Electronic elements and circuit devices

Abstract

Provided are an electronic element in which a physical quantity of a passive element can be varied in a wide range including the case where the physical quantity is 0(zero), and a circuit device. A variable capacitance element (100) comprises a switch portion (10) and an element portion (20) constituting a capacitor. The switch portion (10) includes a source electrode (5), a drain electrode (6), a channel forming film (4) formed overlapping with at least a part of the source electrode (5) and at least a part of the drain electrode (6), a gate insulating film (3) formed overlapping with the channel forming film (4), and a gate electrode (2) formed on the gate insulating film (3). The element portion (20) includes a terminal electrode (5a) (first terminal electrode) electrically connected to the source electrode (5), and a terminal electrode (22) (second terminal electrode) that sandwiches the dielectric layer (3a) or adjoins the dielectric layer (3a), and that constitutes a capacitor between a part (electrode 6c) of the drain electrode (6) and the terminal electrode (22). The dielectric layer and the gate insulating film are of the same insulating film.

Description

[Technical field]

[0001] The present invention relates to an electronic element capable of varying the physical quantity of a passive element, and a circuit device including the electronic element. [Background technology]

[0002] As an electronic element capable of varying the physical quantity of a passive element, for example, a variable capacitance element capable of varying capacitance (capacitor) is known. Specifically, Patent Document 1 discloses a variable capacitance element in which a plate-shaped movable comb electrode and a plate-shaped fixed comb electrode are provided by using micromachining technology so as to face the movable comb electrode with a minute gap interposed therebetween. In addition, Non-Patent Document 1 discloses a variable capacitance element with a two-terminal structure utilizing the ON / OFF operation of a FET (Field Effect Transistor). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-373829 A [Non-patent literature]

[0004] [Non-Patent Document 1] Tokumitsu Eisuke, Kikuchi Kazuya, "Evaluation of Channel Modulation in In2O3 / (Bi,La)4Ti3O12Ferroelectric-Gate Thin Film Transistors by Capacitance-Voltage Measurements", Ferroelectrics, 429, p.15-21, Jun 2012 Summary of the Invention [Problem to be solved by the invention]

[0005] The variable capacitance element disclosed in Patent Document 1 has a small variable capacitance range, at most several times the capacitance before the variation, and the variable capacitance range is insufficient for use in applications such as wideband communication systems and power supply circuits that require large frequency modulation. In addition, the variable capacitance element disclosed in Patent Document 1 is configured to vary the capacitance by changing the distance between opposing comb-tooth electrodes. Therefore, in this variable capacitance element, there is a limit to the distance that can be changed, and in principle the capacitance cannot be made 0 (zero).

[0006] Furthermore, in the variable capacitance element disclosed in Non-Patent Document 1, if the thickness of the gate insulating film (dielectric) is increased in order to increase the withstand voltage, the capacitance value decreases in inverse proportion to the film thickness.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide an electronic element and a circuit device capable of varying the physical quantity of a passive element over a wide range, including the case where the physical quantity becomes 0 (zero). [Means for solving the problem]

[0008] An electronic device according to an embodiment of the present disclosure includes a switch section constituting a field effect transistor, and an element section electrically connected to the switch section and constituting a passive element. The switch section has a source electrode, a drain electrode, a channel formation film formed overlapping at least a part of the source electrode and a part of the drain electrode, a gate insulating film formed overlapping the channel formation film, and a gate electrode formed on the gate insulating film. The element section has a first terminal electrode electrically connected to the source electrode, and a second terminal electrode sandwiching a dielectric layer or contacting the dielectric layer and constituting a passive element between the first terminal electrode and the part of the drain electrode, and the dielectric layer and the gate insulating film are the same insulating film. The dielectric layer includes at least a first dielectric layer and a second dielectric layer formed of the same insulating film as the gate insulating film, and the element portion is a multi-layer passive element formed by sequentially stacking a part of the drain electrode, the first dielectric layer, a second terminal electrode, the second dielectric layer, and a part of the drain electrode. .

[0009] A circuit device according to an embodiment of the present disclosure includes a circuit wiring and the above-described electronic element electrically connected to the circuit wiring. Effect of the Invention

[0010] According to the present disclosure, the electronic element includes an element portion having a first terminal electrode and a second terminal electrode that sandwiches a dielectric layer or is in contact with the dielectric layer and forms a passive element between itself and a part of the drain electrode, so that the physical quantity of the passive element can be varied over a wide range, including the case where the physical quantity is 0 (zero). [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a first embodiment. [Diagram 2] FIG. 2 is a plan view illustrating the configuration of a variable capacitance element according to the first embodiment. [Diagram 3] 5A to 5C are cross-sectional views illustrating a manufacturing method of the variable capacitance element according to the first embodiment. [Figure 4] 1 is a circuit diagram of a multi-valued variable capacitance element according to a first embodiment. [Diagram 5] 10 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a first modified example of the first embodiment. FIG. [Figure 6] FIG. 11 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a second modification of the first embodiment. [Figure 7] FIG. 11 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a third modification of the first embodiment. [Figure 8] FIG. 11 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a second embodiment. [Figure 9] FIG. 11 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a first modified example of the second embodiment. [Figure 10] FIG. 11 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a second modification of the second embodiment. [Figure 11] FIG. 13 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a third modification of the second embodiment. [Figure 12] FIG. 13 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a fourth modification of the second embodiment. [Figure 13] FIG. 11 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a third embodiment. [Figure 14] FIG. 11 is a plan view illustrating the configuration of a variable capacitance element according to a third embodiment. [Figure 15] FIG. 13 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a first modified example of the third embodiment. [Figure 16] FIG. 13 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a second modification of the third embodiment. [Figure 17] FIG. 13 is a cross-sectional view illustrating a configuration of a variable capacitance element according to a third modification of the third embodiment. [Figure 18] FIG. 11 is a cross-sectional view for explaining the configuration of a variable inductance element according to a fourth embodiment. [Figure 19] FIG. 11 is an equivalent circuit diagram of a variable inductance element according to a fourth embodiment. [Figure 20] FIG. 13 is a plan view illustrating the configuration of a variable inductance element according to a modified example of the fourth embodiment. [Figure 21] FIG. 13 is a cross-sectional view illustrating the configuration of a variable inductance element according to a modified example of the fourth embodiment. [Figure 22] FIG. 11 is a cross-sectional view illustrating the configuration of a variable capacitance element according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an electronic device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In particular, in the electronic device according to the embodiment of the present disclosure, an electronic device capable of varying the physical quantity of a passive element will be described. Note that the same reference numerals in the drawings indicate the same or corresponding parts. In addition, in the present disclosure, the case where the physical quantity of a passive element becomes 0 (zero) is not limited to the case where the physical quantity is completely 0 (zero), but may be a physical quantity that is equal to or less than a predetermined quantity (for example, 1 / 10,000 or less) at which the physical quantity can be regarded as 0 (zero) in a state where the physical quantity is present. Furthermore, since the electronic element can switch between a state where the physical quantity of the passive element is present and a state where the physical quantity is 0 (zero), it can also be given a memory characteristic.

[0013] (Embodiment 1) In the first embodiment, a variable capacitance element in which a passive element is a capacitor and a variable physical quantity is capacitance will be described. In particular, in the first embodiment, a variable capacitance element that can be switched between a state in which there is capacitance and a state in which the capacitance is 0 (zero) (hereinafter also referred to as a state in which there is no capacitance) will be described with reference to the drawings. FIG. 1 is a cross-sectional view for explaining the configuration of the variable capacitance element 100 according to the first embodiment. FIG. 2 is a plan view for explaining the configuration of the variable capacitance element 100 according to the first embodiment.

[0014] 1 includes a switch section 10 constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20 constituting a capacitor and electrically connected to the switch section 10. The element section 20 and the switch section 10 are arranged in the horizontal direction with respect to the semiconductor substrate 1.

[0015] The switch section 10 has a gate electrode 2, a gate insulating film 3, a channel forming film 4, a source electrode 5, and a drain electrode 6. In the switch section 10 shown in Fig. 1, the gate electrode 2 is formed on a semiconductor substrate 1, the gate insulating film 3 and the channel forming film 4 are formed in this order on the gate electrode 2, and parts of the source electrode 5 and the drain electrode 6 are formed on them, respectively.

