Variable electronic component and circuit arrangement

Abstract

A variable capacitance element (100) includes a switching section (10) configured as a field effect transistor, and an element section (20) electrically connected to the switching section (10) and configured as a capacitor (passive element). The element section (20) includes a terminal electrode (5a) (first terminal electrode) electrically connected to a source electrode (5), and a terminal electrode (22) (second terminal electrode) configured as a first capacitor (first passive element) between the source electrode (5) and a drain electrode (6), and configured as a second capacitor (second passive element) at least between the drain electrode (6).

Description

TECHNICAL FIELD

[0001] The present application relates to a variable electronic element that makes a physical quantity of a passive element variable, and a circuit device provided with the variable electronic element. BACKGROUND

[0002] In recent years, a variable capacitance element that can make a capacitance (a capacitor) variable has been developed. As a method of making the capacitance variable, a variable capacitance element that uses a microfabrication technique to provide a plate-shaped movable comb electrode and a plate-shaped fixed comb electrode, in which the fixed comb electrode is provided to face the movable comb electrode with a minute gap therebetween, is disclosed in Patent Literature 1.

[0003] Further, as a method of making the capacitance variable, a two-terminal variable capacitance element that utilizes ON / OFF operation of a FET (Field Effect Transistor) is disclosed in Non-Patent Literature 1. In this variable capacitance element, by applying a voltage to a gate electrode by being set to an ON state, electrons of a channel region are accumulated at an interface due to + polarization of a gate insulating film (a dielectric) as an electrode, and thus an electrode area on a source electrode side is expanded to the same area as the gate electrode. Therefore, a capacitance generated between the source electrode and the gate electrode becomes large.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2002-373829

[0007] NON-PATENT LITERATURE

[0008] Non-Patent Literature 1: Tokumitsu Eisuke, Kikuchi Kazuya, "Evaluation of Channel Modulation in In2O3 / (Bi,La)4Ti3O12 Ferroelectric-Gate Thin Film Transistors by Capacitance-Voltage Measurements", Ferroelectrics, 429, p. 15-21, Jun 2012 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, in the variable capacitance element disclosed in Patent Literature 1, the range of the variable capacitance is as small as at most several times the capacitance before the variable operation, and the range of the variable capacitance is not sufficient for use in a communication system, a power supply circuit, or the like that requires a wideband with a large modulation frequency.

[0011] Further, in the variable capacitance element disclosed in Non-Patent Literature 1, if the thickness of the gate insulating film (dielectric) is made thick in order to improve the withstand voltage, the capacitance value is inversely proportional to the thickness. Furthermore, in the variable capacitance element disclosed in Non-Patent Literature 1, if the thickness of the gate insulating film (dielectric) is made thick, the control voltage applied to the gate electrode is proportional to the thickness, and thus the power consumption increases.

[0012] Therefore, an object of the present application is to provide a variable electronic element and a circuit device capable of widening the range of a physical quantity (for example, a variable capacitance) of a passive element that can be varied and obtaining a sufficient withstand voltage without reducing the physical quantity of the passive element.

[0013] Technical Solution for Solving the Problem

[0014] A variable electronic element according to one embodiment of the present disclosure includes a switching section that constitutes a field effect transistor, and an element section that is electrically connected to the switching section and constitutes a passive element. The switching section includes a source electrode, a drain electrode, a channel formation film formed to overlap at least a part of the source electrode and a part of the drain electrode, a gate insulating film formed to overlap the channel formation film, and a gate electrode formed to overlap the gate insulating film. The element section includes a first terminal electrode electrically connected to the source electrode, and a second terminal electrode that constitutes a first passive element between the source electrode and the drain electrode and constitutes a second passive element between at least the drain electrode.

[0015] A circuit device according to one embodiment of the present disclosure includes a circuit wiring and the above-described variable electronic element electrically connected to the circuit wiring.

[0016] Effects of the Invention

[0017] According to the present disclosure, the first passive element is constituted between the source electrode and the second terminal electrode, and the second passive element is constituted between the drain electrode and the second terminal electrode, and thus the range of the physical quantity of the passive element that can be varied can be widened, and a sufficient withstand voltage can be obtained without reducing the physical quantity of the passive element. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a cross-sectional view for explaining the structure of the variable capacitance element according to Embodiment 1.

[0019] Figure 2is a plan view for explaining a structure of the variable capacitance element according to Embodiment 1.

[0020] Figure 3 is a circuit diagram of the variable capacitance element according to Embodiment 1.

[0021] Figure 4 is a graph for explaining a variable capacitance range of the variable capacitance element according to Embodiment 1.

[0022] Figure 5 is a sectional view for explaining a manufacturing method of the variable capacitance element according to Embodiment 1.

[0023] Figure 6 is a circuit diagram of the multi-valued variable capacitance element according to Embodiment 1.

[0024] Figure 7 is a sectional view for explaining a structure of the variable capacitance element according to the modification of Embodiment 1.

[0025] Figure 8 is a sectional view for explaining a structure of the variable inductance element according to Embodiment 2.

[0026] Figure 9 is a circuit diagram of the variable inductance element according to Embodiment 2.

[0027] Figure 10 is a circuit diagram of the circuit device according to Embodiment 3.

[0028] Figure 11 is a graph for explaining a frequency characteristic of the circuit device according to Embodiment 3.

[0029] Figure 12 is a block diagram of the circuit device according to Embodiment 4.

[0030] Figure 13 is a timing chart showing timing of a switch of the circuit device according to Embodiment 4.

[0031] Figure 14 is a block diagram of the circuit device according to Embodiment 5.

[0032] Figure 15 is a circuit diagram of the circuit device according to Embodiment 6.

[0033] Figure 16 is a graph for explaining a switching characteristic of the circuit device according to Embodiment 6.

[0034] Figure 17 is a sectional view for explaining a structure of the variable capacitance element according to Embodiment 7.

[0035] Figure 18 is a plan view for explaining the structure of the variable capacitance element involved in Embodiment 7.

[0036] Figure 19 is a sectional view for explaining the structure of the variable capacitance element involved in Embodiment 8.

[0037] Figure 20 is a plan view for explaining the structure of the variable capacitance element involved in Embodiment 8.

[0038] Figure 21 is a sectional view for explaining the structure of the variable capacitance element involved in the modification of Embodiment 8.

[0039] Figure 22 is a sectional view for explaining the structure of the variable capacitance element involved in the modification.

[0040] Figure 23 is a graph for explaining the relationship between the capacitance and the holding voltage of the variable capacitance element.

[0041] Figure 24 is a graph for explaining the relationship between the capacitance and the holding time of the variable capacitance element. DETAILED DESCRIPTION

[0042] Hereinafter, a variable electronic element involved in an embodiment of the present application will be explained in detail with reference to the drawings. The variable electronic element is an element capable of making a physical quantity of a passive element included therein variable, and among the passive elements included therein, there are a capacitor, an inductor, a resistor, and the like. In addition, the same reference numerals in the drawings indicate the same or corresponding parts.

[0043] (Embodiment 1)

[0044] In Embodiment 1, the passive element included is a capacitor, and a variable capacitance element capable of making the capacitance variable will be explained with reference to the drawings. Figure 1 is a sectional view for explaining the structure of the variable capacitance element 100 involved in Embodiment 1. Figure 2 is a plan view for explaining the structure of the variable capacitance element 100 involved in Embodiment 1. Figure 3 is a circuit diagram of the variable capacitance element 100 involved in Embodiment 1.

[0045] Figure 1 The variable capacitance element 100 shown includes a switch section 10 constituting a field effect transistor formed on a semiconductor substrate 1, and an element section 20 electrically connected to the switch section 10 and constituting a passive element. The element section 20 is provided at the upper portion of the switch section 10.

[0046] 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, the gate electrode 2, the gate insulating film 3, the channel forming film 4, the source electrode 5, and the drain electrode 6 are sequentially stacked on the semiconductor substrate 1.Figure 1 In the illustrated switch section 10, a gate electrode 2 is formed on a semiconductor substrate 1, a gate insulating film 3 and a channel forming film 4 are sequentially formed so as to overlap the gate electrode 2, and a source electrode 5 and a drain electrode 6 are formed on them, respectively.

[0047] More specifically, the switch section 10 is an oxide FET (Field Effect Transistor). As the semiconductor substrate 1, for example, lanthanum aluminate (LAO) is used, on which platinum (Pt) is used to form a given pattern. Figure 2 The gate electrode 2 is formed in a given pattern as illustrated. As the gate insulating film 3, for example, a La-HfO2 film having a film thickness of 70 nm is used, and as the channel forming film 4, for example, an IZO film having a film thickness of 25 nm is used. On the channel forming film 4 of the IZO film, platinum (Pt) is used to form a given pattern. Figure 2 The source electrode 5 and the drain electrode 6 are formed in a given pattern as illustrated. In addition, although a terminal electrode 5a (first terminal electrode) is provided on the source electrode 5 as illustrated, Figure 2 The source electrode 5 and the drain electrode 6 are formed in a given pattern as illustrated. In addition, although a terminal electrode 5a (first terminal electrode) is provided on the source electrode 5 as illustrated,

[0048] The element section 20 is provided on the upper portion of the switch section 10, and includes an Al2O3 film as a dielectric 21 and a terminal electrode 22 (second terminal electrode) of platinum (Pt) formed so as to overlap the dielectric 21. The terminal electrode 22 is formed in a given pattern as illustrated. In addition, as illustrated, Figure 2 The terminal electrode 22 is formed in a given pattern as illustrated. In addition, as illustrated, Figure 2 The gate electrode 2 is drawn out from a region in which the source electrode 5 and the drain electrode 6 overlap, and a control electrode terminal 2a is provided on the gate electrode 2 as illustrated.

