JP5245157B2 - Semiconductor bidirectional switching device - Google Patents

Description

  The present invention relates to a semiconductor device capable of bidirectional switching, and further relates to a bidirectional switching apparatus free from a voltage drop due to a diffusion potential caused by a diode or the like.

  The demand for high-performance power converters such as matrix converters is increasing in the field of power electronics as home appliances and industrial equipment have been improved in performance and power consumption. Therefore, it is indispensable to improve the performance of the bidirectional switch used in the power converter.

  Conventional bidirectional switches have been made by a combination of MOSFET, IGBT, diode, and the like. As the diode, a fast recovery diode or the like has been used. There are mainly four ways.

  The first method is a method of connecting two MOS-FETs in series in opposite directions. A MOS-FET can flow current in both directions, but the withstand voltage is only in one direction. Therefore, a bidirectional switch can be realized by connecting two MOS-FETs in series in opposite directions. However, there is a drawback that resistance increases.

  The second method is a method that compensates for the disadvantages of the first method. A MOS-FET has a high resistance when a current flows in the opposite direction. Therefore, in the first method, a diode is connected in antiparallel to each of the two MOS-FETs, and when flowing in the reverse direction, the current also flows in the diode. Even in this method, when a current passes through the diode, a loss due to the rising voltage of the diode occurs.

  The third method uses an IGBT in which diodes are connected in antiparallel. This method uses an IGBT instead of the MOS-FET of the second method. The IGBT has a low resistance when conducting a current in the forward direction than the MOS-FET because of conductivity modulation. However, the resistance is high when current flows in the opposite direction. Therefore, as a path for passing a current in the reverse direction, a diode is connected in reverse parallel to the IGBT, and when a current is flowed in the reverse direction, the current is passed through the diode.

  Also in this method, since a current flows through the diode, a loss corresponding to the rising voltage of the diode, that is, the diffusion potential occurs.

  The fourth method is a method using reverse blocking IGBT. The reverse blocking IGBT cannot flow current in the reverse direction, but has a breakdown voltage in the reverse direction. If two of them are used and connected in antiparallel, a bidirectional switch can be formed. However, there are problems such as high element resistance in order to realize reverse blocking characteristics.

  As described above, the bidirectional switch can be realized by a combination of semiconductor elements such as MOSFET, IGBT, and diode, but in either case, there is a problem such as high resistance.

  There is an example in which the bidirectional switch is realized by a single element instead of a method using a combination of semiconductor elements. As shown in Non-Patent Document 1, there is a report example of a MOSFET having vertical gates and two vertical gates using a silicon material by N. Luther-King et al.

  However, this element has a heat sink problem. In the case of a normal vertical MOSFET, the drain side has only one drain electrode, so a heat dissipation mechanism may be provided on the drain side. However, since this element has gates at the top and bottom, it is not easy to attach a heat sink such as a heat sink.

  Also, the upper structure and the lower structure are attached by wafer bonding. Since the process of attaching the wafer is after the element structure is created, it is not easy. There are crystal defects and the like at the interface pasted by bonding.

  Also, since there is no electric field management function, it is necessary to lengthen the distance between the gate and the drain in order to increase the breakdown voltage, resulting in an increase in device resistance. Furthermore, since it is not a lateral element, integration is difficult.

  In the situation where higher efficiency of power conversion devices is required in the future, it is necessary to reduce the loss of semiconductor switching elements. Therefore, in the element design, as shown in Patent Document 1 to Patent Document 5 and Non-Patent Document 2 to Non-Patent Document 4, an electron used for a super junction structure for performing electric field management and a low resistance of an IGBT or the like. A structure that causes conductivity modulation by injection of both holes and holes is required.

  The super junction structure is a structure in which n-type semiconductor layers and p-type semiconductor layers are alternately stacked or arranged. This will be described.

  In a MOSFET that does not have a super junction structure, when the gate is off and current is blocked, a depletion layer is formed in a portion from the gate to the drain in accordance with the applied voltage. This depletion layer is where carriers such as electrons or holes are discharged, and has a space charge according to the doping concentration.

  For example, in a normal npn-structure MOSFET, an n-type semiconductor is formed between the source and the gate, a p-type semiconductor is formed at the gate portion, and an n-type semiconductor is formed between the gate and the drain. Since the gap between the gate and drain where the depletion layer is formed is an n-type semiconductor, the depletion layer that has been depleted by discharging electrons due to an externally applied voltage has a positive space charge.

  The electric field strength in this depleted region having a positive space charge is not uniform. This is because electric lines of force generated from space charges are applied to the electric field. Specifically, the electric field strength in the depletion layer can be obtained by solving Poisson's equation, but in general, the electric field is stronger near the gate and weaker on the drain side. When the voltage applied from the outside increases and the electric field in the vicinity of the gate becomes larger than the dielectric breakdown electric field of the material, the element causes dielectric breakdown and current flows.

  On the other hand, in the case of a structure in which n-type semiconductor layers and p-type semiconductor layers are alternately arranged, that is, in the case of a super junction structure, both the n-type semiconductor layer and the p-type semiconductor layer are depleted. When the n-type semiconductor layer is depleted, it becomes a region having a negative space charge, and when the p-type semiconductor layer is depleted, it becomes a region having a positive space charge.

  In this case, the lines of electric force generated from the negative and positive space charges cancel each other. Therefore, the lines of electric force generated from the depleted portion having the space charge do not change the electric field strength greatly, so that the electric field strength of the depleted portion can be made uniform. When compared with a normal MOSFET, when the super junction structure is used, a portion where the electric field is locally increased so that the electric field only in the vicinity of the gate is increased does not occur. Therefore, the breakdown voltage of the element can be increased by using the super junction structure.

  No element using such a super junction structure has a reverse breakdown voltage and a bidirectional switching function. In addition, adopting a structure that causes conductivity modulation by injection of both electrons and holes is also an effective method for reducing the resistance. This is a structure used in an IGBT or the like. However, there is no IGBT capable of bidirectional switching.

  As seen in Non-Patent Document 3, some IGBTs have two gates. A conventional device has a gate only on the cathode side, but this device has a gate on both the cathode side and the anode side. However, the gate on the anode side is for reducing the resistance when a hole current is passed in the opposite direction. Further, the gate on the anode side does not have a function of controlling the flow of electrons from the anode side, and this element does not have a reverse blocking characteristic.

  Although the case of using a silicon material has been described above, a bidirectional switch using a wide gap semiconductor material has also been reported.

  As seen in Non-Patent Document 5, as a conventional device capable of bidirectional switching using a wide gap semiconductor material, there is an AlGaN / GaN heterojunction field effect transistor having two gates. It has two gates between two main electrodes and has a p-doped AlGaN cap layer on the AlGaN / GaN heterojunction only at the gate. Because of the AlGaN cap layer, normally-off operation is possible.

  In addition, a two-dimensional electron gas formed at the AlGaN / GaN heterojunction interface is used as a channel, and there are features such as low resistance and high speed operation. However, when switching from 300 V to 400 V or more, since the thickness of the AlGaN barrier layer is as thin as 20 to 40 nm, electrons emitted from the channel are trapped on the surface of the AlGaN barrier layer or a heterojunction is formed. Current collapse occurs when electrons are trapped inside, and the resistance does not actually become low.

  Moreover, since it is not a silicon material, it is not easy to reduce the price. Furthermore, integration with other elements based on silicon materials is not easy.

JP 2003-273355 A JP 2004-6731 A JP 2005-175416 A JP 2005-333068 A JP 2007-96336 A Ngwendson Luther-King, Mark Sweet, Oana Spulber, Konstantin V. Vershinin, MM De Souza, and EM Sankara Narayanan, 'MOS Control Device Concepts for AC-AC Matrix Converter Applications: The HCD Concept for High-Efficiency Anode-Gated Devices, '' IEEE Transactions on Electron Devices, vol. 52, No. 9, pp. 2075-2080, Sep. 2005. Yu Chen, Kavitha D. Buddharaju, Yung C. Liang, Ganesh S. Samudra and Han Hua Feng, 'Superjunction Power LDMOS on Partial SOI Platform,' Proceedings of the 19th International Symposium on Power Semiconductor Devices & ICs, pp. 177-179 , May 27-30, 2007, Jeju, Korea. F. Udrea, UNK Udugampola, T. Trajkovic and GAJ Amaratunga, 'Reverse Conducting Double Gate Lateral Insulated Gate Bipolar Transistor in SOI Based Technology,' Proceedings of the 19th International Symposium on Power Semiconductor Devices & ICs, pp. 221-224, May 27-30, 2007, Jeju, Korea. Tatsuhiko Fujihira, 'Theory of Semiconductor Superjunction Devices,' Jpn. J. Appl.Phys. Part 1, vol. 36, No. 10, pp. 6254-6262, 1997. Tatsuo Morita, Manabu Yanagihara, Hidetoshi Ishida, Masahiro Hikita, Kazuhiro Kaibara, Hisayoshi Matsuo, Yasuhiro Uemoto, Tetsuzo Ueda, Tsuyoshi Tanaka and Daisuke Ueda, '650V 3.1mΩcm2 GaN-based Monolithic Bidirectional Switch Using Normally-off Gate Injection Transistor,' International Electron Devices Meeting (IEDM), 2007.

  An object of the present invention is to provide a bidirectional switch capable of controlling current in both directions and capable of low resistance operation by double injection and electric field management by a super junction structure.

The semiconductor bidirectional switching device of the present invention controls a current that flows bidirectionally between the first main electrode and the second main electrode. The semiconductor bidirectional switching device includes a first current control unit that controls a current flowing into and out of the first main electrode, and a second current control unit that controls a current flowing into and out of the second main electrode. has between the main electrode and the second main electrodes of both the first current controller second current control unit, respectively, have a structure for controlling both the electron current and hole current, the electron current The structure for controlling both the current and the Hall current includes an n-type semiconductor in which an electron current flows between the first current control unit and the second current control unit, and the first current control unit and the second current control unit. A p-type semiconductor in which a hole current flows between the n-type semiconductor and the p-type semiconductor having a super junction structure. The first current control unit includes a first electronic current control unit and a first electronic current control unit. 1 hall current control unit, and the second current control unit A first current control unit and a second current control unit are connected by an n-type semiconductor layer constituting a super junction structure; The first hall current control unit and the second hall current control unit are connected by a p-type semiconductor layer constituting a super junction structure.

  The semiconductor bidirectional switching device of the present invention can be manufactured using materials such as Si, SiC, GaN, diamond, and GaAs. However, considering the current semiconductor integration technology, the size of the substrate to be supplied, and the process technology, the material for creating a low-cost, high-performance bidirectional switch is a silicon material that is currently widely used. . In order to operate with low loss, it is necessary to reduce the resistance by injecting both holes and electrons, that is, by double injection, or to manage the electric field by the super junction structure to make the electric field strength uniform in the element. .