[0016] More specifically, the switch section 10 is an oxide FET (Field Effect Transistor). For example, lanthanum aluminate (LAO) is used for the semiconductor substrate 1, and a gate electrode 2 is formed thereon with platinum (Pt) in a predetermined pattern as shown in FIG. 2. For example, a La-HfO2 film with a thickness of 70 nm is used for the gate insulating film 3, and an IZO film with a thickness of 25 nm is used for the channel forming film 4. On the channel forming film 4 of the IZO film, a source electrode 5 and a drain electrode 6 are formed with platinum (Pt) in a predetermined pattern as shown in FIG. 2. Note that a terminal electrode 5a (first terminal electrode) is provided on the source electrode 5 shown in FIG. 2, but the source electrode 5 itself may be used as the terminal electrode 5a. For example, the channel width W of the switch section 10 is 100 μm and the channel length L is 10 μm.

[0017] 1, the drain electrode 6 extends not only to the portion formed on the channel formation film 4 but also to the portion constituting the element section 20. Specifically, the drain electrode 6 includes an electrode 6a constituting the switch section 10, an electrode 6c constituting the element section 20, and an electrode 6b connecting the electrode 6a and the electrode 6c. The electrode 6a is a part of the drain electrode 6 formed on the channel formation film 4. The electrode 6c is a part of the drain electrode 6 formed on the semiconductor substrate 1. The electrode 6b is a part of the drain electrode 6 formed penetrating the gate insulating film 3.

[0018] The element section 20 is a capacitor provided on a part of the drain electrode 6 (on the upper part of the electrode 6c). The element section 20 includes the electrode 6c, a dielectric layer 3a formed of the same insulating film as the gate insulating film 3, and a terminal electrode 22 (second terminal electrode) made of platinum (Pt) and formed on the dielectric layer 3a. The terminal electrode 22 is formed in a predetermined pattern as shown in FIG. 2. The gate electrode 2 is drawn out from the region where the source electrode 5 and the drain electrode 6 overlap as shown in FIG. 2, and a control electrode terminal 2a is provided on the gate electrode 2.

[0019] The element section 20 configures a capacitor with the dielectric layer 3a provided between a part of the drain electrode 6 (electrode 6c) and the terminal electrode 22. The capacitor is a portion C1 where the drain electrode 6 and the terminal electrode 22 overlap in a plan view, as shown in Fig. 2. The drain electrode 6 is a floating electrode, and is not directly electrically connected to the terminal electrode 5a of the variable capacitance element 100.

[0020] When the switch unit 10 is in the OFF state, a gate voltage equal to or higher than the threshold is not applied to the gate electrode 2 of the variable capacitance element 100, so that an electron depletion layer is formed at the position of the channel formation film 4 that overlaps with the gate electrode 2 in a planar view, and there is no electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, in the variable capacitance element 100, a voltage is applied only to the source electrode 5, and no voltage is applied between the electrode 6c and the terminal electrode 22, so that a capacitor is not formed.

[0021] On the other hand, when the switch section 10 is in the ON state, a channel is formed in the variable capacitance element 100 by applying a gate voltage equal to or higher than the threshold value to the gate electrode 2, thereby establishing electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, in the variable capacitance element 100, a voltage is applied to the source electrode 5 and the drain electrode 6, and a voltage is also applied between the electrode 6c and the terminal electrode 22, forming a capacitor.

[0022] That is, in the variable capacitance element 100, a state in which there is no capacitor and a state in which there is a capacitor are switched by turning the switch section 10 on and off, thereby turning the capacitor on and off. The variable capacitance element 100 is divided into the switch section 10 which performs an on / off operation by a voltage applied to the gate electrode 2 (control electrode terminal 2a), and the element section 20 which operates with a part (electrode 6c) of the drain electrode 6 and the terminal 22a of the terminal electrode 22 (second terminal electrode) via the terminal electrode 5a (first terminal electrode), and operates with three terminals.

[0023] In addition, in the variable capacitance element 100, the gate electrode 2 (control electrode terminal 2a) of the switch section 10 and the terminal 22a of the terminal electrode 22 (second terminal electrode) of the element section 20 are electrically separated, so that the operation of the switch section 10 is not affected by a signal on the element section 20 side. The terminal electrode 5a (first terminal electrode) and the terminal 22a of the terminal electrode 22 (second terminal electrode) of the variable capacitance element 100 are connected to a filter circuit or the like, while the control electrode terminal 2a for switching between the presence and absence of capacitance is connected to a circuit other than the filter circuit. Therefore, there is a low possibility that the signal applied to the control electrode terminal 2a will be affected by the signal of the filter circuit.

[0024] Furthermore, in the variable capacitance element 100, the electrical resistance of the channel formation film 4 between the source electrode 5 and the drain electrode 6 can be reduced by shortening the channel length L of the switch section 10. Therefore, in the variable capacitance element 100, in order to quickly switch between the presence and absence of capacitance, it is possible to address this by improving the switching speed (time constant) of the switch section 10.

[0025] Next, a method for manufacturing the variable capacitance element 100 will be described with reference to the drawings. FIG. 3 is a cross-sectional view for explaining a method for manufacturing the variable capacitance element according to the first embodiment. First, in FIG. 3(a), a gate electrode 2 and a part of the drain electrode 6 (electrode 6c) made of platinum (Pt) with a film thickness of 80 nm are formed on the (100) surface of a prepared semiconductor substrate 1 made of lanthanum aluminate (LAO). Specifically, the gate electrode 2 is formed by forming a photoresist of a predetermined pattern on the (100) surface of the semiconductor substrate 1 using a photolithography technique, then depositing platinum (Pt) by radio frequency (RF) sputtering, and removing the photoresist by lift-off.

[0026] 3(b), a gate insulating film 3 having a thickness of 70 nm is formed on the surface of the semiconductor substrate 1 on which the gate electrode 2 and a part of the drain electrode 6 (electrode 6c) are formed. Specifically, the gate insulating film 3 is formed by spin-coating a La-HfO2 solution onto the surface of the semiconductor substrate 1 on which the gate electrode 2 is formed using a chemical solution deposition (CSD) method, drying the film at 150°C, and then baking the film at 800°C in an oxygen atmosphere for crystallization.

[0027] In Fig. 3(c), a channel formation film 4 with a thickness of 25 nm is formed on the gate insulating film 3. Specifically, the channel formation film 4 is formed by using chemical solution deposition (CSD) to spin-coat an IZO solution on the gate insulating film 3, drying it at 150°C, and then baking it at 500°C in an oxygen atmosphere to crystallize it.

[0028] In FIG. 3(d), a part of the drain electrode 6 (electrode 6b) is formed penetrating the gate insulating film 3 and the channel forming film 4. Specifically, the electrode 6b is, for example, a via conductor formed by forming a hole penetrating the gate insulating film 3 and the channel forming film 4 at a position overlapping with the electrode and filling the formed hole with a conductive material. Furthermore, in FIG. 3(d), a source electrode 5 and a part of the drain electrode 6 (electrode 6b) made of platinum (Pt) with a thickness of 80 nm are formed on the channel forming film 4. 6a Specifically, the source electrode 5 and the electrode 6aThe electrode is formed by forming a photoresist of a predetermined pattern on the channel forming film 4 using a photolithography technique, then depositing platinum (Pt) by radio frequency (RF) sputtering, and removing the photoresist by lift-off. 6a and electrode 6b are electrically connected to each other.

[0029] 3(e), the channel formation film 4 on a part (electrode 6c) of the drain electrode 6 is removed to form a platinum (Pt) terminal electrode 22 with a thickness of 80 nm. Specifically, the terminal electrode 22 is formed by removing the channel formation film 4, forming a photoresist of a predetermined pattern on the dielectric layer 3a using a photolithography technique, then depositing platinum (Pt) by radio frequency (RF) sputtering, and removing the photoresist by lift-off.

[0030] The variable capacitance element 100 described so far is an element that can be switched between a state in which there is no capacitor and a state in which there is a capacitor. However, a multi-valued variable capacitance element can be configured by forming a plurality of variable capacitance elements 100 in a matrix on a semiconductor substrate 1. FIG. 4 is a circuit diagram of a multi-valued variable capacitance element 100a according to the first embodiment.