[0049] The element section 20 constitutes a first capacitor (first passive element) between the source electrode 5 and the terminal electrode 22, and constitutes a second capacitor (second passive element) at least between the drain electrode 6 and the terminal electrode 22. As illustrated, Figure 2 The first capacitor is a portion Cl in which the source electrode 5 and the terminal electrode 22 overlap in plan view. The second capacitor is a portion C2 in which the drain electrode 6 including the channel forming film 4 and the terminal electrode 22 overlap in plan view.

[0050] In the case where the variable capacitance element 100 is in the off state of the switch section 10, no gate voltage of the threshold value or more is applied to the gate electrode 2, and thus an electron depletion layer exists in the position of the channel forming film 4 overlapping the gate electrode 2 in plan view, and the source electrode 5 and the drain electrode 6 are not conductive. Thus, the variable capacitance element 100 applies a voltage only between the portion of the source electrode 5 and the terminal electrode 22 opposing the source electrode 5, and thus becomes the capacitance of only the first capacitor.

[0051] However, when the switching section 10 is in the ON state, the variable capacitor element 100 forms a channel by applying a gate voltage above a threshold value to the gate electrode 2, thereby turning on the source electrode 5 and the drain electrode 6. Therefore, the variable capacitor element 100 applies a voltage between the source electrode 5 and the drain electrode 6 (including the channel forming film 4 therebetween) and the opposite terminal electrode 22, thus becoming a combined capacitor of the first capacitor and the second capacitor.

[0052] In other words, in the variable capacitor element 100, by turning the switch section 10 on / off, the capacitance of the capacitor can be changed between the case where the first capacitor element is used as the element section 20 and the case where both the first capacitor and the second capacitor element are used as the element section 20. The variable capacitor element 100 consists of a switch section 10 that turns on / off based on the voltage applied to the gate electrode 2 (control electrode terminal 2a), and an element section 20 that operates via terminal electrode 5a (first terminal electrode) and terminal electrode 22 (second terminal electrode), making it a variable capacitor element that operates through three terminals. Therefore, the structure of the variable capacitor element 100 differs from the variable capacitor element disclosed in Non-Patent Document 1, which allows capacitance to be changed via only two terminals: the gate electrode and the source electrode.

[0053] Furthermore, in the switching section 10, from the viewpoint of power consumption, the gate insulating film 3 is preferably made thinner. By making the film thickness thinner, the withstand voltage decreases, but the driving voltage decreases, thus enabling low-voltage driving. Therefore, in the variable capacitor element 100, by utilizing the electrically separated structure of the gate electrode 2 and the element section 20 of the switching section 10, the thickness of the gate insulating film 3 is made thinner to achieve low-voltage driving and low withstand voltage. In addition, by making the dielectric 21 a thick film and making the dielectric 21 a multilayer structure, a large capacitance can be achieved, thus balancing high withstand voltage and large capacitance.

[0054] Furthermore, in the variable capacitor element 100, the gate electrode 2 (control electrode terminal 2a) of the switching section 10 and the terminal electrode 5a (first terminal electrode) and terminal electrode 22 (second terminal electrode) of the element section 20 are electrically separated, so the signal from the element section 20 side will not affect the operation of the switching section 10. Figure 3 As shown in the circuit diagram, terminal electrode 5a (first terminal electrode) and terminal electrode 22a (second terminal electrode) of the variable capacitor element 100 are connected to the converter circuit, etc. On the other hand, the control electrode terminal 2a used to make the capacitance variable is connected to a circuit different from the converter circuit. Therefore, the signal applied to the control electrode terminal 2a is less likely to be affected by the signal of the converter circuit.

[0055] Further, in the variable capacitance element 100, by shortening the channel length L of the switching section 10, it is possible to reduce the resistance of the channel formation film 4 between the source electrode 5 and the drain electrode 6. Therefore, in the variable capacitance element 100, in order to make the capacitance variable at high speed, it is possible to cope with by improving the switching speed (time constant) of the switching section 10.

[0056] Next, the range of the capacitance variable by the variable capacitance element 100 will be described. Figure 4 is a graph for explaining the range of the variable capacitance of the variable capacitance element 100 related to Embodiment 1. As described above, the range of the capacitance variable by the variable capacitance element 100 depends on the capacitance of the second capacitor. That is, the wider the portion C2 in which the drain electrode 6 and the terminal electrode 22 overlap in plan view becomes, the larger the capacitance of the second capacitor becomes, and the wider the range of the capacitance variable by the variable capacitance element 100 can become.

[0057] In Figure 4 the graph, the measured value of the variable capacitance element 100 in which the area of the portion C2 in which the drain electrode 6 and the terminal electrode 22 overlap in plan view is set to 1000 times (area ratio is 1000 times) the area of the portion Cl in which the source electrode 5 and the terminal electrode 22 overlap in plan view. In addition, in Figure 4 , the horizontal axis is set to the applied voltage (unit: V) of the gate electrode 2, and the vertical axis is set to the capacitance (unit: pF) of the variable capacitance element 100.

[0058] If the variable capacitance element 100 designed so that only the capacitance of the first capacitor becomes 0.048 pF and the capacitances of the first capacitor and the second capacitor become 48 pF is measured, as in Figure 4 , the capacitance in the case where the applied voltage of the gate electrode 2 is less than the threshold value becomes 0.052 pF, and the capacitance in the case where the applied voltage of the gate electrode 2 is equal to or more than the threshold value becomes 41 pF. In the variable capacitance element 100, the modulation ratio of the capacitance is 41 / 0.052 = 788.5, and becomes approximately 800 times.

[0059] Next, the manufacturing method of the variable capacitance element 100 will be described using a graph. Figure 5 is a cross-sectional view for explaining the manufacturing method of the variable capacitance element related to Embodiment 1. First, in Figure 5 (a) of FIG. 10, the gate electrode 2 of platinum (Pt) having a film thickness of 80 nm is formed on the (100) surface of the prepared semiconductor substrate 1 of lanthanum aluminate (LAO). Specifically, the gate electrode 2 is formed by forming a given pattern of a photoresist on the (100) surface of the semiconductor substrate 1 using a photolithography technique, then forming a film of platinum (Pt) by high-frequency (RF) sputtering, and removing the photoresist by peeling.

[0060] In Figure 5 (b) of the above, a gate insulating film 3 having a film thickness of 70 nm is formed so as to overlap the face of the semiconductor substrate 1 in which the gate electrode 2 is formed. Specifically, the gate insulating film 3 is formed by spin-coating a La-Hf02solution on the face of the semiconductor substrate 1 in which the gate electrode 2 is formed using a chemical solution deposition method (CSD), and performing film formation, drying it at 150°C, and then performing crystallization by firing at 800°C in an oxygen atmosphere.

[0061] In Figure 5 (c) of the above, a channel formation film 4 having a film thickness of 25 nm is formed so as to overlap the gate insulating film 3. Specifically, the channel formation film 4 is formed by spin-coating an IZO solution on the gate insulating film 3 using a chemical solution deposition method (CSD), and performing film formation, drying it at 150°C, and then performing crystallization by firing at 500°C in an oxygen atmosphere.

[0062] In Figure 5 (d) of the above, a source electrode 5 and a drain electrode 6 of platinum (Pt) having a film thickness of 80 nm are formed on the channel formation film 4. Specifically, the source electrode 5 and the drain electrode 6 are formed by forming a photoresist of a given pattern on the channel formation film 4 using a photolithography technique, then performing film formation of platinum (Pt) by high-frequency (RF) sputtering, and removing the photoresist by peeling.

[0063] In Figure 5 (e) of the above, a dielectric 21 of Al203film having a film thickness of 500 nm is formed on the source electrode 5 and the drain electrode 6. Specifically, the dielectric 21 is formed by forming a photoresist of a given pattern on the source electrode 5 and the drain electrode 6 using a photolithography technique, then performing film formation of Al203film by ECR (Electron Cyclotron Resonance) sputtering, and removing the photoresist by peeling.

[0064] In Figure 5 (f) of the above, a terminal electrode 22 of platinum (Pt) having a film thickness of 80 nm is formed on the dielectric 21. Specifically, the terminal electrode 22 is formed by forming a photoresist of a given pattern on the dielectric 21 using a photolithography technique, then performing film formation of platinum (Pt) by high-frequency (RF) sputtering, and removing the photoresist by peeling.

[0065] As for the variable capacitance element 100 explained so far, an element whose capacitance is variable by two values of the capacitance of only the first capacitor and the combined capacitance of the first capacitor and the second capacitor has been explained. However, by forming a plurality of variable capacitance elements 100 in a matrix shape on the semiconductor substrate 1, a variable capacitance element whose capacitance is multi-valued can be constituted. Figure 6 is a circuit diagram of a multi-valued variable capacitance element 100a to which Embodiment 1 relates. Also, by forming a plurality of variable electronic elements including passive elements other than capacitors, such as inductors and resistors, in a matrix shape, a multi-valued variable electronic element can likewise be constituted.

[0066] In Figure 6 , a circuit diagram of a variable capacitance element 100a in which n x n of the variable capacitance elements 100 shown in Figure 3 are connected in a matrix shape is illustrated. In the variable capacitance element 100a shown in Figure 6 , the terminal 22a of the terminal electrode 5a (first terminal electrode) and the terminal electrode 22 (second terminal electrode) is common to the n x n variable capacitance elements 100. However, the control electrode terminal 2a of each of the n x n variable capacitance elements 100 is respectively provided, and in Figure 6 , terminals G11 to Gnn are illustrated. By supplying a signal to these terminals G11 to Gnn, the desired number of variable capacitance elements 100 can be set to an on state to obtain a desired capacitance, and thus the variable capacitance element 100a can multi-value the variable capacitance.

