよい。この実施形態では、第１絶縁層３６は、酸化シリコン（ＳｉＯ２）であってもよい。第１絶縁材料は、たとえば、酸化シリコン（ＳｉＯ２）、窒化シリコン（Ｓｉ３Ｎ４）等を含む絶縁材料であってもよい。第１絶縁材料は、たとえば、ＣＦ４、ＣＨＦ３、ＳＦ６等のエッチングガスおよびエッチング液によってエッチング可能な絶縁材料であってもよい。第１絶縁層３６は、たとえば、０．１μｍ以上２０μｍ以下の厚さを有していてもよい。 The first insulating layer 36 may contain, for example, the same first insulating material as the embedded insulating layer 8. In this embodiment, the first insulating layer 36 may be silicon oxide (SiO 2 ). The first insulating material may be, for example, an insulating material containing silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or the like. The first insulating material may be, for example, an insulating material that can be etched by an etching gas such as CF 4 , CHF 3 , SF 6 , and an etching solution. The first insulating layer 36 may have a thickness of, for example, 0.1 μm or more and 20 μm or less.
　第１構造５１において第２絶縁層３７は、第１絶縁層３６の端面５３を被覆するように第１絶縁層３６上に形成されている。第２絶縁層３７は、第１絶縁層３６の主面５４および端面５３を連続して被覆していてもよい。この実施形態では、第２絶縁層３７は、第２ベース層７の端面８３と第１絶縁層３６の端面５３との境界部５６に端部８４を有するように第１絶縁層３６の主面５４および端面５３を連続して被覆している。これにより、第２ベース層７の端面８３と第１絶縁層３６の端面５３との境界部５６は、第２ベース層７の端面８３と第２絶縁層３７の端面８６との境界部８５で被覆されている。第２絶縁層３７の端面８６は、第２ベース層７の端面８３に連続する面であり、隙間５５を介して固定接点部４６に対向している。また、第２絶縁層３７は、端面８６に交差する主面８７を有していてもよい。第２絶縁層３７の主面８７は、基板３の第１主面４に沿って形成されている。 In the first structure 51, the second insulating layer 37 is formed on the first insulating layer 36 so as to cover the end surface 53 of the first insulating layer 36. The second insulating layer 37 may continuously cover the main surface 54 and the end surface 53 of the first insulating layer 36. In this embodiment, the second insulating layer 37 has a main surface of the first insulating layer 36 so that the second insulating layer 37 has an end portion 84 at the boundary portion 56 between the end surface 83 of the second base layer 7 and the end surface 53 of the first insulating layer 36. The 54 and the end face 53 are continuously covered. As a result, the boundary portion 56 between the end surface 83 of the second base layer 7 and the end surface 53 of the first insulating layer 36 is formed at the boundary portion 85 between the end surface 83 of the second base layer 7 and the end surface 86 of the second insulating layer 37. It is covered. The end surface 86 of the second insulating layer 37 is a surface continuous with the end surface 83 of the second base layer 7, and faces the fixed contact portion 46 via the gap 55. Further, the second insulating layer 37 may have a main surface 87 intersecting the end surface 86. The main surface 87 of the second insulating layer 37 is formed along the first main surface 4 of the substrate 3.
　第２絶縁層３７は、第１絶縁層３６とは異なる第２絶縁材料を含んでいてもよい。第２絶縁層３７は、第１絶縁層３６に対してエッチング選択比を有する第２絶縁材料であってもよい。第２絶縁層３７は、第１絶縁層３６および埋め込み絶縁層８に対してエッチング選択比を有する第２絶縁材料であってもよい。第２絶縁層３７は、第１絶縁層３６のエッチングに使用可能なエッチングガスおよびエッチング液に対してエッチング耐性を有する第２絶縁材料であってもよい。第２絶縁層３７がエッチング耐性を有するとは、たとえば、第１絶縁層３６用のエッチングガスを使用する場合の第１絶縁層３６および第２絶縁層３７のエッチング選択比（第１絶縁層３６の平均エッチングレート／第２絶縁層３７の平均エッチングレート）が、１０～１０００であってもよい。このようなことから、第２絶縁層３７は、第１絶縁層３６と同じ材料からなる埋め込み絶縁層８のエッチング時に第１絶縁層３６をエッチングから保護するエッチング保護層と定義してもよい。 The second insulating layer 37 may contain a second insulating material different from that of the first insulating layer 36. The second insulating layer 37 may be a second insulating material having an etching selectivity with respect to the first insulating layer 36. The second insulating layer 37 may be a second insulating material having an etching selectivity with respect to the first insulating layer 36 and the embedded insulating layer 8. The second insulating layer 37 may be a second insulating material having etching resistance against an etching gas and an etching solution that can be used for etching the first insulating layer 36. The second insulating layer 37 has etching resistance, for example, when the etching gas for the first insulating layer 36 is used, the etching selectivity of the first insulating layer 36 and the second insulating layer 37 (the first insulating layer 36). The average etching rate of the second insulating layer 37) may be 10 to 1000. Therefore, the second insulating layer 37 may be defined as an etching protective layer that protects the first insulating layer 36 from etching when the embedded insulating layer 8 made of the same material as the first insulating layer 36 is etched.
　この実施形態では、第２絶縁材料は、酸化アルミニウム（Ａｌ２Ｏ３）、酸化タンタル（ＴａＯ２）等を含む絶縁材料であってもよい。第２絶縁材料は、たとえば、ＣＦ４、ＣＨＦ３、ＳＦ６等のエッチングガスおよびエッチング液によってエッチング可能な絶縁材料であってもよい。第２絶縁層３７は、第１絶縁層３６よりも薄くてもよい。第２絶縁層３７は、たとえば、０．０１μｍ以上１０μｍ以下の厚さを有していてもよい。 In this embodiment, the second insulating material may be an insulating material containing aluminum oxide (Al 2 O 3 ), tantalum oxide (TaO 2 ) and the like. The second insulating material may be, for example, an insulating material that can be etched by an etching gas such as CF 4 , CHF 3 , SF 6 , and an etching solution. The second insulating layer 37 may be thinner than the first insulating layer 36. The second insulating layer 37 may have a thickness of, for example, 0.01 μm or more and 10 μm or less.
　可動接点層５２は、第２絶縁層３７を介して第１絶縁層３６に支持されている。可動接点層５２は、第２絶縁層３７の主面８７および端面８６を被覆している。可動接点層５２は、第２絶縁層３７を介して第１絶縁層３６の主面５４および端面５３に対向している。この実施形態では、第１絶縁層３６の厚さ方向において、端面８６の主面８７に近い部分が可動接点層５２で被覆され、端面８６の残りの部分は隙間５５に向かって露出していてもよい。言い換えれば、第１構造５１の第２絶縁層３７と第２ベース層７との境界部８５が隙間５５に面していてもよい。可動接点層５２は、第２絶縁層３７の主面８７に形成されたベース部５７と、ベース部５７から第２絶縁層３７の端面８６よりも固定接点部４６側に突出した突出部５８とを一体的に含んでいてもよい。突出部５８は、第２絶縁層３７の端面８６を被覆する部分であってもよい。可動接点層５２は、たとえば、金（Ａｕ）、アルミニウム（Ａｌ）等の導電材料であってもよい。可動接点層５２は、第１信号線５９に電気的に接続されている。 The movable contact layer 52 is supported by the first insulating layer 36 via the second insulating layer 37. The movable contact layer 52 covers the main surface 87 and the end surface 86 of the second insulating layer 37. The movable contact layer 52 faces the main surface 54 and the end surface 53 of the first insulating layer 36 via the second insulating layer 37. In this embodiment, in the thickness direction of the first insulating layer 36, the portion of the end surface 86 close to the main surface 87 is covered with the movable contact layer 52, and the remaining portion of the end surface 86 is exposed toward the gap 55. May be good. In other words, the boundary portion 85 between the second insulating layer 37 and the second base layer 7 of the first structure 51 may face the gap 55. The movable contact layer 52 includes a base portion 57 formed on the main surface 87 of the second insulating layer 37, and a protruding portion 58 protruding from the base portion 57 toward the fixed contact portion 46 with respect to the end surface 86 of the second insulating layer 37. May be included integrally. The protruding portion 58 may be a portion that covers the end face 86 of the second insulating layer 37. The movable contact layer 52 may be made of a conductive material such as gold (Au) or aluminum (Al). The movable contact layer 52 is electrically connected to the first signal line 59.