[0031] 4 shows a circuit diagram of a variable capacitance element 100a in which n×n pieces of one variable capacitance element 100 shown in FIG. 1 are connected in a matrix. In the variable capacitance element 100a shown in FIG. 4, the terminal electrode 5a (first terminal electrode) and the terminal electrode 22 (second terminal electrode) are common to the n×n variable capacitance elements 100. However, the control electrode terminals 2a of the n×n variable capacitance elements 100 are provided separately, and are shown in FIG. 4 as terminals G11 to Gnn. By supplying signals to these terminals G11 to Gnn, a required number of variable capacitance elements 100 can be turned on to obtain a required capacitance, so that the variable capacitance element 100a can have a multi-value capacitance.

[0032] As described above, the variable capacitance element 100 according to the first embodiment includes the switch section 10 constituting a field effect transistor, and the element section 20 electrically connected to the switch section 10 and constituting a capacitor. The switch section 10 includes a source electrode 5, a drain electrode 6, a channel formation film 4 formed overlapping at least a part of the source electrode 5 and a part of the drain electrode 6, a gate insulating film 3 formed overlapping the channel formation film 4, and a gate electrode 2 formed overlapping the gate insulating film 3. The element section 20 includes a terminal electrode 5a (first terminal electrode) electrically connected to the source electrode 5, and a terminal electrode 22 (second terminal electrode) constituting a capacitor between the part of the drain electrode 6 (electrode 6c) and the part of the drain electrode 6 with the dielectric layer 3a sandwiched therebetween. The dielectric layer 3a and the gate insulating film 3 are the same insulating film.

[0033] As a result, the variable capacitance element 100 of embodiment 1 forms a capacitor between a part of the drain electrode 6 (electrode 6c) and the terminal electrode 22, with a dielectric layer 3a formed from the same insulating film as the gate insulating film 3 in between, so that the capacitance can be varied over a wide range, including the case where the capacitance is 0 (zero).

[0034] Moreover, in the variable capacitance element 100, the number of processes can be reduced by using the same insulating film for the dielectric layer 3a and the gate insulating film 3. Furthermore, in the variable capacitance element 100, the element portion 20 is not formed overlapping the switch portion 10, but is formed horizontally to the semiconductor substrate 1, so that a dielectric material that requires a process that adversely affects the switch portion 10, such as high-temperature processing, or a dielectric material that is affected by the orientation of the base can be selected for the dielectric layer 3a, improving material selectivity.

[0035] In the variable capacitance element 100, a part of the drain electrode 6 (electrode 6c) is formed on the surface of the dielectric layer 3a on the same side as the surface of the gate insulating film 3 on which the gate electrode 2 is formed, and a terminal electrode 22 is formed on the surface of the dielectric layer 3a opposite to the surface of the gate insulating film 3 on which the gate electrode 2 is formed.

[0036] (Variation 1-1) In the variable capacitance element 100, a capacitor is formed by a dielectric layer 3a provided between a part of the drain electrode 6 (electrode 6c) and the terminal electrode 22 as shown in Fig. 1. In order to further increase the capacitance of the capacitor in the variable capacitance element 100, a configuration in which a plurality of dielectric layers constituting the element section 20 are stacked is considered. Fig. 5 is a cross-sectional view for explaining the configuration of a variable capacitance element 100A according to a first modification of the first embodiment. In the variable capacitance element 100A shown in Fig. 5, the same components as those in the variable capacitance element 100 shown in Fig. 1 are denoted by the same reference numerals and detailed description will not be repeated.

[0037] A variable capacitance element 100A shown in FIG. 5 includes a switch section 10 constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20A electrically connected to the switch section 10 and constituting a passive element.

[0038] In the element unit 20A, a capacitor is formed by a dielectric layer 3a provided between a part of the drain electrode 6 (electrode 6c) and the terminal electrode 22, and a capacitor is further formed by a dielectric layer 7 provided between the terminal electrode 22 and a part of the drain electrode 6 (electrode 6d). The dielectric layer sandwiched between the part of the drain electrode 6 (electrodes 6c, 6d) and the terminal electrode 22 includes a dielectric layer 3a (first dielectric layer) formed from the same insulating film as the gate insulating film 3, and a dielectric layer 7 (second dielectric layer) formed from an insulating film different from the gate insulating film 3.

[0039] The element section 20A is a multi-layer capacitor formed by sequentially stacking a part of the drain electrode 6 (electrode 6c), a dielectric layer 3a (first dielectric layer), a terminal electrode 22, a dielectric layer 7 (second dielectric layer), and a part of the drain electrode 6 (electrode 6d). This allows the variable capacitance element 100A including the element section 20A to further increase the capacitance of the capacitor. For example, when the capacitance of the capacitor formed by the dielectric layer 3a is C A , the capacitance of the capacitor formed by the dielectric layer 7 is C B Then, the variable capacitance element 100A has a capacitance C ON But, C ON =CA +C B It becomes.

[0040] The dielectric layer 3a and the dielectric layer 7 may have the same thickness or different thicknesses. Furthermore, the dielectric layer 3a and the dielectric layer 7 may be made of the same dielectric material or different dielectric materials. Specifically, either the dielectric layer 3a or the dielectric layer 7 may be made of a dielectric material whose dielectric constant depends on a DC bias voltage (e.g., (Ba, Sr) TiO By using the dielectric material for either the dielectric layer 3a or the dielectric layer 7, the capacitance C ON For example, when the dielectric layer 7 is made of the dielectric material, a DC bias voltage (V DC ) is applied, the variable capacitance element 100A has a capacitance C ON But, C ON =C A +C B (V DC ) is obtained. C B (V DC ) is the DC bias voltage (V DC ) changes depending on the capacitance C ON It is possible to fine-tune the.

[0041] In the variable capacitance element 100A, a two-layer capacitor is formed by sequentially stacking a part of the drain electrode 6 (electrode 6c), a dielectric layer 3a (first dielectric layer), a terminal electrode 22, a dielectric layer 7 (second dielectric layer), and a part of the drain electrode 6 (electrode 6d) in the element portion 20A, but a three or more layer capacitor may also be formed.

[0042] (Variation 1-2) Fig. 6 is a cross-sectional view for illustrating a configuration of a variable capacitance element 100B according to a second modification of embodiment 1. In variable capacitance element 100B shown in Fig. 6, the same components as those in variable capacitance element 100A shown in Fig. 5 are denoted by the same reference characters and detailed description thereof will not be repeated.

[0043] A variable capacitance element 100B shown in FIG. 6 includes a switch portion 10A constituting a field effect transistor formed on a semiconductor substrate 1, and an element portion 20A constituting a passive element and electrically connected to the switch portion 10A.

[0044] The switch section 10A has a gate electrode 2, a gate insulating film 3, a channel forming film 4, a source electrode 5, a drain electrode 6, and a passivation film 7a. In the switch section 10A shown in Fig. 6, the gate electrode 2 is formed on the semiconductor substrate 1, the gate insulating film 3 and the channel forming film 4 are formed in this order on the gate electrode 2, and parts of the source electrode 5 and the drain electrode 6 are formed on them, respectively, and covered with the passivation film 7a.

[0045] In the variable capacitance element 100B, a part of the dielectric layer 7 covers the channel formation film 4 between the source electrode 5 and the drain electrode 6 to form a passivation film 7a. The passivation film 7a can suppress deterioration of the characteristics of the switch section 10. Furthermore, by forming the passivation film 7a from a part of the dielectric layer 7, the passivation film can be formed by covering the channel formation film 4 without adding a separate process.

[0046] (Variation 1-3) Fig. 7 is a cross-sectional view for illustrating a configuration of a variable capacitance element 100C according to a third modification of embodiment 1. In variable capacitance element 100C shown in Fig. 7, the same components as those in variable capacitance element 100A shown in Fig. 5 are denoted by the same reference characters and detailed description thereof will not be repeated.

[0047] A variable capacitance element 100C shown in FIG. 7 includes a switch portion 10B constituting a field effect transistor formed on a semiconductor substrate 1, and an element portion 20B constituting a passive element and electrically connected to the switch portion 10B.

[0048] The switch section 10B has a gate electrode 2, a gate insulating film 3, a channel forming film 4, a source electrode 5, and a drain electrode 6. However, the switch section 10B employs a top gate structure instead of a bottom gate structure like the switch section 10 shown in Fig. 1. In the switch section 10B, a channel forming film 4 is layered on a dielectric layer 7, a source electrode 5 and a drain electrode 6 are respectively formed on the channel forming film 4, a gate insulating film 3 is formed on the source electrode 5 and the drain electrode 6, and a gate electrode 2 is formed on the gate insulating film 3.

