WO2017208790A1

WO2017208790A1 - Variable capacitor

Info

Publication number: WO2017208790A1
Application number: PCT/JP2017/018127
Authority: WO
Inventors: 直樹牛山; 古本　憲輝; 純弘大塚; 剛國仲
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2016-05-30
Filing date: 2017-05-15
Publication date: 2017-12-07

Abstract

Provided is a variable capacitor, the capacitance of which can be changed without using a driving mechanism or a switch. A variable capacitor (10) comprises a substrate (11), a capacitor unit (20a), a thin film layer (50), and a thin film heater (21). The capacitor unit (20a) has a first electrode (14), a second electrode (15), and a dielectric layer (16) provided between the first electrode (14) and the second electrode (15), and is provided on the substrate (11). The thin film layer (50) covers the capacitor unit (20a). The thin film heater (21) changes the capacitance of the capacitor unit (20a) by adjusting the temperature of the dielectric layer (16).

Description

Variable capacitor

The present invention relates to a variable capacitor, and more particularly to a variable capacitor that can change capacitance.

Conventionally, there is a variable capacitor system that makes the capacitance of a capacitor variable (for example, Patent Document 1).

The variable capacitor system described in Patent Document 1 includes a variable capacitor having a drive mechanism that makes the capacitance variable, and a plurality of switches that electrically connect the plurality of fixed capacitors. The variable capacitor system changes the overall capacitance by changing the combination of a variable capacitor and a plurality of fixed capacitors by controlling the opening and closing of the plurality of switches.

In the variable capacitor disclosed in Patent Document 1, the capacitance is changed by a driving mechanism, or the overall capacitance is changed by a combination with a fixed capacitor. Therefore, there is a possibility that the capacitance cannot be changed to a desired capacitance when foreign matter or the like is mixed into the drive mechanism. Further, even when a switch is used, if the operation reliability of the contact is low, there is a possibility that it cannot be changed to a desired capacitance. Therefore, it is desired to change the capacitance by a method different from that of the conventional variable capacitor.

Japanese Patent No. 4300805

The present invention has been made in view of the above reasons, and an object thereof is to provide a variable capacitor capable of changing the capacitance without using a drive mechanism and a switch.

The variable capacitor according to the first aspect of the present invention includes a substrate, a capacitor portion, a thin film layer, and a temperature adjustment element. The capacitor unit includes a first electrode, a second electrode, and a dielectric layer provided between the first electrode and the second electrode, and is provided on the substrate. The thin film layer covers the capacitor portion. The temperature adjusting element adjusts the temperature of the dielectric layer to change the capacitance of the capacitor unit.

In the variable capacitor of the second aspect according to the present invention, in the first aspect, the substrate has a gap. The thin film layer is disposed between the substrate and the capacitor unit, and has a support layer that supports the capacitor unit. In the support layer, a surface opposite to the surface on which the capacitor portion is laminated is exposed from the gap.

In the variable capacitor according to the third aspect of the present invention, in the first aspect, the substrate has a porous layer. The thin film layer is disposed between the substrate and the capacitor unit, and has a support layer that supports the capacitor unit. In the support layer, the surface opposite to the surface on which the capacitor portion is laminated is in contact with the porous layer.

In the variable capacitor according to the fourth aspect of the present invention, in any one of the first to third aspects, the substrate is a semiconductor substrate.

In the variable capacitor of the fifth aspect according to the present invention, in any of the first to fourth aspects, the temperature adjusting element is provided in the thin film layer.

In the variable capacitor according to the sixth aspect of the present invention, in any one of the first to fifth aspects, the temperature adjustment element is a resistance heating element.

In the variable capacitor according to the seventh aspect of the present invention, in any one of the first to sixth aspects, the dielectric layer is a ferroelectric. The temperature adjusting element is controlled so that the temperature of the dielectric layer is adjusted to be equal to or higher than a Curie temperature at which the dielectric layer changes from a ferroelectric material to a paraelectric material. Change.

The variable capacitor of the eighth aspect according to the present invention further comprises a temperature sensor for detecting the temperature of the capacitor part in any one of the first to seventh aspects.

According to the present invention, the dielectric constant of the dielectric layer can be changed by changing the temperature of the dielectric layer, and as a result, the capacitance of the capacitor unit can be changed.

FIG. 1A is a plan view of a variable capacitor according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view taken along line AA of the same variable capacitor. 2A to 2I are cross-sectional views for explaining a manufacturing process of the variable capacitor described above. 3A and 3B are cross-sectional views for explaining a modification of the variable capacitor described above. FIG. 4A is a plan view of a variable capacitor according to Embodiment 2 of the present invention, and FIG. 4B is a cross-sectional view taken along the line BB of the variable capacitor of the above. FIG. 5A to FIG. 5F are cross-sectional views for explaining the manufacturing process of the variable capacitor described above. 6A is a plan view of a variable capacitor according to Embodiment 3 of the present invention, and FIG. 6B is a cross-sectional view taken along the line CC of the variable capacitor according to the third embodiment. FIG. 7A to FIG. 7I are cross-sectional views for explaining the manufacturing process of the variable capacitor described above. FIG. 8A is a plan view of a variable capacitor according to Embodiment 4 of the present invention, and FIG. 8B is a cross-sectional view of the variable capacitor taken along the line DD of the same. 9A to 9D are cross-sectional views for explaining a manufacturing process of the variable capacitor described above.

The configuration described below is merely an example of the present invention. The present invention is not limited to the following first to fourth embodiments, and various modifications can be made according to the design or the like as long as they do not depart from the technical idea of the present invention. In the following first to fourth embodiments, each drawing to be described is a schematic diagram, and the ratio of the size and thickness of each component in the drawing necessarily reflects the actual dimensional ratio. Is not limited.

(Embodiment 1)
Hereinafter, a variable capacitor 10 according to an embodiment will be described with reference to FIGS. 1A to 2I.

The variable capacitor 10 of the present embodiment changes the capacitance of the capacitor element 20 having the first electrode 14, the second electrode 15, and the dielectric layer 16 by adjusting the temperature of the dielectric layer 16.

The variable capacitor 10 according to the present embodiment is used for impedance adjustment of, for example, a non-contact communication device, a wireless power feeding system, a resonance circuit, and the like.

As shown in FIGS. 1A and 1B, the variable capacitor 10 includes a substrate 11, a support layer 12, an interlayer insulating film 18, a surface protective layer 19, and a thin film heater 21 (temperature adjustment element) in addition to the capacitor element 20. ing. In the variable capacitor 10, the first adhesion layer 13 and the second adhesion layer 17 may be appropriately provided according to the material of the upper and lower layers.

In the variable capacitor 10 of the present embodiment, the substrate 11 is the bottom, and the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, the interlayer insulating film 18, the thin film heater 21, and the surface protection layer 19. Are stacked in this order. Here, a thin film layer 50 is formed by the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, the interlayer insulating film 18, and the surface protective layer 19. At this time, the thickness from the back surface 121 of the support layer 12 to the surface 191 of the surface protective layer 19, that is, the thickness of the thin film layer 50 is several μm.

