JP2010040708A - Bidirectional switching element - Google Patents

Abstract

In a single gate type bidirectional switch element, a threshold voltage is suppressed to be low, a low on-resistance is realized, and a shape restriction is eased.
A first electrode D1 and a second electrode D2 that are connected in series to an AC power source and a load, respectively, and are formed on the substrate surface, and at least a part of the first electrode D1 and the second electrode D2 are formed on the surface 2d of the substrate 2, An intermediate potential portion S that is an intermediate potential with respect to the potential of the first electrode D1 and the potential of the second electrode D2, and at least part of the intermediate potential portion S is connected to the intermediate potential portion S, and control for controlling the intermediate potential portion S It has a horizontal transistor structure including an electrode G, and the intermediate potential portion S and the control electrode G are arranged at a position where a predetermined withstand voltage can be maintained with respect to the first electrode D1 and the second electrode D2.
[Selection] Figure 1

Description

  The present invention relates to a bidirectional switch element for controlling a load such as a lighting device connected to an AC power source.

  Known bidirectional switch elements used for controlling a load connected to an AC power source include triac (bidirectional thyristors), two elements such as MOSFETs and IGBTs connected in series in the reverse direction. These bidirectional switch elements are generally vertical elements in which a current flows between the front and back surfaces of the element, but a HEMT (High Electron Mobility Transistor), which is a horizontal element as shown in Patent Document 1, has also been proposed. ing. Further, in recent years, as a lateral element using GaN / AlGaN, for example, as shown in Non-Patent Document 1, a gate portion provided in the middle is controlled with respect to two electrodes to which the high potential side of AC is connected. A bidirectional switch element that controls an alternating current has been proposed. As shown in FIG. 5A, a single gate type is provided with only one gate G between the two electrodes D1 and D2, and as shown in FIG. 5B, the two electrodes D1 and D2 are provided. A device in which two gates G1 and G2 are provided between them is called a dual gate type.

  In the single gate type bidirectional switch element, since one gate is controlled with reference to the lowest potential part of the element, the control method is relatively simple. Since a certain distance is required between the electrode and the electrode, the specific resistance is higher than that of the dual gate bidirectional switch element. On the other hand, in the dual gate type bidirectional switch element, it is necessary to control two gates, and the control signal standard is different. It is only necessary to secure a certain distance in order to maintain the withstand voltage, and the specific resistance is lower than that of the single gate type bidirectional switch element, and the chip size can be reduced for realizing the same resistance value. Have

  By the way, in the single gate type bidirectional switch element, when the length of the gate is made long in order to constitute a large current element, the gate portion is arranged with respect to the two electrodes in order to maintain the withstand voltage as described above. It must be arranged so as to maintain a certain distance, and there is a restriction that it becomes an elongated element, which causes a practical problem such as selection of a package. Further, as shown in FIG. 6, when the power supply of the gate drive control circuit is directly taken from the AC line, the minimum control voltage is caused by the voltage drop generated in the rectifier (diode bridge) of the power supply circuit. The voltage is slightly higher than the minimum voltage of the AC line, for example, by a voltage drop for one diode. This means that when the bidirectional switch element is turned off, a voltage corresponding to a voltage drop corresponding to one diode is always applied to the gate portion. In order to reliably turn off the bidirectional switch element in this state, it is necessary to make the threshold voltage of the bidirectional switch element sufficiently higher than the voltage drop of the diode. When the threshold voltage is increased, the on-resistance when the bidirectional switch element is energized increases, which causes a problem of increased loss.