[0049] In addition, in the element portion 20B, a part of the drain electrode 6 (electrode 6d) is formed on the semiconductor substrate 1 side, so that the part of the drain electrode 6 (electrode 6d), the dielectric layer 7 (second dielectric layer), the terminal electrode 22, the dielectric layer 3a (first dielectric layer), and the part of the drain electrode 6 (electrode 6c) are stacked in this order to form a two-layer capacitor.

[0050] The variable capacitance element 100C employs a switch section 10B having a top gate structure, and can achieve the same effects as the variable capacitance element 100A employing the switch section 10 having a bottom gate structure. Also, a switch section having a top gate structure may be employed for the switch section of the variable capacitance element 100 shown in FIG.

[0051] (Embodiment 2) In the variable capacitance element 100 according to the first embodiment, a configuration has been described in which a part (electrode 6c) of the drain electrode 6, which is a floating electrode, in the element section 20 is formed on the semiconductor substrate 1 side. In the variable capacitance element according to the second embodiment, a configuration has been described in which a terminal electrode in the element section is formed on the semiconductor substrate side. FIG. 8 is a cross-sectional view for illustrating the configuration of the variable capacitance element 200 according to the second embodiment. Note that in the variable capacitance element 200 shown in FIG. 8, the same components as those in the variable capacitance element 100 shown in FIG. 1 are denoted by the same reference numerals and detailed description will not be repeated.

[0052] 8 includes a switch section 10 constituting a field effect transistor, and an element section 20C constituting a passive element and electrically connected to the switch section 10. The element section 20C and the switch section 10 are arranged in the horizontal direction with respect to the semiconductor substrate 1.

[0053] The switch section 10 has a gate electrode 2, a gate insulating film 3, a channel forming film 4, a source electrode 5, and a drain electrode 6. In the switch section 10 shown in Fig. 8, the gate electrode 2 is formed on the semiconductor substrate 1, the gate insulating film 3 and the channel forming film 4 are formed in this order on the gate electrode 2, and parts of the source electrode 5 and the drain electrode 6 are formed on them, respectively.

[0054] figure 8 1, the drain electrode 6 extends not only to the portion formed on the channel formation film 4 but also to the portion constituting the element portion 20C. The element portion 20C is a capacitor provided on a part of the drain electrode 6. The element portion 20C includes a part of the drain electrode 6, a dielectric layer 3a formed of the same insulating film as the gate insulating film 3, and a platinum (Pt) terminal electrode 22 (second terminal electrode) formed on the dielectric layer 3a. The drain electrode 6 is a floating electrode and is not electrically connected directly to the terminal electrode 5a of the variable capacitance element 200.

[0055] When the switch section 10 is in the OFF state, the variable capacitance element 200 does not apply a gate voltage equal to or higher than the threshold to the gate electrode 2, so that an electron depletion layer is formed at the position of the channel formation film 4 that overlaps with the gate electrode 2 in a plan view, and the source electrode 5 and the drain electrode 6 are not electrically connected. 6 Since no voltage is applied between the capacitor and the terminal electrode 22, no capacitor is formed.

[0056] On the other hand, when the switch section 10 is in the ON state, a channel is formed in the variable capacitance element 200 by applying a gate voltage equal to or higher than the threshold to the gate electrode 2, and the source electrode 5 and the drain electrode 6 are electrically connected. 6 Since a voltage is also applied between the terminal electrode 22 and the capacitor, a capacitor is formed.

[0057] That is, in the variable capacitance element 200, a state in which there is no capacitor and a state in which there is a capacitor are switched by turning the switch section 10 on and off, thereby turning the capacitor on and off. The variable capacitance element 200 is divided into the switch section 10 which performs an on / off operation by a voltage applied to the gate electrode 2 (control electrode terminal 2a), and an element section 20C which operates with a part of the drain electrode 6 and the terminal 22a of the terminal electrode 22 (second terminal electrode) via the terminal electrode 5a (first terminal electrode), and operates with three terminals.

[0058] As described above, in the variable capacitance element 200 of embodiment 2, the terminal electrode 22 is formed on the surface of the dielectric layer 3a on the same side as the surface of the gate insulating film 3 on which the gate electrode 2 is formed, and a part of the drain electrode 6 is formed on the surface of the dielectric layer 3a opposite to the surface of the gate insulating film 3 on which the gate electrode 2 is formed.

[0059] As a result, the variable capacitance element 200 of embodiment 1 forms a capacitor between a part of the drain electrode 6 and the terminal electrode 22, sandwiching a dielectric layer 3a formed from the same insulating film as the gate insulating film 3, so that the capacitance can be varied over a wide range, including the case where the capacitance is 0 (zero).

[0060] (Variation 2-1) In the variable capacitance element 200, as shown in FIG. 8, a capacitor is formed by a dielectric layer 3a provided between a part of the drain electrode 6 and the terminal electrode 22. In order to further increase the capacitance of the capacitor in the variable capacitance element 200, a configuration in which a plurality of dielectric layers constituting the element portion 20C are stacked is considered. FIG. 9 is a cross-sectional view for explaining the configuration of a variable capacitance element 200A according to a first modification of the second embodiment. In the variable capacitance element 200A shown in FIG. 9, the same components as those in the variable capacitance element 200 shown in FIG. 8 are denoted by the same reference numerals and detailed description will not be repeated.

[0061] A variable capacitance element 200A shown in FIG. 9 includes a switch section 10 constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20D electrically connected to the switch section 10 and constituting a passive element.

[0062] In the element unit 20D, a capacitor is formed by a dielectric layer 3a provided between a part of the drain electrode 6 and a part of the terminal electrode 22 (terminal electrode 221), and a capacitor is further formed by a dielectric layer 7 provided between a part of the drain electrode 6 and a part of the terminal electrode 22 (terminal electrode 222). The terminal electrode 22 includes a terminal electrode 221 formed on the semiconductor substrate 1, a terminal electrode 222 formed on the dielectric layer 7, and a terminal electrode 223 connecting the terminal electrode 221 and the terminal electrode 222. The dielectric layer sandwiched between the part of the drain electrode 6 and the part of the terminal electrode 22 (terminal electrodes 221, 222) includes a dielectric layer 3a (first dielectric layer) formed of the same insulating film as the gate insulating film 3, and a dielectric layer 7 (second dielectric layer) formed of an insulating film different from the gate insulating film 3.

[0063] The element section 20D configures a multi-layer capacitor by sequentially stacking a part of the terminal electrode 22 (terminal electrode 221), a dielectric layer 3a (first dielectric layer), a drain electrode 6, a dielectric layer 7 (second dielectric layer), and a part of the terminal electrode 22 (terminal electrode 222). This allows the variable capacitance element 200A including the element section 20D to further increase the capacitance of the capacitor. The dielectric layer 3a and the dielectric layer 7 may have the same film thickness or different film thicknesses. Furthermore, the dielectric layer 3a and the dielectric layer 7 may be made of the same dielectric material or different dielectric materials.

[0064] In the variable capacitance element 200A, a two-layer capacitor is formed by sequentially stacking a part of the terminal electrode 22 (terminal electrode 221), a dielectric layer 3a (first dielectric layer), a drain electrode 6, a dielectric layer 7 (second dielectric layer), and a part of the terminal electrode 22 (terminal electrode 222) in the element portion 20D, but a three or more layer capacitor may also be formed.

[0065] (Variation 2-2) Fig. 10 is a cross-sectional view for illustrating a configuration of a variable capacitance element 200B according to a second modification of embodiment 2. In variable capacitance element 200B shown in Fig. 10, the same components as those in variable capacitance element 200A shown in Fig. 9 are denoted by the same reference characters and detailed description thereof will not be repeated.

[0066] A variable capacitance element 200B shown in FIG. 10 includes a switch portion 10A constituting a field effect transistor formed on a semiconductor substrate 1, and an element portion 20D constituting a passive element and electrically connected to the switch portion 10A.