In the present embodiment, with the center point of the surface of the support layer 12 as the origin, the X axis and the Y axis that are orthogonal to each other on the surface of the support layer 12 are defined, and the Z axis that is orthogonal to the surface of the support layer 12 is defined. Yes. In FIGS. 1A and 1B, arrows indicating the X-axis direction, the Y-axis direction, and the Z-axis direction are described, but these arrows are merely described for the purpose of assisting the explanation, It is not accompanied by an entity. Further, the definition of the above direction is not intended to limit the usage pattern of the variable capacitor 10 of the present embodiment.

The substrate 11 is a semiconductor substrate, for example, a single crystal Si substrate. The main surface 111 of the substrate 11 is a (100) plane. The substrate 11 is formed in a rectangular plate shape. The thickness of the substrate 11 is, for example, 500 to 600 μm. The central part of the substrate 11 has a rectangular gap 30 penetrating in the thickness direction.

The support layer 12 is a laminated film of a SiO ₂ film (silicon oxide film) on the substrate 11 and a Si ₃ N ₄ film (silicon nitride film) on the SiO ₂ film, and is formed on one main surface 111 of the substrate 11. Is provided. In the substrate 11 described above, the air gap 30 is formed so that the surface (back surface 121 described above) opposite to the surface on which the capacitor element 20 is provided in the support layer 12 is exposed.

The first adhesion layer 13 is made of a Ti film. The first adhesion layer 13 is laminated on the support layer 12 and enhances the adhesion between the support layer 12 and the first electrode 14. The first adhesion layer 13 is not limited to the Ti film, and may be formed of, for example, a BST film ((Ba, Sr) TiO ₃ film: barium strontium titanate film).

The first electrode 14 is laminated on the first adhesion layer 13. A dielectric layer 16 made of a dielectric material (here, a ferroelectric material) is laminated on the first electrode 14. A second electrode 15 is laminated on the dielectric layer 16. The first electrode 14 is formed of a Pt film. The dielectric layer 16 is formed of a BST film. The second electrode 15 is formed of a Pt film.

The capacitor element 20 includes a capacitor portion 20a, a first pad electrode 20b, and a second pad electrode 20c. Further, the capacitor element 20 has a first wiring portion between the capacitor portion 20a and the first pad electrode 20b, and a second wiring portion between the capacitor portion 20a and the second pad electrode 20c. The capacitor portion 20 a corresponds to a portion above the central portion of the support layer 12 in the laminated structure of the first electrode 14, the dielectric layer 16, and the second electrode 15. The exposed portion of the first electrode 14 corresponds to the first pad electrode 20b. The exposed portion of the second electrode 15 corresponds to the second pad electrode 20c.

In FIG. 1B, the laminated structure of the first electrode 14, the dielectric layer 16, and the second electrode 15 also extends to the portion that becomes the first wiring portion between the capacitor portion 20a and the first pad electrode 20b. The first wiring portion may not have the dielectric layer 16 and the second electrode 15. Similarly, in FIG. 1B, the laminated structure of the first electrode 14, the dielectric layer 16, and the second electrode 15 extends to the portion that becomes the second wiring portion between the capacitor portion 20 a and the second pad electrode 20 c. However, the first electrode 14 and the dielectric layer 16 may not be provided in the second wiring portion.

The gap 30 is located below the first electrode 14 of the capacitor element 20 (the direction opposite to the arrow on the Z axis). From the viewpoint of thermally insulating the capacitor unit 20 a and the substrate 11, the capacitor unit 20 a and the air gap 30 in the capacitor element 20 overlap when the variable capacitor 10 is viewed in the direction from the surface protective layer 19 to the substrate 11. In addition, it is preferable that the capacitor portion 20a is defined.

The second adhesion layer 17 is made of a Ti film and is laminated on the second electrode 15. The second adhesion layer 17 enhances the adhesion between the interlayer insulating film 18 and the second electrode 15. The second adhesion layer 17 is not limited to the Ti film, and may be formed of, for example, a BST film.

The interlayer insulating film 18 is made of a SiO ₂ film (silicon oxide film) and is provided so as to cover the capacitor element 20. The interlayer insulating film 18 electrically insulates between the capacitor element 20 and the thin film heater 21.

The thin film heater 21 is a resistance heating element. The thin film heater 21 is laminated on the interlayer insulating film 18. The thin film heater 21 includes a first pad electrode 211, a second pad electrode 212,

wiring portions

213 and 214, and a heater portion 215. The heater unit 215 heats the capacitor unit 20a described above. The heater portion 215 is formed in a meandering shape. The heater part 215 is provided in the upper part of the capacitor | condenser part 20a. In other words, the heater unit 215 is provided at a position where heat insulation is performed from the substrate 11. The wiring part 213 is provided to connect the heater part 215 and the first pad electrode 211. The wiring part 214 is provided to connect the heater part 215 and the second pad electrode 212. The heater part 215 is heated by electrically connecting the first pad electrode 211 and the second pad electrode 212 to a power source. Heat generated from the heater portion 215 of the thin film heater 21 is transmitted to the dielectric layer 16 of the capacitor portion 20a.

The surface protective layer 19 is made of a SiO ₂ film (silicon oxide film), and is laminated on the interlayer insulating film 18 so as to cover the thin film heater 21.

The variable capacitor 10 further includes a first opening 31 extending from the surface protective layer 19 to the first pad electrode 20b, and a second opening 32 extending from the surface protective layer 19 to the second pad electrode 20c. . By electrically connecting the first pad electrode 20b and the second pad electrode 20c to a power source, charges are accumulated in the capacitor unit 20a.

Further, the variable capacitor 10 includes a third opening 33 extending from the surface protective layer 19 to the first pad electrode 211 of the thin film heater 21, and a fourth opening extending from the surface protective layer 19 to the second pad electrode 212 of the thin film heater 21. And a portion 34. When a voltage is applied between the first pad electrode 211 and the second pad electrode 212 of the thin film heater 21, the thin film heater 21 generates heat. The heat generated from the thin film heater 21 is transmitted to the dielectric layer 16 of the capacitor unit 20a. At this time, since the heater portion 215 of the thin film heater 21 is provided above the capacitor portion 20a via the interlayer insulating film 18, heat is transmitted to the entire dielectric layer 16 in the capacitor portion 20a. The relative permittivity of the dielectric layer 16 changes as the temperature changes. Therefore, the capacitance of the capacitor element 20 is changed by the temperature of the dielectric layer 16 being changed by the heat transmitted from the thin film heater 21. In other words, the capacitance of the capacitor element 20 changes according to the temperature of the dielectric layer 16. In the variable capacitor 10, the capacitance applied to the capacitor element 20 is adjusted by adjusting the voltage applied to the thin film heater 21. In order to adjust the capacitance of the capacitor element 20, it is only necessary that the heater unit 215 can generate Joule heat. Therefore, the amount of current flowing through the thin film heater 21 may be adjusted.