　図２を参照して、固定接点部４６は、固定構造１７のフレーム部１９に設けられている。フレーム部１９は、互いに機械的に分離された第１フレーム部６０および第２フレーム部６１を含む。第１フレーム部６０および第２フレーム部６１には、可動接点部４５と固定接点部４６との接触によって導通する第２信号線６２が形成されている。固定接点部４６は、埋め込み絶縁層８に支持された第２構造６３を有している。第２構造６３は、第２ベース層７と、第１絶縁層３６と、第２絶縁層３７と、固定接点層６４とを含む。 With reference to FIG. 2, the fixed contact portion 46 is provided in the frame portion 19 of the fixed structure 17. The frame portion 19 includes a first frame portion 60 and a second frame portion 61 that are mechanically separated from each other. The first frame portion 60 and the second frame portion 61 are formed with a second signal line 62 that conducts by contact between the movable contact portion 45 and the fixed contact portion 46. The fixed contact portion 46 has a second structure 63 supported by the embedded insulating layer 8. The second structure 63 includes a second base layer 7, a first insulating layer 36, a second insulating layer 37, and a fixed contact layer 64.
　第２構造６３において第１絶縁層３６は、第２ベース層７上に形成されている。第１絶縁層３６は、基板３の厚さ方向（この実施形態では、第３方向Ｚ）に沿う端面６５と、当該端面６５に交差する主面６６を有している。第１絶縁層３６の主面６６は、基板３の第１主面４に沿って形成されている。第２構造６３の第１絶縁層３６の端面６５は、可動接点部４５との間の隙間５５を介して可動接点部４５に対向している。第１絶縁層３６の端面６５に連なるように、第２ベース層７は、隙間５５を介して固定接点部４６に対向する端面８８を有している。 In the second structure 63, the first insulating layer 36 is formed on the second base layer 7. The first insulating layer 36 has an end surface 65 along the thickness direction of the substrate 3 (in this embodiment, the third direction Z) and a main surface 66 intersecting the end surface 65. The main surface 66 of the first insulating layer 36 is formed along the first main surface 4 of the substrate 3. The end surface 65 of the first insulating layer 36 of the second structure 63 faces the movable contact portion 45 via a gap 55 between the first insulating layer 36 and the movable contact portion 45. The second base layer 7 has an end face 88 facing the fixed contact portion 46 via a gap 55 so as to be connected to the end face 65 of the first insulating layer 36.
　第２構造６３において第２絶縁層３７は、第１絶縁層３６の端面６５を被覆するように第１絶縁層３６上に形成されている。第２絶縁層３７は、第１絶縁層３６の主面６６および端面６５を連続して被覆していてもよい。この実施形態では、第２絶縁層３７は、第２ベース層７の端面８８と第１絶縁層３６の端面６５との境界部６７に端部８９を有するように第１絶縁層３６の主面６６および端面６５を連続して被覆している。これにより、第２ベース層７の端面８８と第１絶縁層３６の端面６５との境界部６７は、第２ベース層７の端面８８と第２絶縁層３７の端面９１との境界部９０で被覆されている。第２絶縁層３７の端面９１は、第２ベース層７の端面８８に連続する面であり、隙間５５を介して可動接点部４５に対向している。また、第２絶縁層３７は、端面９１に交差する主面９２を有していてもよい。第２絶縁層３７の主面９２は、基板３の第１主面４に沿って形成されている。 In the second structure 63, the second insulating layer 37 is formed on the first insulating layer 36 so as to cover the end face 65 of the first insulating layer 36. The second insulating layer 37 may continuously cover the main surface 66 and the end surface 65 of the first insulating layer 36. In this embodiment, the second insulating layer 37 has a main surface of the first insulating layer 36 so that the second insulating layer 37 has an end portion 89 at a boundary portion 67 between the end surface 88 of the second base layer 7 and the end surface 65 of the first insulating layer 36. The 66 and the end face 65 are continuously covered. As a result, the boundary portion 67 between the end face 88 of the second base layer 7 and the end face 65 of the first insulating layer 36 is formed at the boundary portion 90 between the end face 88 of the second base layer 7 and the end face 91 of the second insulating layer 37. It is covered. The end surface 91 of the second insulating layer 37 is a surface continuous with the end surface 88 of the second base layer 7, and faces the movable contact portion 45 via the gap 55. Further, the second insulating layer 37 may have a main surface 92 that intersects the end surface 91. The main surface 92 of the second insulating layer 37 is formed along the first main surface 4 of the substrate 3.
　固定接点層６４は、第２絶縁層３７を介して第１絶縁層３６に支持されている。固定接点層６４は、第２絶縁層３７の主面９２および端面９１を被覆している。固定接点層６４は、第２絶縁層３７を介して第１絶縁層３６の主面６６および端面６５に対向している。この実施形態では、第１絶縁層３６の厚さ方向において、端面９１の主面９２に近い部分が固定接点層６４で被覆され、端面９１の残りの部分は隙間５５に向かって露出していてもよい。言い換えれば、第２構造６３の第２絶縁層３７と第２ベース層７との境界部９０が隙間５５に面していてもよい。固定接点層６４は、第２絶縁層３７の主面９２に形成されたベース部６８と、ベース部６８から第２絶縁層３７の端面９１よりも可動接点部４５側に突出した突出部６９とを一体的に含んでいてもよい。突出部６９は、第２絶縁層３７の端面９１を被覆する部分であってもよい。固定接点層６４は、たとえば、金（Ａｕ）、アルミニウム（Ａｌ）等の導電材料であってもよい。固定接点層６４は、第２信号線６２に電気的に接続されている。 The fixed contact layer 64 is supported by the first insulating layer 36 via the second insulating layer 37. The fixed contact layer 64 covers the main surface 92 and the end surface 91 of the second insulating layer 37. The fixed contact layer 64 faces the main surface 66 and the end surface 65 of the first insulating layer 36 via the second insulating layer 37. In this embodiment, in the thickness direction of the first insulating layer 36, the portion of the end surface 91 near the main surface 92 is covered with the fixed contact layer 64, and the remaining portion of the end surface 91 is exposed toward the gap 55. May be good. In other words, the boundary portion 90 between the second insulating layer 37 and the second base layer 7 of the second structure 63 may face the gap 55. The fixed contact layer 64 includes a base portion 68 formed on the main surface 92 of the second insulating layer 37 and a protruding portion 69 protruding from the base portion 68 toward the movable contact portion 45 side of the end surface 91 of the second insulating layer 37. May be included integrally. The protruding portion 69 may be a portion that covers the end face 91 of the second insulating layer 37. The fixed contact layer 64 may be, for example, a conductive material such as gold (Au) or aluminum (Al). The fixed contact layer 64 is electrically connected to the second signal line 62.
　図３Ａおよび図３Ｂは、図１のＭＥＭＳスイッチＡ１の動作を示す模式図である。図４Ａおよび図４Ｂは、図１のＭＥＭＳスイッチＡ１の動作を示す模式図（拡大図）である。 3A and 3B are schematic views showing the operation of the MEMS switch A1 of FIG. 4A and 4B are schematic views (enlarged views) showing the operation of the MEMS switch A1 of FIG.
　ＭＥＭＳスイッチＡ１を駆動させるには、たとえば、静電アクチュエータ２の可動電極２４と固定電極２１との間に電位差が形成されるように電圧が印加される。これにより、図３Ｂおよび図４Ｂに示すように、ビーム部２７が変形して連結部材２２が変位する。この連結部材２２の変位によって可動接点部４５が固定接点部４６に近づき、可動接点部４５を固定接点部４６に接触させることができる。この接触によって、ＭＥＭＳスイッチＡ１がオンとなり第１信号線５９と第２信号線６２との間が導通し、導通回路が形成される。一方、可動電極２４および固定電極２１への電圧の印加を解除すると、変形していたビーム部２７が復元する。これにより、可動接点部４５が固定接点部４６から離間して非接触となり、ＭＥＭＳスイッチＡ１がオフとなる。 To drive the MEMS switch A1, for example, a voltage is applied so that a potential difference is formed between the movable electrode 24 and the fixed electrode 21 of the electrostatic actuator 2. As a result, as shown in FIGS. 3B and 4B, the beam portion 27 is deformed and the connecting member 22 is displaced. Due to the displacement of the connecting member 22, the movable contact portion 45 approaches the fixed contact portion 46, and the movable contact portion 45 can be brought into contact with the fixed contact portion 46. By this contact, the MEMS switch A1 is turned on, the first signal line 59 and the second signal line 62 are made conductive, and a conduction circuit is formed. On the other hand, when the application of the voltage to the movable electrode 24 and the fixed electrode 21 is released, the deformed beam portion 27 is restored. As a result, the movable contact portion 45 is separated from the fixed contact portion 46 and becomes non-contact, and the MEMS switch A1 is turned off.