  However, in double injection, both holes and electrons are involved as carriers. The super junction structure is a structure in which n-type semiconductor layers and p-type semiconductor layers are alternately arranged, and both holes and electrons are also involved. Therefore, an element structure that makes use of the characteristics of these structures and enables the function of a bidirectional switch has a structure that controls both the flow of electrons and the flow of holes to and from two main electrodes through which switching currents enter and exit. It is an element structure.

  Specifically, it is an element structure in which the control structure for controlling the flow of electrons in the n-type semiconductor layer constituting the super junction structure, that is, the electron current, is provided in two main electrodes through which the switching current enters and exits. At the same time, it is an element structure in which the control structure for controlling the flow of holes in the p-type semiconductor constituting the super junction, that is, the hole current, is provided in the two main electrodes through which the switching current enters and exits.

  In order to provide the double injection effect in both directions, a structure for controlling the flow of electrons and holes using pn junctions is provided on the two main electrodes. The control of the electron current and the control of the hall current can be controlled by current injection similar to the control of the bipolar transistor or control by the electric field effect similar to the control of the MOS-FET. However, in order to provide both on the same main electrode, they are separated by an insulator or the like. Alternatively, the positional relationship between the p-type semiconductor layer and the n-type semiconductor layer is devised.

  In addition, when the main electrode is provided with a function for controlling the flow of electrons and holes, it is possible to control each with separate electrodes. However, due to the process of the element, etc., it is short-circuited and controlled with one electrode. Sometimes it is better. When the MOS structure is used, it can be operated as a diode by controlling the threshold voltage.

  Also, if there are control electrodes on both of the two main electrodes, this is disadvantageous for a vertical device. Therefore, a pn junction is used to enable a bidirectional switch with the control electrode of one main electrode. By injecting electrons from one main electrode side, the flow of holes from the other side is turned on. Alternatively, by injecting holes from one main electrode side, the flow of electrons from the other is turned on.

  By providing a structure for controlling the flow of electrons and holes in the two main electrodes, a bidirectional switch having the super junction structure and having the advantage of the withstand voltage characteristic can be realized.

  Further, if both of the control of electrons of the two main electrodes are turned on, a switching element that can be turned on without a diffusion potential, that is, can be energized, and is effective for a low voltage application. The same applies to the control of the hall.

  Furthermore, if electrons and holes are controlled by two main electrodes, the effect of double injection can be obtained in the super junction structure. This is possible for bidirectional current. This is an effect which is not a conventional element.

  In addition, by controlling the threshold voltage, it is possible to function as a diode in normal times, that is, when the control circuit is off or when the main power supply is stopped, while having a withstand voltage in both directions.

  An element having a control structure of electrons and holes in the main electrode, a super junction structure, and utilizing double injection by a pn junction enables bidirectional switching only with the control electrode of one of the main electrodes.

  There are roughly two methods for controlling the flow of electrons and the flow of holes flowing between two main electrodes. The first method is a method in which all current control is performed directly by the control electrode. It is a field effect type or a current injection type. The second method is a method of controlling by the current flowing from the opposite main electrode. For example, there is a method of turning on the flow of holes flowing out from the second main electrode side by the flow of electrons flowing from the first main electrode side. In this case, the number of control electrodes is reduced.

  A first method for controlling the current, that is, a method for performing all current control directly by the control electrode will be described first. There are two basic methods of current control in the electron current controller and the hole current controller performed by the control electrode. The first is a method of controlling by current injection used in bipolar transistors such as npn transistors and pnp transistors. The second is a method using a MOS gate structure used in a field effect transistor.

(Embodiment 1)
First, a bidirectional switch that controls current in the same way as a bipolar transistor will be described. FIG. 1 shows a structure in which an electron current control unit and a hole current control unit that are adjacent to each other with an insulator interposed therebetween are connected to both the first main electrode 21 and the second main electrode 22. The electron current controller and the hole current controller in each main electrode are alternately arranged.

  Further, the structure shown in FIG. 1 is a structure in which the electron current control unit and the hole current control unit on the same main electrode side are connected to the same control electrode. It is also possible to control the electron current control unit and the hall current control unit on the same main electrode side with different control electrodes. When controlling with different control electrodes, both the main electrode 21 side and the main electrode 22 side are provided with one electrode for controlling the electron current and one electrode for controlling the hole current. It is possible to control the switch.

  However, when the process becomes complicated, the capacity between the control electrodes becomes a problem, the control circuit needs to be simplified, etc., the electronic current control unit and the hall current control unit on the same main electrode side are A structure that can be performed with the same control electrode is preferable.

  This bidirectional switch is formed on the insulating substrate 1 so as to be integrated. As the insulating substrate 1, for example, a p-type, n-type, or high-resistance silicon semiconductor layer 2 formed on a buried oxide film 3 can be used.

  The element surface of FIG. 1 is shown in FIG. 3 shows a cross-sectional structure of a portion where the n-type semiconductor layer 11, the p-type semiconductor layer 12, the n-type semiconductor layer 13, the p-type semiconductor layer 14, and the n-type semiconductor layer 15 are arranged, that is, a cross section taken along line AB in FIG. Shown in 4 shows a cross-sectional structure of a portion where the p-type semiconductor layer 16, the n-type semiconductor layer 17, the p-type semiconductor layer 18, the n-type semiconductor layer 19, and the p-type semiconductor layer 20 are arranged, that is, a cross section taken along line CD in FIG. Shown in

  As shown in FIGS. 3 and 4, the positional relationship of the semiconductor layers on the insulating substrate 1 is uniform without changing in the thickness direction. The insulator 4 is located between the electron current control unit and the hole current control unit, and prevents electrons or holes from flowing between the electron current control unit and the hole current control unit. In order to form the insulator 4, a hole is formed until reaching the insulating film 3, and then the side surface of the hole is oxidized. Then fill in the holes as needed.

  A super junction structure is formed between the first current control unit on the first main electrode 21 side and the second current control unit on the second main electrode 22 side. The n-type semiconductor layer 13 and the p-type semiconductor layer 18 forming the super junction structure are in direct contact with each other at the element center. The n-type semiconductor layer 13 and the p-type semiconductor layer 18 are arranged periodically and alternately in a direction perpendicular to the direction in which the current flows. It is necessary to control the width and doping concentration of the n-type semiconductor layer 13 and the p-type semiconductor layer 18. This may be achieved by using a conventional super junction design method.

  The electron current control unit and the hole current control unit of the first main electrode 21 and the second main electrode 22 are also formed side by side with the same cycle as the cycle of the super junction. The first electronic current control unit that controls the electron current flowing into and out of the first main electrode 21 includes an n-type semiconductor layer 11, a p-type semiconductor layer 12, and a p-type semiconductor layer 12 that are electrically connected to the main electrode 21. It consists of the 1st control electrode 23 connected to. By making the potential of the control electrode 23 higher than the potential of the main electrode 21 and injecting holes from the control electrode 23, the electron current control unit is turned on, and between the n-type semiconductor layer 11 and the n-type semiconductor layer 13. An electronic current flows.

  The second electronic current control unit that controls the electron current flowing into and out of the second main electrode 22 includes an n-type semiconductor layer 15, a p-type semiconductor layer 14, and a p-type semiconductor layer 14 that are electrically connected to the main electrode 22. The second control electrode 24 is connected to the. By making the potential of the control electrode 24 higher than the potential of the main electrode 22 and injecting holes from the control electrode 24, the electron current control unit is turned on, and between the n-type semiconductor layer 15 and the n-type semiconductor layer 13. An electronic current flows.

  The p-type semiconductor layer 12 and the p-type semiconductor layer 14 correspond to the base layer of an npn-type bipolar transistor. It operates on the same principle as a bipolar transistor controlled by a base current. In the electronic current control unit in the on state, electrons flow from both the main electrode side and the super junction side. In the off-state electron current control unit, electrons do not flow from the main electrode side.

  However, the electronic current control unit in the off state flows from the super junction side to the main electrode side because it is the same as the pn diode flowing in the forward direction. For example, when flowing from the n-type semiconductor layer 13 constituting the super junction to the n-type semiconductor layer 11, electrons in the n-type semiconductor layer 13 are diffused between the n-type semiconductor layer 13 and the p-type semiconductor layer 12. After overcoming the flow, it flows through the p-type semiconductor layer 12 to the n-type semiconductor layer 11.

  The first hole current control unit that controls the hole current flowing into and out of the first main electrode 21 includes a p-type semiconductor layer 16, an n-type semiconductor layer 17, and an n-type semiconductor layer 17 that are electrically connected to the main electrode 21. It consists of the 1st control electrode 23 connected to. By making the potential of the control electrode 23 lower than the potential of the main electrode 21 and injecting electrons from the control electrode 23, the hole current control unit is turned on, and between the p-type semiconductor layer 16 and the p-type semiconductor layer 18. Hall current flows.

  The second hole current control unit that controls the hole current flowing into and out of the second main electrode 22 includes a p-type semiconductor layer 20, an n-type semiconductor layer 19, and an n-type semiconductor layer 19 that are electrically connected to the main electrode 22. The second control electrode 24 is connected to the. By making the potential of the control electrode 24 lower than the potential of the main electrode 22 and injecting electrons from the control electrode 24, the hole current control unit is turned on, and between the p-type semiconductor layer 20 and the p-type semiconductor layer 18. Hall current flows.

  The n-type semiconductor layer 17 and the n-type semiconductor 19 correspond to the base layer of a pnp bipolar transistor. It operates on the same principle as a bipolar transistor controlled by a base current. In the hole current control unit in the on state, holes flow from both the main electrode side and the super junction side. In the Hall current control unit in the off state, holes do not flow from the main electrode side.

  However, the Hall current controller in the off state flows from the super junction side because it is the same as the pn diode flowing in the forward direction. For example, when flowing from the p-type semiconductor layer 18 constituting the super junction to the p-type semiconductor layer 20, the hole in the p-type semiconductor layer 18 is a diffusion potential between the p-type semiconductor layer 18 and the n-type semiconductor layer 19. After overcoming the flow, it flows through the n-type semiconductor layer 19 to the p-type semiconductor layer 20.

  Further, the electron current control unit and the hall current control unit on the same main electrode side are connected to the same control electrode. Therefore, when one is turned on, the other is turned off. For example, when the electronic current control unit is turned on, the hole current control unit is turned off. When the control electrode and the main electrode are set to the same potential, both the electron current control unit and the hall current control unit are off.