Here, the heater portion 215 of the thin film heater 21 is controlled so as to adjust the temperature of the dielectric layer 16 of the capacitor portion 20a to be equal to or higher than the Curie temperature at which the dielectric layer 16 changes from a ferroelectric material to a paraelectric material. Thus, it is preferable to change the capacitance of the capacitor portion 20a.

Next, a method for manufacturing the variable capacitor 10 of this embodiment will be described with reference to FIGS. 2A to 2I.

A SiO ₂ film is formed on the main surface 111 of the substrate 11 by a thermal oxidation method, and subsequently, a Si ₃ N ₄ film is formed by LPCVD (low pressure chemical vapor deposition), whereby the SiO ₂ film and the Si ₃ N film are formed. _A support layer 12 made of a laminated film with _four films is formed (see FIG. 2A). The first adhesion layer 13 is formed on the support layer 12 by sputtering, for example. Alternatively, the first adhesive layer 13 may be formed by applying a BST paste as a base of the first adhesive layer 13 on the support layer 12 by spin coating and baking at 600 to 700 degrees. Next, the first conductive layer 14a that is the basis of the first electrode 14 is formed on the first adhesion layer 13 by, for example, sputtering. The insulating layer 16a is formed by applying a BST paste as a base of the dielectric layer 16 on the first conductive layer 14a by spin coating and baking at 600 to 700 degrees. Thereafter, the second conductive layer 15a that is the basis of the second electrode 15 is formed on the insulating layer 16a by, for example, sputtering. Next, the adhesion layer 17a is formed on the second conductive layer 15a by, for example, sputtering (see FIG. 2B). Alternatively, the adhesion layer 17a may be formed by applying a BST paste as a base of the second adhesion layer 17 on the second conductive layer 15a by a spin coating method and baking at 600 to 700 degrees.

By patterning the first conductive layer 14a, the insulating layer 16a, the second conductive layer 15a, and the adhesion layer 17a by a photolithography technique and an etching technique, the first electrode 14, the dielectric layer 16, the second electrode 15, and the second adhesion layer are patterned. Layer 17 and the like are formed (see FIG. 2C).

Thereafter, an interlayer insulating film 18 is formed by CVD (chemical vapor deposition) or sputtering so as to cover the capacitor element 20 (see FIG. 2D). Next, a platinum film 21a is formed on the interlayer insulating film 18 by sputtering (see FIG. 2E).

The thin film heater 21 is formed by patterning the platinum film 21a by a photolithography technique and an etching technique (see FIG. 2F). Next, the surface protective layer 19 is formed by CVD or sputtering so as to cover the thin film heater 21 (see FIG. 2G).

A first opening 31 from the surface protective layer 19 to the first electrode 14 and a second opening 32 from the surface protective layer 19 to the second electrode 15 are formed by photolithography technique and reactive ion etching (RIE). The first electrode 14 and a part of the second electrode 15 are exposed. The exposed portion of the first electrode 14 becomes the first pad electrode 20b, and the exposed portion of the second electrode 15 becomes the second pad electrode 20c (see FIG. 2H). Similarly, a third opening 33 and a fourth opening 34 extending from the surface protective layer 19 to the thin film heater 21 are also formed, and a part of the thin film heater 21 is exposed. A portion of the thin film heater 21 exposed from the third opening 33 serves as the first pad electrode 211, and a portion of the thin film heater 21 exposed from the fourth opening 34 serves as the second pad electrode 212.

Next, using the photolithography technique and the etching technique, the space 30 is formed by etching the region where the gap 30 is to be formed from the back surface of the substrate 11 (see FIG. 2I). For etching the substrate 11, it is desirable to use, for example, an inductively coupled plasma (ICP) type dry etching apparatus or a reactive ion etching (RIE) apparatus. Alternatively, the gap 30 may be formed by etching with an alkaline solution (for example, a TMAH solution, a KOH aqueous solution, or the like) from the back surface of the substrate 11.

The variable capacitor 10 is manufactured through the above steps.

In this embodiment, the variable capacitor 10 includes the thin film heater 21 as a resistance heating element, but is not limited to the thin film heater 21 and may be a Peltier element, for example.

Further, the variable capacitor 10 may include a temperature sensor 60 for detecting the temperature of the capacitor portion 20a in the capacitor element 20 in the thin film layer 50 (see FIG. 3A). The variable capacitor 10 is controlled by a control circuit provided separately, for example. The control circuit adjusts the voltage applied to the thin film heater 21 according to the temperature detected by the temperature sensor 60. In FIG. 3A, the temperature sensor 60 is configured to be provided on the surface protective layer 19 in the upward direction of the air gap 30 (the Z-axis arrow direction). The temperature sensor 60 may be provided in the interlayer insulating film 18 in the vicinity of the thin film heater 21. The temperature sensor 60 is preferably provided above the gap 30. By providing the temperature sensor 60 above the gap 30, the detection sensitivity can be increased. The temperature sensor 60 is not limited to this configuration, and may be in the thin film layer 50. Alternatively, the thin film heater 21 may have the function of the temperature sensor 60.

The thin film heater 21 is disposed in a layer opposite to the substrate 11 from the capacitor portion 20a (a layer made of the interlayer insulating film 18 and the surface protective layer 19), but the thin film heater 21 is connected to the capacitor portion 20a. You may arrange | position in the layer between the board | substrates 11. The thin film heater 21 may be disposed in the support layer 12 as shown in FIG. 3B, for example. Alternatively, the thin film heater 21 may be provided in the dielectric layer 16 of the capacitor unit 20a. That is, the thin film heater 21 only needs to be provided in the thin film layer 50.

(Embodiment 2)
A variable capacitor 10A according to the present embodiment will be described with reference to FIGS. 4A to 5F with a focus on differences from the first embodiment. The variable capacitor 10A according to the present embodiment is different from the variable capacitor 10 according to the first embodiment in the position where the thin film heater 21 is provided. Constituent elements similar to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

As shown in FIGS. 4A and 4B, the variable capacitor 10 A of this embodiment includes a substrate 11, a support layer 12, an interlayer, in addition to the capacitor element 20 having the first electrode 14, the second electrode 15, and the dielectric layer 16. An insulating film 18 and a thin film heater 21 are provided. In the variable capacitor 10A, the first adhesion layer 13 and the second adhesion layer 17 may be appropriately provided according to the material of the upper and lower layers.

In the variable capacitor 10A of the present embodiment, as in the first embodiment, the substrate 11 is the lowermost part, and the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, and the interlayer insulating film 18 are arranged in this order. Are stacked. Here, the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, and the interlayer insulating film 18 form a thin film layer 50. The thickness of the thin film layer 50 is several μm.