In addition, as a background that such a new bidirectional switch element is required, there is a demand for downsizing of a load control device such as a lighting device. Generally, such a load control device is housed and used in a metal box or the like provided on a wall surface. However, a bidirectional switch element such as a triac is used for a heat sink or the like in order to obtain a sufficient output. Heat dissipation measures are required, and there is a limit to downsizing the load control device. For this reason, the load control device cannot be used in combination with other sensors or switches at the size of the box that is generally used at present. Therefore, in order to enable a load control device and other sensors and switches to be installed in a general-sized box, it is necessary to reduce the size of the bidirectional switch element, reduce the threshold voltage, and realize a low on-resistance. It has been.
Japanese Patent Laid-Open No. 8-51202 Osamu Machida, 5 others, "GaN bidirectional switch", Proceedings of the 2008 Annual Conference of the Institute of Electrical Engineers of Japan, March 19-21, 2008, Volume 4, p269

  The present invention has been made in order to solve the above-described problems of the conventional example, and both have a lateral transistor structure that can reduce the threshold voltage, realize a low on-resistance, and relax the shape restriction. An object is to provide a directional switch element.

  In order to achieve the above object, a first aspect of the present invention is a bidirectional switch element, which is connected in series to an AC power source and a load, respectively, and is formed with a first electrode and a second electrode formed on a substrate surface. An intermediate potential portion formed at least in part on the surface of the substrate and having an intermediate potential with respect to the potential of the first electrode and the potential of the second electrode; and at least a portion thereof connected to the intermediate potential portion. , Having a horizontal transistor structure including a control electrode for controlling the intermediate potential portion, wherein the intermediate potential portion and the control electrode are predetermined with respect to the first electrode and the second electrode. It is arranged at a position where the withstand voltage can be maintained.

  According to a second aspect of the present invention, in the bidirectional switch element according to the first aspect, the first electrode and the second electrode are arranged such that center lines in the width direction thereof are located on the same line, and the intermediate electrode The potential portion and the control electrode are provided in parallel to the arrangement of the first electrode and the second electrode.

  According to a third aspect of the present invention, in the bidirectional switch element according to the second aspect, the first electrode and the second electrode are comb-like shapes each having a plurality of electrode portions arranged in parallel to each other. The electrode parts arranged in a tooth shape are arranged so as to face each other, and the intermediate potential part and the control electrode are respectively arranged between the electrode parts arranged in a comb tooth shape. And

  According to a fourth aspect of the present invention, in the bidirectional switch element according to any one of the first to third aspects, the intermediate potential portion and the control electrode are stacked on a surface of a substrate. And

  According to a fifth aspect of the present invention, in the bidirectional switch element according to any one of the first to fourth aspects, the intermediate potential portion penetrates the substrate in a direction perpendicular to the surface thereof, It is connected to the back surface, and the entire back surface of the substrate has the same potential as the intermediate potential portion.

  The invention according to claim 6 is the bidirectional switch element according to claim 5, wherein the control electrode is formed so as to cover a portion of the intermediate potential portion formed on the surface of the substrate. Features.

  According to the first aspect of the present invention, at least a part of the intermediate potential portion that is an intermediate potential with respect to the potential of the first electrode and the potential of the second electrode, and the control electrode connected to the intermediate potential portion are the first electrode and Since the second electrode is disposed at a position where a predetermined withstand voltage can be maintained, for example, when the first electrode is on the high potential side and the second electrode is on the low potential side, the bidirectional switch element is off. When a signal of 0V is applied to the control electrode, the current is reliably interrupted at least between the first electrode, the control electrode and the intermediate potential portion. On the other hand, when the bidirectional switch element is on, that is, when a signal having a voltage equal to or higher than a predetermined threshold is applied to the control electrode, a current flows through the path of the first electrode, the intermediate potential portion, and the second electrode. In this way, by forming the intermediate potential portion at a position where a predetermined withstand voltage can be maintained with respect to the first electrode and the second electrode, the threshold voltage of the signal applied to the control electrode is reduced to a necessary minimum level. Even if it is made to do, a bidirectional | two-way switch element can be turned on / off reliably and low on-resistance can be implement | achieved. Further, since the positions and shapes of the first electrode, the second electrode, the intermediate potential portion, and the control electrode are not particularly limited, the chip shape and size of the bidirectional switch element are not limited, and the restriction on the shape is relaxed. As a result, downsizing of the bidirectional switch element itself and a load control device using the bidirectional switch element can be realized.