[0067] The switch section 10A has a gate electrode 2, a gate insulating film 3, a channel forming film 4, a source electrode 5, a drain electrode 6, and a passivation film 7a. In the switch section 10A shown in Fig. 10, the gate electrode 2 is formed on the semiconductor substrate 1, the gate insulating film 3 and the channel forming film 4 are formed in this order on the gate electrode 2, and parts of the source electrode 5 and the drain electrode 6 are formed on them, respectively, and covered with the passivation film 7a.

[0068] In the variable capacitance element 200B, a part of the dielectric layer 7 covers the channel formation film 4 between the source electrode 5 and the drain electrode 6 to form a passivation film 7a. The passivation film 7a can suppress deterioration of the characteristics of the switch section 10A. In addition, by forming the passivation film 7a from a part of the dielectric layer 7, the passivation film can be formed by covering the channel formation film 4 without adding a separate process.

[0069] (Variation 2-3) Fig. 11 is a cross-sectional view illustrating a configuration of a variable capacitance element 200C according to a third modification of embodiment 2. In variable capacitance element 200C shown in Fig. 11, the same components as those in variable capacitance element 200A shown in Fig. 9 are denoted by the same reference characters and detailed description thereof will not be repeated.

[0070] The variable capacitance element shown in FIG. 200C The semiconductor device includes a switch section 10B constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20E constituting a passive element and electrically connected to the switch section 10B.

[0071] The switch section 10B has a gate electrode 2, a gate insulating film 3, a channel forming film 4, a source electrode 5, and a drain electrode 6. However, the switch section 10B employs a top gate structure instead of a bottom gate structure like the switch section 10 shown in Fig. 9. In the switch section 10B, a channel forming film 4 is layered on a dielectric layer 7, a source electrode 5 and a drain electrode 6 are respectively formed on the channel forming film 4, a gate insulating film 3 is formed on the source electrode 5 and the drain electrode 6, and a gate electrode 2 is formed on the gate insulating film 3.

[0072] The element portion 20E constitutes a two-layer capacitor by sequentially stacking a portion of the terminal electrode 22 (terminal electrode 222), a dielectric layer 7 (second dielectric layer), a drain electrode 6, a dielectric layer 3a (first dielectric layer), and a portion of the terminal electrode 22 (terminal electrode 221).

[0073] The variable capacitance element 200C employs a switch section 10B having a top gate structure, and can achieve the same effects as the variable capacitance element 200A employing the switch section 10 having a bottom gate structure. Also, a switch section having a top gate structure may be employed for the switch section of the variable capacitance element 200 shown in FIG.

[0074] (Variation 2-4) Fig. 12 is a cross-sectional view for illustrating a configuration of a variable capacitance element 200D according to a fourth modification of embodiment 2. In variable capacitance element 200D shown in Fig. 12, the same components as those in variable capacitance element 200 shown in Fig. 8 are denoted by the same reference characters and detailed description thereof will not be repeated.

[0075] The variable capacitance element shown in FIG. 200D The semiconductor device includes a switch section 10C constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20C electrically connected to the switch section 10C and constituting a passive element.

[0076] The switch section 10C has a gate electrode 2, a gate insulating film 3, a channel forming film 4, a source electrode 5, and a drain electrode 6. However, the switch section 10C has a bottom contact structure in which the channel forming film 4 is formed above the source electrode 5 and the drain electrode 6, rather than a top contact structure in which the channel forming film 4 is formed below the source electrode 5 and the drain electrode 6 as in the switch section 10 shown in Fig. 8. The bottom contact structure is a structure in which the source electrode 5 and the drain electrode 6 are in contact with each other below the channel forming film 4.

[0077] The variable capacitance element 200D employs a switch section 10C having a bottom contact structure, and has the same effects as the variable capacitance element 200A employing the switch section 10 having a top contact structure. Also, a switch section having a bottom contact structure may be employed for the switch section of the variable capacitance element 100 shown in FIG.

[0078] (Embodiment 3) It has been explained that in the variable capacitance element 200 according to the second embodiment, the switch section 10 is turned on / off to switch between a state in which there is no capacitor and a state in which there is a capacitor, thereby turning the capacitor on / off. In the variable capacitance element according to the third embodiment, the switch section is turned on / off to switch between a state in which there is no capacitor but a state in which the capacitance of the capacitor is small and a state in which the capacitance of the capacitor is large. FIG. 13 is a cross-sectional view for explaining the configuration of the variable capacitance element 300 according to the third embodiment. FIG. 14 is a plan view for explaining the configuration of the variable capacitance element 300 according to the third embodiment. In the variable capacitance element 300 shown in FIGS. 13 and 14, the same components as those in the variable capacitance element 200 shown in FIG. 8 are denoted by the same reference numerals, and detailed description thereof will not be repeated.

[0079] 13 includes a switch section 10 constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20FA constituting a passive element and electrically connected to the switch section 10. The element section 20FA and the switch section 10 are arranged in the horizontal direction with respect to the semiconductor substrate 1.

[0080] The element portion 20FA includes a dielectric layer 3a and a terminal electrode 22 (second terminal electrode) formed on the dielectric layer 3a. The terminal electrode 22 is formed in a pattern that avoids a channel region formed between the source electrode 5 and the drain electrode 6, as shown in Fig. 14. Therefore, in the cross-sectional view shown in Fig. 13, the terminal electrode 22 is provided not only on the terminal electrode 22A formed below the drain electrode 6, but also on the terminal electrode 22B formed below the source electrode 5.

[0081] The element portion 20FA forms a first capacitor between the drain electrode 6 and the terminal electrode 22A, and forms a second capacitor between the source electrode 5 and the terminal electrode 22B. The first capacitor is a portion C1 where the drain electrode 6 and the terminal electrode 22A overlap in a planar view, as shown in Fig. 14. The second capacitor is a portion C2 where the source electrode 5 and the terminal electrode 22B overlap in a planar view.

[0082] When the switch unit 10 is in the OFF state, the variable capacitance element 300 does not apply a gate voltage equal to or higher than the threshold to the gate electrode 2, so that an electron depletion layer is formed at the position of the channel formation film 4 that overlaps with the gate electrode 2 in a planar view, and there is no electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, in the variable capacitance element 300, a voltage is applied only between the source electrode 5 and the portion of the terminal electrode 22B facing the source electrode 5, so that the capacitance is that of the second capacitor only.

[0083] However, when the switch section 10 is in the ON state, application of a gate voltage equal to or higher than a threshold to the gate electrode 2 forms a channel in the variable capacitance element 300, establishing electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, the variable capacitance element 300 has a voltage applied between the source electrode 5 and the drain electrode 6 and the opposing terminal electrode 22, resulting in a combined capacitance of the first capacitor and the second capacitor.

[0084] In the variable capacitance element 300, the terminal electrode 22 does not have to be formed in a pattern that bypasses the entire channel region formed between the source electrode 5 and the drain electrode 6 as shown in FIG. 14, and may be formed in a pattern that overlaps with part of the channel region.

[0085] As described above, in the variable capacitance element 300, a part of the terminal electrode 22 (terminal electrode 22B) faces a part of the source electrode 5 with the dielectric layer 3a sandwiched therebetween. This allows the variable capacitance element 300 to switch the state of the element unit 20FA between the second capacitor state and the first capacitor+second capacitor state by turning the switch section 10 ON / OFF.

[0086] (Variation 3-1) In the variable capacitance element 300, as shown in FIG. 13, a capacitor is formed by a dielectric layer 3a provided between the drain electrode 6 and the terminal electrode 22A, and between the source electrode 5 and the terminal electrode 22B. In order to further increase the capacitance of the capacitor in the variable capacitance element 300, a configuration in which a plurality of dielectric layers constituting the element portion 20FA are stacked is considered. FIG. 15 is a cross-sectional view for explaining the configuration of a variable capacitance element 300A according to a first modification of the third embodiment. In the variable capacitance element 300A shown in FIG. 13 The same components as those of the variable capacitance element 300 shown in FIG.

[0087] A variable capacitance element 300A shown in FIG. 15 includes a switch section 10A constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20F constituting a passive element and electrically connected to the switch section 10A.