In the present embodiment, with the center point of the surface of the support layer 12 as the origin, the X axis and the Y axis that are orthogonal to each other on the surface of the support layer 12 are defined, and the Z axis that is orthogonal to the surface of the support layer 12 is defined. Yes. In FIGS. 4A and 4B, arrows indicating the X-axis direction, the Y-axis direction, and the Z-axis direction are described, but these arrows are merely described for the purpose of assisting the explanation, It is not accompanied by an entity. Further, the definition of the above direction is not intended to limit the usage pattern of the variable capacitor 10A of the present embodiment.

The central part of the substrate 11 of this embodiment has a rectangular gap 30 penetrating in the thickness direction. The cross section of the gap 30 in the Z-axis direction has a trapezoidal shape. The main surface 111 of the substrate 11 made of a single crystal Si substrate is a (100) plane.

In the present embodiment, the thin film heater 21 is provided on the first adhesion layer 13 in the same manner as the first electrode 14 of the capacitor element 20. The heater portion 215 of the thin film heater 21 is formed in a meandering shape. The heater portion 215 of the thin film heater 21 is provided above the gap 30 of the substrate 11 and around the capacitor portion 20a (particularly, the first electrode 14). The thin film heater 21 is heated by electrically connecting the first pad electrode 211 and the second pad electrode 212 to a power source. By heating the periphery of the capacitor portion 20 a by the thin film heater 21, the heat generated by the thin film heater 21 is transmitted to the dielectric layer 16.

In the variable capacitor 10A of the present embodiment, when a voltage is applied to the first pad electrode 211 and the second pad electrode 212 of the thin film heater 21, the heater unit 215 of the thin film heater 21 generates heat. Heat generated from the heater unit 215 is transmitted to the dielectric layer 16 of the capacitor unit 20a. Here, since the heater portion 215 is provided around the first electrode 14, heat is transferred from the periphery of the dielectric layer 16 to the dielectric layer 16. In the capacitor unit 20a, the capacitance is changed according to the temperature of the dielectric layer 16. In the variable capacitor 10A, the voltage applied to the thin film heater 21 is adjusted, so that the capacitance of the capacitor unit 20a is adjusted.

Here, the heater unit 215 of the thin film heater 21 of the present embodiment changes the capacitance of the capacitor unit 20a by being controlled so as to adjust the temperature of the dielectric layer 16 of the capacitor unit 20a to be equal to or higher than the Curie temperature. It is preferable to make it.

Next, a method for manufacturing the variable capacitor 10A according to the present embodiment will be described with reference to FIGS. 5A to 5F.

A SiO ₂ film is formed on the main surface 111 on the substrate 11 by a thermal oxidation method, and subsequently, a Si ₃ N ₄ film is formed by LPCVD, whereby a laminated film of the SiO ₂ film and the Si ₃ N ₄ film is formed. A support layer 12 is formed (see FIG. 5A). The first adhesion layer 13 is formed on the support layer 12 by sputtering, for example. Alternatively, the first adhesive layer 13 may be formed by applying a BST paste as a base of the first adhesive layer 13 on the support layer 12 by spin coating and baking at 600 to 700 degrees. Next, the first conductive layer 100 that is the basis of the first electrode 14 and the thin film heater 21 is formed on the first adhesion layer 13 by, for example, sputtering. The insulating layer 16a is formed by applying a BST paste as a base of the dielectric layer 16 on the first conductive layer 100 by spin coating and baking at 600 to 700 degrees. Thereafter, the second conductive layer 15a that is the basis of the second electrode 15 is formed on the insulating layer 16a by, for example, sputtering. Next, the adhesion layer 17a is formed on the second conductive layer 15a by sputtering, for example (see FIG. 5B). Alternatively, the adhesion layer 17a may be formed by applying a BST paste as a base of the second adhesion layer 17 on the second conductive layer 15a by a spin coating method and baking at 600 to 700 degrees.

The first electrode 14, the thin film heater 21, the dielectric layer 16, and the second electrode 15 are patterned by patterning the first conductive layer 100, the insulating layer 16 a, the second conductive layer 15 a, and the adhesion layer 17 a using a photolithography technique and an etching technique. Then, the second adhesion layer 17 and the like are formed (see FIG. 5C).

Thereafter, an interlayer insulating film 18 is formed by CVD or sputtering so as to cover the capacitor element 20 (see FIG. 5D).

A first opening 31 extending from the interlayer insulating film 18 to the first electrode 14 and a second opening 32 extending from the surface protective layer 19 to the second electrode 15 are formed by photolithography and reactive ion etching (RIE). The first electrode 14 and a part of the second electrode 15 are exposed. The exposed portion of the first electrode 14 becomes the first pad electrode 20b, and the exposed portion of the second electrode 15 becomes the second pad electrode 20c (see FIG. 5E). Similarly, a third opening 33 and a fourth opening 34 from the interlayer insulating film 18 to the thin film heater 21 are also formed, and a part of the thin film heater 21 is exposed. A portion of the thin film heater 21 exposed from the third opening 33 serves as the first pad electrode 211, and a portion of the thin film heater 21 exposed from the fourth opening 34 serves as the second pad electrode 212.

Using the photolithography technology and the etching technology, the space 30 is formed by etching the region where the space 30 is to be formed from the back surface of the substrate 11 (see FIG. 5F). For the etching of the substrate 11, for example, an inductively coupled plasma (ICP) type dry etching apparatus or RIE apparatus is preferably used. Alternatively, the gap 30 may be formed by etching with an alkaline solution (for example, a TMAH solution, a KOH aqueous solution, or the like) from the back surface of the substrate 11.

The variable capacitor 10A is manufactured through the above steps.

In the present embodiment, the thin film heater 21 is disposed around the first electrode 14 of the capacitor element 20. However, the thin film heater 21 is disposed around the dielectric layer 16 or the second electrode 15 of the capacitor element 20. May be.

Also in the present embodiment, similarly to the first embodiment, the variable capacitor 10A includes the thin film heater 21 as a resistance heating element, but is not limited to the thin film heater 21, and a Peltier element, for example, may be used.

Also in the present embodiment, similarly to the first embodiment, the variable capacitor 10 A may include the temperature sensor 60 for detecting the temperature of the capacitor element 20 in the thin film layer 50. The variable capacitor 10A is controlled by, for example, a separately provided control circuit. The control circuit adjusts the voltage applied to the thin film heater 21 according to the temperature detected by the temperature sensor 60. Alternatively, the thin film heater 21 may have the function of the temperature sensor 60.

Usually, the heat generated by the thin film heater escapes to the outside through the substrate. For this reason, it becomes difficult to warm as the distance from the central portion of the dielectric layer increases. As a result, a temperature difference occurs in the dielectric layer. Therefore, in the present embodiment, the thin film heater 21 is provided around the capacitor element 20 (particularly, the first electrode 14). Thereby, the temperature in the dielectric layer 16 in the capacitor portion 20a can be made uniform.