  As a method for forming a semiconductor layer structure, a method for forming a main electrode, a method for forming a control electrode, and the like, a known bipolar transistor manufacturing method may be used. At the junction between the n-type semiconductor layer 11 and the electrode of the n-type semiconductor layer 15 electrically connected to each of the main electrode 21 and the main electrode 22, a high-concentration n-type is used to reduce ohmic resistance as necessary. A semiconductor layer may be provided. Alternatively, the doping concentration is adjusted.

  Similarly, the junction between the p-type semiconductor layer 16 and the electrode of the p-type semiconductor layer 20 electrically connected to each of the main electrode 21 and the main electrode 22 has a high concentration in order to reduce ohmic resistance as necessary. A p-type semiconductor layer may be provided. Alternatively, the doping concentration is adjusted. The high concentration layer for reducing the ohmic resistance to the n-type semiconductor layer or the p-type semiconductor layer is the same in the other embodiments, and is formed on the electrode portion as necessary.

  When bidirectional switching is performed using this element, it is necessary to control the voltages of the control electrode 23 and the control electrode 24. The control method is as follows. First, the case where the element is turned off will be described. In order to prevent a current from flowing from the main electrode 21 toward the main electrode 22 when the potential of the main electrode 21 is higher than the potential of the main electrode 22, holes flow from the main electrode 21 and electrons from the main electrode 22. Must be prevented at the same time. For this purpose, the potential of the control electrode 23 may be the same or higher than that of the main electrode 21, and the potential of the control electrode 24 may be the same or lower than that of the main electrode 22.

  In order to prevent a current from flowing from the main electrode 22 toward the main electrode 21 when the potential of the main electrode 22 is higher than the potential of the main electrode 21, the potential of the control electrode 23 should be the same as that of the main electrode 21. Alternatively, it may be lowered and the potential of the control electrode 24 may be the same as or higher than that of the main electrode 22. When the potential of the control electrode 23 is set to the same potential as the main electrode 21 and the potential of the control electrode 24 is set to the same potential as that of the main electrode 22, bidirectional current is blocked.

  Next, a case where a current is passed from the main electrode 21 toward the main electrode 22 will be described. There are three ways to pass current. In the first method, the potential of the control electrode 23 is set higher than the potential of the main electrode 21, and the potential of the control electrode 24 is set higher than the potential of the main electrode 22. The electronic current control units of both the main electrode 21 and the main electrode 22 are turned on. In addition, the hole current control portions of both the main electrode 21 and the main electrode 22 are off. In this case, electrons are carriers. The hole does not flow. Therefore, conductivity modulation due to double injection does not occur. This is an effective method when the voltage of power to be switched is low.

  The second method is a method in which the potential of the control electrode 23 is made lower than the potential of the main electrode 21 and the potential of the control electrode 24 is made lower than the potential of the main electrode 22. The hall current control units of both the main electrode 21 and the main electrode 22 are turned on. In addition, the electronic current control units of both the main electrode 21 and the main electrode 22 are off. In this case, the hole becomes the carrier. Electrons do not flow. Therefore, conductivity modulation due to double injection does not occur.

  The third method is a method of turning on the hole current control unit on the main electrode 21 side and turning on the electron current control on the main electrode 22 side. For this purpose, the potential of the control electrode 23 is set lower than the potential of the main electrode 21, and the potential of the control electrode 24 is set higher than the potential of the main electrode 22. Holes from the main electric current 21 flow from the p-type semiconductor layer 16 to the n-type semiconductor layer 17 and the p-type semiconductor layer 18. Electrons from the main electrode 22 side flow from the n-type semiconductor layer 15 to the p-type semiconductor layer 14 and the n-type semiconductor layer 13.

  However, the electrode of the p-type semiconductor layer 12 of the electron current control unit on the main electrode 21 side and the electrode of the n-type semiconductor layer 17 of the hole current control unit are both connected to the same control electrode 23. Therefore, when the hole current control unit on the main electrode 21 side is turned on, the electron current control unit is not turned on.

  Similarly, the electrode of the p-type semiconductor layer 14 of the electron current control unit on the main electrode 22 side and the electrode of the n-type semiconductor layer 19 of the hole current control unit are both connected to the same control electrode 24. Therefore, when the electronic current control unit on the main electrode 22 side is turned on, the hole current control unit is not turned on.

  Therefore, in the third method, the holes flowing through the p-type semiconductor layer 18 from the main electrode 21 side toward the main electrode 22 side overcome the diffusion potential between the p-type semiconductor layer 18 and the n-type semiconductor layer 19. After that, it passes through the n-type semiconductor layer 19. Similarly, electrons flowing through the n-type semiconductor layer 13 from the main electrode 22 side toward the main electrode 21 side overcome the diffusion potential between the n-type semiconductor layer 13 and the p-type semiconductor layer 12 and then the p-type semiconductor. Pass through to layer 12.

  As described above, although there is a voltage drop due to the diffusion potential, both holes and electrons are injected, and thus conductivity modulation similar to that of IGBT occurs. This mainly occurs in the super junction structure portion composed of the n-type semiconductor layer 13 and the p-type semiconductor layer 18 that are adjacent to each other. Specifically, holes are supplied from the p-type semiconductor layer 18 to the n-type semiconductor layer 13 and further supplied from the n-type semiconductor layer 13 to the p-type semiconductor layer 18. As the number of carriers increases, the resistance decreases. This effect is more likely to occur as these layers are narrower. The longer the length, the more likely it will occur.

  When the switching power voltage is high and the withstand voltage is designed to be high, the element length becomes long and the resistance increases, but it is possible to suppress a large increase in resistance by conductivity modulation. As a result, even if there is a voltage drop due to the diffusion potential, it is possible to reduce the element resistance exceeding the voltage drop due to the diffusion potential by conductivity modulation. Therefore, this method is effective as a method for turning on the element when used for an application requiring a high breakdown voltage.

  By controlling the electron current flowing in the n-type semiconductor layer constituting the super junction and the hole current flowing in the p-type semiconductor layer also constituting the super junction to flow in the ON state, double injection is performed. The effect of lowering resistance can also be obtained. As described above, it is impossible to obtain the effect of reducing the resistance by double injection in the super junction structure in the conventional super junction structure transistor.

  In the above description, the case where the current flows from the main electrode 21 toward the main electrode 22 has been described, but the same applies to the case where the current flows from the main electrode 22 to the main electrode 21. Since it has a symmetric structure, it may be operated symmetrically.

  Next, a case where the bidirectional switch is used as a diode will be described. The third method of flowing current is also a method of blocking current in the reverse direction. For example, when the potential of the control electrode 23 is made lower than that of the main electrode 21 and the potential of the control electrode 24 is made higher than that of the main electrode 22, current flows from the main electrode 21 side to the main electrode 22 side. No current flows to the electrode 21 side. When the control electrode is in this state, the bidirectional switch operates as a diode.

  When only one of the four current control units is turned on, the diode operates. For example, if the electronic current control unit on the main electrode 21 side is turned on, current does not flow from the main electrode 21 side to the main electrode 22 side, but current flows from the main electrode 22 side to the main electrode 21 side. As another example, if the hall current control unit on the main electrode 21 side is turned on, current flows from the main electrode 21 side to the main electrode 22 side, and no current flows from the main electrode 22 side to the main electrode 21 side.

  Using this characteristic, the bidirectional switch can be used as a feedback diode or a free wheel diode. That is, a diode is used when the current cannot be completely stopped in a circuit having a reactor such as a coil or leakage inductance, but it can be used in the same manner as the diode in that case. It can also be used when energy needs to be regenerated using diode characteristics.

  Next, latch-up will be described. When the conductivity modulation by double injection occurs in the super junction structure, the bidirectional switch of the present invention may not be controlled by the control electrode and may always be turned on. In other words, latch-up can occur. This happens as follows.

  For example, it is assumed that the potential of the main electrode 21 is higher than the potential of the main electrode 22 and current flows from the main electrode 21 side to the main electrode 22 side. When conductivity modulation occurs, holes also flow through the n-type semiconductor layer 13 constituting the super junction structure. The holes enter the electron current control unit on the main electrode 22 side, and flow into the p-type semiconductor layer 14 of the electron current control unit. As a result, the electron current control unit cannot be turned off.

  Further, when conductivity modulation occurs, electrons also flow through the p-type semiconductor layer 18 constituting the super junction. The electrons enter the hole current control unit on the main electrode 21 side, flow into the n-type semiconductor layer 17 of the hole current control unit, and as a result, the hole current control cannot be turned off. As a result, since both the hole current control unit on the main electrode 21 side and the electron current control unit on the main electrode 22 side cannot be turned off, latch-up occurs.

  At this time, in order to turn off the bidirectional switch, the flow of electrons and holes may be controlled. As for electrons, the electrons that have flowed from the super junction structure portion into the hole current control unit on the main electrode 21 side may flow into the electron current control unit on the main electrode 21 side. With respect to the holes, the holes that have flowed from the super junction structure portion into the electron current control unit on the main electrode 22 side may flow into the hole current control unit on the main electrode 22 side.

  That is, on the main electrode side having a high voltage, the hole current control unit is turned off and the electronic current control is turned on. On the main electrode side where the voltage is low, the Hall current control unit is turned on and the electronic current control unit is turned off. Specifically, in this case, the potential of the control electrode 23 may be set higher than that of the main electrode 21 and the potential of the control electrode 24 may be set lower than that of the main electrode 22.

  At this time, electrons are discharged from the n-type semiconductor layer 17 through the control electrode 23 in the hole current control unit on the main electrode 21 side. Therefore, it is difficult for holes to enter from the p-type semiconductor layer 16 to the n-type semiconductor layer 17, and the amount of holes entering the super junction structure side is reduced. Therefore, the conductivity modulation in the super junction structure is weakened and the resistance is increased. Since the resistance has increased, the amount of electrons entering the n-type semiconductor layer 17 through the super junction structure is reduced.

  On the other hand, in the electron current control unit on the main electrode 21 side, holes are injected from the control electrode 23 into the p-type semiconductor layer 12, so that electrons easily enter the p-type semiconductor layer 12 from the super junction side. As a result, the electron current flowing out to the main electrode 21 side mainly passes through the electron current control unit.

  Also, holes are discharged from the p-type semiconductor layer 14 through the control electrode 24 in the electron current control unit on the main electrode 22 side. Therefore, it becomes difficult for electrons to enter from the n-type semiconductor layer 15 to the p-type semiconductor layer 14, and the amount of electrons entering the super junction structure side is reduced. Therefore, the conductivity modulation in the super junction structure is weakened and the resistance is increased. Since the resistance has increased, the amount of holes entering the p-type semiconductor layer 14 through the super junction structure is reduced.