  According to the invention of claim 2, the first electrode and the second electrode are arranged so that the center lines in the width direction thereof are located on the same line, and the intermediate potential portion and the control electrode are the first electrode and the second electrode, respectively. Since it is provided in parallel with the arrangement of the electrodes, the size of the bidirectional switch element in the width direction of the first electrode and the second electrode can be reduced. In other words, a plurality of sets of the first electrode, the second electrode, the intermediate potential portion, and the control electrode can be arranged in the width direction of the first electrode and the second electrode.

  According to the invention of claim 3, the first electrode and the second electrode are each in a comb-like shape having a plurality of electrode portions arranged in parallel to each other, and the electrode portions arranged in a comb-like shape are opposed to each other. Since the intermediate potential portion and the control electrode are respectively disposed between the electrode portions arranged in a comb shape, a large current is taken out without increasing the chip size of the bidirectional switch element. be able to.

  According to the invention of claim 4, since the intermediate potential portion and the control electrode are laminated on the surface of the substrate, the bidirectional switch element can be manufactured by using a general semiconductor element manufacturing process. .

  According to the invention of claim 5, the intermediate potential portion penetrates the substrate in a direction perpendicular to the surface thereof, is connected to the back surface of the substrate, and the entire back surface of the substrate has the same potential as the intermediate potential portion. Since the back surface of the substrate functions as an intermediate potential portion and the area of the intermediate potential portion increases, the resistance value in the current path can be reduced. Moreover, the back surface of a board | substrate can be used as an electrode and heat dissipation improves.

  According to the invention of claim 6, since the control electrode is formed so as to cover a portion of the intermediate potential portion formed on the surface of the substrate, masking when forming the control electrode becomes easy. Productivity is improved.

  A bidirectional switch element 1A according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view showing a configuration of a bidirectional switch element 1A according to the first embodiment. 2 is an enlarged view of a range A in FIG. 1, and FIG. 3 is a cross-sectional view along BB.

  As shown in FIG. 3, the substrate 2 of the bidirectional switch element 1 includes a conductor layer 2a, and a GaN layer 2b and an AlGaN layer 2c laminated on the conductor layer 2a. In this embodiment, a two-dimensional electron gas layer generated at the AlGaN / GaN hetero interface is used as the channel layer. As shown in FIG. 1, the surface 2d of the substrate 2 has a first electrode D1 and a second electrode D2 connected in series to the AC power source 3 and the load 4, respectively, and the potential of the first electrode D1 and the second potential. An intermediate potential portion S that is an intermediate potential with respect to the potential of the electrode D2 is formed. Further, a control electrode (gate) G is stacked on the intermediate potential portion S. As the control electrode G, for example, a Schottky electrode is used. The first electrode D1 and the second electrode D2 are comb teeth having a plurality of electrode portions 11, 12, 13..., 21, 22, 23. The electrode parts arranged in the are arranged so as to face each other. The intermediate potential portion S and the control electrode G are respectively disposed between the electrode portions 11, 12, 13..., 21, 22, 23. It has a shape (substantially fish spine shape) similar to the planar shape of the space to be formed.

  Next, a lateral transistor structure constituting the bidirectional switch element 1 will be described. As shown in FIG. 2, the electrode part 11 of the first electrode D1 and the electrode part 12 of the second electrode D2 are arranged so that the center lines in the width direction are located on the same line, and the correspondence of the intermediate potential part S The portion 31 and the corresponding portion 41 of the control electrode G are provided in parallel to the arrangement of the electrode portion 11 of the first electrode D1 and the electrode portion 21 of the second electrode D2, respectively. The distance between the electrode portion 11 of the first electrode D1, the electrode portion 12 of the second electrode D2, the corresponding portion 31 of the intermediate potential portion S, and the corresponding portion 41 of the control electrode G in the width direction can maintain a predetermined withstand voltage. Set to distance. The same applies to the direction perpendicular to the width direction, that is, the longitudinal direction of the electrode portion 11 of the first electrode D1 and the electrode portion 12 of the second electrode D2. Moreover, these relationships are the same also about the other electrode parts 12 and 22, 13, and 23 .... That is, the intermediate potential portion S and the control electrode G are arranged at positions where a predetermined withstand voltage can be maintained with respect to the first electrode D1 and the second electrode D2.