　なお、図４Ａおよび図４Ｂに示すように、可動接点部４５の第２ベース層７は、第２ビーム部４８に対して固定接点部４６側に選択的に突出していてもよい。また、固定接点部４６の第２ベース層７は、第１フレーム部６０に対して可動接点部４５側に選択的に突出していてもよい。 As shown in FIGS. 4A and 4B, the second base layer 7 of the movable contact portion 45 may selectively project toward the fixed contact portion 46 with respect to the second beam portion 48. Further, the second base layer 7 of the fixed contact portion 46 may selectively project toward the movable contact portion 45 with respect to the first frame portion 60.
　図５Ａ～図５Ｈは、図１のＭＥＭＳスイッチＡ１の製造工程の一部を工程順に示す図である。 5A to 5H are diagrams showing a part of the manufacturing process of the MEMS switch A1 of FIG. 1 in the order of processes.
　ＭＥＭＳスイッチＡ１を製造するには、たとえば、図５Ａを参照して、ＭＥＭＳスイッチＡ１の基板３を形成するウエハ７３が準備される。ウエハ７３は、第１ウエハ主面７４と、第１ウエハ主面７４の反対側の第２ウエハ主面７５とを有している。第１ウエハ主面７４が第２ベース層７の第１主面１１であり、第２ウエハ主面７５が第１ベース層６の第２主面１０である。ウエハ７３は、この実施形態ではＳＯＩウエハである。 In order to manufacture the MEMS switch A1, for example, a wafer 73 forming the substrate 3 of the MEMS switch A1 is prepared with reference to FIG. 5A. The wafer 73 has a first wafer main surface 74 and a second wafer main surface 75 on the opposite side of the first wafer main surface 74. The first wafer main surface 74 is the first main surface 11 of the second base layer 7, and the second wafer main surface 75 is the second main surface 10 of the first base layer 6. The wafer 73 is an SOI wafer in this embodiment.
　次に、図５Ｂを参照して、ウエハ７３の第１ウエハ主面７４に、第１絶縁層３６が形成される。第１絶縁層３６は、たとえば、ＣＶＤ（Chemical Vapor Deposition）法、熱酸化法等によって形成されてもよい。 Next, with reference to FIG. 5B, the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73. The first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
　次に、図５Ｃを参照して、第１絶縁層３６の不要部分が除去される。これにより、第１絶縁層３６に第１開孔９３が形成され、第１開孔９３から第２ベース層７の第１主面１１の一部が露出する。 Next, referring to FIG. 5C, the unnecessary portion of the first insulating layer 36 is removed. As a result, the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
　次に、図５Ｄを参照して、第１絶縁層３６上に第２絶縁層３７が形成される。第２絶縁層３７は、たとえば、原子層堆積法（ALD：Atomic Layer Deposition）によって形成されてもよい。第１絶縁層３６の主面５４，６６、および第１開孔９３に露出する第１絶縁層３６の端面５３，６５は、第２絶縁層３７に被覆される。 Next, referring to FIG. 5D, the second insulating layer 37 is formed on the first insulating layer 36. The second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD). The main surfaces 54 and 66 of the first insulating layer 36 and the end surfaces 53 and 65 of the first insulating layer 36 exposed to the first opening 93 are covered with the second insulating layer 37.
　次に、図５Ｅを参照して、第１絶縁層３６および第２絶縁層３７の不要部分が除去される。これにより、第２ベース層７の第１主面１１の一部が露出する。 Next, referring to FIG. 5E, unnecessary portions of the first insulating layer 36 and the second insulating layer 37 are removed. As a result, a part of the first main surface 11 of the second base layer 7 is exposed.
　次に、図５Ｆを参照して、第２ベース層７の第１主面１１から第２ベース層７を貫通して埋め込み絶縁層８に達する貫通孔としてのトレンチ７６が形成される。トレンチ７６は、たとえば、異方性のディープＲＩＥ（Reactive Ion Etching）によって形成されてもよい。 Next, with reference to FIG. 5F, a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8. The trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching).
　次に、図５Ｇを参照して、埋め込み絶縁層８をエッチング可能なエッチングガスが供給される。エッチングガスとしては、たとえば、フッ素系ガス（たとえば、ＨＦ等）が使用される。これにより、埋め込み絶縁層８が選択的に除去される。埋め込み絶縁層８が除去された部分には、第１ベース層６と第２ベース層７で挟まれた空洞１６が形成される。空洞１６の形成によって、固定構造１７および可動構造１８が分離して形成される。一方、埋め込み絶縁層８の一部は、第１ベース層６と第２ベース層７とに接触して挟まれた状態で残存する。 Next, referring to FIG. 5G, an etching gas capable of etching the embedded insulating layer 8 is supplied. As the etching gas, for example, a fluorine-based gas (for example, HF or the like) is used. As a result, the embedded insulating layer 8 is selectively removed. A cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed. By forming the cavity 16, the fixed structure 17 and the movable structure 18 are separately formed. On the other hand, a part of the embedded insulating layer 8 remains in contact with and sandwiched between the first base layer 6 and the second base layer 7.
　次に、図５Ｈを参照して、可動接点層５２および固定接点層６４が形成される。可動接点層５２および固定接点層６４は、これらの導電材料（金属材料）の堆積によって形成される。可動接点層５２および固定接点層６４の堆積は、たとえば、ＣＶＤ（Chemical Vapor Deposition）法、ＰＶＤ（Physical Vapor Deposition）法等によって行われてもよい。この際、導電材料の一部が、第１絶縁層３６上に堆積せず、第２ベース層７の端面８３，８８、空洞１６等に残渣７７として堆積してもよい。残渣７７は、可動接点層５２および固定接点層６４とは、物理的かつ電気的に分離されている。 Next, with reference to FIG. 5H, the movable contact layer 52 and the fixed contact layer 64 are formed. The movable contact layer 52 and the fixed contact layer 64 are formed by depositing these conductive materials (metal materials). The movable contact layer 52 and the fixed contact layer 64 may be deposited by, for example, a CVD (Chemical Vapor Deposition) method, a PVD (Physical Vapor Deposition) method, or the like. At this time, a part of the conductive material may not be deposited on the first insulating layer 36, but may be deposited as a residue 77 on the end faces 83, 88, the cavity 16 and the like of the second base layer 7. The residue 77 is physically and electrically separated from the movable contact layer 52 and the fixed contact layer 64.
　その後、たとえば第１信号線５９、第２信号線６２等の必要な配線等が形成され、ウエハ７３が各チップ単位に分割されることによって、ＭＥＭＳスイッチＡ１が得られる。 After that, for example, necessary wirings such as the first signal line 59 and the second signal line 62 are formed, and the wafer 73 is divided into chip units to obtain the MEMS switch A1.
　図５Ａ～図５Ｈの方法によれば、第１絶縁層３６の端面５３，６５が第２絶縁層３７で被覆されている。これにより、トレンチ７６を介して埋め込み絶縁層８をエッチングする際に（図５Ｇ）、第１絶縁層３６が端面５３，６５からエッチングされることを抑制することができる。そのため、可動接点層５２および固定接点層６４の直下の第１絶縁層３６がエッチングにより除去されることを防止できるので、可動接点層５２および固定接点層６４を第１絶縁層３６によって安定的に支持することができる。その結果、可動接点部４５と固定接点部４６との接触信頼性を向上することができる。 According to the methods of FIGS. 5A to 5H, the end faces 53 and 65 of the first insulating layer 36 are covered with the second insulating layer 37. This makes it possible to prevent the first insulating layer 36 from being etched from the end faces 53 and 65 when the embedded insulating layer 8 is etched through the trench 76 (FIG. 5G). Therefore, it is possible to prevent the first insulating layer 36 immediately below the movable contact layer 52 and the fixed contact layer 64 from being removed by etching, so that the movable contact layer 52 and the fixed contact layer 64 can be stably separated by the first insulating layer 36. Can be supported. As a result, the contact reliability between the movable contact portion 45 and the fixed contact portion 46 can be improved.
　また、可動接点層５２および固定接点層６４の直下の第１絶縁層３６が過度にエッチングされると、可動接点層５２および固定接点層６４の一部が宙に浮いて第２ベース層７（半導体）と接触する場合がある。この種の接触は、ＭＥＭＳスイッチＡ１のスイッチング不良を起こすおそれがある。これに対し、本開示のＭＥＭＳスイッチＡ１では、そのようなスイッチング不良を抑制することができる。 Further, when the first insulating layer 36 directly under the movable contact layer 52 and the fixed contact layer 64 is excessively etched, a part of the movable contact layer 52 and the fixed contact layer 64 floats in the air and the second base layer 7 ( It may come into contact with semiconductors). This type of contact may cause switching failure of the MEMS switch A1. On the other hand, in the MEMS switch A1 of the present disclosure, such switching failure can be suppressed.