(Embodiment 3)
A variable capacitor 10B according to the present embodiment will be described with reference to FIGS. 6A to 7I, focusing on differences from the first embodiment. The variable capacitor 10B of the present embodiment is different from the variable capacitor 10 of the first embodiment in that the support layer 12 is formed in a beam structure. Constituent elements similar to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

As shown in FIGS. 6A and 6B, the variable capacitor 10 B of this embodiment includes a substrate 11, a support layer 12, an interlayer, in addition to the capacitor element 20 having the first electrode 14, the second electrode 15, and the dielectric layer 16. An insulating film 18, a surface protective layer 19, and a thin film heater 21 are provided. In the variable capacitor 10B, the first adhesion layer 13 and the second adhesion layer 17 may be appropriately provided according to the material of the upper and lower layers.

In the variable capacitor 10B of the present embodiment, as in the first embodiment, the substrate 11 is the bottom, and the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, the interlayer insulating film 18, and the thin film The heater 21 and the surface protective layer 19 are laminated in this order. Here, a thin film layer 50 is formed by the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, the interlayer insulating film 18, and the surface protective layer 19. The thickness of the thin film layer 50 is several μm.

In the present embodiment, with the center point of the surface of the support layer 12 as the origin, the X axis and the Y axis that are orthogonal to each other on the surface of the support layer 12 are defined, and the Z axis that is orthogonal to the surface of the support layer 12 is defined. Yes. In FIGS. 6A and 6B, arrows indicating the X-axis direction, the Y-axis direction, and the Z-axis direction are described, but these arrows are merely described for the purpose of assisting the explanation, It is not accompanied by an entity. Further, the definition of the above direction is not intended to limit the usage pattern of the variable capacitor 10B of the present embodiment.

As in the first embodiment, the capacitor element 20 includes a capacitor portion 20a, a first pad electrode 20b, a second pad electrode 20c, a first wiring portion 20d, and a second wiring portion 20e (see FIG. 6A). In the present embodiment, as in the first embodiment, the first electrode 14, the dielectric layer 16, and the second electrode 15 are also formed on the portion that becomes the first wiring portion 20 d between the capacitor portion 20 a and the first pad electrode 20 b. Assume that the laminated structure extends. Similarly, it is assumed that the laminated structure of the first electrode 14, the dielectric layer 16, and the second electrode 15 extends to a portion that becomes the second wiring portion 20 e between the capacitor portion 20 a and the second pad electrode 20 c. The first wiring portion 20d may not include the dielectric layer 16 and the second electrode 15. Similarly, the first wiring 14 and the dielectric layer 16 may not be provided in the second wiring portion 20e.

The substrate 11 is provided with a quadrangular pyramid-shaped gap 30 from the main surface 111 in the direction opposite to the Z-axis direction. The main surface 111 of the substrate 11 made of a single crystal Si substrate is a (100) plane. A support layer 12 is provided on the main surface 111.

The support layer 12 includes a support portion 12a, a holding portion 12b provided on the inside thereof, and four beam portions 12c to 12f that connect the support portion 12a and the holding portion 12b.

The outer and inner shapes of the support portion 12a are formed in a square shape.

The holding portion 12b and the beam portions 12c to 12f are exposed by the gap 30.

The holding unit 12b holds at least the capacitor unit 20a of the capacitor element 20. Specifically, the first adhesion layer 13, the capacitor part 20 a, the second adhesion layer 17, the interlayer insulating film 18, the heater part 215 of the thin film heater 21, and the surface protection layer 19 are laminated on the holding part 12 b. .

The first wiring portion 20d is at least stacked on the beam portion 12c (see FIG. 6A). In the present embodiment, the first contact layer 13, the second contact layer 17, the interlayer insulating film 18, and the surface protective layer 19 are stacked on the beam portion 12 c in addition to the first wiring portion 20 d. The beam portion 12c is provided between a first opening 31 and a holding portion 12b described later.

At least the second wiring part 20e is laminated on the beam part 12e (see FIG. 6A). In the present embodiment, the first adhesive layer 13, the second adhesive layer 17, the interlayer insulating film 18, and the surface protective layer 19 are stacked on the beam portion 12e in addition to the second wiring portion 20e. The beam portion 12e is provided between a holding portion 12b and a second opening portion 32 (described later) in a direction opposite to the first opening portion 31.

At least the first pad electrode 20b is laminated on the first corner portion 122 of the support portion 12a (see FIG. 6A). In the present embodiment, in addition to the first pad electrode 20b, the first adhesion layer 13, the dielectric layer 16, the interlayer insulating film 18, and the surface protective layer 19 are stacked on the first corner portion 122.

At least the second pad electrode 20c is stacked on the second corner 123 of the support 12a (see FIG. 6A). In the present embodiment, the second corner portion 123 includes, in addition to the second pad electrode 20c, the first adhesion layer 13, the first electrode 14 (first electrode portion), the second adhesion layer 17, the interlayer insulating film 18, and the surface. A protective layer 19 is laminated.

Further, the first corner portion 122 is provided with a first opening 31 from the surface protective layer 19 to the first pad electrode 20b (see FIG. 6A). In the second corner 123, a second opening 32 extending from the surface protective layer 19 to the second pad electrode 20c is provided (see FIG. 6A). By electrically connecting the first pad electrode 20b and the second pad electrode 20c to a power source, charges are accumulated in the capacitor unit 20a.

At least a wiring portion 213 of the thin film heater 21 is laminated on the beam portion 12d (see FIG. 6A). In the present embodiment, a first adhesion layer 13, an interlayer insulating film 18, and a surface protection layer 19 are stacked on the beam portion 12 d in addition to the wiring portion 213. The beam portion 12d is provided between a third opening 33 and a holding portion 12b, which will be described later.

At least a wiring portion 214 of the thin film heater 21 is laminated on the beam portion 12f (see FIG. 6A). In the present embodiment, the first adhesive layer 13, the interlayer insulating film 18, and the surface protective layer 19 are stacked in addition to the wiring portion 214 on the beam portion 12 f. The beam portion 12f is provided between a holding portion 12b and a fourth opening portion 34 (described later) opposite to the third opening portion 33.

At least the first pad electrode 211 is stacked on the third corner portion 124 of the support portion 12a (see FIG. 6A). In the present embodiment, in addition to the first pad electrode 211, the first adhesion layer 13, the interlayer insulating film 18, and the surface protective layer 19 are stacked on the third corner portion 124.

At least the second pad electrode 212 is laminated on the fourth corner portion 125 of the support portion 12a (see FIG. 6A). In the present embodiment, in addition to the second pad electrode 212, the first adhesion layer 13, the interlayer insulating film 18, and the surface protective layer 19 are stacked on the fourth corner portion 125.

Further, a third opening 33 extending from the surface protective layer 19 to the first pad electrode 211 is provided in the third corner portion 124 (see FIG. 6A). A fourth opening 34 extending from the surface protective layer 19 to the second pad electrode 212 is provided in the fourth corner 125 (see FIG. 6A). When a voltage is applied through the third opening and the fourth opening 34, the heater part 215 of the thin film heater 21 generates heat. Heat generated from the heater unit 215 is transmitted to the dielectric layer 16 of the capacitor unit 20a.