  On the other hand, in the hole current control section on the main electrode 22 side, electrons are injected from the control electrode 24 into the n-type semiconductor layer 19, so that holes can easily enter the n-type semiconductor layer 19 from the super junction side. As a result, the hole current flowing out to the main electrode 22 side mainly passes through the hole current control unit. As a result, the hall current control unit on the main electrode 21 side and the electron current control unit on the main electrode 22 side are turned off, and the bidirectional switch is turned off.

  In the above Embodiment 1, the horizontal bidirectional switch formed on the insulating substrate has been described. However, vertical devices with this layer structure are also possible. The electron current controller and the hole current controller are insulated using a trench structure or the like. An n-type and a p-type layer structure may be formed by ion implantation or epi growth.

(Embodiment 2)
Next, FIG. 5 shows a bidirectional switch using a field effect type control electrode. This is a MOS gate structure using an oxide as an insulator. However, a field-effect gate structure using an insulator such as a high dielectric constant material (High-K material) can be used as necessary. The bidirectional switch is formed on the insulating substrate 1 so as to be integrated. The first main electrode 41 and the second main electrode 42 are connected to an electron current control unit and a hole current control unit that are alternately arranged with an insulator interposed therebetween.

  The structure shown in FIG. 5 is a structure in which the electron current control unit and the hall current control unit on the same main electrode side are connected to the same control electrode. It is also possible to control the electron current control unit and the hall current control unit on the same main electrode side with different control electrodes. In the case of controlling with different control electrodes, both the main electrode 41 side and the main electrode 42 side are provided with one electrode for controlling the electron current and one electrode for controlling the hall current. It is possible to control the switch.

  However, when the process becomes complicated, the capacity between the control electrodes becomes a problem, the control circuit needs to be simplified, etc., the electronic current control unit and the hall current control unit on the same main electrode side are A structure that can be performed with the same control electrode is preferable.

  The semiconductor surface from which the first main electrode 41, the second main electrode 42, the first control electrode 43, the second control electrode 44, the insulating layer 45, and the insulating layer 46 are removed for the description of the semiconductor structure of the device. The structure is shown in FIG.

  The cross-sectional structure of the portion where the n-type semiconductor layer 31, the p-type semiconductor layer 32, the n-type semiconductor layer 33, the p-type semiconductor layer 34, and the n-type semiconductor layer 35 are arranged, that is, the cross-sectional structure along the AB direction in FIG. As shown in FIG. The cross-sectional structure of the portion where the p-type semiconductor layer 36, the n-type semiconductor layer 37, the p-type semiconductor layer 38, the n-type semiconductor layer 39, and the p-type semiconductor layer 40 are arranged, that is, the cross-sectional structure along the CD direction in FIG. As shown in FIG.

  The insulator 4 between the electron current control unit and the hole current control unit is provided from the element surface to the insulating substrate, and prevents electrons or holes from flowing between the electron current control unit and the hole current control unit. A super junction structure is formed between the first current control unit on the first main electrode 41 side and the second current control unit on the second main electrode 42 side. The n-type semiconductor layer 33 and the p-type semiconductor layer 38 forming the super junction structure are in direct contact with each other at the element center. The n-type semiconductor layers 33 and the p-type semiconductor layers 38 are arranged periodically and alternately in a direction perpendicular to the direction in which the current flows. It is necessary to control the width and doping concentration of the n-type semiconductor layer 33 and the p-type semiconductor layer 38. This may be achieved by using a conventional super junction design method.

  Next, the electronic current control unit will be described. The first electronic current control unit that controls the electronic current flowing into and out of the first main electrode 41 includes an n-type semiconductor layer 31 that is electrically connected to the main electrode 41 and a p-type semiconductor that is electrically connected to the main electrode 41. The oxide film 45 and the first control electrode 43 are provided on the layer 32 and the p-type semiconductor layer 32. A channel is formed at the interface between the p-type semiconductor layer 32 and the oxide film 45. The electron density in the channel is controlled by the voltage applied to the control electrode 43.

  If the potential of the control electrode 43 and the potential of the main electrode 41 are equal, there is no electron in the portion where the channel is formed, and the electron current control unit is off. When the potential of the control electrode 43 is made higher than the potential of the main electrode 41, electrons are present in the channel portion and an electron current flows between the n-type semiconductor layer 31 and the n-type semiconductor layer 33.

  The second electronic current control unit that controls the electron current flowing into and out of the second main electrode 42 includes an n-type semiconductor layer 35 that is electrically connected to the main electrode 42, and a p-type semiconductor that is electrically connected to the main electrode 42. The layer 34 includes an oxide film 46 and a second control electrode 44 provided on the p-type semiconductor layer 34. A channel is formed at the interface between the p-type semiconductor layer 34 and the oxide film 46. The electron density in the channel is controlled by the voltage applied to the control electrode 44.

  If the potential of the control electrode 44 is equal to the potential of the main electrode 42, there is no electron in the portion where the channel is formed, and the electron current control unit is off. When the potential of the control electrode 44 is made higher than the potential of the main electrode 42, electrons are present in the channel portion and an electron current flows between the n-type semiconductor layer 35 and the n-type semiconductor layer 33. The principle of current control is the same as that of an n-channel MOS transistor. The p-type semiconductor layer 32 and the p-type semiconductor 34 correspond to a MOS base layer or body.

  When the electron current control unit is off, electrons do not flow from the main electrode side to the super junction side. However, it flows from the super junction side to the main electrode side because it is the same as the case of flowing in the forward direction of the pn diode. In order to explain this characteristic, for example, the potential of the control electrode 43 is equal to or lower than the potential of the main electrode 41, and no electron channel is formed at the interface between the p-type semiconductor layer 32 and the oxide film 45. Consider a case where the electron current control unit on the electrode 41 side is off. In addition, it is assumed that the electron current control unit on the main electrode 42 side is on and electrons can flow from the main electrode 42 side to the n-type semiconductor layer 33 constituting the super junction.

  In this case, in order for electrons to flow from the n-type semiconductor layer 33 constituting the super junction to the p-type semiconductor layer 32, it is necessary to overcome the diffusion potential between the n-type semiconductor layer 33 and the p-type semiconductor layer 32. The n-type semiconductor layer 33 and the p-type semiconductor layer 32 can be regarded as pn diodes, and the direction in which electrons flow in this case is the forward direction of the pn diode. Therefore, like the pn diode, the current flows according to a current-voltage characteristic having a rising voltage determined by a diffusion potential between the n-type semiconductor layer 33 and the p-type semiconductor layer 32.

  Next, the hall current control unit will be described. The first hole current control unit that controls the hole current flowing into and out of the first main electrode 41 includes a p-type semiconductor layer 36 that is electrically connected to the main electrode 41 and an n-type semiconductor that is electrically connected to the main electrode 41. The oxide film 45 and the first control electrode 43 are provided on the layer 37 and the n-type semiconductor layer 37. A channel is formed at the interface between the n-type semiconductor layer 37 and the oxide film 45. The hole density in the channel is controlled by the voltage applied to the control electrode 43.

  When the potential of the control electrode 43 is equal to the potential of the main electrode 41, there is no hole in the portion where the channel is formed, and the hole current control unit is off. When the potential of the control electrode 43 is made lower than the potential of the main electrode 41, holes exist in the channel portion and a hole current flows between the p-type semiconductor layer 36 and the p-type semiconductor layer 38.

  The second hole current control unit that controls the hole current flowing into and out of the second main electrode 42 includes a p-type semiconductor layer 40 that is electrically connected to the main electrode 42, and an n-type semiconductor that is electrically connected to the main electrode 42. The layer 39 includes an oxide film 46 and a second control electrode 44 provided on the n-type semiconductor layer 39. A channel is formed at the interface between the n-type semiconductor layer 39 and the oxide film 46. The voltage applied to the control electrode 44 controls the hole density in the channel.

  If the potential of the control electrode 44 is equal to the potential of the main electrode 42, there is no hole in the portion where the channel is formed, and the hole current control unit is off. When the potential of the control electrode 44 is made lower than the potential of the main electrode 42, holes exist in the channel portion and a hole current flows between the p-type semiconductor layer 40 and the p-type semiconductor layer 38. The principle of current control is the same as that of a p-channel MOS transistor. The n-type semiconductor layer 37 and the n-type semiconductor 39 correspond to a MOS base layer or body.

  When the hole current control unit is off, no hole flows from the main electrode side to the super junction side. However, it flows from the super junction side to the main electrode side because it is the same as the case of flowing in the forward direction of the pn diode. In order to explain this characteristic, for example, the potential of the control electrode 43 is equal to or higher than the potential of the main electrode 41, and no hole channel is formed at the interface between the n-type semiconductor layer 37 and the oxide film 45. Consider a case where the hole current control unit on the electrode 41 side is off. Further, it is assumed that the hole current control unit on the main electrode 42 side is on and holes can flow from the main electrode 42 side to the p-type semiconductor layer 38 constituting the super junction.

  In this case, in order for holes to flow from the p-type semiconductor layer 38 constituting the super junction to the n-type semiconductor layer 37, it is necessary to overcome the diffusion potential between the p-type semiconductor layer 38 and the n-type semiconductor layer 37. The p-type semiconductor layer 38 and the n-type semiconductor layer 37 can be regarded as pn diodes, and the direction in which holes flow in this case is the forward direction of the pn diode. Therefore, like the pn diode, the current flows according to a current-voltage characteristic having a rising voltage determined by a diffusion potential between the p-type semiconductor layer 38 and the n-type semiconductor layer 37.

  The electrode of the hall current control unit and the electrode of the electron current control unit are connected to the same control electrode. Therefore, the Hall current control unit and the electronic current control unit cannot be turned on at the same time. Can be turned on one by one. The structure shown in FIG. 5 is a normally-off control electrode.

  If the control electrode 43 and the main electrode 41 are set to the same potential, both the electron current control unit and the hole current control unit are off. If the potential of the control electrode 43 is made higher than the potential of the main electrode 41, the electron current control unit is turned on and the hole current control unit is turned off. Conversely, if the potential of the control electrode 43 is made lower than the potential of the main electrode 41, the electron current control unit is turned off and the hole current control unit is turned on.

  Similarly, if the control electrode 44 and the main electrode 42 are set to the same potential, both the electron current control unit and the hole current control unit are off. If the potential of the control electrode 44 is made higher than the potential of the main electrode 42, the electron current control unit is turned on and the hole current control unit is turned off. Conversely, if the potential of the control electrode 44 is made lower than the potential of the main electrode 42, the electron current control unit is turned off and the hole current control unit is turned on.