  In this way, the intermediate potential portion S, which is an intermediate potential with respect to the potential of the first electrode D1 and the potential of the second electrode D2, and the intermediate potential portion S are connected to the intermediate potential portion S to control the intermediate potential portion S. Since the control electrode G is disposed at a position where a predetermined withstand voltage can be maintained with respect to the first electrode D1 and the second electrode D2, for example, the first electrode D1 is on the high potential side, and the second electrode D2 is on the low potential side. When the bidirectional switch element 1 is off, that is, when a signal of 0 V is applied to the control electrode G, the current flows at least between the first electrode D1, the control electrode G, and the intermediate potential portion S. Is reliably cut off (current is blocked directly under the control electrode (gate) G). On the other hand, when the bidirectional switch element 1 is turned on, that is, when a signal having a voltage equal to or higher than a predetermined threshold is applied to the control electrode G, as shown by the arrow in FIG. , 13..., A current flows through a path of the intermediate potential portion S and the second electrode D2 (electrode portions 21, 22, 23...). The same applies to the reverse case.

  Thus, by forming the intermediate potential portion S at a position where a predetermined withstand voltage can be maintained with respect to the first electrode D1 and the second electrode D2, the threshold voltage of the signal applied to the control electrode G is minimized. The bidirectional switch element 1 can be reliably turned on / off even when the level is lowered to the level, and a low on-resistance can be realized. Further, the electrode portions 11, 12, 13... Of the first electrode D1 and the electrode portions 21, 22, 23... Of the second electrode D2 are arranged such that the center lines in the width direction are on the same line. Since the corresponding portion 31 of the intermediate potential portion S and the corresponding portion 41 of the control electrode G are arranged in parallel to the arrangement of the electrode portions of the first electrode D1 and the second electrode D2, the width The dimension of the bidirectional switch element 1 in the direction can be reduced. In other words, the electrode portions 11, 12, 13... Of the first electrode D1 and the electrode portions 21, 22, 23... Of the second electrode D2 can be arranged in a comb shape in the width direction. A large current can be taken out without increasing the chip size of the bidirectional switch element 1. Furthermore, since the intermediate potential portion S and the control electrode G are stacked on the surface 2d of the substrate 2, the bidirectional switch element 1 can be manufactured using a general semiconductor element manufacturing process.

  Next, a bidirectional switch element 1A according to a second embodiment of the present invention will be described with reference to FIG. In addition, about the part which is common with the bidirectional | two-way switch element 1 which concerns on the said 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 4, a via hole 2 f penetrating the AlGaN layer 2 c and the GaN layer 2 b is formed inside the substrate 2 and at a position corresponding to the intermediate potential portion S, and almost the entire back surface 2 e of the substrate 2. The electrode layer 2g is formed. That is, the intermediate potential portion S is substantially connected to the back surface 2e of the substrate 2 through the conductor layer 2a through the AlGaN layer 2c and the GaN layer 2b in a direction perpendicular to the surface 2d of the substrate 2. Yes. As a result, the entire electrode layer 2g on the back surface 2e of the substrate 2 has the same potential as the intermediate potential portion S, and the back surface 2e (electrode layer 2g) of the substrate 2 functions as the intermediate potential portion S. Therefore, the resistance value in the current path can be reduced. Moreover, the back surface 2e of the board | substrate 2 can be used as an electrode, and heat dissipation improves. Furthermore, since the area of the intermediate potential portion S substantially increases, the area of the intermediate potential portion S formed on the surface 2d of the substrate 2 can be reduced, and the control electrode G can be connected to the intermediate potential portion. S can be formed so as to cover a portion formed on the surface 2 d of the substrate 2. Therefore, masking when forming the control electrode G becomes easy and productivity is improved.