[0067] Further, in the variable capacitance element 100, the structure in which the element portion 20 is provided above the switch portion 10 as shown in Figure 1 , but the element portion 20 can also be provided below the switch portion 10. Specifically, a variable capacitance element in which the element portion 20 is provided below the switch portion 10 is explained. Figure 7 is a cross-sectional view for explaining the structure of a variable capacitance element 100b, 100c to which a modification of Embodiment 1 relates. Also, in Figure 7 , the same reference numerals are attached to the same structures as the variable capacitance element 100 shown in Figure 1 , and detailed explanations are not repeated.

[0068] Figure 7The (a) is a variable capacitance element 100b in which a multi-layer ceramic capacitor (MLCC: multi-layer ceramic capacitor) is used for the element portion 20b. In the variable capacitance element 100b, the source electrode 5 and the drain electrode 6 are formed on the upper surface of the multi-layer ceramic capacitor of the element portion 20b, and the channel formation film 4, the gate insulating film 3, and the gate electrode 2 are sequentially formed thereon to constitute the switching portion 10.

[0069] In the multi-layer ceramic capacitor of the element portion 20b, a portion of a first capacitor connected to the source electrode 5 and a portion of a second capacitor connected to the drain electrode 6 are included. The portion of the first capacitor is a structure in which the electrode 25b connected to the source electrode 5 and the electrode 24b connected to the terminal electrode 22b which is an external electrode of the multi-layer ceramic capacitor are sandwiched with a dielectric 21b such as barium titanate and stacked. Further, the portion of the second capacitor is a structure in which the electrode 23b connected to the drain electrode 6 and the electrode 24b connected to the terminal electrode 22b are sandwiched with the dielectric 21b and stacked.

[0070] The variable capacitance element 100b, like the variable capacitance element 100, in the case where the switching portion 10 is in the off state, no gate voltage above the threshold value is applied to the gate electrode 2, and thus an electron depletion layer exists at the position of the channel formation film 4 overlapping the gate electrode 2 in plan view, and the source electrode 5 and the drain electrode 6 are not conductive. Thus, the variable capacitance element 100b applies a voltage to the dielectric 21b between the electrode 25b connected to the source electrode 5 and the electrode 24b connected to the terminal electrode 22b, and thus becomes the capacitance of only the first capacitor.

[0071] On the other hand, the variable capacitance element 100b, in the case where the switching portion 10 is in the on state, forms a channel by applying a gate voltage above the threshold value to the gate electrode 2, and the source electrode 5 and the drain electrode 6 are conductive. Thus, the variable capacitance element 100b applies a voltage to the dielectric 21b between the electrode 25b connected to the source electrode 5 and the electrode 23b connected to the drain electrode 6 and the electrode 24b connected to the terminal electrode 22b, and thus becomes the combined capacitance of the first capacitor and the second capacitor.

[0072] As for the portion of the multi-layer ceramic capacitor of the element portion 20b, various structures such as LTCC (Low Temperature Co-fired Ceramics), HTCC (High Temperature Co-Fired Ceramics), and the like can be applied.

[0073] Figure 7(b) is a variable capacitance element 100c in which a silicon capacitor is used for the element portion 20c. In the variable capacitance element 100c, the source electrode 5 and the drain electrode 6 are formed on the upper surface of the silicon capacitor of the element portion 20c, and the channel formation film 4, the gate insulating film 3, and the gate electrode 2 are sequentially formed thereon to constitute the switching portion 10.

[0074] The silicon capacitor of the element portion 20c is formed by a semiconductor process, and includes an N+ layer 24c formed by implanting n-type impurity ions into the silicon substrate la, a dielectric 21c formed on the surface of the N+ layer 24c, and a polysilicon layer 25c connected to the source electrode 5 or a polysilicon layer 23c connected to the drain electrode 6 formed on the surface of the dielectric 21c. The dielectric 21c includes an inorganic material such as silicon oxide, silicon nitride, hafnium oxide, hafnium silicate, aluminum oxide, barium titanate, or the like formed by a CVD (Chemical Vapor Deposition) method or the like. In addition, a plurality of grooves or a plurality of columns are formed in the silicon substrate la to have a convex-concave shape.

[0075] In the silicon capacitor of the element portion 20c, a portion of a first capacitor connected to the source electrode 5 and a portion of a second capacitor connected to the drain electrode 6 are included. The portion of the first capacitor includes a portion of the dielectric 21c interposed between the polysilicon layer 25c connected to the source electrode 5 and the N+ layer 24c connected to the terminal electrode 22c. Further, the portion of the second capacitor includes a portion of the dielectric 21c interposed between the polysilicon layer 23c connected to the drain electrode 6 and the N+ layer 24c connected to the terminal electrode 22c.

[0076] The variable capacitance element 100c, like the variable capacitance element 100, in the case where the switching portion 10 is in the off state, no gate voltage above the threshold value is applied to the gate electrode 2, and thus an electron depletion layer exists at the position of the channel formation film 4 overlapping the gate electrode 2 in plan view, and the source electrode 5 and the drain electrode 6 are not conductive. Thus, the variable capacitance element 100c applies a voltage only to the portion of the dielectric 21c interposed between the polysilicon layer 25c connected to the source electrode 5 and the N+ layer 24c connected to the terminal electrode 22c, and thus becomes the capacitance of only the first capacitor.

[0077] On the other hand, the variable capacitance element 100c in the case where the switching portion 10 is in the on state, a channel is formed by applying a gate voltage above the threshold value to the gate electrode 2, and the source electrode 5 and the drain electrode 6 are conductive. Thus, the variable capacitance element 100c applies a voltage to the portions of the dielectric 21c interposed between the polysilicon layer 25c connected to the source electrode 5 and the polysilicon layer 23c connected to the drain electrode 6 and the N+ layer 24c connected to the terminal electrode 22c, and thus becomes the combined capacitance of the first capacitor and the second capacitor.

[0078] Further, in the silicon capacitor of the element portion 20c, the capacitance of the element portion 20c is increased by providing the convex-concave shaped portion in the silicon substrate la, but the dielectric 21c can also be in a parallel-plate shape as long as the required capacitance can be ensured.

[0079] As described above, the variable capacitance element 100 according to Embodiment 1 includes the switching portion 10 that constitutes a field effect transistor, and the element portion 20 that is electrically connected to the switching portion 10 and constitutes a capacitor (passive element). The switching portion 10 has a source electrode 5, a drain electrode 6, a channel formation film 4 that is formed so as to at least overlap with a part of the source electrode 5 and a part of the drain electrode 6, a gate insulating film 3 that is formed so as to overlap with the channel formation film 4, and a gate electrode 2 that is formed so as to overlap with the gate insulating film 3. The element portion 20 has a terminal electrode 5a (first terminal electrode) that is electrically connected to the source electrode 5, and a terminal electrode 22 (second terminal electrode) that constitutes a first capacitor (first passive element) between the source electrode 5 and the terminal electrode 22 and constitutes a second capacitor (second passive element) at least between the drain electrode 6 and the terminal electrode 22. Thus, the variable capacitance element 100 can make the capacitance of the capacitor variable by switching between a case where the element portion 20 is constituted by the first capacitor and a case where the element portion 20 is constituted by the first capacitor and the second capacitor by causing the switching portion 10 to perform on / off operation. Further, the switching portion 10 is preferably provided in an upper portion or a lower portion of the element portion 20.

[0080] Thus, the variable capacitance element 100 according to Embodiment 1 can widen the range in which the capacitance of the capacitor can be made variable and can obtain sufficient withstand voltage without reducing the capacitance of the capacitor by constituting the first capacitor between the source electrode 5 and the terminal electrode 22 and constituting the second capacitor between the drain electrode 6 and the terminal electrode 22.

[0081] Further, preferably, the element portion 20 further has a dielectric 21 that is provided so as to overlap with the source electrode 5 and the drain electrode 6, the first capacitor that constitutes the first passive element is constituted by the dielectric 21 between the source electrode 5 and the terminal electrode 22, and the second capacitor that constitutes the second passive element is constituted by at least the dielectric 21 between the drain electrode 6 and the terminal electrode 22.

[0082] Further, preferably, the gate electrode 2 is formed on the semiconductor substrate 1, the gate insulating film 3 is formed on the gate electrode 2 and the semiconductor substrate 1, the channel formation film 4 is formed on the gate insulating film 3, the source electrode 5 and the drain electrode 6 are formed on the channel formation film 4, the dielectric 21 is formed on the source electrode 5 and the drain electrode 6, and the terminal electrode 22 is formed on the dielectric 21.

[0083] (Embodiment 2)

[0084] As for the variable electronic element related to Embodiment 1, the variable capacitance element in which a passive element included is a capacitor and in which the capacitance is variable has been described, but the passive element included is not limited to a capacitor. As for the variable inductance element related to Embodiment 2, a variable inductance element in which a passive element included is an inductor and in which the inductance is variable will be described with reference to the drawings. Figure 8 is a sectional view for illustrating the structure of the variable inductance element 200 related to Embodiment 2. Figure 9 is a circuit diagram of the variable inductance element 200 related to Embodiment 2. In addition, in the variable inductance element 200 shown in Figure 8 , Figure 9 , the same reference numerals are attached to the same structures as those of the variable capacitance element 100 shown in Figure 1 , Figure 3 , and detailed description will not be repeated.

[0085] Figure 8 The variable inductance element 200 shown in

[0086] 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 Figure 8 , the source electrode 5 and the drain electrode 6 are formed on the upper surface of the element section 20A, and the switch section 10 is constituted by sequentially forming the channel formation film 4, the gate insulating film 3, and the gate electrode 2 thereon.