  The above is a partial description of the structure and function of the bidirectional switch. The production method of the semiconductor layer structure, the ohmic electrode used for the main electrode, the MOS structure of the current control unit, and the like is the same as the production method of a known MOS transistor.

  When bidirectional switching is performed using this element, it is necessary to control the voltages of the control electrode 43 and the control electrode 44. The control method is as follows. First, the case where the bidirectional switch is turned off will be described.

  It is only necessary to stop holes from flowing from the main electrode on the side having a higher voltage applied from the outside and electrons from flowing from the main electrode on the side having a lower voltage applied from the outside. The potential of the control electrode on the higher voltage side may be equal to or higher than that of the main electrode, and the potential of the control electrode on the lower voltage side may be equal to or lower than that of the main electrode.

  Specifically, in order to prevent a current from flowing from the main electrode 41 toward the main electrode 42 when the potential of the main electrode 41 is higher than the potential of the main electrode 42, the potential of the control electrode 43 is set to the main electrode 41. What is necessary is just to make it higher and to make the electric potential of the control electrode 44 lower than the main electrode 42.

  Similarly, in order to prevent a current from flowing from the main electrode 42 toward the main electrode 41 when the potential of the main electrode 42 is higher than the potential of the main electrode 41, the potential of the control electrode 43 is set lower than that of the main electrode 41. Then, the potential of the control electrode 44 may be made higher than that of the main electrode 42.

  Since the structure shown in FIG. 5 is a normally-off structure, if the potential of the control electrode 43 is set to the same potential as that of the main electrode 41 and the potential of the control electrode 44 is set to the same potential as that of the main electrode 42, the direction of the control electrode 43 is No current flows. For this reason, when designing a circuit for controlling the control electrode, the control electrode 43 has the same potential as the main electrode 41 and the control electrode 44 has the same potential as the main electrode 41 when the control circuit is in a normal state such as when the power is off. If the potential is the same as that of the electrode 42, a normally-off bidirectional switch is obtained.

  Next, a method of flowing current, that is, a method of turning on the bidirectional switch will be described. A case will be described in which the potential of the main electrode 41 is higher than the potential of the main electrode 42 and current flows from the main electrode 41 toward the main electrode 42. Moreover, since the element is symmetric in the method of flowing current in the reverse direction, the element may be operated symmetrically. There are three ways to pass current.

  The first method is mainly a method of flowing electrons. In this case, the electronic current control units of both the main electrode 41 and the main electrode 42 are turned on. That is, the potential of the control electrode 43 is set higher than the potential of the main electrode 41, and the potential of the control electrode 44 is set higher than the potential of the main electrode 42. In this case, electrons are carriers. The hole does not flow. Therefore, conductivity modulation due to double injection does not occur. This is an effective method when the voltage of power to be switched is low.

  The second method is mainly a method of flowing holes. In this case, the hole current control units of both the main electrode 41 and the main electrode 42 are turned on. That is, the potential of the control electrode 43 is set lower than the potential of the main electrode 41, and the potential of the control electrode 44 is set lower than the potential of the main electrode 42. In this case, the hole becomes the carrier. Electrons do not flow. Therefore, conductivity modulation due to double injection does not occur.

  The third method is a method of turning on the hole current control unit on the main electrode 41 side and turning on the electron current control unit on the main electrode 42 side. For this purpose, the potential of the control electrode 43 is made lower than the potential of the main electrode 41, and a hole channel is formed at the interface between the n-type semiconductor layer 37 and the oxide film 45. Further, the potential of the control electrode 44 is set higher than the potential of the main electrode 42, and an electron channel is formed at the interface between the p-type semiconductor layer 34 and the oxide film 46. Accordingly, holes from the main electrode 41 side flow from the p-type semiconductor layer 36 to the p-type semiconductor layer 38 through the hole channel at the interface between the n-type semiconductor layer 37 and the oxide film 45. Electrons from the main electrode 42 side flow from the n-type semiconductor layer 35 to the n-type semiconductor layer 33 through the electron channel at the interface between the p-type semiconductor layer 34 and the oxide film 46.

  In the third method, electrons flowing through the n-type semiconductor layer 33 from the main electrode 42 side toward the main electrode 41 side overcome the diffusion potential when passing through the p-type semiconductor layer 32. Similarly, holes flowing in the p-type semiconductor layer 38 from the main electrode 41 side to the main electrode 42 side will overcome the diffusion potential when passing through the n-type semiconductor layer 39.

  It is also possible for electrons flowing through the n-type semiconductor layer 33 to flow to the p-type semiconductor layer 38 and holes flowing through the p-type semiconductor layer 38 to flow to the n-type semiconductor layer 33. In this case, the conductivity by double injection Modulation occurs and resistance decreases. Thus, since both holes and electrons are injected, conductivity modulation similar to that of IGBT occurs. Therefore, it is effective when used for an application with a high breakdown voltage.

  In the above description, the case where the current flows from the main electrode 41 toward the main electrode 42 has been described, but the same applies to the case where the current flows from the main electrode 42 to the main electrode 41. It is also possible to operate this bidirectional switch like a diode.

  The third method of flowing current in this embodiment is a method of blocking current in the reverse direction, and no current flows in the reverse direction. Therefore, it functions as a diode.

  As another method, if only one of the four current control units is turned on, it functions as a diode. For example, if the electronic current control unit on the main electrode 41 side is turned on, no current flows from the main electrode 41 side to the main electrode 42 side, but current flows from the main electrode 42 side to the main electrode 41 side. As another example, if the hall current control unit on the main electrode 41 side is turned on, current flows from the main electrode 41 side to the main electrode 42 side, but no current flows from the main electrode 42 side to the main electrode 41 side. .

  This characteristic can be used as a feedback diode or a freewheeling diode. A diode is used when the current cannot be completely stopped in a circuit having a reactor such as a coil or leakage inductance, but it can be used in the same manner as the diode in that case. It can also be used when energy needs to be regenerated using diode characteristics.

  The horizontal bidirectional switch having the field effect type current controller formed on the insulating substrate is described above. However, vertical devices with this layer structure are also possible. The electron current controller and the hole current controller are insulated using a trench structure or the like. In addition, if a gate portion is formed in this trench structure, it is possible to shorten the cycle in which the n-type semiconductor layer and the p-type semiconductor layer constituting the super junction are repeated. Further, n-type and p-type layer structures may be formed by ion implantation or epi growth.

(Embodiment 3)
The design of the power supply device is important when the power supply of the control circuit for controlling the control electrode is not turned on, that is, in the normal state (normal). In the control of a motor or the like, when the gate control circuit stops operating when the main power is cut off or at the time of a power failure, it is necessary to feed back current to regenerate energy or protect the circuit.

  At present, a diode clamp circuit for this purpose is used separately. However, if the bidirectional switch can function as a feedback diode when the gate circuit does not function, a circuit for feeding back current is unnecessary.

  For this purpose, the threshold voltage of the current control unit may be controlled in the bidirectional switch using the field effect type current control unit shown in FIG. The bidirectional switch can be diode-operated at normal time (normal) or turned on without a diffusion potential. For threshold control, a layer for threshold control may be provided as shown in FIG.

  FIG. 9 does not show the main electrode, the control electrode, and the oxide film of the MOS structure, but is the same as FIG. The structure shown in FIG. 9 controls the threshold voltage in the portion shown in FIG. 5 where a channel is formed at the interface between the insulator or oxide film under the control electrode of the current control unit and the semiconductor underneath. A layer is created for this purpose.

  A cross-sectional structure of a portion where the n-type semiconductor layer 31, the p-type semiconductor layer 32, the threshold voltage control layer 47, the n-type semiconductor layer 33, the threshold voltage control layer 48, the p-type semiconductor layer 34, and the n-type semiconductor layer 35 are arranged. As shown in FIG. A cross-sectional structure of a portion where the p-type semiconductor layer 36, the n-type semiconductor layer 37, the threshold voltage control layer 49, the p-type semiconductor layer 38, the threshold voltage control layer 50, the n-type semiconductor layer 39, and the p-type semiconductor layer 40 are arranged. As shown in FIG.

  The threshold voltage control layer 47 controls the threshold voltage of the electronic current control unit on the main electrode 41 side. The threshold voltage control layer 48 controls the threshold voltage of the electron current control unit on the main electrode 42 side. The threshold voltage control layer 49 controls the threshold voltage of the hole current control unit on the main electrode 41 side. The threshold voltage control layer 50 controls the threshold voltage of the hole current control unit on the main electrode 42 side.

  The threshold voltage can be controlled by changing the doping concentration of the threshold voltage control layer. The threshold voltage also depends on the thickness of an insulating film such as an oxide film between the control electrode. For this purpose, a conventional design method may be used.

  In order to make the electron current control unit normally on, an n-type threshold voltage control layer may be provided at the interface between the p-type semiconductor layer and the oxide film where the electron channel is formed, that is, on the surface of the p-type semiconductor layer. . A thin n-type semiconductor layer is formed by ion implantation or diffusion. The amount and thickness of ion implantation are designed so that the n-type semiconductor layer functions as a channel through which electrons flow if the potential of the control electrode is equal to the potential of the main electrode. What is necessary is just to design so that a threshold voltage may be about -3 to -5V.

  If n-type doping is performed at a slightly higher concentration of the threshold voltage control layer, the threshold voltage can be lowered, for example, -10 V or less. On the other hand, if it is p-type, it can be about + 5V. Similarly, if p-type is used at a higher concentration, + 10V or more can be achieved.

  Similarly, in order to make the hole current control part normally on, there is a p-type threshold voltage control layer at the interface between the n-type semiconductor layer and the oxide film where the hole channel is formed, that is, on the surface of the n-type semiconductor layer. That's fine. A thin p-type semiconductor layer is formed by ion implantation or diffusion. The ion implantation amount and thickness are designed so that the p-type semiconductor layer functions as a channel through which holes flow if the potential of the control electrode is equal to the potential of the main electrode. The threshold voltage may be designed to be about 3 to 5V.

  If the p-type doping is performed at a slightly higher concentration of the threshold voltage control layer, the threshold voltage can be made higher, for example, 10 V or higher. On the other hand, if it is made n-type, it can be made about -5V. Similarly, if n-type is used at a higher concentration, it can be made -10V or less.

  The case where threshold voltage control is performed below to function as a diode in a normal state will be described below. In the first method, the electronic current control unit of the main electrode on the downstream side in the forward direction when it is desired to function as a diode, that is, on the downstream side when current is passed, is set to be normally on. The other three current controls are normally off. For example, in order to function as a diode that allows a current to flow when the potential of the main electrode 41 is higher than the potential of the main electrode 42 and blocks the current when the potential of the main electrode 41 is lower than the potential of the main electrode 42, the main electrode 42 The electronic current control unit on the side is normally turned on.