　図６は、本開示の一実施形態に係るＭＥＭＳスイッチＢ１の模式的な断面図である。以下では、前述の実施形態に係るＭＥＭＳスイッチＡ１に対して述べた構造に対応する構造については同一の参照符号を付して説明を省略する。 FIG. 6 is a schematic cross-sectional view of the MEMS switch B1 according to the embodiment of the present disclosure. In the following, the same reference numerals will be given to the structures corresponding to the structures described for the MEMS switch A1 according to the above-described embodiment, and the description thereof will be omitted.
　図６のＭＥＭＳスイッチＢ１では、可動電極２４、固定電極２１およびビーム部２７は、それぞれ、空洞１６に対して浮いた状態で形成された第３構造９４を有している。第３構造９４は、第２ベース層７と、第１絶縁層３６と、第２絶縁層３７とを含む。 In the MEMS switch B1 of FIG. 6, the movable electrode 24, the fixed electrode 21, and the beam portion 27 each have a third structure 94 formed in a floating state with respect to the cavity 16. The third structure 94 includes a second base layer 7, a first insulating layer 36, and a second insulating layer 37.
　第３構造９４において第１絶縁層３６は、第２ベース層７上に形成されている。第１絶縁層３６は、基板３の厚さ方向（この実施形態では、第３方向Ｚ）に沿う端面９５と、当該端面９５に交差する主面９６を有している。第１絶縁層３６の主面９６は、基板３の第１主面４に沿って形成されている。第１絶縁層３６の端面９５に連なるように、第２ベース層７は端面９７を有している。 In the third structure 94, the first insulating layer 36 is formed on the second base layer 7. The first insulating layer 36 has an end surface 95 along the thickness direction of the substrate 3 (in this embodiment, the third direction Z) and a main surface 96 intersecting the end surface 95. The main surface 96 of the first insulating layer 36 is formed along the first main surface 4 of the substrate 3. The second base layer 7 has an end face 97 so as to be connected to the end face 95 of the first insulating layer 36.
　第３構造９４において第２絶縁層３７は、第１絶縁層３６の端面９５を被覆するように第１絶縁層３６上に形成されている。第２絶縁層３７は、第１絶縁層３６の主面９６および端面９５を連続して被覆していてもよい。この実施形態では、第２絶縁層３７は、第２ベース層７の端面９７と第１絶縁層３６の端面９５との境界部９９に端部９８を有するように第１絶縁層３６の主面９６および端面９５を連続して被覆している。これにより、第２ベース層７の端面９７と第１絶縁層３６の端面９５との境界部９９は、第２ベース層７の端面９７と第２絶縁層３７の端面１０１との境界部１００で被覆されている。第２絶縁層３７の端面１０１は、第２ベース層７の端面９７に連続する面である。また、第２絶縁層３７は、端面１０１に交差する主面１０２を有していてもよい。第２絶縁層３７の主面１０２は、基板３の第１主面４に沿って形成されている。 In the third structure 94, the second insulating layer 37 is formed on the first insulating layer 36 so as to cover the end face 95 of the first insulating layer 36. The second insulating layer 37 may continuously cover the main surface 96 and the end surface 95 of the first insulating layer 36. In this embodiment, the second insulating layer 37 has a main surface of the first insulating layer 36 so that the second insulating layer 37 has an end portion 98 at a boundary portion 99 between the end surface 97 of the second base layer 7 and the end surface 95 of the first insulating layer 36. 96 and end face 95 are continuously covered. As a result, the boundary portion 99 between the end face 97 of the second base layer 7 and the end face 95 of the first insulating layer 36 is the boundary portion 100 between the end face 97 of the second base layer 7 and the end face 101 of the second insulating layer 37. It is covered. The end surface 101 of the second insulating layer 37 is a surface continuous with the end surface 97 of the second base layer 7. Further, the second insulating layer 37 may have a main surface 102 that intersects the end surface 101. The main surface 102 of the second insulating layer 37 is formed along the first main surface 4 of the substrate 3.
　図７Ａ～図７Ｈは、図６のＭＥＭＳスイッチＢ１の製造工程の一部を工程順に示す図である。 7A to 7H are diagrams showing a part of the manufacturing process of the MEMS switch B1 of FIG. 6 in the order of the processes.
　ＭＥＭＳスイッチＢ１を製造するには、たとえば、図７Ａを参照して、ＭＥＭＳスイッチＢ１の基板３を形成するウエハ７３が準備される。 To manufacture the MEMS switch B1, for example, a wafer 73 forming the substrate 3 of the MEMS switch B1 is prepared with reference to FIG. 7A.
　次に、図７Ｂを参照して、ウエハ７３の第１ウエハ主面７４に、第１絶縁層３６が形成される。第１絶縁層３６は、たとえば、ＣＶＤ（Chemical Vapor Deposition）法、熱酸化法等によって形成されてもよい。 Next, with reference to FIG. 7B, the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73. The first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
　次に、図７Ｃを参照して、第１絶縁層３６の不要部分が除去される。これにより、第１絶縁層３６に第１開孔９３が形成され、第１開孔９３から第２ベース層７の第１主面１１の一部が露出する。 Next, referring to FIG. 7C, the unnecessary portion of the first insulating layer 36 is removed. As a result, the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
　次に、図７Ｄを参照して、第１絶縁層３６上に第２絶縁層３７が形成される。第２絶縁層３７は、たとえば、原子層堆積法（ALD：Atomic Layer Deposition）によって形成されてもよい。第１絶縁層３６の主面５４，６６，９６、および第１開孔９３に露出する第１絶縁層３６の端面５３，６５，９５は、第２絶縁層３７に被覆される。 Next, referring to FIG. 7D, the second insulating layer 37 is formed on the first insulating layer 36. The second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD). The main surfaces 54, 66, 96 of the first insulating layer 36 and the end faces 53, 65, 95 of the first insulating layer 36 exposed to the first opening 93 are covered with the second insulating layer 37.
　次に、図７Ｅを参照して、第２絶縁層３７の不要部分が除去される。これにより、第２ベース層７の第１主面１１の一部が露出する。 Next, referring to FIG. 7E, the unnecessary portion of the second insulating layer 37 is removed. As a result, a part of the first main surface 11 of the second base layer 7 is exposed.
　次に、図７Ｆを参照して、第２ベース層７の第１主面１１から第２ベース層７を貫通して埋め込み絶縁層８に達する貫通孔としてのトレンチ７６が形成される。トレンチ７６は、たとえば、異方性のディープＲＩＥ（Reactive Ion Etching）によって形成されてもよい。 Next, with reference to FIG. 7F, a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8. The trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching).
　次に、図７Ｇを参照して、埋め込み絶縁層８をエッチング可能なエッチングガスが供給される。エッチングガスとしては、たとえば、フッ素系ガス（たとえば、ＨＦ等）が使用される。これにより、埋め込み絶縁層８が選択的に除去される。埋め込み絶縁層８が除去された部分には、第１ベース層６と第２ベース層７で挟まれた空洞１６が形成される。 Next, referring to FIG. 7G, an etching gas capable of etching the embedded insulating layer 8 is supplied. As the etching gas, for example, a fluorine-based gas (for example, HF or the like) is used. As a result, the embedded insulating layer 8 is selectively removed. A cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed.
　次に、図７Ｈを参照して、可動接点層５２および固定接点層６４が形成される。 Next, with reference to FIG. 7H, the movable contact layer 52 and the fixed contact layer 64 are formed.
　その後、たとえば第１信号線５９、第２信号線６２等の必要な配線等が形成され、ウエハ７３が各チップ単位に分割されることによって、ＭＥＭＳスイッチＢ１が得られる。 After that, for example, necessary wirings such as the first signal line 59 and the second signal line 62 are formed, and the wafer 73 is divided into chip units to obtain the MEMS switch B1.
　図７Ａ～図７Ｈの方法によれば、第１絶縁層３６の端面５３，６５が第２絶縁層３７で被覆されている。これにより、図５Ａ～図５Ｈの方法と同様の効果を得ることができる。 According to the methods of FIGS. 7A to 7H, the end faces 53 and 65 of the first insulating layer 36 are covered with the second insulating layer 37. Thereby, the same effect as the method of FIGS. 5A to 5H can be obtained.
　さらに、第１絶縁層３６の端面９５が第２絶縁層３７で被覆されている。これにより、トレンチ７６を介して埋め込み絶縁層８をエッチングする際に（図７Ｇ）、第１絶縁層３６が端面９５からエッチングされることを抑制することができる。そのため、可動電極２４および固定電極２１の第１主面１１を第１絶縁層３６で確実に被覆できるので、可動電極２４および固定電極２１の絶縁信頼性を向上することができる。 Further, the end face 95 of the first insulating layer 36 is covered with the second insulating layer 37. This makes it possible to prevent the first insulating layer 36 from being etched from the end face 95 when the embedded insulating layer 8 is etched through the trench 76 (FIG. 7G). Therefore, the first main surface 11 of the movable electrode 24 and the fixed electrode 21 can be reliably covered with the first insulating layer 36, so that the insulation reliability of the movable electrode 24 and the fixed electrode 21 can be improved.