[0087] As shown in Figure 8 , in the variable inductance element 200, the element section 20A is an inductor, and includes a portion of a first inductor connected to the source electrode 5 and a portion of a second inductor connected to the drain electrode 6. The portion of the first inductor includes a coil electrode 23 connected to the source electrode 5 and a terminal electrode 22A which is an external electrode of the inductor. The portion of the second inductor includes a coil electrode 24 connected to the drain electrode 6 and the terminal electrode 22A which is the external electrode of the inductor. The coil electrode 23 and the coil electrode 24 are formed in the same non-magnetic ceramic 25. In addition, as shown in Figure 8 , the terminal electrode 5a (first terminal electrode) is provided on the source electrode 5, but the source electrode 5 itself can be used as the terminal electrode 5a. Furthermore, as shown in Figure 8 , the control electrode terminal 2a is provided on the gate electrode 2, but the gate electrode 2 itself can be used as the control electrode terminal 2a. Furthermore, as shown in Figure 8The terminal electrode 22A is provided with a terminal 22a of the terminal electrode 22A as illustrated, but the terminal electrode 22A itself can be used as the terminal 22a.

[0088] The variable inductance element 200, like the variable capacitance element 100, in the case where the switch section 10 is in the off state, the gate electrode 2 is not applied with a gate voltage above the threshold value, and thus there is an electron depletion layer at the position of the channel formation film 4 overlapping the gate electrode 2 in plan view, the source electrode 5 and the drain electrode 6 are not conductive. Thus, the variable inductance element 200 has a current flow only through the coil electrode 24 between the source electrode 5 and the terminal electrode 22A, and thus becomes the inductance of only the first inductor.

[0089] On the other hand, the variable inductance element 200, in the case where the switch section 10 is in the on state, by applying a gate voltage above the threshold value to the gate electrode 2, a channel is formed, and the source electrode 5 and the drain electrode 6 are conductive. Thus, the variable inductance element 200 has a current flow through the coil electrode 23 between the source electrode 5 and the terminal electrode 22A, and the coil electrode 24 between the drain electrode 6 and the terminal electrode 22A, and thus becomes the combined inductance of the first inductor and the second inductor.

[0090] According to Figure 9 As is also understood from the circuit diagram illustrated, the terminal 22a of the terminal electrode 5a (first terminal electrode) and the terminal electrode 22A (second terminal electrode) of the variable inductance element 200 is connected to a converter circuit or the like, and on the other hand, the control electrode terminal 2a for making the inductance variable is connected to a circuit different from the converter circuit. Thus, the possibility that the signal applied to the control electrode terminal 2a is affected by the signal of the converter circuit is low.

[0091] As above, in the variable inductance element 200 related to Embodiment 2, the passive element is an inductor, and the element section 20A has the first inductor electrically connected between the source electrode 5 and the terminal electrode 22A and becoming the first passive element, and the second inductor electrically connected between the drain electrode 6 and the terminal electrode 22A and becoming the second passive element.

[0092] Thus, the variable inductance element 200 related to Embodiment 2 configures the first inductor between the source electrode 5 and the terminal electrode 22A, and configures the second inductor between the drain electrode 6 and the terminal electrode 22A, and thus can widen the range in which the inductance of the inductor can be made variable, and can obtain sufficient voltage resistance without reducing the inductance of the inductor.

[0093] In addition, a plurality of variable inductance elements 200 can be formed in a matrix shape, thereby configuring a multi-valued variable inductance element. Furthermore, a plurality of variable inductance elements 200 can be formed in a matrix shape, thereby configuring a multi-valued variable inductance element. Figure 8The coil electrodes 23, 24 shown are changed to resistive elements, whereby the passive elements are provided as resistors to be variable resistor elements. Furthermore, the structure of the switching section 10 explained in Embodiment 1 and Embodiment 2 is not limited to the explained structure, and can be, for example, a silicon MOSFET, a GaN FET, or the like.

[0094] (Embodiment 3)

[0095] As explained in Embodiment 1 and Embodiment 2, the variable capacitance elements 100, 100a and the variable inductance element 200 have the following characteristics in their structures, that is, the amplitude of the physical quantity of the passive elements that can be varied can be widened, and sufficient withstand voltage can be obtained without reducing the physical quantity of the passive elements. Hereinafter, a circuit device including the variable capacitance elements 100, 100a, the variable inductance element 200 that utilize this characteristic will be explained.

[0096] Figure 10 is a circuit diagram of the circuit device to which Embodiment 3 relates. Figure 10 (b) of Figure 10 is an equivalent circuit of (a) of Figure 10 The circuit device 300 shown in (a) is a circuit that adjusts the output level according to load variation, and is an LLC resonant converter. The circuit device 300 as the LLC resonant converter can convert an input voltage Vin to an output voltage Vout. The circuit device 300 has switching elements Q1, Q2, a transformer T, a resonant capacitor Cr, leakage inductors Lr, Lr1, Lr2, an exciting inductor Lm, output rectifier diodes D1, D2, and an output capacitor Co. The output capacitor Co is connected to a load resistor Ro.

[0097] The input / output voltage ratio (|Vout / Vin|) of the circuit device 300 as the LLC resonant converter can be expressed as (Formula 1).

[0098] [Formula 1]

[0099] (Formula 1)

[0100] In addition, each variable of (Formula 1) can be expressed as (Formula 2) and (Formula 3).

[0101] [Formula 2]

[0102] (Formula 2)

[0103] [Formula 3]

[0104] (Formula 3)

[0105] According to Equation 1, the input-output voltage ratio of the LLC resonant converter can be adjusted by modulating the switching frequency f of the switching elements Q1 and Q2. Moreover, in the LLC resonant converter, it is usually operated above the frequency at which the input-output voltage ratio reaches its maximum value, and the switching frequency is changed according to the load variation, thereby adjusting the output voltage (Vout) of the LLC resonant converter.

[0106] For example, when reducing the output voltage (Vout), an LLC resonant converter needs to be set to a switching frequency higher than the frequency at which the input-output voltage ratio reaches its maximum. However, the power loss of an LLC resonant converter depends on the switching frequency; therefore, increasing the switching frequency to reduce the output voltage (Vout) of the LLC resonant converter will result in increased power loss.

[0107] Therefore, in the circuit device 300, in order to reduce the output voltage (Vout) of the LLC resonant converter without increasing the switching frequency, the variable capacitor element 100 of Embodiment 1 is used for the resonant capacitor Cr. By setting the resonant capacitor Cr as a variable capacitor element 100, the circuit device 300 is able to reduce the output voltage (Vout) without increasing the switching frequency.

[0108] Figure 11 This is a graph illustrating the frequency characteristics of the circuit device 300 according to Embodiment 3. Figure 11 In (a), the frequency characteristics of the input-output voltage ratio are shown when the capacitance is set to 1.5 times, 10 times, and 100 times that of the resonant capacitor Cr (e.g., 0.02 μF). Figure 11 (b) is Figure 11 An enlarged view of a portion of the curve in (a). Figure 11 (a) and Figure 11 In (b), the horizontal axis is set to the operating frequency (in Hz), and the vertical axis is set to the input-output voltage ratio.

[0109] exist Figure 11 (a) and Figure 11 In (b), the frequency response of the input-output voltage ratio when the capacitance of the resonant capacitor Cr is set to 100 times is curve A, and the frequency response when the capacitance of the resonant capacitor Cr is set to 10 times is curve B. Furthermore, in Figure 11 (a) and Figure 11 In (b), the frequency characteristic of the input-output voltage ratio when the capacitance of the resonant capacitor Cr is set to 1.5 times is curve C, and the characteristic when the capacitance of the resonant capacitor Cr is kept constant is curve D.

[0110] like Figure 10As shown in (b), curves A through D exhibit significant variations in the input-output voltage ratio at the same operating frequency (shown by the dashed line). Specifically, the input-output voltage ratio for curve D is |Vout / Vin| = 4.0, and for curve C it is |Vout / Vin| = 2.2. Furthermore, the input-output voltage ratio for curve B is |Vout / Vin| = 0.9, and for curve A it is |Vout / Vin| = 0.8. In other words, by varying the capacitance of the resonant capacitor Cr by a factor of 10, the input-output voltage ratio can be varied within the range of 4.0 to 0.9 without changing the operating frequency.

[0111] In this way, by using a variable capacitance element 100 for the resonant capacitor Cr of the circuit device 300, the output voltage (Vout) can be reduced without increasing power loss. In particular, by using a multi-valued variable capacitance element 100a for the resonant capacitor Cr of the circuit device 300, the capacitance of the resonant capacitor Cr can be dynamically varied, and the input-output voltage ratio can be changed in multiple stages.

[0112] (Implementation Method 4)

[0113] Next, the soft-switching control of the LLC resonant converter will be explained. The LLC resonant converter is as follows: Figure 12 The circuit structure shown uses an LC resonant circuit, which enables low-loss soft switching. In particular, by using a variable capacitance element 100 for the resonant capacitor Cr, for example, for switching amplifiers (PWM (Pulse Width Modulation) amplifiers, the switching losses can be significantly reduced by dynamically changing the capacitance of the resonant capacitor Cr.

[0114] Figure 12 This is a block diagram of the circuit device involved in Embodiment 4. Figure 13 The circuit shown is a switching amplifier, in which an LLC resonant converter is used in the D-stage output stage 301, with the resonant capacitor Cr set as a variable capacitance element 100. In the D-stage output stage 301, by dynamically changing the capacitance value of the resonant capacitor Cr (variable capacitance element 100), the capacitive impedance after the D-stage output stage 301 can be reduced, thereby achieving low-loss soft switching.