  In addition, a control power supply circuit that drives the control electrode 43 is designed so that the potential of the control electrode 43 and the potential of the main electrode 41 are equal at the normal time (in other words, when the main power supply is cut off or during a power failure). In this case, the electronic current control unit and the hole current control unit controlled by the control electrode 43 have a normally-off structure.

  Similarly, a control power supply circuit for driving the control electrode 44 is designed so that the potential of the control electrode 44 and the potential of the main electrode 42 are equal in normal time (normal). In this way, the electronic current controller controlled by the control electrode 44 has a normally-on structure. The hole current control unit has a normally-off structure. With such a structure and control method, the bidirectional switch functions as a diode in a normal state. Moreover, only an electronic current flows in this structure.

  In the second method, the hole current control unit of the main electrode on the upstream side in the forward direction when it is desired to function as a diode, that is, on the upstream side when current is passed, is set to be normally on. The other three current controls are normally off. For example, in order to function as a diode that allows current to flow when the potential of the main electrode 41 is higher than the potential of the main electrode 42 and to block current when the potential of the main electrode 41 is lower than the potential of the main electrode 42, the main electrode 41 Side Hall current control section is normally on.

  If the control method of the control electrode is performed in the same manner as in the first method, the bidirectional switch having this structure functions as a diode in a normal state, that is, in a normal state. Further, in this structure, only a hole current flows.

  As described above, the first method and the second method that function as a diode in a normal state have been described. If both are combined, both electrons and holes flow in the super junction structure when a current flows in the forward direction. It becomes a low resistance diode.

(Embodiment 4)
Although the method for operating as a diode in the normal state has been described above, it is also possible to create a normally-on bidirectional switch. The potential of the main electrode 41 is V1, and the potential of the main electrode 42 is V2. The potential of the control electrode 43 is Vc1, and the potential of the control electrode 44 is Vc2. The threshold voltage is usually defined as the potential of the control electrode relative to the potential of the main electrode. For example, in FET, it is the gate potential with respect to the source potential.

  The threshold voltage of the electron current control unit on the main electrode 1 side is Vn1, and the threshold voltage of the hole current control unit is Vp1. If Vc1-V1> Vn1, the electronic current controller is on. If not, it is off. Similarly, if Vc1-V1 <Vp1, the hole current control unit is on. If not, it is off.

  Similarly, the threshold voltage of the electron current controller on the main electrode 2 side is Vn2, and the threshold voltage of the hole current controller is Vp2. If Vc2-V2> Vn2, the electronic current controller is on. If not, it is off. Similarly, if Vc2-V2 <Vp2, the hole current control unit is on. If not, it is off.

  The circuit for controlling the control electrodes is designed so that V1 = Vc1 and V2 = Vc2 in a normal state. In this case, if the threshold voltage control layer is designed so that Vn1 <0 <Vp1 and Vn2 <0 <Vp2, a normally-on bidirectional switch is obtained.

(Embodiment 5)
Further, in the normal state, it acts as a diode, and when it is on, both the electron current and the hall current can flow without a diffusion potential. For example, in the case of normal use as a diode in which current flows from the main electrode 1 to the main electrode 2, the threshold voltage is controlled so as to satisfy the conditions of 0 <Vn1 <Vp1 and Vn2 <Vp2 <0.

  In this way, on the main electrode 21 side, when Vc1-V1 <Vn1, only the hole current control unit is on. When Vn1 <Vc1-V1 <Vp1, both the hole current control unit and the electron current control unit are on. When Vp1 <Vc1-V1, only the electronic current control unit is turned on.

  The main electrode 42 side is as follows. When Vc2-V2 <Vn2, only the hall current control unit is on. When Vn2 <Vc2-V2 <Vp2, both the hole current control unit and the electron current control unit are on. When Vp2 <Vc2-V2, only the electronic current control unit is turned on. Specifically, for example, Vn1 = 5V, Vp1 = 15V, Vn2 = -15V, and Vp2 = -5V.

  The circuit design of the current control electrode is as follows. In the normal case, the potentials of the control electrode and the main electrode are equal, that is, Vc1-V1 = 0 and Vc2-V2 = 0. At this time, Vc1-V1 is controlled at three levels of 0V, + 10V, and + 20V. Vc2-V2 is controlled at three levels of -20V, -10V, and 0V.

  During normal operation, that is, when Vc1-V1 = 0 and Vc2-V2 = 0, a current flows from the main electrode 41 to the main electrode 42, and operates as a diode that blocks current from the main electrode 42 to the main electrode 41. To do. Further, when Vc1-V1 = 10V and Vc2-V2 = -10V, it becomes possible to flow hole current and electron current without diffusion potential. When Vc1−V1 = 20V and Vc2−V2 = −20V, current is blocked from the main electrode 41 to the main electrode 42, and operates as a diode for flowing current from the main electrode 42 to the main electrode 41.

(Embodiment 6)
Next, a method for stopping latch-up will be described. In the second embodiment, the main electrode 41 is connected to the n-type semiconductor layer 37, and the main electrode 42 is connected to the n-type semiconductor layer 39. Further, there is no insulating film between the n-type semiconductor layer 33 and the p-type semiconductor layer 38. Therefore, although depending on the shape of the element, for example, when the potential of the main electrode 41 is higher than the potential of the main electrode 42, one of the p-type semiconductor layers 38 near the control electrode 44 from the n-type semiconductor layer 39. A path through which electrons pass immediately through the portion to the n-type semiconductor layer 33, pass through the n-type semiconductor layer 33, pass through a part of the p-type semiconductor layer 38 near the control electrode 43, and immediately pass through the n-type semiconductor layer 37. There is. This is the electron flow path A. The flow of electrons through the path A cannot be considered alone because it passes through the pn junction many times.

  Similarly, the main electrode 41 is connected to the p-type semiconductor layer 32, and the main electrode 42 is connected to the p-type semiconductor layer 34. Further, there is no insulating film between the n-type semiconductor layer 33 and the p-type semiconductor layer 38. Therefore, depending on the shape of the element, for example, when the potential of the main electrode 41 is higher than the potential of the main electrode 42, a part of the n-type semiconductor layer 33 near the control electrode 43 from the p-type semiconductor layer 32. Passing through the p-type semiconductor layer 38 immediately after passing through the p-type semiconductor layer 38 and passing through a part of the n-type semiconductor layer 33 in the vicinity of the control electrode 44 through the p-type semiconductor layer 38, there is a passage through which holes pass. is there. This is the path B of the hole flow. This flow of holes through the path B cannot be considered alone because it passes through the pn junction many times.

  However, let us consider a case where there is a large amount of current flowing through the element, and both the flow of electrons in path A and the flow of holes in path B exist. In the portion where the flow of electrons and holes coincides, conductivity modulation occurs and the resistance decreases. In the vicinity of the control electrode 43, there is a flow of both electrons and holes, so that the resistance is reduced. Even in the vicinity of the control electrode 44, since there is a flow of both electrons and holes, the resistance is reduced. Therefore, it continues to flow even if there is a pn junction.

  In order to prevent such a current, the hole current control unit on the main electrode side having a high voltage is turned off to turn on the electron current control unit, and the electron current control unit on the main electrode side having a low voltage is turned off. Turn on the current control. For example, when blocking such a current that flows in a state where the potential of the main electrode 41 is higher than the potential of the main electrode 42, the potential of the control electrode 43 is set higher than that of the main electrode 41, and the potential of the control electrode 44 is set to the main electrode 41. Lower than 42.

  At this time, on the main electrode 41 side, an electron channel is formed at the interface between the oxide film 45 and the p-type semiconductor layer 32 due to the potential of the control electrode 43. For this reason, electrons traveling to the main electrode 41 through the n-type semiconductor layer 33 do not need to overcome the diffusion potential, and pass through the channel at the interface between the oxide film 45 and the p-type semiconductor layer 32 to the n-type semiconductor layer 31. I'll go through.

  Since this electron flow passes through the channel on the surface of the p-type semiconductor layer 32, it passes through the n-type semiconductor layer 33, near the control electrode 43, and immediately passes through a part of the p-type semiconductor layer 38. The barrier is smaller than the flow of electrons passing through.

  The same applies to the flow of holes. On the main electrode 42 side, a hole channel is formed at the interface between the oxide film 46 and the n-type semiconductor layer 39 due to the potential of the control electrode 44. Therefore, the holes passing through the p-type semiconductor layer 38 toward the main electrode 42 do not need to overcome the diffusion potential, and pass through the channel at the interface between the oxide film 46 and the n-type semiconductor layer 39 to the p-type semiconductor layer 40. I'll go through.

  Since the flow of holes passes through the channel on the surface of the n-type semiconductor layer 39, it passes through the p-type semiconductor layer 38 and in the vicinity of the control electrode 44 and immediately passes through a part of the n-type semiconductor layer 33. The barrier is smaller than the flow of holes that go through.

  Therefore, as described above, the hole current control unit on the main electrode side having a high voltage is turned off to turn on the electron current control unit, and the electron current control unit on the main electrode side having a low voltage is turned off to turn on the hole current control unit. If the method of turning on is used, the flow of electrons and the flow of holes can be separated, and the device can be stably stopped without latch-up.

(Embodiment 7)
However, if the control with the control electrode cannot prevent the structure, it is necessary to change the structure. Latch-up occurs when both an electron flow path A and a hole flow path B exist.

  In order to prevent such a current path, the p-type semiconductor layer 32, the p-type semiconductor layer 34, the n-type semiconductor layer 37, and the n-type semiconductor layer 32 corresponding to the base layer and having the MOS structure of the control electrode in the structures of FIGS. A structure in which the semiconductor layer 39 is divided into two is effective. For example, the p-type semiconductor layer 32 is divided into two parts: a part that contacts the main electrode 41 and a part that has a MOS structure. Since the base layer having the MOS structure is in a floating state, if necessary, for example, in the electronic current control unit, the part having the MOS structure is changed from the part of the p-type semiconductor layer that contacts the main electrode 41 under the control of the control electrode 43. It is effective to supply the hall to

  FIG. 12 shows the structure. FIG. 13 shows the surface of the semiconductor structure from which the main electrode, control electrode, and insulating film of this structure are removed. Further, a cross-sectional structure of a portion where the p-type semiconductor layer 67, the n-type semiconductor layer 51, the p-type semiconductor layer 52, the n-type semiconductor layer 53, the p-type semiconductor layer 54, the n-type semiconductor layer 55, and the p-type semiconductor layer 68 are arranged, That is, FIG. 14 shows a cross-sectional structure along the direction AB in FIG. A cross-sectional structure of a portion where the n-type semiconductor layer 69, the p-type semiconductor layer 56, the n-type semiconductor layer 57, the p-type semiconductor layer 58, the n-type semiconductor layer 59, the p-type semiconductor layer 60, and the n-type semiconductor layer 70 are arranged, that is, FIG. 13 shows a cross-sectional structure along the CD direction in FIG.