　図８は、本開示の一実施形態に係るＭＥＭＳスイッチＣ１の模式的な断面図である。以下では、前述の実施形態に係るＭＥＭＳスイッチＡ１およびＢ１に対して述べた構造に対応する構造については同一の参照符号を付して説明を省略する。 FIG. 8 is a schematic cross-sectional view of the MEMS switch C1 according to the embodiment of the present disclosure. In the following, the same reference numerals will be given to the structures corresponding to the structures described for the MEMS switches A1 and B1 according to the above-described embodiment, and the description thereof will be omitted.
　ＭＥＭＳスイッチＣ１では、第１構造５１、第２構造６３および第３構造９４において第２絶縁層３７は、第１絶縁層３６の端面５３，６５，９５に加えてさらに、第２ベース層７の端面８３，８８，９７を被覆している。第２絶縁層３７は、第２ベース層７の端面８３，８８，９７と第１絶縁層３６の端面５３，６５，９５との境界部５６，６７，９９を横切るように、第１絶縁層３６の端面５３，６５，９５および第２ベース層７の端面８３，８８，９７を一体的に被覆している。第１構造５１、第２構造６３および第３構造９４において、第２ベース層７の第２主面１２は、第２絶縁層３７で被覆されておらず、空洞１６に対して露出している。 In the MEMS switch C1, in the first structure 51, the second structure 63, and the third structure 94, the second insulating layer 37 is a second base layer 7 in addition to the end faces 53, 65, 95 of the first insulating layer 36. It covers the end faces 83, 88, 97. The second insulating layer 37 is a first insulating layer so as to cross the boundary portions 56, 67, 99 between the end faces 83, 88, 97 of the second base layer 7 and the end faces 53, 65, 95 of the first insulating layer 36. The end faces 53, 65, 95 of 36 and the end faces 83, 88, 97 of the second base layer 7 are integrally covered. In the first structure 51, the second structure 63, and the third structure 94, the second main surface 12 of the second base layer 7 is not covered with the second insulating layer 37 and is exposed to the cavity 16. ..
　図９Ａ～図９Ｈは、図８のＭＥＭＳスイッチＣ１の製造工程の一部を工程順に示す図である。 9A to 9H are diagrams showing a part of the manufacturing process of the MEMS switch C1 of FIG. 8 in the order of the processes.
　ＭＥＭＳスイッチＣ１を製造するには、たとえば、図９Ａを参照して、ＭＥＭＳスイッチＣ１の基板３を形成するウエハ７３が準備される。 To manufacture the MEMS switch C1, for example, a wafer 73 forming the substrate 3 of the MEMS switch C1 is prepared with reference to FIG. 9A.
　次に、図９Ｂを参照して、ウエハ７３の第１ウエハ主面７４に、第１絶縁層３６が形成される。第１絶縁層３６は、たとえば、ＣＶＤ（Chemical Vapor Deposition）法、熱酸化法等によって形成されてもよい。 Next, with reference to FIG. 9B, the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73. The first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
　次に、図９Ｃを参照して、第１絶縁層３６の不要部分が除去される。これにより、第１絶縁層３６に第１開孔９３が形成され、第１開孔９３から第２ベース層７の第１主面１１の一部が露出する。 Next, referring to FIG. 9C, the unnecessary portion of the first insulating layer 36 is removed. As a result, the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
　次に、図９Ｄを参照して、第２ベース層７の第１主面１１から第２ベース層７を貫通して埋め込み絶縁層８に達する貫通孔としてのトレンチ７６が形成される。トレンチ７６は、たとえば、異方性のディープＲＩＥ（Reactive Ion Etching）によって形成されてもよい。 Next, with reference to FIG. 9D, a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8. The trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching).
　次に、図９Ｅを参照して、第１絶縁層３６上に第２絶縁層３７が形成される。第２絶縁層３７は、たとえば、原子層堆積法（ALD：Atomic Layer Deposition）によって形成されてもよい。第１絶縁層３６の主面５４，６６，９６、第１開孔９３に露出する第１絶縁層３６の端面５３，６５，９５、およびトレンチ７６に露出する第２ベース層７の端面８３，８８，９７は、第２絶縁層３７に被覆される。 Next, referring to FIG. 9E, the second insulating layer 37 is formed on the first insulating layer 36. The second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD). The main surfaces 54, 66, 96 of the first insulating layer 36, the end faces 53, 65, 95 of the first insulating layer 36 exposed to the first opening 93, and the end faces 83 of the second base layer 7 exposed to the trench 76, 88 and 97 are covered with the second insulating layer 37.
　次に、図９Ｆを参照して、第２絶縁層３７の不要部分が除去される。これにより、埋め込み絶縁層８の一部が露出する。 Next, referring to FIG. 9F, the unnecessary portion of the second insulating layer 37 is removed. As a result, a part of the embedded insulating layer 8 is exposed.
　次に、図９Ｇを参照して、埋め込み絶縁層８をエッチング可能なエッチングガスが供給される。エッチングガスとしては、たとえば、フッ素系ガス（たとえば、ＨＦ等）が使用される。これにより、埋め込み絶縁層８が選択的に除去される。埋め込み絶縁層８が除去された部分には、第１ベース層６と第２ベース層７で挟まれた空洞１６が形成される。 Next, referring to FIG. 9G, an etching gas capable of etching the embedded insulating layer 8 is supplied. As the etching gas, for example, a fluorine-based gas (for example, HF or the like) is used. As a result, the embedded insulating layer 8 is selectively removed. A cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed.
　次に、図９Ｈを参照して、可動接点層５２および固定接点層６４が形成される。 Next, with reference to FIG. 9H, the movable contact layer 52 and the fixed contact layer 64 are formed.
　その後、たとえば第１信号線５９、第２信号線６２等の必要な配線等が形成され、ウエハ７３が各チップ単位に分割されることによって、ＭＥＭＳスイッチＣ１が得られる。 After that, for example, necessary wirings such as the first signal line 59 and the second signal line 62 are formed, and the wafer 73 is divided into chip units to obtain the MEMS switch C1.
　図９Ａ～図９Ｈの方法によれば、第１絶縁層３６の端面５３，６５，９５が第２絶縁層３７で被覆されている。これにより、図５Ａ～図５Ｈの方法および図７Ａ～図７Ｈの方法と同様の効果を得ることができる。 According to the methods of FIGS. 9A to 9H, the end faces 53, 65, 95 of the first insulating layer 36 are covered with the second insulating layer 37. Thereby, the same effect as the method of FIGS. 5A to 5H and the method of FIGS. 7A to 7H can be obtained.
　さらに、ＭＥＭＳスイッチＣ１によれば、たとえば、埋め込み絶縁層８の一部をエッチングによって除去して第１ベース層６と第２ベース層７との間に空洞１６を形成する際に、第３構造９４の第２ベース層７が端面９７からエッチングされることを抑制することができる。これにより、たとえば、可動電極２４と固定電極２１との間の距離ｄ１～ｄ３を、ほぼ設計通りに維持することができる。 Further, according to the MEMS switch C1, for example, when a part of the embedded insulating layer 8 is removed by etching to form a cavity 16 between the first base layer 6 and the second base layer 7, a third structure is formed. It is possible to prevent the second base layer 7 of 94 from being etched from the end face 97. Thereby, for example, the distances d1 to d3 between the movable electrode 24 and the fixed electrode 21 can be maintained substantially as designed.
　図１０は、本開示の一実施形態に係るＭＥＭＳスイッチＤ１の模式的な断面図である。以下では、前述の実施形態に係るＭＥＭＳスイッチＡ１～Ｃ１に対して述べた構造に対応する構造については同一の参照符号を付して説明を省略する。 FIG. 10 is a schematic cross-sectional view of the MEMS switch D1 according to the embodiment of the present disclosure. In the following, the same reference numerals will be given to the structures corresponding to the structures described for the MEMS switches A1 to C1 according to the above-described embodiment, and the description thereof will be omitted.
　ＭＥＭＳスイッチＤ１では、第１構造５１、第２構造６３および第３構造９４において、第２ベース層７の端面８３，８８，９７と第１絶縁層３６の端面５３，６５，９５との間には、第１絶縁層３６の一部が第２ベース層７の端面８３，８８，９７に対して突出するように、段差１０３が形成されている。 In the MEMS switch D1, in the first structure 51, the second structure 63, and the third structure 94, between the end faces 83, 88, 97 of the second base layer 7 and the end faces 53, 65, 95 of the first insulating layer 36. Is formed with a step 103 so that a part of the first insulating layer 36 projects from the end faces 83, 88, 97 of the second base layer 7.