[0115] The diagrams are used to illustrate in detail the LLC resonant converter that achieves low-loss soft switching. Figure 13 This is a timing diagram showing the timing of the switches in the circuit device according to Embodiment 4. In a typical switch, such as... Figure 13 As shown in (a), the voltage VDS and current I D The switching occurs simultaneously, and the current I is lower than when the PWM is off. D The drop delay, therefore at voltage V DS and current I D The crossing section generates switching losses (P=IV). For example... Figure 13 The switch shown in (a) is called a hard switch.

[0116] On the other hand, in an LLC resonant converter, the voltage and current oscillate at the LC resonant frequency, thereby achieving... Figure 13 As shown in (b), it is possible to achieve a voltage V DS When the voltage is zero, the PWM is set to the ON state (ZVS: Zero Voltage Switching). Furthermore, in an LLC resonant converter, by oscillating the voltage and current at the LC resonant frequency, it is possible to control the current I... D When the current is zero, the PWM is set to the ON state (ZCS: Zero Current Switching). Therefore, in LLC resonant converters, switching losses can be reduced. This will be as follows... Figure 10 The switch shown in (b) is called a soft switch.

[0117] like Figure 14 The LLC resonant converter (circuit device 300) shown has two resonant frequencies: the resonant frequency fr of the resonant capacitor Cr and the leakage inductor Lr, and the resonant frequency fm of the resonant capacitor Cr, the leakage inductor Lr, and the magnetizing inductor Lm. In the circuit device 300, which is an LLC resonant converter, the condition for soft switching is determined by the relationship between the resonant frequencies fr and fm and the switching frequency f. For example, when the switching frequency f is smaller than the resonant frequency fm (f < fm), the circuit device 300 satisfies the condition for hard switching. However, this condition is not typically used because it results in gain inversion.

[0118] Furthermore, when the switching frequency f is greater than the resonant frequency fm but smaller than the resonant frequency fr (fm < f < fr), the circuit device 300 satisfies the soft-switching condition. Moreover, when the switching frequency f is equal to the resonant frequency fr (f = fr), the circuit device 300 satisfies the hard-switching condition. Furthermore, when the switching frequency f is greater than the resonant frequency fr (fr < f), the circuit device 300 satisfies the soft-switching condition.

[0119] In the circuit device 300, which serves as an LLC resonant converter, the conditions for the soft-switching state to be established vary depending on the load conditions and can be determined by the conditions shown in (Equation 4) and (Equation 5).

[0120] [Math. 4]

[0121] [Math. 4]

[0122] [Math. 5]

[0123] [Math. 5]

[0124] In a case where the condition of (Math. 4) is satisfied, the output rectifying diode D2 is not turned on, and thus the state of soft switching is established in the circuit device 300. On the other hand, in a case where the condition of (Math. 5) is satisfied, the output rectifying diode D2 is turned on, and thus the state of soft switching is not established in the circuit device 300.

[0125] For example, in a case where Vout is fixed, the condition in which soft switching is established changes due to a variation in Vin and a voltage Vcr of the resonance capacitor Cr, and thus a condition in which switching loss increases occurs in the circuit device 300. Here, the voltage Vcr varies depending on a load condition and a capacitance of the resonance capacitor Cr. Thus, in the circuit device 300, the capacitance is made variable by using the variable capacitance element 100 for the resonance capacitor Cr, and thus the condition in which soft switching is established can be controlled.

[0126] In the circuit device 300, the variable capacitance element 100 is used for the resonance capacitor Cr. As explained in Embodiment 1, the variable capacitance element 100 can make the capacitance variable to a large extent compared to a conventional variable capacitance element, and thus can cope with a large variation in input voltage Vin and a load condition.

[0127] As such, by using the variable capacitance element 100 for the resonance capacitor Cr of the circuit device 300, the capacitance of the resonance capacitor Cr can be made variable to a large extent, and the condition in which soft switching is established can be widely ensured. In particular, by using the multi-valued variable capacitance element 100a for the resonance capacitor Cr of the circuit device 300, the capacitance of the resonance capacitor Cr can be made variable dynamically, and the adjustment of the condition in which soft switching is established can be performed in multiple stages.

[0128] In addition, in addition to using the variable capacitance element 100 for the resonance capacitor Cr of the circuit device 300, the same effect can be obtained by using the variable inductance element explained in Embodiment 2 for the leakage inductor Lr and the magnetizing inductor Lm. Furthermore, the circuit device in which the resonance capacitor Cr or the like is made variable to be able to adjust the condition in which soft switching is established is not limited to the circuit device 300 which is an LLC resonant converter, and can be applied to circuit devices of various resonant modes such as a current resonant circuit, a voltage resonant circuit, a multiple resonant circuit, a series resonant circuit, a parallel resonant circuit, and the like.

[0129] (Embodiment 5)

[0130] Next, a circuit structure in which the variable capacitance element explained in Embodiment 1 and the variable inductance element explained in Embodiment 2 are applied to a wireless communication terminal of a multi-band is explained. Along with the spread of IoT (Internet of Things), in a wireless communication system, it is desirable to provide optimal communication characteristics according to each condition of a place of use, a time, an available frequency, a required signal transmission speed, and the like. For example, in order to communicate a large capacity and a high density of data, in a wireless communication system, it is required to utilize a very wide frequency band of several tens of MHz to 5 GHz in one wireless communication terminal.

[0131] Therefore, in a wireless communication terminal, it is necessary to provide a plurality of RF circuits corresponding to each frequency in order to require multi-banding, and to appropriately switch the used RF circuit. However, if a plurality of RF circuits are provided, the circuit scale and the number of parts of the wireless communication terminal increase, and miniaturization and cost reduction of the terminal become difficult.

[0132] Therefore, in a wireless communication terminal, it is necessary to share a circuit module for a plurality of frequencies to reduce the circuit scale and the number of parts. However, if the circuit module is shared for a plurality of frequencies, it is necessary to suppress signal reflection between the circuit modules, and to achieve impedance matching according to each frequency. In addition, in order to share a reception antenna of the wireless communication terminal, it is necessary to greatly modulate the resonance frequency of the antenna. In a wireless communication terminal, if the capacitance value of a capacitor is made variable in order to perform impedance matching and modulation of the resonance frequency, it is possible to cover a plurality of frequency bands while reducing the circuit scale and the number of parts.

[0133] The variable capacitance element 100 explained in Embodiment 1 can widen the range of the variable capacitance compared to the conventional variable capacitance element. Therefore, in a wireless communication terminal using the variable capacitance element 100, it is possible to cover a wide frequency band. In addition, the variable capacitance element 100 switches the capacitance value according to the voltage applied to the control electrode terminal 2a, and therefore the capacitance value does not change nonlinearly (gently) with respect to the voltage as in the conventional variable capacitance element. Therefore, in a wireless communication terminal using the variable capacitance element 100, a distorted signal is not generated, and a jamming signal is not generated to other frequencies.

[0134] Figure 15 is a block diagram of the circuit device 400 related to Embodiment 5. The circuit device 400 is a communication circuit module provided in a wireless communication terminal, and can be shared for a plurality of frequencies. Therefore, in the circuit device 400, the capacitor in which the capacitance value needs to be made variable in order to perform impedance matching and modulation of the resonance frequency is applied to the variable capacitance element 100.

[0135] In the circuit device 400, the variable capacitance element 100 can vary the capacitance in a range of 10 times to 1000 times, and thus can perform impedance matching, modulation of resonance frequency, and covering of a wider reception band. Further, in the circuit device 400, the variable capacitance element 100 varies the capacitance in a digital manner, and thus can suppress distortion signals. Thus, by using the circuit device 400, a multi-band wireless communication terminal capable of covering multiple bands while reducing the circuit scale and the number of components can be implemented. In addition, the variable capacitance element 100a that is multi-valued can be used for the capacitor of the circuit device 400.

[0136] (Embodiment 6)

[0137] Next, a structure in which the variable capacitance element described in Embodiment 1 is used for a DC circuit breaker to reduce loss will be described. The structure of the DC circuit breaker can also be applied to an on-off device, a connecting device, and an arc suppression device of various power supply circuits. Further, the DC circuit breaker can be used for, for example, an energy harvesting device such as a solar power generator, a fuel cell, and a lithium ion battery.

[0138] In the DC circuit breaker, it is expected that a power semiconductor switch using SiC (silicon carbide) and GaN (gallium nitride) that can achieve high withstand voltage, high temperature operation, and high speed operation compared to MOSFET is used instead of a metal contact. However, in the case where the power semiconductor switch is used instead of the metal contact for the DC circuit breaker, although a switch of several hundred V to several tens of A can be achieved, the conduction loss caused by heat generated at the time of conduction of the semiconductor becomes very large, and there is a problem in that a cooling device or the like needs to be provided.

[0139] On the other hand, in the case where the metal contact is used for the DC circuit breaker, although the conduction loss can be reduced, arc discharge occurs at the time of breaking, and thus the loss at the time of breaking becomes very large. Thus, a DC circuit breaker using a hybrid switching circuit that conducts by the metal contact having small conduction loss at the time of making and commutates the current to a semiconductor switch of a MOSFET only at the time of breaking to suppress arc discharge has been proposed. In addition, regarding the hybrid switching circuit, for example, it is described in "Ryuichi Shimada, "Smart Switch (Hybrid On-Off / Connecting Device) Using Semiconductor Device", Journal of Power Electronics, March 2017, Vol. 42, p. 53-57".

[0140] Figure 16is a circuit diagram of the circuit device 500 according to Embodiment 6. The circuit device 500 is a hybrid switching circuit for a DC circuit breaker, having a metallic contact SI and a semiconductor switch S2 of a MOSFET. In the circuit device 500, it is possible to open and close without electric arc discharge at the metallic contact SI, and thus there is no contact wear, the life is long, and it is possible to perform high-speed current breaking without noise caused by electric arc discharge.