  In addition, this invention is not limited to the structure of the said embodiment, The 1st electrode D1 and 2nd electrode D2 which were respectively connected in series with respect to alternating current power supply and load, and were formed on the substrate surface, At least a portion thereof is formed on the surface 2d of the substrate 2, and an intermediate potential portion S that is an intermediate potential with respect to the potential of the first electrode D1 and the potential of the second electrode D2, and at least a portion thereof is connected to the intermediate potential portion S. And has a lateral transistor structure including a control electrode G for controlling the intermediate potential portion S. The intermediate potential portion S and the control electrode G are connected to the first electrode D1 and the second electrode D2. The position and shape of the first electrode D1, the second electrode D2, the intermediate potential portion S, and the control electrode G are not particularly limited as long as they are arranged at a position where a predetermined withstand voltage can be maintained. Therefore, the chip shape and size of the bidirectional switch element 1 are not limited, and the restriction on the shape is relaxed. As a result, downsizing of the bidirectional switch element 1 itself and a load control device using the bidirectional switch element 1 can be realized.

The top view which shows the structure of the bidirectional | two-way switch element concerning 1st Embodiment of this invention. FIG. 2 is an enlarged view of a range A of a bidirectional switch element in FIG. 1 and showing a current flow direction in a horizontal transistor structure. BB sectional drawing in FIG. Sectional drawing which shows the structure of the bidirectional | two-way switch element concerning 2nd Embodiment of this invention. It is a figure which shows the structure of the conventional horizontal type | mold bidirectional | two-way switch element, (a) is a single gate type in which only one gate is provided between two electrodes, (b) is 2 between two electrodes. A cross-sectional view showing a dual gate configuration in which two gates are provided. The figure which shows the structure of the drive circuit of the conventional single gate type bidirectional | two-way switch element.

Explanation of symbols

1, 1A Bidirectional switch element 2 Substrate 2a Conductor layer 2b GaN layer 2c AlGaN layer 2d (Substrate) front surface 2e (Substrate) back surface 2f Via hole 2g Electrode layer 3 AC power supply 4 Load 11, 12, 13... 1 electrode comb-like) electrode part 21, 22, 23... (Second electrode comb-like) electrode part 31 corresponding part of intermediate potential part 41 corresponding part of control electrode D1 first electrode D2 second electrode S Intermediate potential part G Control electrode

Claims (6)

A first electrode and a second electrode connected in series to an AC power source and a load, respectively, formed on the substrate surface;
An intermediate potential portion formed at least in part on the surface of the substrate, and having an intermediate potential with respect to the potential of the first electrode and the potential of the second electrode;
At least a part of the transistor is connected to the intermediate potential portion, and has a lateral transistor structure including a control electrode for controlling the intermediate potential portion,
The bidirectional switch element, wherein the intermediate potential portion and the control electrode are arranged at a position where a predetermined withstand voltage can be maintained with respect to the first electrode and the second electrode. The first electrode and the second electrode are arranged so that their center lines in the width direction are located on the same line,
2. The bidirectional switch element according to claim 1, wherein the intermediate potential portion and the control electrode are provided in parallel to the arrangement of the first electrode and the second electrode. The first electrode and the second electrode are each in a comb-like shape having a plurality of electrode portions arranged in parallel with each other, and the electrode portions arranged in a comb-teeth shape are arranged to face each other,
3. The bidirectional switch element according to claim 2, wherein the intermediate potential portion and the control electrode are respectively disposed between the electrode portions arranged in a comb shape.   The bidirectional switch element according to any one of claims 1 to 3, wherein the intermediate potential portion and the control electrode are stacked on a surface of a substrate.   2. The intermediate potential portion penetrates the substrate in a direction perpendicular to the surface thereof, is connected to the back surface of the substrate, and the entire back surface of the substrate has the same potential as the intermediate potential portion. The bidirectional switch element according to claim 4. 6. The bidirectional switch element according to claim 5, wherein the control electrode is formed to cover a portion of the intermediate potential portion formed on the surface of the substrate.

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