　図１１Ａ～図１１Ｈは、図１０のＭＥＭＳスイッチＤ１の製造工程の一部を工程順に示す図である。 11A to 11H are diagrams showing a part of the manufacturing process of the MEMS switch D1 of FIG. 10 in the order of processes.
　ＭＥＭＳスイッチＤ１を製造するには、たとえば、図１１Ａを参照して、ＭＥＭＳスイッチＤ１の基板３を形成するウエハ７３が準備される。 To manufacture the MEMS switch D1, for example, a wafer 73 forming the substrate 3 of the MEMS switch D1 is prepared with reference to FIG. 11A.
　次に、図１１Ｂを参照して、ウエハ７３の第１ウエハ主面７４に、第１絶縁層３６が形成される。第１絶縁層３６は、たとえば、ＣＶＤ（Chemical Vapor Deposition）法、熱酸化法等によって形成されてもよい。 Next, with reference to FIG. 11B, the first insulating layer 36 is formed on the first wafer main surface 74 of the wafer 73. The first insulating layer 36 may be formed by, for example, a CVD (Chemical Vapor Deposition) method, a thermal oxidation method, or the like.
　次に、図１１Ｃを参照して、第１絶縁層３６の不要部分が除去される。これにより、第１絶縁層３６に第１開孔９３が形成され、第１開孔９３から第２ベース層７の第１主面１１の一部が露出する。 Next, referring to FIG. 11C, the unnecessary portion of the first insulating layer 36 is removed. As a result, the first opening 93 is formed in the first insulating layer 36, and a part of the first main surface 11 of the second base layer 7 is exposed from the first opening 93.
　次に、図１１Ｄを参照して、第２ベース層７の第１主面１１から第２ベース層７を貫通して埋め込み絶縁層８に達する貫通孔としてのトレンチ７６が形成される。トレンチ７６は、たとえば、異方性のディープＲＩＥ（Reactive Ion Etching）によって形成されてもよい。これにより、段差１０３が形成される。 Next, with reference to FIG. 11D, a trench 76 is formed as a through hole that penetrates from the first main surface 11 of the second base layer 7 to the second base layer 7 and reaches the embedded insulating layer 8. The trench 76 may be formed by, for example, an anisotropic deep RIE (Reactive Ion Etching). As a result, the step 103 is formed.
　次に、図１１Ｅを参照して、第１絶縁層３６上に第２絶縁層３７が形成される。第２絶縁層３７は、たとえば、原子層堆積法（ALD：Atomic Layer Deposition）によって形成されてもよい。第１絶縁層３６の主面５４，６６，９６、第１開孔９３に露出する第１絶縁層３６の端面５３，６５，９５、およびトレンチ７６に露出する第２絶縁層３７の端面８３，８８，９７は、第２絶縁層３７に被覆される。 Next, referring to FIG. 11E, the second insulating layer 37 is formed on the first insulating layer 36. The second insulating layer 37 may be formed by, for example, an atomic layer deposition method (ALD). The main surfaces 54, 66, 96 of the first insulating layer 36, the end faces 53, 65, 95 of the first insulating layer 36 exposed to the first opening 93, and the end faces 83 of the second insulating layer 37 exposed to the trench 76, 88 and 97 are covered with the second insulating layer 37.
　次に、図１１Ｆを参照して、第２絶縁層３７の不要部分が除去される。これにより、埋め込み絶縁層８の一部が露出する。 Next, referring to FIG. 11F, the unnecessary portion of the second insulating layer 37 is removed. As a result, a part of the embedded insulating layer 8 is exposed.
　次に、図１１Ｇを参照して、埋め込み絶縁層８をエッチング可能なエッチングガスが供給される。エッチングガスとしては、たとえば、フッ素系ガス（たとえば、ＨＦ等）が使用される。これにより、埋め込み絶縁層８が選択的に除去される。埋め込み絶縁層８が除去された部分には、第１ベース層６と第２ベース層７で挟まれた空洞１６が形成される。 Next, referring to FIG. 11G, an etching gas capable of etching the embedded insulating layer 8 is supplied. As the etching gas, for example, a fluorine-based gas (for example, HF or the like) is used. As a result, the embedded insulating layer 8 is selectively removed. A cavity 16 sandwiched between the first base layer 6 and the second base layer 7 is formed in the portion from which the embedded insulating layer 8 has been removed.
　次に、図１１Ｈを参照して、可動接点層５２および固定接点層６４が形成される。 Next, with reference to FIG. 11H, the movable contact layer 52 and the fixed contact layer 64 are formed.
　その後、たとえば第１信号線５９、第２信号線６２等の必要な配線等が形成され、ウエハ７３が各チップ単位に分割されることによって、ＭＥＭＳスイッチＤ１が得られる。 After that, for example, necessary wirings such as the first signal line 59 and the second signal line 62 are formed, and the wafer 73 is divided into chip units to obtain the MEMS switch D1.
　図１１Ａ～図１１Ｈの方法によれば、図５Ａ～図５Ｈの方法、図７Ａ～図７Ｈの方法、および図９Ａ～図９Ｈの方法と同様の効果を得ることができる。 According to the methods of FIGS. 11A to 11H, the same effects as the methods of FIGS. 5A to 5H, the methods of FIGS. 7A to 7H, and the methods of FIGS. 9A to 9H can be obtained.
　以上、本開示の実施形態について説明したが、本開示のＭＥＭＳスイッチＡ１，Ｂ１，Ｃ１，Ｄ１は他の形態で実施することもできる。 Although the embodiments of the present disclosure have been described above, the MEMS switches A1, B1, C1, and D1 of the present disclosure can also be implemented in other embodiments.
　たとえば、前述の実施形態では、可動構造１８は、静電アクチュエータ２の静電駆動によって変位しているが、圧電素子を含む圧電アクチュエータの圧電駆動によって変位してもよい。また、静電駆動と圧電駆動との組み合わせによって可動構造１８を変位させてもよい。 For example, in the above-described embodiment, the movable structure 18 is displaced by the electrostatic drive of the electrostatic actuator 2, but it may be displaced by the piezoelectric drive of the piezoelectric actuator including the piezoelectric element. Further, the movable structure 18 may be displaced by a combination of electrostatic drive and piezoelectric drive.
　その他、特許請求の範囲に記載された事項の範囲で種々の設計変更を施すことが可能である。 In addition, various design changes can be made within the scope of the matters stated in the claims.
　本出願は、２０２１年１月１２日に日本国特許庁に提出された特願２０２１－００２８３８号に対応しており、この出願の全開示はここに引用により組み込まれるものとする。 This application corresponds to Japanese Patent Application No. 2021-002838 submitted to the Japan Patent Office on January 12, 2021, and the entire disclosure of this application shall be incorporated herein by reference.