[0141] In the circuit device 500, when the metallic contact SI is on, a current flows through the metallic contact SI, and when the metallic contact SI is off, the semiconductor switch S2 becomes on at the threshold voltage Vth of the MOSFET, and a current flows through the semiconductor switch S2. After the metallic contact SI becomes off, the transient recovery voltage V of the metallic contact SI is given by (Formula 6). In addition, Vth is the threshold voltage of the MOSFET, and t is time.

[0142] [Formula 6]

[0143] (Formula 6)

[0144] The transient recovery voltage V of the metallic contact SI increases linearly with respect to time t, but the energy consumed at this time becomes circuit loss. Figure 16 is a graph for explaining the switching characteristics of the circuit device 500 according to Embodiment 6. In the graph of Figure 16 , the horizontal axis is time t, and the vertical axis is the transient recovery voltage V. As shown in the graph Rl of Figure 16 , after the metallic contact SI becomes off, the transient recovery voltage V of the metallic contact SI increases linearly with respect to time t.

[0145] Therefore, in order to reduce the circuit loss, the transient recovery voltage V of the metallic contact SI is preferably as steep as possible after the metallic contact SI becomes off. As shown in the graph R2 of Figure 15 , by steeply increasing the transient recovery voltage V of the metallic contact SI, it is possible to reduce the circuit loss. According to (Formula 6), the smaller the capacitance of the capacitor C, the more the transient recovery voltage V is steeply increased, and the more the circuit loss is reduced. On the other hand, in order to absorb the electric charge that generates electric arc discharge when the metallic contact SI is on (and immediately after the metallic contact SI becomes off), it is necessary to set the capacitance of the capacitor C to a relatively large capacitance (for example, several tens of nF) in advance.

[0146] Therefore, in the circuit device 500, as shown in Figure 17As shown, the variable capacitance element explained in Embodiment 1 is used for the capacitor C, so that the capacitance of the capacitor C can be greatly varied at the time of the on and off of the metal contact S1. Therefore, in the circuit device 500, a DC circuit breaker is realized in which the arc discharge is suppressed and the circuit loss is very low. In the variable capacitance element explained in Embodiment 1, a high withstand voltage is obtained while the capacitance is varied in a wider range than in the conventional variable capacitance element. In addition, the multi-valued variable capacitance element 100a can also be used for the capacitor C of the circuit device 500.

[0147] (Embodiment 7)

[0148] In Embodiment 1, the switching section 10 is explained as having the gate electrode 2, the gate insulating film 3, the channel formation film 4, the source electrode 5, and the drain electrode 6. Among them, the drain electrode 6 is a floating electrode, and the switching section in which the drain electrode 6 is not provided can be constituted. In the variable electronic element related to Embodiment 7, the structure of the switching section in which the drain electrode as the floating electrode is not provided is explained with reference to the drawings. Figure 18 is a sectional view for explaining the structure of the variable capacitance element 100d related to Embodiment 7. Figure 17 is a plan view for explaining the structure of the variable capacitance element 100d related to Embodiment 7. In addition, in Figure 18 and Figure 1 In the variable capacitance element 100d shown in Figure 2 and Figure 17 the same reference numerals are attached to the same structures as the variable capacitance element 100 shown in

[0149] Figure 17 The variable capacitance element 100d shown in

[0150] The switching section 10d has the gate electrode 2d, the gate insulating film 3, the channel formation film 4, and the source electrode 5. In Figure 18 the switching section 10d shown in

[0151] In the switching section 10d, the drain electrode is not provided, and instead, as shown in Figure 18As shown, the gate electrode 2d is widened, and most of the terminal electrode 22 overlaps with the gate electrode 2d in top view. Therefore, if the switch section 10d is in the ON state, the variable capacitor element 100d applies a gate voltage to the gate electrode 2d, and channel charge is generated in the portion of the channel forming film 4 that overlaps with the gate electrode 2d in top view. The variable capacitor element 100d applies a voltage between the source electrode 5, the portion of the channel forming film 4, and the terminal electrode 22 opposite to that portion, thereby forming a capacitor.

[0152] On the other hand, when the switch section 10d is in the off state, the variable capacitor element 100d does not apply a gate voltage to the gate electrode 2d, so no channel charge is generated in the channel film 4. Therefore, the variable capacitor element 100d only applies a voltage between the source electrode 5 and the terminal electrode 22 opposite to the source electrode 5, thus becoming the capacitance of only the first capacitor.

[0153] Furthermore, the element section 20 forms a first capacitor (first passive element) between the source electrode 5 and the terminal electrode 22, and a second capacitor (second passive element) between the gate electrode 2d and the terminal electrode 22. Specifically, as... Figure 17 As shown, the first capacitor is the portion C1 where the source electrode 5 and the terminal electrode 22 overlap in a top view. The second capacitor is the portion C3 where the gate electrode 2d and the terminal electrode 22 overlap in a top view.

[0154] Even the variable capacitor element 100d can switch between the case where the first capacitor element is set as element 20 and the case where both the first capacitor element and the second capacitor element are set as element 20 by turning the switch section 10d on / off, thus making the capacitance of the capacitor variable. Even the variable capacitor element 100d is divided into a switch section 10d that turns on / off according to the voltage applied to the gate electrode 2d (control electrode terminal 2a) and an element section 20 that operates through terminal electrode 5a (first terminal electrode) and terminal electrode 22 (second terminal electrode), and is also a variable capacitor element that operates through three terminals.

[0155] However, in the variable capacitor element 100d, the capacitance of the second capacitor element can be changed by the channel charge generated by the channel forming film 4 without providing a drain electrode. Therefore, the capacitance of the second capacitor element can be continuously varied according to the voltage applied to the gate electrode 2d. Furthermore, in the variable capacitor element 100d, by omitting the drain electrode (which serves as a floating electrode), residual charge to the floating electrode can be reduced when the switching section 10d performs an on / off operation. This stabilizes the capacitor's potential and reduces the risk of failure due to short circuits. Moreover, in the variable capacitor element 100d, by omitting the drain electrode (which serves as a floating electrode), the conductivity can be varied in stages over a wide area of ​​the channel forming film 4 according to the applied gate voltage level. This allows for more continuous variation in the capacitor's capacitance.

[0156] As described above, in Embodiment 7, the variable capacitor element 100d uses a portion C3 where the gate electrode 2d and the channel forming film 4 overlap in plan view, instead of the drain electrode. A second capacitor element is formed between this portion C3 and the terminal electrode 22. Thus, the variable capacitor element 100d allows the capacitance of the second capacitor element to be continuously variable.

[0157] In the variable capacitor element 100d, for example... Figure 19 The structure shown is an element section 20 positioned above the switch section 10d, but the element section 20 can also be positioned below the switch section 10d. Furthermore, multiple variable capacitor elements 100d can be formed in a matrix, thereby similarly constituting a multi-valued variable electronic element. Moreover, the structure of the variable capacitor elements 100d can also be applied to variable electronic elements other than capacitors, such as inductors and resistors.

[0158] (Implementation Method 8)

[0159] In the variable capacitor element 100 described in Embodiment 1, a terminal electrode 22 is also formed on the upper part of the channel region formed between the source electrode 5 and the drain electrode 6. Therefore, the variable capacitor element 100 may sometimes affect the on / off state of the switch section 10 due to the voltage applied to the terminal 22a of the terminal electrode 22. That is, the capacitance value of the variable capacitor element 100 may change due to the signal between the terminal electrode 5a (first terminal electrode) and the terminal electrode 22a (second terminal electrode).

[0160] Therefore, in the variable electronic element according to Embodiment 8, the structure in which the capacitance value does not change due to the signal between the first terminal electrode and the second terminal electrode will be described with reference to the accompanying drawings. Figure 20 This is a cross-sectional view used to illustrate the structure of the variable capacitor element 100e according to Embodiment 8.Figure 19 is a plan view for explaining the structure of the variable capacitance element 100e involved in Embodiment 8. In addition, in the variable capacitance element 100e shown in Figure 20 and Figure 1 , the same reference numerals are assigned to the same structures as those of the variable capacitance element 100 shown in Figure 2 and Figure 19 , and the detailed explanation will not be repeated.

[0161] Figure 20 The variable capacitance element 100e shown in Fig. 18 includes the switching section 10 constituting a field effect transistor formed on the semiconductor substrate 1, and the element section 20e electrically connected to the switching section 10 and constituting a passive element. The element section 20e is provided at the upper portion of the switching section 10.

[0162] The element section 20e includes an Al203film as the dielectric 21 and a terminal electrode 22e (second terminal electrode) of platinum (Pt) formed so as to overlap the dielectric 21. As shown in Figure 19 , the terminal electrode 22e is formed by a pattern avoiding the channel region formed between the source electrode 5 and the drain electrode 6. Therefore, in the cross-sectional view shown in Figure 20 , it is illustrated that the terminal electrode 22e is separated into the terminal electrode 22e1 formed at the upper portion of the source electrode 5 and the terminal electrode 22e2 formed at the upper portion of the drain electrode 6.

[0163] The element section 20e constitutes a first capacitor (first passive element) between the source electrode 5 and the terminal electrode 22e1, and a second capacitor (second passive element) between the drain electrode 6 and the terminal electrode 22e2. As shown in Figure 1 , the first capacitor is a portion Cl in which the source electrode 5 and the terminal electrode 22e1 overlap each other in plan view. The second capacitor is a portion C4 in which the drain electrode 6 and the terminal electrode 22e2 overlap each other in plan view.

[0164] In the case where the switching section 10 is in the off state, the variable capacitance element 100e does not apply a gate voltage of the threshold value or more to the gate electrode 2, and therefore an electron depletion layer exists at the position of the channel formation film 4 overlapping the gate electrode 2 in plan view, and the source electrode 5 and the drain electrode 6 are not conductive. Thus, the variable capacitance element 100e applies a voltage only between the source electrode 5 and the terminal electrode 22e1 opposing the source electrode 5, and therefore becomes the capacitance of only the first capacitor.