In FIG. 6B, for convenience of explanation, components other than the first adhesion layer 13, the interlayer insulating film 18, and the surface protective layer 19 are omitted in the beam portion 12c and the beam portion 12d.

Further, the variable capacitor 10 has a plurality of through holes 40 extending from the surface protective layer 19 to the air gap 30 of the substrate 11. Thereby, the heater part 215 of the thin film heater 21 laminated | stacked on the holding | maintenance part 12b can be thermally insulated from the board | substrate 11. FIG. Moreover, the length with respect to the X-axis direction in the support layer 12 laminated | stacked on the holding | maintenance part 12b is several hundred micrometers. Since the thickness from the back surface 121 of the support layer 12 to the surface 191 of the surface protective layer 19 is several μm with respect to a length of several hundred μm in the X-axis direction, the heat generated from the thin film heater 21 is supported by the support portion 12a. It is easier to be transmitted to the dielectric layer 16 than the layers stacked on each other.

Next, a method for manufacturing the variable capacitor 10 of the present embodiment will be described with reference to FIGS. 7A to 7I.

A SiO ₂ film is formed on the main surface 111 of the substrate 11 by a thermal oxidation method, and subsequently, a Si ₃ N ₄ film is formed by LPCVD, so that a laminated film of the SiO ₂ film and the Si ₃ N ₄ film is formed. A support layer 12 is formed (see FIG. 7A). The first adhesion layer 13 is formed on the support layer 12 by sputtering, for example. Alternatively, the first adhesive layer 13 may be formed by applying a BST paste as a base of the first adhesive layer 13 on the support layer 12 by spin coating and baking at 600 to 700 degrees. Next, the first conductive layer 14a that is the basis of the first electrode 14 is formed on the first adhesion layer 13 by, for example, sputtering. The insulating layer 16a is formed by applying a BST paste as a base of the dielectric layer 16 on the first conductive layer 14a by spin coating and baking at 600 to 700 degrees. Thereafter, the second conductive layer 15a that is the basis of the second electrode 15 is formed on the insulating layer 16a by, for example, sputtering. Next, the adhesion layer 17a is formed on the second conductive layer 15a by, for example, sputtering (see FIG. 7B). Alternatively, the adhesion layer 17a may be formed by applying a BST paste as a base of the second adhesion layer 17 on the second conductive layer 15a by spin coating and baking at 600 to 700 degrees.

By patterning the first conductive layer 14a, the insulating layer 16a, the second conductive layer 15a, and the adhesion layer 17a by a photolithography technique and an etching technique, the first electrode 14, the second electrode 15, the dielectric layer 16, and the second adhesion layer are patterned. Layer 17 and the like are formed (see FIG. 7C).

Thereafter, an interlayer insulating film 18 is formed by CVD or sputtering so as to cover the capacitor element 20 (see FIG. 7D). Next, a platinum film 21a serving as a base of the thin film heater 21 is formed on the interlayer insulating film 18 by sputtering (see FIG. 7E).

The thin film heater 21 is formed by patterning the platinum film 21a by a photolithography technique and an etching technique (see FIG. 7F). Next, the surface protective layer 19 is formed by CVD or sputtering so as to cover the thin film heater 21 (see FIG. 7G).

A plurality of through holes 40 extending from the surface protective layer 19 to the substrate 11 are formed by photolithography technology and reactive ion etching (RIE) (see FIG. 7H). Similarly, a first opening 31 extending from the surface protective layer 19 to the first electrode 14 and a second opening 32 extending from the surface protective layer 19 to the second electrode 15 are formed, and the first electrode 14 and the second electrode 15 are formed. To expose a part of The exposed portion of the first electrode 14 becomes the first pad electrode 20b, and the exposed portion of the second electrode 15 becomes the second pad electrode 20c. Further, a third opening 33 and a fourth opening 34 extending from the surface protective layer 19 to the thin film heater 21 are also formed, and a part of the thin film heater 21 is exposed. A portion of the thin film heater 21 exposed from the third opening 33 serves as the first pad electrode 211, and a portion of the thin film heater 21 exposed from the fourth opening 34 serves as the second pad electrode 212.

Using the photolithography technique and the etching technique, the space 30 is formed by etching the region where the space 30 is to be formed in the substrate 11 from the main surface 111 of the substrate 11 (see FIG. 7I). Etching of the substrate 11 is performed by, for example, performing crystal anisotropic etching from the main surface 111 of the substrate 11 through the plurality of through holes 40 by wet using an alkaline solution (for example, TMAH solution, KOH aqueous solution, etc.). 30 is desirable.

The variable capacitor 10B is manufactured through the above steps.

In the present embodiment, the variable capacitor 10B includes the thin film heater 21 as a resistance heating element as in the first embodiment. However, the present invention is not limited to the thin film heater 21, and a Peltier element, for example, may be used.

Also in the present embodiment, as in the first embodiment, the variable capacitor 10B may include the temperature sensor 60 for detecting the temperature of the capacitor unit 20a in the thin film layer 50. The variable capacitor 10B is controlled by, for example, a separately provided control circuit. The control circuit adjusts the voltage applied to the thin film heater 21 according to the temperature detected by the temperature sensor 60. Alternatively, the thin film heater 21 may have the function of the temperature sensor 60.

The thin film heater 21 is arranged in a layer opposite to the direction of the substrate 11 from the capacitor unit 20a. However, the thin film heater 21 is disposed in a layer between the capacitor unit 20a and the substrate 11, for example, in the support layer 12. It may be arranged. Or the thin film heater 21 may be arrange | positioned in the dielectric material layer 16 of the capacitor | condenser part 20a.

(Embodiment 4)
A variable capacitor 10C according to the present embodiment will be described with reference to FIGS. 8A to 9D, focusing on differences from the first embodiment. The variable capacitor 10C according to the present embodiment is different from the variable capacitor 10 according to the first embodiment in that a part of the substrate 11 is formed of a porous layer. Constituent elements similar to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

Similar to the variable capacitor 10 of the first embodiment, the variable capacitor 10C of the present embodiment uses the capacitance of the capacitor element 20 having the first electrode 14, the second electrode 15, and the dielectric layer 16 as the dielectric layer. It is made to change by adjusting the temperature of 16.

As shown in FIGS. 8A and 8B, the variable capacitor 10 C according to the present embodiment includes a substrate 11, a support layer 12, an interlayer insulating film 18, a surface protective layer 19, and a thin film heater 21 (temperature adjusting element) )have. In the variable capacitor 10 C, the first adhesion layer 13 and the second adhesion layer 17 may be appropriately provided according to the material of the upper and lower layers.