２　　　　　：静電アクチュエータ
３　　　　　：基板
４　　　　　：第１主面
５　　　　　：第２主面
６　　　　　：第１ベース層
７　　　　　：第２ベース層
８　　　　　：埋め込み絶縁層
９　　　　　：第１主面
１０　　　　：第２主面
１１　　　　：第１主面
１２　　　　：第２主面
１３　　　　：第１接合面
１４　　　　：第２接合面
１５　　　　：側面
１６　　　　：空洞
１７　　　　：固定構造
１８　　　　：可動構造
１９　　　　：フレーム部
２０　　　　：第１カンチレバー構造
２１　　　　：固定電極
２１Ａ　　　：第１固定電極
２１Ｂ　　　：第２固定電極
２２　　　　：連結部材
２３　　　　：第２カンチレバー構造
２４　　　　：可動電極
２４Ａ　　　：第１可動電極
２４Ｂ　　　：第２可動電極
２５　　　　：櫛歯型電極
２７　　　　：ビーム部
２８　　　　：第１端部
２９　　　　：第２端部
３６　　　　：第１絶縁層
３７　　　　：第２絶縁層
４５　　　　：可動接点部
４６　　　　：固定接点部
４７　　　　：端部
４８　　　　：第２ビーム部
４９　　　　：第１側部
５０　　　　：第２側部
５１　　　　：第１構造
５２　　　　：可動接点層
５３　　　　：端面
５４　　　　：主面
５５　　　　：隙間
５６　　　　：境界部
５７　　　　：ベース部
５８　　　　：突出部
５９　　　　：第１信号線
６０　　　　：第１フレーム部
６１　　　　：第２フレーム部
６２　　　　：第２信号線
６３　　　　：第２構造
６４　　　　：固定接点層
６５　　　　：端面
６６　　　　：主面
６７　　　　：境界部
６８　　　　：ベース部
６９　　　　：突出部
７２　　　　：非対称構造
７３　　　　：ウエハ
７４　　　　：第１ウエハ主面
７５　　　　：第２ウエハ主面
７６　　　　：トレンチ
７７　　　　：残渣
８３　　　　：端面
８４　　　　：端部
８５　　　　：境界部
８６　　　　：端面
８７　　　　：主面
８８　　　　：端面
８９　　　　：端部
９０　　　　：境界部
９１　　　　：端面
９２　　　　：主面
９３　　　　：第１開孔
９４　　　　：第３構造
９５　　　　：端面
９６　　　　：主面
９７　　　　：端面
９８　　　　：端部
９９　　　　：境界部
１００　　　：境界部
１０１　　　：端面
１０２　　　：主面
１０３　　　：段差
Ａ１　　　　：ＭＥＭＳスイッチ
Ｂ１　　　　：ＭＥＭＳスイッチ
Ｃ１　　　　：ＭＥＭＳスイッチ
Ｄ１　　　　：ＭＥＭＳスイッチ
Ｆ１　　　　：第１静電気力
Ｆ２　　　　：第２静電気力
Ｘ　　　　　：第１方向
Ｙ　　　　　：第２方向
Ｚ　　　　　：第３方向
ｄ１　　　　：距離
ｄ２　　　　：距離
ｄ３　　　　：距離
  2: Electrostatic actuator 3: Substrate 4: First main surface 5: Second main surface 6: First base layer 7: Second base layer 8: Embedded insulating layer 9: First main surface 10: Second main surface 11 : 1st main surface 12: 2nd main surface 13: 1st joint surface 14: 2nd joint surface 15: Side surface 16: Cavity 17: Fixed structure 18: Movable structure 19: Frame portion 20: 1st cantilever structure 21: Fixed Electrode 21A: 1st fixed electrode 21B: 2nd fixed electrode 22: Connecting member 23: 2nd cantilever structure 24: Movable electrode 24A: 1st movable electrode 24B: 2nd movable electrode 25: Comb tooth type electrode 27: Beam portion 28 : 1st end 29: 2nd end 36: 1st insulating layer 37: 2nd insulating layer 45: Movable contact part 46: Fixed contact part 47: End part 48: 2nd beam part 49: 1st side part 50 : Second side portion 51: First structure 52: Movable contact layer 53: End surface 54: Main surface 55: Gap 56: Boundary portion 57: Base portion 58: Protruding portion 59: First signal line 60: First frame portion 61 : Second frame portion 62: Second signal line 63: Second structure 64: Fixed contact layer 65: End face 66: Main surface 67: Boundary portion 68: Base portion 69: Protruding portion 72: Asymmetric structure 73: Wafer 74: First 1 wafer main surface 75: 2nd wafer main surface 76: trench 77: residue 83: end surface 84: end 85: boundary 86: end surface 87: main surface 88: end surface 89: end 90: boundary 91: end surface 92 : Main surface 93: First opening 94: Third structure 95: End surface 96: Main surface 97: End surface 98: End portion 99: Boundary portion 100: Boundary portion 101: End surface 102: Main surface 103: Step A1: MEMS switch B1: MEMS switch C1: MEMS switch D1: MEMS switch F1 : 1st electrostatic force F2: 2nd electrostatic force X: 1st direction Y: 2nd direction Z: 3rd direction d1: Distance d2: Distance d3: Distance

Claims (15)

  1. 　第１主面およびその反対側の第２主面を有し、空洞が内部に形成された基板と、
    　前記基板の前記第１主面側に形成され、電気信号を機械的動作に変換するアクチュエータ部と、
    　前記基板の前記第１主面側に前記空洞に浮いた状態で形成され、前記アクチュエータ部の機械的動作によって変位可能な可動接点部と、
    　前記可動接点部と対向し、前記可動接点部の変位によって前記可動接点部と接触および非接触可能な固定接点部とを含み、
    　前記可動接点部および前記固定接点部の少なくとも一方は、前記基板と、前記基板上に形成された第１絶縁層と、前記基板の厚さ方向に沿う前記第１絶縁層の端面を被覆するように前記第１絶縁層上に形成され、前記第１絶縁層とは異なる材料を含む第２絶縁層と、前記第１絶縁層に支持された導電性の接点層とを含む第１構造を有している、ＭＥＭＳスイッチ。     A substrate having a first main surface and a second main surface on the opposite side, and a cavity formed inside,
    An actuator unit formed on the first main surface side of the substrate and converting an electric signal into a mechanical operation,
    A movable contact portion formed on the first main surface side of the substrate in a state of floating in the cavity and displaceable by the mechanical operation of the actuator portion.
    A fixed contact portion facing the movable contact portion and capable of contacting and not contacting the movable contact portion due to displacement of the movable contact portion is included.
    At least one of the movable contact portion and the fixed contact portion covers the substrate, the first insulating layer formed on the substrate, and the end face of the first insulating layer along the thickness direction of the substrate. Has a first structure including a second insulating layer formed on the first insulating layer and containing a material different from the first insulating layer, and a conductive contact layer supported by the first insulating layer. The MEMS switch.
  2. 　前記基板は、第１ベース層と、前記第１ベース層上に形成され、前記第１絶縁層と同じ材料を含む埋め込み絶縁層と、前記埋め込み絶縁層上に形成された第２ベース層とを含み、
    　前記空洞は、前記第１ベース層と前記第２ベース層との間に形成され、前記埋め込み絶縁層によって側方から区画されており、
    　前記第１構造において前記第１絶縁層は、前記第２ベース層上に形成されている、請求項１に記載のＭＥＭＳスイッチ。     The substrate includes a first base layer, an embedded insulating layer formed on the first base layer and containing the same material as the first insulating layer, and a second base layer formed on the embedded insulating layer. Including
    The cavity is formed between the first base layer and the second base layer, and is partitioned from the side by the embedded insulating layer.
    The MEMS switch according to claim 1, wherein in the first structure, the first insulating layer is formed on the second base layer.
  3. 　前記第１構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、
    　前記第１構造において前記第２絶縁層は、前記第２ベース層の端面と前記第１絶縁層の端面との境界部に端部を有するように前記第１絶縁層の端面を被覆している、請求項２に記載のＭＥＭＳスイッチ。     In the first structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate.
    In the first structure, the second insulating layer covers the end face of the first insulating layer so as to have an end portion at a boundary between the end face of the second base layer and the end face of the first insulating layer. , The MEMS switch according to claim 2.
  4. 　前記第１構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、
    　前記第１構造において前記第２絶縁層は、前記第１絶縁層の端面に加えてさらに、前記第２ベース層の端面を被覆している、請求項２に記載のＭＥＭＳスイッチ。     In the first structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate.
    The MEMS switch according to claim 2, wherein in the first structure, the second insulating layer further covers the end face of the second base layer in addition to the end face of the first insulating layer.
  5. 　前記第１構造において前記第２ベース層の端面と前記第１絶縁層の端面との間には、前記第１絶縁層の一部が前記第２ベース層の端面に対して突出するように、段差が形成されている、請求項４に記載のＭＥＭＳスイッチ。 In the first structure, between the end face of the second base layer and the end face of the first insulating layer, a part of the first insulating layer projects with respect to the end face of the second base layer. The MEMS switch according to claim 4, wherein a step is formed.
  6. 　前記アクチュエータ部は、前記空洞に対して浮いた状態で前記第２ベース層に形成された静電アクチュエータであって、交互に配列された固定電極および可動電極を含み、前記可動電極と前記固定電極との間の静電気力によって変位する櫛歯型の静電アクチュエータを含み、
    　前記可動接点部は、前記可動電極に連結された連結部材を介して前記静電アクチュエータに対して変位可能に設けられている、請求項２～５のいずれか一項に記載のＭＥＭＳスイッチ。     The actuator portion is an electrostatic actuator formed on the second base layer while floating with respect to the cavity, and includes fixed electrodes and movable electrodes arranged alternately, and the movable electrodes and the fixed electrodes are included. Including a comb-tooth type electrostatic actuator that is displaced by electrostatic force between and
    The MEMS switch according to any one of claims 2 to 5, wherein the movable contact portion is provided so as to be displaceable with respect to the electrostatic actuator via a connecting member connected to the movable electrode.
  7. 　前記可動電極および前記固定電極の少なくとも一方は、前記第２ベース層と、前記第１絶縁層と、前記第２絶縁層とを含む第２構造を有している、請求項６に記載のＭＥＭＳスイッチ。 The MEMS according to claim 6, wherein at least one of the movable electrode and the fixed electrode has a second structure including the second base layer, the first insulating layer, and the second insulating layer. switch.