[0165] However, when the switching section 10 is in the ON state, the variable capacitor element 100e forms a channel by applying a gate voltage of more than a threshold to the gate electrode 2, thus turning on the source electrode 5 and the drain electrode 6. Therefore, the variable capacitor element 100e applies a voltage between the source electrode 5 and the drain electrode 6 and the opposite terminal electrode 22e (first region + second region), thus becoming a combined capacitor of the first capacitor and the second capacitor. Here, the portion of the terminal electrode 22e that overlaps with the source electrode 5 in top view is designated as the first region (terminal electrode 22e1), and the portion that overlaps with the drain electrode in top view is designated as the second region (terminal electrode 22e2).

[0166] The variable capacitor element 100e does not overlap with the channel region formed between the source electrode 5 and the drain electrode 6 when viewed from above because the terminal electrode 22e does not overlap with it. Figure 20 Compared to the variable capacitor element 100 shown, the capacitance is smaller when the switch section 10 is in the ON state. However, as described above, the capacitance value of the variable capacitor element 100e becomes less susceptible to change due to the signal between terminal electrode 5a (first terminal electrode) and terminal electrode 22a (second terminal electrode). Of course, regarding the variable capacitor element 100e, even if terminal electrode 22a is not as... Figure 19 As shown, the pattern is formed by bypassing the entire portion of the channel region formed between the source electrode 5 and the drain electrode 6. Even if the pattern overlaps with a portion of the channel region, it can suppress the capacitance value fluctuation caused by the signal between the first terminal electrode and the second terminal electrode.

[0167] As described above, the terminal electrode 22e of the variable capacitor element 100e has a first region that overlaps with the source electrode 5 in plan view and a second region that overlaps with the drain electrode 6 in plan view. The first and second regions are electrically connected by bypassing at least a portion of the channel region formed between the source electrode 5 and the drain electrode 6. Here, the term "terminal electrode 22e bypassing at least a portion of the channel region formed between the source electrode 5 and the drain electrode 6" means that it has a portion that does not overlap with at least a portion of the channel region in plan view.

[0168] In the variable capacitor element 100e, for example... Figure 21 The structure shown is an element section 20e mounted on the switch section 10, but the element section 20e can also be mounted below the switch section 10. Furthermore, multiple variable capacitor elements 100e can be formed in a matrix, thereby similarly constituting a multi-valued variable electronic element. Moreover, the structure of the variable capacitor element 100e can also be applied to variable electronic elements other than capacitors, such as inductors and resistors.

[0169] In the variable capacitance element 100e related to Embodiment 8, it is explained that the terminal electrode 22e is formed by a pattern that avoids the channel region formed between the source electrode 5 and the drain electrode 6. However, it is also possible that, in accordance with the pattern of the terminal electrode, the dielectric is also formed by a pattern that avoids the channel region. Specifically, Figure 21 is a cross-sectional view for explaining the structure of the variable capacitance element 100f related to a modification of Embodiment 8. In addition, in the variable capacitance element 100f shown in Figure 19 , the same structures as those of the variable capacitance element 100e shown in Figure 20 and Figure 21 are denoted by the same reference numerals, and detailed explanations will not be repeated.

[0170] Figure 20 The variable capacitance element 100f shown in includes the switching section 10 that constitutes a field effect transistor formed on the semiconductor substrate 1, and the element section 20f that is electrically connected to the switching section 10 and constitutes a passive element. The element section 20f is provided at the upper portion of the switching section 10.

[0171] The element section 20f includes the Al203 film as the dielectric 21f and the terminal electrode 22e (second terminal electrode) of platinum (Pt) formed so as to overlap the dielectric 21f. As shown in Figure 21 , the terminal electrode 22e is formed by a pattern that avoids the channel region formed between the source electrode 5 and the drain electrode 6. In addition, the dielectric 21f is formed by a pattern that avoids the channel region formed between the source electrode 5 and the drain electrode 6 in accordance with the pattern of the terminal electrode 22e. Therefore, in Figure 2 , a cross-sectional view is illustrated in which the dielectric 21f1 and the terminal electrode 22e1 formed at the upper portion of the source electrode 5 and the dielectric 21f2 and the terminal electrode 22e2 formed at the upper portion of the drain electrode 6 are separated. In addition, when the terminal electrode 22e bypasses at least a portion of the channel region formed between the source electrode 5 and the drain electrode 6, the dielectric 21f is formed by a pattern that avoids at least a portion of the channel region formed between the source electrode 5 and the drain electrode 6 in accordance with the pattern of the terminal electrode 22e.

[0172] (Modification)

[0173] In the variable capacitance elements 100, 100a to 100d and the variable inductance element 200 explained in the foregoing embodiments, in order to improve the speed of change, that is, the switching speed, it is necessary to increase the Q value (Q = 1 / ωCR) of the switching section 10. Here, ω is the angular frequency. That is, by reducing the parasitic resistance R and the capacitor C (parasitic capacitance), it is possible to improve the switching speed.

[0174] The parasitic resistance R corresponds to the series resistance of the channel formation film 4, and is given by R = p (L / (Wt)). Here, p is the specific resistance inherent to the material of the channel formation film 4, L is the channel length, W is the channel width, and t is the film thickness of the channel formation film 4.

[0175] As described above, the parasitic resistance R depends on the value of the channel length L / channel width W. Therefore, the Q value can be improved by increasing the channel width W with respect to the channel length L. As Figure 1 As shown, the switch section 10 is provided with the source electrode 5 and the drain electrode 6 on the channel formation film 4, and thus can easily change the channel length L and the channel width W according to the device design.

[0176] On the other hand, the capacitor C (parasitic capacitance) corresponds to the capacitance of the gate insulating film 3 of the switch section 10, and is proportional to the relative dielectric constant of the gate insulating film 3 and inversely proportional to the film thickness. Therefore, since the switch section 10 is a separate configuration from the element section 20, the capacitor C (parasitic capacitance) can be adjusted independently.

[0177] For example, in the variable capacitance element 100 described in Embodiment 1, if the channel length L is set to 10 μm, the channel width W is set to 100 μm, the parasitic resistance R is set to 1 kΩ, and the capacitor C (parasitic capacitance) is set to 10 pF, the Q value becomes 0.02 at 1 MHz. Here, if the channel length L is made fine to 1 μm, the channel width W is set to 1000 μm, the film thickness of the gate insulating film 3 is made 10 times (7000 μm), and the relative dielectric constant of the gate insulating film 3 is made 1 / 5 (40 to 50 times), the Q value becomes 100. Therefore, the switch section 10 can improve the switching speed by 5000 times.

[0178] In the foregoing embodiments, the use of the IZO film for the channel formation film 4 is described, but this is one example, and other films such as an ITO film can be used. Further, in the foregoing embodiments, the use of the La-Hf02film for the gate insulating film 3 is described, but this is one example, and other films such as a Ce-Hf02film can be used.

[0179] In the variable electronic element described in the foregoing embodiments, for example, in the variable capacitance element 100, as Figure 1As shown, the channel formation film 4 is formed on the lower side (top contact structure) of the source electrode 5 and the drain electrode 6. The top contact structure is a structure in which, as viewed from the gate electrode 2 side, the upper side of the channel formation film 4 is in contact with the source electrode 5 and the drain electrode 6. However, this is not restrictive, and in the variable electronic element, for example, in the variable capacitance element 100, the channel formation film 4 can also be formed on the upper side (bottom contact structure) of the source electrode 5 and the drain electrode 6. The bottom contact structure is a structure in which, as viewed from the gate electrode 2 side, the lower side of the channel formation film 4 is in contact with the source electrode 5 and the drain electrode 6.

[0180] In the variable electronic element described in the foregoing embodiment, for example, in the variable capacitance element 100, a bottom gate structure is employed in which, as shown, Figure 22 the gate electrode 2 is formed on the semiconductor substrate 1, the gate insulating film 3 and the channel formation film 4 are sequentially formed so as to overlap the gate electrode 2, and the source electrode 5 and the drain electrode 6 are formed on them, respectively. However, this is not restrictive, and the variable electronic element can also be a top gate structure. Figure 22 is a cross-sectional view for explaining the structure of the variable capacitance element 100g involved in the modification. In the variable capacitance element 100g, as shown, Figure 22 the element portion 20 is provided in the lower portion of the switch portion 10. The switch portion 10 employs a top gate structure in which, as shown, the source electrode 5 and the drain electrode 6 are formed on the dielectric 21, the channel formation film 4 and the gate insulating film 3 are sequentially formed so as to overlap the source electrode 5 and the drain electrode 6, and the gate electrode 2 is formed on the gate insulating film 3. In addition, in the variable capacitance element 100g shown in Figure 1 the same structure as the variable capacitance element 100 shown in Figure 22 the same reference numerals are attached to the same structures, and detailed description will not be repeated.

[0181] In the variable capacitance element 100g of the top gate structure, as shown, Figure 1 a top contact structure is employed in which, as viewed from the gate electrode 2 side, the upper side of the channel formation film 4 is in contact with the source electrode 5 and the drain electrode 6. However, this is not restrictive, and even in the variable capacitance element 100g of the top gate structure, a bottom contact structure can also be employed in which, as viewed from the gate electrode 2 side, the lower side of the channel formation film 4 is in contact with the source electrode 5 and the drain electrode 6.

[0182] Hereinafter, materials that can be employed for the gate insulating film 3 and the dielectric 21 are listed collectively. Of course, the materials are not limited to the following description.