In the variable capacitor 10 of the present embodiment, as in the first embodiment, the substrate 11 is the lowermost part, and the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, the interlayer insulating film 18, and the thin film The heater 21 and the surface protective layer 19 are laminated in this order. Here, a thin film layer 50 is formed by the support layer 12, the first adhesion layer 13, the capacitor element 20, the second adhesion layer 17, the interlayer insulating film 18, and the surface protective layer 19. At this time, the thickness from the back surface 121 of the support layer 12 to the surface 191 of the surface protective layer 19, that is, the thickness of the thin film layer 50 is several μm.

In the present embodiment, with the center point of the surface of the support layer 12 as the origin, the X axis and the Y axis that are orthogonal to each other on the surface of the support layer 12 are defined, and the Z axis that is orthogonal to the surface of the support layer 12 is defined. Yes. 8A and 8B show arrows indicating the X-axis direction, the Y-axis direction, and the Z-axis direction, but these arrows are merely shown for the purpose of assisting the explanation, It is not accompanied by an entity. Further, the definition of the above direction is not intended to limit the usage pattern of the variable capacitor 10 of the present embodiment.

The substrate 11 is a semiconductor substrate, and has a rectangular parallelepiped porous layer 30a in the thickness direction from the main surface 111 at the central portion thereof. The main surface 111 of the substrate 11 made of a single crystal Si substrate is a (100) plane. The thickness (length in the Z-axis direction) of the porous layer 30a is, for example, 10 μm. In addition, this numerical value is an example and is not the meaning limited to this numerical value.

The porous layer 30a is located below the first electrode 14 of the capacitor element 20 (the direction opposite to the Z-axis arrow). From the viewpoint of thermally insulating the capacitor portion 20a and the substrate 11, when the variable capacitor 10 is viewed in the direction from the surface protective layer 19 to the substrate 11, the capacitor portion 20a and the porous layer 30a of the capacitor element 20 are It is preferable that the capacitor portion 20a is defined so as to overlap.

As in the first embodiment, the support layer 12 is composed of a laminated film of a SiO ₂ film on the substrate 11 and a Si ₃ N ₄ film on the SiO ₂ film. In the support layer 12, the surface (back surface 121) opposite to the surface on which the capacitor element 20 is provided is in contact with the porous layer 30a (see FIG. 8B).

Since the first adhesive layer 13, the capacitor element 20, the second adhesive layer 17, the interlayer insulating film 18, the surface protective layer 19, and the thin film heater 21 are the same as those in the first embodiment, the description thereof is omitted here.

Similarly to the first embodiment, the variable capacitor 10C according to the present embodiment includes a first opening 31 extending from the surface protective layer 19 to the first pad electrode 20b, and a second opening extending from the surface protective layer 19 to the second pad electrode 20c. An opening 32 is further provided. By electrically connecting the first pad electrode 20b and the second pad electrode 20c to a power source, charges are accumulated in the capacitor unit 20a.

Further, similarly to the first embodiment, the variable capacitor 10 C includes a third opening 33 extending from the surface protective layer 19 to the first pad electrode 211 of the thin film heater 21, and a second pad of the thin film heater 21 from the surface protective layer 19. A fourth opening 34 reaching the electrode 212 is further provided. When a voltage is applied between the first pad electrode 211 and the second pad electrode 212 of the thin film heater 21, the thin film heater 21 generates heat. The heat generated from the thin film heater 21 is transmitted to the dielectric layer 16 of the capacitor unit 20a. At this time, since the heater portion 215 of the thin film heater 21 is provided above the capacitor portion 20a via the interlayer insulating film 18, heat is transmitted to the entire dielectric layer 16 in the capacitor portion 20a. The relative permittivity of the dielectric layer 16 changes as the temperature changes. Therefore, the capacitance of the capacitor element 20 is changed by the temperature of the dielectric layer 16 being changed by the heat transmitted from the thin film heater 21. In other words, the capacitance of the capacitor element 20 changes according to the temperature of the dielectric layer 16. In the variable capacitor 10, the capacitance applied to the capacitor element 20 is adjusted by adjusting the voltage applied to the thin film heater 21. In order to adjust the capacitance of the capacitor element 20, it is only necessary that the heater unit 215 can generate Joule heat. Therefore, the amount of current flowing through the thin film heater 21 may be adjusted.

Next, a method for manufacturing the variable capacitor 10C according to the present embodiment will be described with reference to FIGS. 9A to 9D.

A current-carrying electrode 300 is attached on the main surface 111 of the substrate 11 (see FIG. 9A). A porous layer 30a is formed by anodizing the substrate 11 to which the energizing electrode 300 is attached (see FIG. 9B). Specifically, the substrate 11 to which the energizing electrode 300 is attached is immersed in an electric field solution, and a platinum electrode is disposed so as to face the surface 112 opposite to the main surface 111. The positive electrode side of the current source is connected to the energizing electrode 300, and the negative electrode side is connected to the platinum electrode. Then, according to the thickness and porosity of the porous layer 30a, a current having a predetermined current density is allowed to flow from the current source between the energization electrode and the platinum electrode for a predetermined time. Further, in order to increase the porosity, each of the specific resistance and current density of the substrate 11 may be increased. The porosity of the porous layer 30a can be set to 5% to 80%. The average pore diameter of the porous layer 30a can be set to 0.1 μm to 3 μm.

After the porous layer 30a is formed on the substrate 11, the energizing electrode 300 is removed (see FIG. 9C). A SiO ₂ film is formed on the main surface 111 on the substrate 11 from which the energizing electrode 300 has been removed by a thermal oxidation method, and then an Si ₃ N ₄ film is formed by LPCVD, whereby the SiO ₂ film and the Si ₃ film are formed. A support layer 12 made of a laminated film with an N ₄ film is formed (see FIG. 9D).

Since the subsequent steps are the same as the steps from FIG. 2B to FIG. 2H described in the first embodiment, description thereof is omitted here.

The variable capacitor 10C is manufactured through the above steps.

In the present embodiment, the variable capacitor 10C includes the thin film heater 21 as a resistance heating element. However, the variable capacitor 10C is not limited to the thin film heater 21 and may be a Peltier element, for example.

Further, the variable capacitor 10 C may include a temperature sensor 60 for detecting the temperature of the capacitor unit 20 a in the capacitor element 20 in the thin film layer 50, as in the first embodiment. The variable capacitor 10C is controlled by a control circuit provided separately, for example. The control circuit adjusts the voltage applied to the thin film heater 21 according to the temperature detected by the temperature sensor 60. Alternatively, the thin film heater 21 may have the function of the temperature sensor 60.

The thin film heater 21 is disposed in a layer opposite to the substrate 11 from the capacitor portion 20a (a layer made of the interlayer insulating film 18 and the surface protective layer 19), but the thin film heater 21 is connected to the capacitor portion 20a. You may arrange | position in the layer between the board | substrates 11. For example, the thin film heater 21 may be disposed in the support layer 12. Alternatively, the thin film heater 21 may be provided in the dielectric layer 16 of the capacitor unit 20a. That is, the thin film heater 21 only needs to be provided in the thin film layer 50.