  8. 　前記第２構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、
    　前記第２構造において前記第２絶縁層は、前記第２ベース層の端面と前記第１絶縁層の端面との境界部に端部を有するように前記第１絶縁層の端面を被覆している、請求項７に記載のＭＥＭＳスイッチ。     In the second structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate.
    In the second structure, the second insulating layer covers the end face of the first insulating layer so as to have an end portion at the boundary between the end face of the second base layer and the end face of the first insulating layer. , The MEMS switch according to claim 7.
  9. 　前記第２構造において前記第２ベース層は、前記基板の厚さ方向において前記第１絶縁層の端面に連なる端面を有しており、
    　前記第２構造において前記第２絶縁層は、前記第１絶縁層の端面に加えてさらに、前記第２ベース層の端面を被覆している、請求項７に記載のＭＥＭＳスイッチ。     In the second structure, the second base layer has an end face connected to the end face of the first insulating layer in the thickness direction of the substrate.
    The MEMS switch according to claim 7, wherein in the second structure, the second insulating layer further covers the end face of the second base layer in addition to the end face of the first insulating layer.
  10. 　前記第２構造において前記第２ベース層の端面と前記第１絶縁層の端面との間には、前記第１絶縁層の一部が前記第２ベース層の端面に対して突出するように、段差が形成されている、請求項９に記載のＭＥＭＳスイッチ。 In the second structure, between the end face of the second base layer and the end face of the first insulating layer, a part of the first insulating layer projects with respect to the end face of the second base layer. The MEMS switch according to claim 9, wherein a step is formed.
  11. 　前記第１絶縁層は、前記第１絶縁層の端面に交差する主面を有しており、
    　前記第２絶縁層は、前記第１絶縁層の前記主面および前記端面を連続して被覆しており、
    　前記接点層は、前記第２絶縁層を介して前記第１絶縁層の前記主面および前記端面に対向している、請求項１～１０のいずれか一項に記載のＭＥＭＳスイッチ。     The first insulating layer has a main surface that intersects the end surface of the first insulating layer.
    The second insulating layer continuously covers the main surface and the end surface of the first insulating layer.
    The MEMS switch according to any one of claims 1 to 10, wherein the contact layer faces the main surface and the end surface of the first insulating layer via the second insulating layer.
  12. 　前記第１絶縁層は、酸化シリコン（ＳｉＯ２）を含み、
    　前記第２絶縁層は、酸化アルミニウム（Ａｌ２Ｏ３）を含む、請求項１～１１のいずれか一項に記載のＭＥＭＳスイッチ。     The first insulating layer contains silicon oxide (SiO 2 ) and contains silicon oxide (SiO 2).
    The MEMS switch according to any one of claims 1 to 11, wherein the second insulating layer contains aluminum oxide (Al 2 O 3 ).
  13. 　第１ベース層と、前記第１ベース層上に形成された埋め込み絶縁層と、前記埋め込み絶縁層上に形成された第２ベース層とを含む基板の前記第２ベース層上に、前記埋め込み絶縁層と同じ材料を含む第１絶縁層を形成する工程と、
    　前記第１絶縁層に選択的に第１開孔を形成する工程と、
    　前記第１絶縁層の主面、および前記第１開孔に露出する前記第１絶縁層の端面を被覆するように、前記第１絶縁層とは異なる材料を含む第２絶縁層を前記第１絶縁層上に形成する工程と、
    　前記第２ベース層に所定パターンを有する貫通孔を形成することによって、前記貫通孔によって区画された前記第２ベース層、当該第２ベース層上の前記第１絶縁層および前記第２絶縁層を含む可動接点部および固定接点部を形成する工程と、
    　前記貫通孔を介して前記埋め込み絶縁層をエッチングすることによって、前記第１ベース層と前記第２ベース層との間に空洞を形成する工程と、
    　前記埋め込み絶縁層のエッチング後、導電材料を所定パターンで堆積することによって、前記第１絶縁層上に接点層を形成する工程とを含む、ＭＥＭＳスイッチの製造方法。     The embedded insulation on the second base layer of the substrate including the first base layer, the embedded insulating layer formed on the first base layer, and the second base layer formed on the embedded insulating layer. The process of forming the first insulating layer containing the same material as the layer,
    The step of selectively forming the first opening in the first insulating layer and
    The first insulating layer containing a material different from that of the first insulating layer is provided so as to cover the main surface of the first insulating layer and the end surface of the first insulating layer exposed to the first opening. The process of forming on the insulating layer and
    By forming a through hole having a predetermined pattern in the second base layer, the second base layer partitioned by the through hole, the first insulating layer on the second base layer, and the second insulating layer are formed. The process of forming the movable contact part and the fixed contact part including
    A step of forming a cavity between the first base layer and the second base layer by etching the embedded insulating layer through the through hole.
    A method for manufacturing a MEMS switch, which comprises a step of forming a contact layer on the first insulating layer by depositing a conductive material in a predetermined pattern after etching the embedded insulating layer.
  14. 　第１ベース層と、前記第１ベース層上に形成された埋め込み絶縁層と、前記埋め込み絶縁層上に形成された第２ベース層とを含む基板の前記第２ベース層上に、前記埋め込み絶縁層と同じ材料を含む第１絶縁層を形成する工程と、
    　前記第１絶縁層に選択的に第１開孔を形成する工程と、
    　前記第２ベース層に所定パターンを有する貫通孔を形成することによって、前記貫通孔によって区画された前記第２ベース層、当該第２ベース層上の前記第１絶縁層を含む可動接点部および固定接点部を形成する工程と、
    　前記第１絶縁層の主面、前記第１開孔に露出する前記第１絶縁層の端面、および前記貫通孔に露出する前記第２ベース層の端面を被覆するように、前記第１絶縁層とは異なる材料を含む第２絶縁層を前記第１絶縁層上に形成する工程と、
    　前記貫通孔を介して前記埋め込み絶縁層をエッチングすることによって、前記第１ベース層と前記第２ベース層との間に空洞を形成する工程と、
    　前記埋め込み絶縁層のエッチング後、導電材料を所定パターンで堆積することによって、前記第１絶縁層上に接点層を形成する工程とを含む、ＭＥＭＳスイッチの製造方法。     The embedded insulation on the second base layer of the substrate including the first base layer, the embedded insulating layer formed on the first base layer, and the second base layer formed on the embedded insulating layer. The process of forming the first insulating layer containing the same material as the layer,
    The step of selectively forming the first opening in the first insulating layer and
    By forming a through hole having a predetermined pattern in the second base layer, the second base layer partitioned by the through hole, a movable contact portion including the first insulating layer on the second base layer, and fixing The process of forming the contact part and
    The first insulating layer so as to cover the main surface of the first insulating layer, the end surface of the first insulating layer exposed to the first opening, and the end surface of the second base layer exposed to the through hole. A step of forming a second insulating layer containing a material different from the above on the first insulating layer, and
    A step of forming a cavity between the first base layer and the second base layer by etching the embedded insulating layer through the through hole.
    A method for manufacturing a MEMS switch, which comprises a step of forming a contact layer on the first insulating layer by depositing a conductive material in a predetermined pattern after etching the embedded insulating layer.
  15. 　前記第２絶縁層を形成する工程は、原子層堆積法（ALD：Atomic Layer Deposition）によって前記第２絶縁層を形成する工程を含む、請求項１３または１４に記載のＭＥＭＳスイッチの製造方法。
          The method for manufacturing a MEMS switch according to claim 13 or 14, wherein the step of forming the second insulating layer includes a step of forming the second insulating layer by an atomic layer deposition method (ALD).
PCT/JP2021/043956 2021-01-12 2021-11-30 Mems switch and manufacturing method for mems switch WO2022153697A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012243389A (en) * 2011-05-13 2012-12-10 Advantest Corp Switching device, transmission line change-over device, manufacturing method, and test device
JP2013026195A (en) * 2011-07-26 2013-02-04 Advantest Corp Switching device, manufacturing method of the same, transmission channel switching device, and testing device
JP2015088339A (en) * 2013-10-30 2015-05-07 国立大学法人東北大学 Integrated circuit device including piezoelectric mems switch and manufacturing method of the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012243389A (en) * 2011-05-13 2012-12-10 Advantest Corp Switching device, transmission line change-over device, manufacturing method, and test device
JP2013026195A (en) * 2011-07-26 2013-02-04 Advantest Corp Switching device, manufacturing method of the same, transmission channel switching device, and testing device
JP2015088339A (en) * 2013-10-30 2015-05-07 国立大学法人東北大学 Integrated circuit device including piezoelectric mems switch and manufacturing method of the same

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