  In this structure, the p-type semiconductor layer 52 is not directly in contact with the first main electrode 61, and a p-type semiconductor layer 67 that is in contact with the main electrode 61 is newly provided. The flow of holes between the p-type semiconductor layer 52 and the p-type semiconductor layer 67 can be controlled by the first control electrode 63. The p-type semiconductor 54 is not directly in contact with the second main electrode 62, and a p-type semiconductor layer 68 that is in contact with the main electrode 62 is newly provided. The hole flow between the p-type semiconductor layer 54 and the p-type semiconductor layer 68 can be controlled by the second control electrode 64.

  Further, the n-type semiconductor layer 57 is not directly in contact with the first main electrode 61, and an n-type semiconductor layer 69 that is in contact with the main electrode 61 is newly provided. The flow of electrons between the n-type semiconductor layer 57 and the n-type semiconductor layer 69 can be controlled by the first control electrode 63. The n-type semiconductor 59 is not directly in contact with the second main electrode 62, and an n-type semiconductor layer 70 that is in contact with the main electrode 62 is newly provided. The flow of electrons between the n-type semiconductor layer 59 and the n-type semiconductor layer 70 can be controlled by the second control electrode 64.

  In this structure, when the gate is off, no problem occurs because electrons and holes are not supplied to the p-type semiconductor layer 52, the p-type semiconductor layer 54, the n-type semiconductor layer 57, and the n-type semiconductor layer 59. .

(Embodiment 8)
When the electronic current control unit for controlling the current of the main electrode and the hall current control unit are electrically insulated using an insulating layer, a region where current flows is narrowed by the width of the insulating layer. In addition, when the element on the insulating substrate is thick, the process of forming the vertical insulating layer becomes difficult. Therefore, an embodiment in which an insulating layer is not used is shown.

  This bidirectional switch is formed on a buried oxide film formed on a p-type or n-type silicon semiconductor so that integration is possible. This structure is shown in FIG. In order to show the structure of the semiconductor, FIG. 17 shows the semiconductor surface structure from which the main electrode, the control electrode, and the oxide film are removed.

  In addition, a cross-sectional structure of a portion where the n-type semiconductor layer 71, the p-type semiconductor layer 76, the n-type semiconductor layer 73, the p-type semiconductor layer 80, and the n-type semiconductor layer 75 are arranged, that is, a cross section along the AB direction in FIG. The structure is shown in FIG. The cross-sectional structure of the portion where the p-type semiconductor layer 76, the n-type semiconductor layer 73, the p-type semiconductor layer 78, the n-type semiconductor layer 73, and the p-type semiconductor layer 80 are arranged, that is, the cross-sectional structure along the CD direction in FIG. It shows in FIG.

  The semiconductor structure of this element includes an n-type semiconductor layer 71 and a p-type semiconductor layer 76 electrically connected to the first main electrode 81, an n-type semiconductor layer 73 between the current control portions of the two main electrodes, and The p-type semiconductor layer 78 includes an n-type semiconductor layer 75 and a p-type semiconductor layer 80 electrically connected to the second main electrode 82.

  The first electronic current control unit that controls the electronic current that enters and exits the first main electrode 81 includes an n-type semiconductor layer 71 that is electrically connected to the main electrode 81, a first control electrode 83, and a control electrode 83. The oxide film 85 under the oxide film 85 and the p-type semiconductor layer 76 under the oxide film 85 are formed. A channel is formed at the interface between the p-type semiconductor layer 76 and the oxide film 85. The electron density in the channel is controlled by the voltage applied to the control electrode 83, and the electron current flowing between the n-type semiconductor layer 71 and the n-type semiconductor layer 73 is controlled.

  The second electronic current control unit that controls the electronic current that enters and exits the second main electrode 82 includes an n-type semiconductor layer 75 that is electrically connected to the main electrode 82, a second control electrode 84, and a control electrode 84. The oxide film 86 is formed under the oxide film 86, and the p-type semiconductor layer 80 is formed under the oxide film 86. A channel is formed at the interface between the p-type semiconductor layer 80 and the oxide film 86. The voltage applied to the control electrode 84 controls the electron density in the channel, and the electron current flowing between the n-type semiconductor layer 75 and the n-type semiconductor layer 73 is controlled.

  The first hole current control unit that controls the hole current flowing into and out of the first main electrode 81 includes a p-type semiconductor layer 76 that is electrically connected to the main electrode 81, a first control electrode 83, and a control electrode 83. The oxide film 85 under the oxide film 85 and the n-type semiconductor layer 73 under the oxide film 85 are formed. A channel is formed at the interface between the n-type semiconductor layer 73 and the oxide film 85. The voltage applied to the control electrode 83 controls the hole density in the channel, and the hole current flowing between the p-type semiconductor layer 76 and the p-type semiconductor layer 78 is controlled.

  The second Hall current controller that controls the Hall current flowing into and out of the second main electrode 82 includes a p-type semiconductor layer 80 that is electrically connected to the main electrode 82, a second control electrode 84, and a control electrode 84. The oxide film 86 under the oxide film 86 and the n-type semiconductor layer 73 under the oxide film 86 are formed. A channel is formed at the interface between the n-type semiconductor layer 73 and the oxide film 86. The voltage applied to the control electrode 84 controls the hole density in the channel, and the hole current flowing between the p-type semiconductor layer 80 and the p-type semiconductor layer 78 is controlled.

  In a normal transistor, the doping concentration of the base layer that forms the channel by the gate voltage is higher than that of the drift layer so that the depletion layer does not extend to the base layer when the transistor is off. On the other hand, in the element shown in FIG. 16, the n-type semiconductor layer 73 corresponding to the base layer of the hole current control unit has a doping concentration determined by the super junction design and is not so high. This is because the electric field management is performed in the super junction structure, so that the depletion layer hardly extends under the control electrode of the hole current control unit.

  However, it cannot be said that the n-type semiconductor layer 73 forming the super junction structure is wide enough. At that time, it is preferable to provide a layer having a high doping concentration only under the oxide film of the hole current control section.

(Embodiment 9)
This structure is shown in FIG. The main electrode, the control electrode, and the oxide film are removed. This is a structure in which an n-type semiconductor layer having a high doping concentration is used only in a portion under the oxide film that controls the hole current in the element of FIG. An n-type semiconductor layer 77 is formed for controlling the hole current on the main electrode 81 side. An n-type semiconductor layer 79 is formed for controlling the hole current on the main electrode 82 side. Thereby, it is possible to prevent the depletion layer from extending under the oxide film.

(Embodiment 10)
In the structure shown in FIGS. 16 and 20, it can be seen that the element operates even if the n-type and p-type, which are the attributes of the semiconductor, are reversed as they are. Further, it is not necessary that the main electrode 1 side and the main electrode 2 side are symmetrical. The structure is shown in FIG. The main electrode, the control electrode, and the oxide film are removed. Further, the semiconductor layer constituting the element on the insulating substrate is uniform in the film thickness direction. Such a structure can also be operated.

(Embodiment 11)
Further, an embodiment of a structure capable of increasing the thickness of the semiconductor layer is shown in FIG. In FIG. 22, the main electrode, the control electrode, and the insulating film are removed so that the semiconductor structure can be seen. The positions of the main electrode and the control electrode insulating film are the same as those in FIG. This is formed on the insulating substrate 1. However, an insulating substrate is not necessary, and it can be formed on a high-resistance substrate or a p-type substrate.

  FIG. 23 is a cross-sectional view at the position where the n-type semiconductor layer 91, the n-type semiconductor layer 93, and the n-type semiconductor layer 95 are aligned on the semiconductor surface in FIG. Similarly, FIG. 24 is a cross-sectional view at the position where the p-type semiconductor layer 96, the p-type semiconductor layer 98, and the p-type semiconductor layer 100 are aligned on the semiconductor surface in FIG.

  The semiconductor structure of this element has an n-type semiconductor layer 91 and a p-type semiconductor layer 96 electrically connected to the first main electrode 101, and an n-type semiconductor layer that forms a super junction between two current control units. 93, a p-type semiconductor layer 98, and an n-type semiconductor layer 95 and a p-type semiconductor layer 100 electrically connected to the second main electrode 102.

  The first electronic current control unit that controls the electronic current flowing into and out of the first main electrode 101 includes an n-type semiconductor layer 91 that is electrically connected to the main electrode 101, a first control electrode 103, and a control electrode 103. And an ap type semiconductor layer 96 below the oxide film 105. A channel is formed at the interface between the p-type semiconductor layer 96 and the oxide film 105. The electron density in the channel is controlled by the voltage applied to the control electrode 103, and the electron current flowing between the n-type semiconductor layer 91 and the n-type semiconductor layer 93 is controlled.

  The second electronic current control unit that controls the electron current that enters and exits the second main electrode 102 includes an n-type semiconductor layer 95 that is electrically connected to the main electrode 102, a second control electrode 104, and a control electrode 104. An oxide film 106 under the oxide film 106 and a p-type semiconductor layer 100 under the oxide film 106. A channel is formed at the interface between the p-type semiconductor layer 100 and the oxide film 106. The electron density in the channel is controlled by the voltage applied to the control electrode 104, and the electron current flowing between the n-type semiconductor layer 95 and the n-type semiconductor layer 93 is controlled.

  The first Hall current control unit that controls the Hall current flowing into and out of the first main electrode 101 includes a p-type semiconductor layer 96 electrically connected to the main electrode 101, a first control electrode 103, and a control electrode 103. And an n-type semiconductor layer 93 below the oxide film 105. A channel is formed at the interface between the n-type semiconductor layer 93 and the oxide film 105. The voltage applied to the control electrode 103 controls the hole density in the channel, and the hole current flowing between the p-type semiconductor layer 96 and the p-type semiconductor layer 98 is controlled.

  The second Hall current control unit that controls the Hall current flowing into and out of the second main electrode 102 includes a p-type semiconductor layer 100 that is electrically connected to the main electrode 102, a second control electrode 104, and a control electrode 104. The oxide film 106 under the oxide film 106 and the n-type semiconductor layer 93 under the oxide film 106 are formed. A channel is formed at the interface between the n-type semiconductor layer 93 and the oxide film 106. The voltage applied to the control electrode 104 controls the hole density in the channel, and the hole current flowing between the p-type semiconductor layer 100 and the p-type semiconductor layer 98 is controlled.