Further, the substrate 11 provided in the variable capacitor 10C of the present embodiment is a semiconductor substrate, but is not limited to a semiconductor substrate, and may be a substrate made of ceramic or the like.

Moreover, although a part of the substrate 11 is formed as the porous layer 30a, the present invention is not limited to this, and the entire substrate 11 may be formed as the porous layer 30a.

Further, the variable capacitor 10C of the present embodiment forms a porous layer 30a instead of the gap 30 of the variable capacitor 10 of the first embodiment. Similarly, a porous layer 30a may be formed instead of the gap 30 of the variable capacitor 10A of the second embodiment, or a porous layer 30a may be formed instead of the gap 30 of the variable capacitor 10B of the third embodiment. May be.

(Summary)
As described above, the variable capacitor 10 (10A, 10B, 10C) of the first aspect includes the substrate 11, the capacitor unit 20a, the thin film layer 50, and the temperature adjusting element (thin film heater 21). The capacitor unit 20 a includes the first electrode 14, the second electrode 15, and the dielectric layer 16 provided between the first electrode 14 and the second electrode 15, and is provided on the substrate 11. The thin film layer 50 covers the capacitor portion 20a. The temperature adjusting element adjusts the temperature of the dielectric layer 16 to change the capacitance of the capacitor unit 20a.

According to this configuration, in the variable capacitor 10 (10A, 10B, 10C), since the relative dielectric constant of the dielectric layer 16 depends on the temperature, the capacitance of the capacitor element is changed by changing the temperature. Can be made.

In the variable capacitor 10 (10A, 10B) of the second aspect, the substrate 11 has a gap 30 in the first aspect. The thin film layer 50 is disposed between the substrate 11 and the capacitor portion 20a, and has a support layer 12 that supports the capacitor portion 20a. In the support layer 12, the surface opposite to the surface on which the capacitor portion 20 a is laminated is exposed from the gap 30.

According to this configuration, when the variable capacitor 10 is viewed in the direction from the capacitor unit 20 a to the substrate 11, the capacitor unit 20 a overlaps the air gap 30, so that the heat generated by the thin film heater 21 passes through the substrate 11. It becomes difficult to escape. Further, by providing the support layer 12, the residual stress of the layer (thin film) laminated on the support layer 12 can be adjusted.

In the variable capacitor 10C according to the third aspect, in the first aspect, the substrate 11 has the porous layer 30a. The thin film layer 50 is disposed between the substrate 11 and the capacitor portion 20a, and has a support layer 12 that supports the capacitor portion 20a. In the support layer 12, the surface opposite to the surface on which the capacitor portion 20a is laminated is in contact with the porous layer 30a.

According to this configuration, the strength of the substrate 11 is increased as compared with the case where the air gap 30 is provided in the substrate 11. Since the capacitor portion 20a overlaps the porous layer 30a, the heat generated by the thin film heater 21 is difficult to escape via the substrate 11 other than the porous layer 30a. Further, by providing the support layer 12, the residual stress of the layer (thin film) laminated on the support layer 12 can be adjusted.

In the variable capacitor 10 (10A, 10B, 10C) of the fourth aspect, in any one of the first to third aspects, the substrate 11 is a semiconductor substrate.

According to this configuration, the substrate 11 can be easily processed, and the substrate 11 can be formed at a time, so that the manufacturing cost can be reduced.

In the variable capacitor 10 (10A, 10B, 10C) of the fifth aspect, the temperature adjusting element is provided in the thin film layer 50 in any of the first to fourth aspects.

According to this configuration, since the distance from the thin film heater 21 to the dielectric layer 16 is short, the response is excellent, the heat loss is small, and the temperature of the dielectric layer 16 can be changed with low power consumption.

In the variable capacitor 10 (10A, 10B, 10C) of the sixth aspect, in any of the first to fifth aspects, the temperature adjustment element is a resistance heating element.

According to this configuration, the formation by the semiconductor processing technology is facilitated, and the thin film heater 21 can be formed at a time, so that the manufacturing cost can be suppressed.

In the variable capacitor 10 (10A, 10B, 10C) of the seventh aspect, in any one of the first to sixth aspects, the dielectric layer 16 is a ferroelectric substance. The temperature adjustment element changes the capacitance of the capacitor portion 20a by controlling the temperature of the dielectric layer 16 to be equal to or higher than the Curie temperature at which the dielectric layer 16 changes from a ferroelectric material to a paraelectric material. Let

According to this configuration, since the temperature of the dielectric layer 16 of the capacitor unit 20a is adjusted, heat loss can be suppressed.

The variable capacitor 10 (10A, 10B, 10C) of the eighth aspect further includes a temperature sensor 60 for detecting the temperature of the capacitor unit 20a in any one of the first to seventh aspects.

According to this configuration, the voltage applied to the thin film heater 21 can be adjusted based on the detection result. That is, the temperature of the dielectric layer 16 can be adjusted by adjusting the heat generated by the thin film heater 21 based on the detection result.

10, 10A, 10B, 10C Variable capacitor 11 Substrate 12 Support layer 14 First electrode 15 Second electrode 16 Dielectric layer 20a Capacitor part 21 Thin film heater (temperature adjusting element)
30 Void 30a Porous layer 50 Thin film layer 60 Temperature sensor

Claims

A substrate,
A first electrode, a second electrode, and a dielectric layer provided between the first electrode and the second electrode, and a capacitor unit provided on the substrate;
A thin film layer covering the capacitor portion;
A variable capacitance capacitor comprising: a temperature adjustment element that adjusts a temperature of the dielectric layer to change a capacitance of the capacitor unit.
The substrate has voids;
The thin film layer is disposed between the substrate and the capacitor unit, and has a support layer that supports the capacitor unit,
2. The variable capacitor according to claim 1, wherein a surface of the support layer opposite to a surface on which the capacitor portion is laminated is exposed from the gap.
The substrate has a porous layer;
The thin film layer is disposed between the substrate and the capacitor unit, and has a support layer that supports the capacitor unit,
2. The variable capacitor according to claim 1, wherein a surface of the support layer opposite to a surface on which the capacitor portion is laminated is in contact with the porous layer.
The variable capacitor according to any one of claims 1 to 3, wherein the substrate is a semiconductor substrate.
The variable capacitor according to any one of claims 1 to 4, wherein the temperature adjustment element is provided in the thin film layer.
The variable capacitor according to any one of claims 1 to 5, wherein the temperature adjusting element is a resistance heating element.
The dielectric layer is a ferroelectric;
The temperature adjusting element is controlled so that the temperature of the dielectric layer is adjusted to be equal to or higher than a Curie temperature at which the dielectric layer changes from a ferroelectric material to a paraelectric material. The variable capacitor according to any one of claims 1 to 6, wherein the capacitor is changed.
The variable capacitor according to any one of claims 1 to 7, further comprising a temperature sensor that detects a temperature of the capacitor unit.