[0183] • Amorphous or polycrystalline metal oxides such as SiO2, Al2O3, HfO2, ZrO2, La2O3, Ta2O5

[0184] • Nitride films such as SiN, Si3N4, SiON

[0185] • Ferroelectric films of HfO2 and a ferroelectric film in which at least one or more of Si, Ce, Y, Zr, Bi, Ni, Ta, La, and the like are doped in HfO2 as trivalent or tetravalent or pentavalent metal atoms, a ferroelectric material using PbTiO3 as a parent crystal, a ferroelectric material using BaTiO3 as a parent crystal, a ferroelectric material having a Bi layered structure, other metal oxides having a perovskite-type crystal, a metal oxide having a pyrochlore-type crystal, an organic ferroelectric material, other resin materials (polyimide, acrylic, epoxy, polypropylene, polyester, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polylactic acid, and the like)

[0186] Hereinafter, materials that can be used for the channel formation film 4 are listed collectively. Of course, the materials are not limited to those described below.

[0187] • n-type oxide semiconductors of 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

[0188] • p-type oxide semiconductors of Cu-O, Sn-O, Zn-O

[0189] • amorphous p-type oxide semiconductors of Cu-Sn-I

[0190] • Si semiconductors such as n-type Si, p-type Si, SiC, and the like

[0191] • nitride semiconductors such as GaN and the like

[0192] • two-dimensional conductive materials of graphene and transition metal chalcogen compounds

[0193] • perovskite conductive materials such as LaNiO3, BaSnO3, SrTiO3, and the like

[0194] In the variable capacitance elements 100 to 100g described in the above embodiments, in the case where a ferroelectric film such as a La-HfO2 film is used for the gate insulating film 3, a structure including a ferroelectric gate transistor is included. Thus, the variable capacitance elements 100 to 100g have a memory characteristic derived from the structure of the ferroelectric gate transistor. Specifically, in the case where a ferroelectric film is used for the gate insulating film 3, the variable capacitance elements 100 to 100g have a memory characteristic in which the capacitance value of the variable capacitance element 100 is changed by the application of voltage to the gate electrode 3a. Figure 23In the variable capacitance element 100 shown, by applying a holding voltage of 0 (zero) V or a small fixed value (for example, -1.0 V) to the gate electrode 2, it is possible to maintain the capacitance value C that is generated in a case where an on voltage (for example, +10 V) is applied to the gate electrode 2 and a capacitor is formed between the terminal electrode 22 and the drain electrode 6 on . Likewise, in the variable capacitance element 100, by applying a holding voltage of 0 (zero) V or a small fixed value (for example, -1.0 V) to the gate electrode 2, it is possible to maintain the capacitance value C that is generated in a case where an off voltage (for example, -10 V) is applied to the gate electrode 2 and a capacitor is not formed between the terminal electrode 22 and the drain electrode 6 off .

[0195] Figure 23 is a graph for explaining the relationship between the capacitance of the variable capacitance element and the holding voltage. In Figure 23 , the horizontal axis is the gate voltage and the vertical axis is the capacitance. In a case where a ferroelectric gate transistor is formed using a ferroelectric film such as a La-Hf02film for the gate insulating film 3, as shown in Figure 23 , with respect to the gate voltage Vg applied to the gate electrode 2, the change in the capacitance value C generated between the terminal electrode 22 and the drain electrode 6 becomes a hysteresis curve. In Figure 24 , it is known that by applying a holding voltage of -1.0 V to the gate electrode 2, it is possible to maintain the capacitance value C on and the capacitance value C off .

[0196] Figure 24 is a graph for explaining the relationship between the capacitance of the variable capacitance element and the holding time. In Figure 24 , the horizontal axis is the time and the vertical axis is the capacitance. As shown in ​ , in a state where a holding voltage of -1.0 V is applied to the gate electrode 2, it is possible to maintain the capacitance value C 5 and the capacitance value C on without changing for a period of 1.0 x 10 off seconds (27 hours). Therefore, in the variable capacitance elements 100 to 100g, in a case where a structure using a ferroelectric gate transistor is adopted, it is not necessary to apply a high gate voltage in order to maintain the capacitance, and thus it is possible to achieve power saving and to suppress the deterioration of the element.

[0197] It should be considered that the embodiments disclosed this time are illustrative in all respects, but not restrictive. The scope of the present application is not shown by the above description, but shown by the claims, and intended to include all modifications equivalent in meaning and scope to the claims.

[0198] BRIEF DESCRIPTION OF DRAWINGS

[0199] 1: semiconductor substrate, 1a: silicon substrate, 2: gate electrode, 2a: control electrode terminal, 3: gate insulating film, 4: channel forming film, 5: source electrode, 5a, 22: terminal electrode, 6: drain electrode, 10: switching section, 20: element section, 21: dielectric, 22a: terminal, 23, 24: coil electrode, 25: non-magnetic ceramic, 100, 100a-g: variable capacitance element, 200: variable inductance element, 300, 400, 500: circuit device.

Claims

1. A variable electronic component, comprising: a switching section configured as a field effect transistor; and a component section electrically connected to the switching section and configured as a passive component, the switching section having: a source electrode; a drain electrode; a channel formation 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 so as to overlap the channel formation film; and a gate electrode formed so as to overlap the gate insulating film, the component section having: a first terminal electrode electrically connected to the source electrode; and a second terminal electrode configured as a first passive component between the source electrode and the drain electrode and configured as a second passive component between at least the drain electrode, the second terminal electrode having a portion overlapping the gate electrode and the channel formation film in plan view, the second passive component being configured between the portion and the second terminal electrode, the switching section being caused to perform on / off operation to switch between a case where the component section is configured by the first passive component and a case where the component section is configured by the first passive component and the second passive component, thereby making a physical quantity of the passive component included in the variable electronic component variable.

2. A variable electronic component, comprising: a switching section configured as a field effect transistor; and a component section electrically connected to the switching section and configured as a passive component, the switching section having: a source electrode; a drain electrode; a channel formation 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 so as to overlap the channel formation film; and a gate electrode formed so as to overlap the gate insulating film, the component section having: a first terminal electrode electrically connected to the source electrode; and a second terminal electrode configured as a first passive component between the source electrode and the drain electrode and configured as a second passive component between at least the drain electrode, the second terminal electrode having: a first region overlapping the source electrode in plan view; and a second region overlapping the drain electrode in plan view, the first region and the second region being electrically connected by bypassing at least a part of a channel region formed between the source electrode and the drain electrode, the switching section being caused to perform on / off operation to switch between a case where the component section is configured by the first passive component and a case where the component section is configured by the first passive component and the second passive component, thereby making a physical quantity of the passive component included in the variable electronic component variable.

3. The variable electronic component according to claim 1 or 2, wherein the switching section is provided at an upper portion or a lower portion of the component section.

4. The variable electronic component according to claim 1 or 2, wherein the passive component is any one of a capacitor, an inductor, and a resistor.

5. The variable electronic component according to claim 1 or 2, wherein the passive component is a capacitor, the component section further having: a dielectric provided so as to overlap the source electrode and the drain electrode. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ a first capacitor constituted by the dielectric between the source electrode and the second terminal electrode, a second capacitor constituted by the dielectric between the drain electrode and the second terminal electrode.

6. The variable electronic element according to claim 5, wherein the gate electrode is formed on a semiconductor substrate, the gate insulating film is formed on the gate electrode and the semiconductor substrate, the channel formation film is formed on the gate insulating film, the source electrode and the drain electrode are formed on the channel formation film, the dielectric is formed on the source electrode and the drain electrode, the second terminal electrode is formed on the dielectric.

7. The variable electronic element according to claim 1 or 2, wherein the passive element is an inductor, the element portion has: a first inductor electrically connected between the source electrode and the second terminal electrode, constituting the first passive element; and a second inductor electrically connected between the drain electrode and the second terminal electrode, constituting the second passive element.

8. A variable electronic element comprising: a switching portion constituting a field effect transistor; and an element portion electrically connected to the switching portion, constituting a passive element, the switching portion has: a source electrode; a drain electrode; a channel formation film formed so as to at least overlap a part of the source electrode and a part of the drain electrode; a gate insulating film formed so as to overlap the channel formation film; and a gate electrode formed so as to overlap the gate insulating film, the element portion has: a first terminal electrode electrically connected to the source electrode; a second terminal electrode constituting a first passive element between the source electrode and the second terminal electrode, and constituting a second passive element at least between the drain electrode and the second terminal electrode, the passive element is a capacitor, the element portion further has: a dielectric provided so as to overlap the source electrode and the drain electrode, a first capacitor constituted by the dielectric between the source electrode and the second terminal electrode, a second capacitor constituted by the dielectric between the drain electrode and the second terminal electrode, the second terminal electrode has: a first region overlapping the source electrode in plan view; and a second region overlapping the drain electrode in plan view, the first region and the second region are electrically connected while bypassing at least a part of a channel region formed between the source electrode and the drain electrode, the dielectric is formed so as to avoid at least a part of the channel region formed between the source electrode and the drain electrode in accordance with a pattern of the second terminal electrode, by causing the switching portion to perform on / off operation, a case where the element portion is constituted by the first passive element and a case where the element portion is constituted by the first passive element and the second passive element are switched, whereby a physical quantity of the passive element included in the variable electronic element is made variable.

9. The variable electronic element according to claim 8, wherein ​ ​ The gate electrode is formed on a semiconductor substrate, The gate insulating film is formed on the gate electrode and the semiconductor substrate, The channel formation film is formed on the gate insulating film, The source electrode and the drain electrode are formed on the channel formation film, The dielectric is formed on the source electrode and the drain electrode, The second terminal electrode is formed on the dielectric.

10. A circuit device comprising: a circuit wiring; and the variable electronic element according to any one of claims 1 to 9, electrically connected to the circuit wiring.

Images