[0088] The first capacitor of the element unit 20F includes a capacitor constituted by a dielectric layer 3a provided between a part of the drain electrode 6 and a part of the terminal electrode 22 (terminal electrode 22A), and a capacitor constituted by a dielectric layer 7 provided between a part of the drain electrode 6 and a part of the terminal electrode 22 (terminal electrode 22C). The terminal electrode 22 includes a terminal electrode 22A formed on the semiconductor substrate 1, a terminal electrode 22C formed on the dielectric layer 7, and a terminal electrode 22D connecting the terminal electrode 22A and the terminal electrode 22C. The dielectric layer sandwiched between the part of the drain electrode 6 and the part of the terminal electrode 22 (terminal electrodes 22A, 22C) includes a dielectric layer 3a (first dielectric layer) formed of the same insulating film as the gate insulating film 3, and a dielectric layer 7 (second dielectric layer) formed of an insulating film different from the gate insulating film 3.

[0089] The first capacitor of the element unit 20F is a multi-layer capacitor formed by sequentially stacking a part of the terminal electrode 22 (terminal electrode 22A), a dielectric layer 3a (first dielectric layer), a drain electrode 6, a dielectric layer 7 (second dielectric layer), and a part of the terminal electrode 22 (terminal electrode 22C). This allows the variable capacitance element 300A including the element unit 20F to have a larger capacitance. The dielectric layer 3a and the dielectric layer 7 may have the same film thickness or different film thicknesses. Furthermore, the dielectric layer 3a and the dielectric layer 7 may be made of the same dielectric material or different dielectric materials.

[0090] In the variable capacitance element 300A, in the first capacitor of the element portion 20F, a part of the terminal electrode 22 (terminal electrode 22A), a dielectric layer 3a (first dielectric layer), a drain electrode 6, a dielectric layer 7 (second dielectric layer), and a part of the terminal electrode 22 (terminal electrode 22C) are stacked in order to form a two-layer capacitor, but a three or more layer capacitor may also be formed.

[0091] (Variation 3-2) Fig. 16 is a cross-sectional view for illustrating a configuration of a variable capacitance element 300B according to a second modification of embodiment 3. In variable capacitance element 300B shown in Fig. 16, the same components as those in variable capacitance element 300A shown in Fig. 15 are denoted by the same reference characters and detailed description thereof will not be repeated.

[0092] A variable capacitance element 300B shown in FIG. 16 includes a switch portion 10A constituting a field effect transistor formed on a semiconductor substrate 1, and an element portion 20G constituting a passive element and electrically connected to the switch portion 10A.

[0093] The second capacitor of element unit 20G is not a capacitor constituted by a dielectric layer 3a provided between source electrode 5 and a part (terminal electrode 22B) of terminal electrode 22, but a capacitor constituted by a dielectric layer 7 provided between source electrode 5 and a part (terminal electrode 22E) of terminal electrode 22. In the second capacitor of element unit 20G, dielectric layer 7 formed on drain electrode 6 is extended onto source electrode 5, and terminal electrode 22E is formed at a position overlapping with source electrode 5 in plan view.

[0094] That is, a part of the terminal electrode 22 (terminal electrode 22E) faces a part of the source electrode 5 with the dielectric layer 7 sandwiched therebetween. The terminal electrode 22E is electrically connected to the terminal electrode 22C, bypassing the channel region. The dielectric layer 7 also constitutes a passivation film 7a that covers the channel formation film 4 between the source electrode 5 and the drain electrode 6.

[0095] The second capacitor of the element unit 20G may further include a terminal electrode 22B. When the terminal electrode 22B is provided, the second capacitor of the element unit 20G is configured as a two-layer capacitor by sequentially stacking a part of the terminal electrode 22 (terminal electrode 22B), the dielectric layer 3a (first dielectric layer), a part of the source electrode 5, the dielectric layer 7 (second dielectric layer), and a part of the terminal electrode 22 (terminal electrode 22E).

[0096] (Variation 3-3) Fig. 17 is a cross-sectional view for illustrating a configuration of a variable capacitance element 300C according to a third modification of embodiment 3. In variable capacitance element 300C shown in Fig. 17, the same components as those in variable capacitance element 300A shown in Fig. 15 are denoted by the same reference characters and detailed description thereof will not be repeated.

[0097] A variable capacitance element 300C shown in FIG. 17 includes a switch portion 10A constituting a field effect transistor formed on a semiconductor substrate 1, and an element portion 20H constituting a passive element and electrically connected to the switch portion 10A.

[0098] The element unit 20H is formed by extending the dielectric layer 7 formed on the drain electrode 6 onto the source electrode 5, and further extending the terminal electrode 22C onto the source electrode 5. That is, in the element unit 20H, unlike the element unit 20G shown in Fig. 16, the terminal electrode 22C is formed by extending onto the source electrode 5 without bypassing the channel region. Therefore, a part of the terminal electrode 22C faces the channel formation film 4 with the dielectric layer 7 interposed therebetween.

[0099] The element unit 20H may further be provided with a terminal electrode 22B. When the terminal electrode 22B is provided, the second capacitor of the element unit 20H is a two-layer capacitor formed by sequentially stacking a part of the terminal electrode 22 (terminal electrode 22B), the dielectric layer 3a (first dielectric layer), a part of the source electrode 5, the dielectric layer 7 (second dielectric layer), and a part of the terminal electrode 22 (a part of the terminal electrode 22C).

[0100] (Embodiment 4) In the electronic devices according to the first to third embodiments, the passive element included in the variable capacitance element is a capacitor, and the physical quantity to be varied is capacitance. However, the passive element included in the variable capacitance element is not limited to a capacitor. In the electronic device according to the fourth embodiment, the passive element included in the variable inductance element is an inductor, and the physical quantity to be varied is inductance. FIG. 18 is a cross-sectional view for explaining the configuration of the variable inductance element 400 according to the fourth embodiment. FIG. 19 is an equivalent circuit diagram of the variable inductance element 400 according to the fourth embodiment. In the variable inductance element 400 shown in FIGS. 18 and 19, the same components as those in the variable capacitance element 100 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will not be repeated. In the variable inductance element 400, the same materials can be used for the same components as those in the variable capacitance element 100.

[0101] 18 includes a switch section 10 constituting a field effect transistor, and an element section 40 constituting a passive element and electrically connected to the switch section 10. The element section 40 is provided on the right side of the switch section 10 in the figure.

[0102] The switch section 10 has a gate electrode 2, a gate insulating film 3, a channel formation film 4, a source electrode 5, and a drain electrode 6. In the switch section 10 shown in Fig. 18, the gate electrode 2 is formed on the semiconductor substrate 1, the gate insulating film 3 and the channel formation film 4 are formed in this order on the gate electrode 2, and parts of the source electrode 5 and the drain electrode 6 are formed on them, respectively.

[0103] In the variable inductance element 400, the element section 40 is an inductor, and one end of a coil electrode 41 is electrically connected to a part of the drain electrode 6 (the upper part of the electrode 6c). The coil electrode 41 is formed by laminating in a dielectric layer 3a formed of the same insulating film as the gate insulating film 3, and the other end is electrically connected to the terminal 22a. 40 has a terminal electrode 5a (first terminal electrode) electrically connected to the source electrode 5, and a terminal 22a (second terminal electrode) that constitutes an inductor (coil electrode 41) between itself and a part of the drain electrode 6 across the dielectric layer 3a. In the variable inductance element 400, the switch section 10 is the first inductor L1, and the element section 40 is the second inductor L2. Note that the first inductor L1 does not include a coil electrode, and therefore has an inductance equal to or less than a predetermined amount (for example, 1 / 10,000 or less) that can be regarded as 0 (zero). On the other hand, the second inductor L2 includes a coil electrode 41, and therefore has an inductance due to the coil electrode 41.

[0104] In the variable inductance element 400, similarly to the variable capacitance element 100, when the switch unit 10 is in the OFF state, a gate voltage equal to or higher than the threshold is not applied to the gate electrode 2, so that an electron depletion layer is formed at the position of the channel formation film 4 that overlaps with the gate electrode 2 in a planar view, and there is no electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, the variable inductance element 400 has the inductance of only the first inductor L1.

[0105] On the other hand, when the switch unit 10 is in the ON state, a channel is formed in the variable inductance element 400 by applying a gate voltage equal to or higher than the threshold value to the gate electrode 2, thereby establishing electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, the variable inductance element 400 becomes the inductance of the second inductor L2 because a current flows through the coil electrode 41 between the drain electrode 6 and the terminal 22a.

[0106] That is, in the variable inductance element 400, a state in which there is no inductor and a state in which there is an inductor are switched by turning the switch section 10 on and off, thereby turning the inductor on and off. The variable inductance element 400 is divided into the switch section 10 which turns on and off by a voltage applied to the gate electrode 2 (control electrode terminal 2a), and the element section 40 which operates with a part of the drain electrode 6 (electrode 6c) and the terminal 22a of the terminal electrode 22 (second terminal electrode) via the terminal electrode 5a (first terminal electrode), and operates with three terminals.

[0107] As can be seen from the equivalent circuit diagram shown in Fig. 19(a), the variable inductance element 400 has the terminal electrode 5a (first terminal electrode) and the terminal 22a (second terminal electrode) connected to a converter circuit or the like, while the control electrode terminal 2a for varying the inductance is connected to a circuit other than the converter circuit. Therefore, the signal applied to the control electrode terminal 2a is unlikely to be affected by the signal of the converter circuit. Note that the variable inductance element 400 may have the terminal electrode 5a (first terminal electrode) and the terminal 22a (second terminal electrode) electrically connected by wiring, as shown in the equivalent circuit diagram shown in Fig. 19(b).

[0108] In the variable inductance element 400, the second inductor L2 is formed by laminating the coil electrode 41 in the dielectric layer 3a as shown in FIG. 18, but the coil electrode may be formed planarly on the dielectric layer 3a. FIG. 20 is a plan view for explaining the configuration of the variable inductance element 400A according to a modification of the fourth embodiment. FIG. 21 is a cross-sectional view for explaining the configuration of the variable inductance element 400A according to a modification of the fourth embodiment. In the variable inductance element 400A shown in FIGS. 20 and 21, the same components as those in the variable capacitance element 100 shown in FIG. 1 and the variable inductance element 400 shown in FIG. 18 are denoted by the same reference numerals and detailed description will not be repeated. In the variable inductance element 400A, the same materials can be used for the same components as those in the variable capacitance element 100.

[0109] In the variable inductance element 400A, the element section 40A is an inductor, and one end of the coil electrode 42 is electrically connected to the drain electrode 6. The coil electrode 42 is formed in a planar manner on the dielectric layer 3a formed of the same insulating film as the gate insulating film 3, and the other end is electrically connected to the terminal 22a. That is, the element section 40A has a terminal electrode 5a (first terminal electrode) electrically connected to the source electrode 5, and a terminal 22a (second terminal electrode) in contact with the dielectric layer 3a and constituting an inductor (coil electrode 42) between the terminal 5a and a part of the drain electrode 6. In the variable inductance element 400A, the switch section 10 is the first inductor L1, and the element section 40A is the second inductor L2. Note that the second inductor L2 includes the coil electrode 42, and therefore has an inductance due to the coil electrode 42.

[0110] As described above, the variable inductance element 400, 400A according to the fourth embodiment includes the switch section 10 constituting a field effect transistor, and the element section 40, 40A electrically connected to the switch section 10 and constituting an inductor. The switch section 10 includes a source electrode 5, a drain electrode 6, a channel formation film 4 formed overlapping at least a part of the source electrode 5 and a part of the drain electrode 6, a gate insulating film 3 formed overlapping the channel formation film 4, and a gate electrode 2 formed overlapping the gate insulating film 3. The element section 40, 40A includes a terminal electrode 5a (first terminal electrode) electrically connected to the source electrode 5, and a terminal 22a (second terminal electrode) constituting an inductor with the coil electrodes 41, 42 between the element section 40, 40A and the drain electrode 6.

[0111] As a result, the variable inductance elements 400, 400A according to the fourth embodiment form an inductor between the drain electrode 6 and the terminal 22a, and therefore the inductance can be varied in a wide range including the case where the inductance becomes 0 (zero).

[0112] A multi-valued variable inductance element may be configured by forming a plurality of variable inductance elements 400, 400A in a matrix. Also, by changing the coil electrode 41 shown in Fig. 18 to a resistive element, a passive element may be a resistor to form a variable resistor element. Furthermore, the switch section 10 may be configured, for example, with a silicon MOSFET or a GaN FET.

[0113] In addition, the variable inductance element 400 employs an inductor configured by a coil electrode 41 connecting a part of the drain electrode (electrode 6c) and the second terminal electrode (terminal 22a) instead of a capacitor configured by sandwiching a dielectric layer between a part of the drain electrode (electrode 6c) and the second terminal electrode (terminal electrode 22) of the variable capacitance element 100 shown in Fig. 1. Similarly, a variable inductance element may be formed by employing an inductor instead of a part configuring a capacitor in the variable capacitance elements 100A to 100C, 200, 200A to 200D, 300, and 300A to 300C. Moreover, a variable resistance element may be formed by employing a resistor instead of a part configuring a capacitor in the variable capacitance elements 100A to 100C, 200, 200A to 200D, 300, and 300A to 300C. In the variable capacitance elements 100A to 100C, 200A to 200C, and 300A to 300C, different types of passive elements (capacitors, inductors, resistors) may be provided on different dielectric materials.

[0114] (Embodiment 5) In the variable capacitance element 100A shown in FIG. 5, a variable capacitance element in which two layers, the dielectric layer 3a and the dielectric layer 7, are laminated on the semiconductor substrate 1 has been described, but the number of dielectric layers laminated on the semiconductor substrate 1 may be three or more. In the electronic element according to the fifth embodiment, a variable capacitance element in which three dielectric layers are laminated on a substrate will be described with reference to the drawings. Of course, the variable capacitance element may have four or more dielectric layers laminated on a substrate. FIG. 22 is a cross-sectional view for explaining the configuration of a variable capacitance element 500 according to the fifth embodiment. In the variable capacitance element 500 shown in FIG. 22, the same components as those of the variable capacitance elements 100, 100A, etc. shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will not be repeated. In the variable capacitance element 500, the same materials can be used for the same components as those of the variable capacitance elements 100, 100A, etc.

[0115] 22 includes a dielectric layer 3a (first dielectric layer), a dielectric layer 7 (second dielectric layer), and a dielectric layer 3b (third dielectric layer) stacked on a semiconductor substrate 1, and a switch section 10 constituting a field effect transistor is included in the dielectric layer 3b. The variable capacitance element 500 further includes an element section 20I constituting a capacitor, which is electrically connected to the switch section 10, in the dielectric layer 3a and the dielectric layer 7. The element section 20I and the switch section 10 are arranged in a vertical direction with respect to the semiconductor substrate 1.

[0116] The switch section 10 has a gate electrode 2, a dielectric layer 3b constituting a gate insulating film, a channel forming film 4, a source electrode 5, and a drain electrode 6. In the switch section 10 shown in Fig. 22, the gate electrode 2 is formed on the dielectric layer 3b (third dielectric layer), the channel forming film 4 is formed by overlapping it on the dielectric layer 3b on which the gate electrode 2 is formed, and the source electrode 5 and parts of the drain electrode 6 (electrodes 6a) are formed thereon.

[0117] The element section 20I configures a multi-layer capacitor by sequentially stacking a part of the terminal electrode 22 (terminal electrode 221), a dielectric layer 3a (first dielectric layer), a part of the drain electrode 6 (electrode 6c), a dielectric layer 7 (second dielectric layer), and a part of the terminal electrode 22 (terminal electrode 222). This allows the variable capacitance element 500 including the element section 20I to further increase the capacitance of the capacitor. The dielectric layer 7 (second dielectric layer) and the dielectric layer 3b (third dielectric layer) constituting the gate insulating film are the same insulating film (dielectric material). Of course, the dielectric layer 7 and the dielectric layer 3b may be made of the same dielectric material as the dielectric layer 3a (i.e., all are the same dielectric material). Furthermore, the dielectric layer 3a and the dielectric layer 3b may be made of the same dielectric material, the dielectric layer 3a and the dielectric layer 7 may be made of the same dielectric material, or the dielectric layers 3a, 3b, and 7 may all be made of different dielectric materials. Furthermore, the dielectric layers 3a, 3b, and the dielectric layer 7 may have the same film thickness or all different film thicknesses.

[0118] In the variable capacitance element 500, in the element portion 20I, the switch portion 10 is formed in the dielectric layer 3b (third dielectric layer) of the three dielectric layers 3a, 3b, and 7 stacked on the semiconductor substrate 1, and the remaining two dielectric layers 3a and 7 form the element portion 20I as a two-layer capacitor, but the element portion 20I may also be formed as a capacitor with three or more layers.

[0119] When the switch unit 10 is in the OFF state, a gate voltage equal to or higher than the threshold value is not applied to the gate electrode 2, so that an electron depletion layer is present at the position of the channel formation film 4 that overlaps with the gate electrode 2 in a planar view, and there is no electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, in the variable capacitance element 500, a voltage is applied only to the source electrode 5, and no voltage is applied between the electrode 6c and the terminal electrode 22, so that a capacitor is not formed.

[0120] On the other hand, when the switch section 10 is in the ON state, a channel is formed in the variable capacitance element 500 by applying a gate voltage equal to or higher than the threshold value to the gate electrode 2, thereby establishing electrical continuity between the source electrode 5 and the drain electrode 6. Therefore, in the variable capacitance element 500, a voltage is applied to the source electrode 5 and the drain electrode 6, and a voltage is also applied between the electrode 6c and the terminal electrode 22, forming a capacitor.

[0121] The configuration of the variable capacitance element 500 shown in FIG. 22 may be a variable inductance element by adopting an inductor instead of the part constituting the capacitor, or a variable resistance element by adopting a resistor instead of the part constituting the capacitor.

[0122] (Modification) Below is a list of materials that can be used for the gate insulating film 3 and the dielectric layers 3a and 7. Of course, the materials are not limited to the following list. Amorphous or polycrystalline metal oxides such as SiO2, Al2O3, HfO2, ZrO2, La2O3, Ta2O5 ·Nitride films such as SiN, Si3N4, and SiON Ferroelectric HfO2, and ferroelectric films in which HfO2 is doped with at least one type of trivalent, tetravalent or pentavalent metal atom such as Si, Ce, Y, Zr, Bi, Ni, Ta or La, ferroelectric materials with PbTiO3 as the host crystal, ferroelectric materials with (Ba,Sr)TiO3 as the host crystal, ferroelectric materials with Bi layer structure, other metal oxides with perovskite crystal, metal oxides with pyrochlore crystal, organic ferroelectric materials, other resin materials (polyimide, acrylic, epoxy, polypropylene, polyester, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polylactic acid, etc.) Below is a list of materials that can be used for the channel formation film 4. Of course, the materials are not limited to the following list. In-O, In-Sn-O, In-Zn-O, In-Sn-Zn-O, In-Ga-Zn-O, In-Ga-O, Ga-O, Zn-O, Al-Zn-O, Sn-O, Ti-O based n-type oxide semiconductors Cu-O, Sn-O, Zn-O based p-type oxide semiconductors Cu-Sn-I amorphous p-type oxide semiconductor ·Si semiconductors such as n-type Si, p-type Si, and SiC -Nitride semiconductors such as GaN Graphene, a two-dimensional conductive material based on transition metal chalcogenides ·Perovskite-type conductive materials such as LaNiO3, BaSnO3, SrTiO3 The variable capacitance elements 100, 200, 300, etc. described above can be applied to various circuit devices. The circuit devices include circuit wiring and the variable capacitance elements 100, 200, 300 described above that are electrically connected to the circuit wiring. For example, the variable capacitance elements 100, 200, 300 described above can be applied to circuit devices such as LLC resonant converters, communication circuits provided in wireless communication terminals, and hybrid switch circuits used in DC circuit breakers.

[0123] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0124] 1 semiconductor substrate, 2 gate electrode, 2a control electrode terminal, 3 gate insulating film, 3a, 7 dielectric layer, 4 channel forming film, 5 source electrode, 5a, 22 terminal electrode, 6 drain electrode, 10 switch portion, 20, 40 element portion, 41, 42 coil electrodes, 100, 200, 300, 500 variable capacitance element, 400 variable inductance element.

Claims

1. A switch portion constituting a field effect transistor; an element portion electrically connected to the switch portion and constituting a passive element; The switch unit is A source electrode; A drain electrode; a channel forming film formed so as to overlap at least a part of the source electrode and a part of the drain electrode; a gate insulating film formed on the channel forming film; a gate electrode formed on the gate insulating film, The element portion is a first terminal electrode electrically connected to the source electrode; a second terminal electrode sandwiching a dielectric layer therebetween or in contact with the dielectric layer to form the passive element between itself and a part of the drain electrode; the dielectric layer and the gate insulating film are the same insulating film, the dielectric layer includes at least a first dielectric layer formed of the same insulating film as the gate insulating film, and a second dielectric layer; The element portion is an electronic element comprising a plurality of layers of the passive element, the passive element being configured by sequentially stacking a portion of the drain electrode, the first dielectric layer, the second terminal electrode, the second dielectric layer, and a portion of the drain electrode.

2. The electronic device according to claim 1 , wherein the switch portion and the element portion are disposed horizontally with respect to a substrate.

3. a portion of the drain electrode is formed on a surface of the dielectric layer on the same side as a surface of the gate insulating film on which the gate electrode is formed; 3. The electronic element according to claim 1, wherein the second terminal electrode is formed on a surface of the dielectric layer opposite to a surface of the gate insulating film on which the gate electrode is formed.

4. the second terminal electrode is formed on a surface of the dielectric layer on the same side as a surface of the gate insulating film on which the gate electrode is formed, 3. The electronic device according to claim 1, wherein a portion of said drain electrode is formed on a surface of said dielectric layer opposite to a surface of said gate insulating film on which said gate electrode is formed.

5. The electronic device according to claim 1 or 2, wherein a portion of the second dielectric layer covers the channel-forming film between the source electrode and the drain electrode.

6. The electronic element according to claim 1 , wherein a portion of the second terminal electrode faces a portion of the source electrode with the first dielectric layer interposed therebetween.

7. The electronic element according to claim 1 , wherein a portion of the second terminal electrode faces a portion of the source electrode with the second dielectric layer interposed therebetween.

8. The electronic element according to claim 7 , wherein a portion of the second terminal electrode faces the channel formation film with the second dielectric layer interposed therebetween.

9. 3. The electronic element according to claim 1, wherein the passive element is any one of a capacitor formed by sandwiching the dielectric layer between a portion of the drain electrode and the second terminal electrode, an inductor formed by a coil electrode connecting the portion of the drain electrode and the second terminal electrode, and a resistor formed by a resistive element connecting the portion of the drain electrode and the second terminal electrode.

10. The passive element is an inductor, 3. The electronic element according to claim 1, wherein the first terminal electrode and the second terminal electrode are connected by a wiring.

11. A switch section constituting a field effect transistor; an element portion electrically connected to the switch portion and constituting a passive element; The switch unit is A source electrode; A drain electrode; a channel forming film formed so as to overlap at least a part of the source electrode and a part of the drain electrode; a gate insulating film formed on the channel forming film; a gate electrode formed on the gate insulating film, The element portion is a first terminal electrode electrically connected to the source electrode; a second terminal electrode sandwiching a dielectric layer therebetween or in contact with the dielectric layer to form the passive element between itself and a part of the drain electrode; the dielectric layer and the gate insulating film are the same insulating film, The passive element is an inductor, the first terminal electrode, the drain electrode, and the second terminal electrode are formed on a surface of the dielectric layer opposite to a surface of the gate insulating film on which the gate electrode is formed.

12. A switch section constituting a field effect transistor; an element portion electrically connected to the switch portion and constituting a passive element; The switch unit is A source electrode; A drain electrode; a channel forming film formed so as to overlap at least a part of the source electrode and a part of the drain electrode; a gate insulating film formed on the channel forming film; a gate electrode formed on the gate insulating film, The element portion is a first terminal electrode electrically connected to the source electrode; a second terminal electrode sandwiching a dielectric layer therebetween or in contact with the dielectric layer to form the passive element between itself and a part of the drain electrode; the dielectric layer and the gate insulating film are the same insulating film, the switch section and the element section are disposed horizontally with respect to a substrate, The dielectric layer is laminated on the substrate in three or more layers, The switch portion uses the uppermost layer of the dielectric layer as the gate insulating film, The element portion is an electronic element, the passive element being configured using a layer other than the dielectric layer used in the gate insulating film.

13. Circuit wiring, A circuit device comprising: the electronic element according to claim 1 , which is electrically connected to the circuit wiring.

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