  In the structure shown in FIG. 22, it can be seen that the element operates even if the n-type and p-type, which are the attributes of the semiconductor, are reversed as they are.

Embodiment 12
FIG. 25 shows a bidirectional switch in which the same structure is used for both electronic current control and hall current control. This bidirectional switch is formed on a buried oxide film formed on a p-type or n-type silicon semiconductor.

  The n-type semiconductor layer 111 and the p-type semiconductor layer 116 are electrically connected to the main electrode 121. The p-type semiconductor layer 120 and the n-type semiconductor layer 115 are electrically connected to the main electrode 122. There is an n-type semiconductor layer 117 between the p-type semiconductor layer 116 and the p-type semiconductor layer 120. Under the n-type semiconductor layer 117, a p-type semiconductor layer 118 and an n-type semiconductor layer 113 are periodically stacked. The n-type semiconductor layer 117, the p-type semiconductor layer 118 and the n-type semiconductor layer 113 that are periodically stacked constitute a super junction structure.

  An oxide film 125 and a control electrode 123 are formed on the side surfaces of the n-type semiconductor layer 111, the p-type semiconductor layer 116, the n-type semiconductor layer 117, and the periodically stacked p-type semiconductor layer 118 and n-type semiconductor layer 113. ing. An oxide film 126 and a control electrode 124 are formed on the side surfaces of the n-type semiconductor layer 115, the p-type semiconductor layer 120, the n-type semiconductor layer 117, and the periodically stacked p-type semiconductor layer 118 and n-type semiconductor layer 113. ing.

  Control of the electron current flowing into and out of the first main electrode 121 is performed by controlling the channel formed at the interface between the p-type semiconductor layer 116 and the oxide film 125 and the channel formed at the interface between the p-type semiconductor layer 118 and the oxide film 125. This is performed by controlling with the potential of the first control electrode 123. By making the potential of the control electrode 123 higher than the potential of the main electrode 121, electron channels are formed at the interface between the p-type semiconductor layer 116 and the oxide film 125 and at the interface between the p-type semiconductor layer 118 and the oxide film 125. . As a result, electrons can flow from the n-type semiconductor layer 111 electrically connected to the main electrode 121 to the n-type semiconductor layer 117 and the n-type semiconductor layer 113. It is also possible to flow in the reverse direction.

  The control of the hole current flowing into and out of the first main electrode 121 is performed by controlling the channel formed at the interface between the n-type semiconductor layer 117 and the oxide film 125 and the channel formed at the interface between the n-type semiconductor layer 113 and the oxide film 125. This is performed by controlling with the potential of the first control electrode 123. By making the potential of the control electrode 123 lower than the potential of the main electrode 121, a hole channel is formed at the interface between the n-type semiconductor layer 117 and the oxide film 125 and at the interface between the n-type semiconductor layer 113 and the oxide film 125. . As a result, holes can flow from the p-type semiconductor layer 116 electrically connected to the main electrode 121 to the p-type semiconductor layer 118. It is also possible to flow in the reverse direction.

  The same applies to the control of the electron current on the second main electrode 122 side and the control of the hole current. Also, current blocking and diode operation are the same as in other embodiments using the MOS structure.

  In the above, the method of performing all current control directly by the control electrode has been described. Another method is to control by the current flowing from the opposite main electrode. For example, there is a method of turning on the flow of holes flowing out from the second main electrode side by the flow of electrons flowing from the first main electrode side. In this case, the number of control electrodes is reduced. This method will be described below.

  In this method, the flow of holes is turned on by the flow of electrons from the opposite main electrode, or the flow of electrons is turned on by the flow of holes from the opposite main electrode. Therefore, there are three ways to switch bidirectionally.

  The first method is a method in which the control of the hole currents of the two main electrodes is both turned on by the electron current from the opposite side. The second method is a method in which the control of the electron currents of the two main electrodes are both turned on by the hole current from the opposite side. The third method is a method in which the control of the electron current and the hole current of one main electrode is both turned on by the hole current and the electron current from the opposite side.

  The first method will be described. A first electronic current controller controlled by the control electrode is formed on the first main electrode, and a second electronic current controller controlled by the control electrode is formed on the second main electrode. In addition, a first hole current control unit that turns on a hole current by an electron current from the second main electrode side is formed in the first main electrode, and electrons from the first main electrode side are formed in the second main electrode. A second hole current control unit that turns on the hole current by the current is formed.

  A first n-type semiconductor layer is formed between the first electron current controller and the second hole current controller. A second n-type semiconductor layer is formed between the second electron current controller and the first hole current controller.

  When the super junction structure is not used, the first n-type semiconductor layer is formed between the current control unit on the first main electrode side and the current control unit on the second main electrode side, so that only the n-type semiconductor layer exists. The layer and the second n-type semiconductor layer are the same. The first n-type semiconductor layer and the second n-type semiconductor layer may be the same.

(Embodiment 13)
FIG. 26 shows an embodiment of a structure in which a MOS structure is used for this electronic current control unit. In this case, since the main electrode is also electrically connected to the p-type base layer having the MOS structure, the hole current can flow through the p-type base layer. Therefore, it becomes a simple structure.

  This bidirectional switch is formed on an insulating substrate 1 using a buried oxide film formed on a p-type or n-type silicon semiconductor so that it can be integrated. FIG. 27 shows a structure in which the main electrode, the control electrode, and the oxide film are removed in order to show the structure of the semiconductor. The semiconductor layer structure on the insulating substrate 1 is uniform in the thickness direction except for the electron current control unit. FIG. 28 shows the surface structure of the semiconductor.

  28 is a cross-sectional structure taken along the line AB of FIG. 28, that is, at a position where the n-type semiconductor layer 131, the p-type semiconductor layer 132, the n-type semiconductor layer 133, the p-type semiconductor layer 134, and the n-type semiconductor layer 135 are aligned on the semiconductor surface. A cross-sectional view is shown in FIG.

  Similarly, FIG. 30 shows a cross-sectional structure taken along line CD in FIG. 28, that is, a cross-sectional view at a position where the n-type semiconductor layer 137, the p-type semiconductor layer 138, and the n-type semiconductor layer 139 are aligned on the semiconductor surface.

  The first electronic current control unit that controls the electronic current flowing into and out of the first main electrode 141 includes an n-type semiconductor layer 131 that is electrically connected to the main electrode 141, a first control electrode 143, and a control electrode 143. An oxide film 145 below the oxide film 145 and a p-type semiconductor layer 132 below the oxide film 145 and electrically connected to the main electrode 141. A channel is formed at the interface between the p-type semiconductor layer 132 and the oxide film 145. The electron density in the channel is controlled by the voltage applied to the control electrode 143, and the electron current flowing between the n-type semiconductor layer 131 and the n-type semiconductor layer 133 is controlled. This is a normal MOS gate structure.

  The hole current that enters and exits the first main electrode 141 flows through the p-type semiconductor layer 132 that is electrically connected to the main electrode 141. It is turned on by electrons passing through the n-type semiconductor layer 133 from the main electrode 142 side. Electrons that have passed through the n-type semiconductor layer 133 from the main electrode 142 side overcome the diffusion potential existing between the n-type semiconductor layer 133 and the p-type semiconductor layer 132 and flow to the p-type semiconductor layer 132. At the same time, holes flow from the p-type semiconductor layer 132 to the n-type semiconductor layer 133. This is the same operation as the forward direction of the pn diode. A pn junction formed by the p-type semiconductor layer 132 and the n-type semiconductor layer 133 operates as a first hole current control unit.

  The holes that have flowed from the p-type semiconductor layer 132 to the n-type semiconductor layer 133 then flow to the p-type semiconductor layer 138 as well. The holes flowing in the p-type semiconductor layer 138 to the main electrode 142 side overcome the diffusion potential formed by the p-type semiconductor layer 138 and the n-type semiconductor layer 139 and flow to the n-type semiconductor layer 139. This is the same operation as the forward direction of the pn diode. Therefore, electrons are supplied from the n-type semiconductor layer 139.

  The second electronic current control unit that controls the electronic current that enters and exits the second main electrode 142 includes an n-type semiconductor layer 135 that is electrically connected to the main electrode 142, a second control electrode 144, and a control electrode 144. An oxide film 146 below the oxide film 146 and a p-type semiconductor layer 134 below the oxide film 146 and electrically connected to the main electrode 142. A channel is formed at the interface between the p-type semiconductor layer 134 and the oxide film 146. The electron density in the channel is controlled by the voltage applied to the control electrode 144, and the electron current flowing between the n-type semiconductor layer 135 and the n-type semiconductor layer 133 is controlled. This is a normal MOS gate structure.

  The hole current that enters and exits the second main electrode 142 flows through the p-type semiconductor layer 134 that is electrically connected to the main electrode 142. It is turned on by electrons passing through the n-type semiconductor layer 133 from the main electrode 141 side. Electrons passing through the n-type semiconductor layer 133 from the main electrode 141 side flow over the diffusion potential existing between the n-type semiconductor layer 133 and the p-type semiconductor layer 134 and flow to the p-type semiconductor layer 134. At the same time, holes flow from the p-type semiconductor layer 134 to the n-type semiconductor layer 133. This is the same operation as the forward direction of the pn diode. A pn junction formed by the p-type semiconductor layer 134 and the n-type semiconductor layer 133 operates as a second hole current control unit.

  The holes that have flowed from the p-type semiconductor layer 134 to the n-type semiconductor layer 133 then flow to the p-type semiconductor layer 138 as well. The holes flowing in the p-type semiconductor layer 138 toward the main electrode 141 flow over the diffusion potential formed by the p-type semiconductor layer 138 and the n-type semiconductor layer 137 and flow to the n-type semiconductor layer 137. This is the same operation as the forward direction of the pn diode. For this reason, electrons are supplied from the n-type semiconductor layer 137.

  First, the n-type semiconductor layer 131, the p-type semiconductor layer 132, the n-type semiconductor layer 133, the p-type semiconductor layer 134, the n-type semiconductor layer 135, the main electrode 141 and the main electrode 142, the control electrode 143 and the control electrode 144, oxidation Only the structure composed of the film 145 and the oxide film 146 will be considered.

  This structure is the same as that in which an electron injection structure, that is, an n-channel MOS structure is formed on the p-type collector layer side in the IGBT. Therefore, operation is possible only with this structure. In addition, since both have an electronic current control function, the safe operation area can be expanded. That is, the off operation can be reliably performed.

  Consider a case where the IGBT is turned off when a positive voltage is applied to the collector side. At this time, electrons are discharged through the p-type collector layer. Therefore, holes are injected again to pass through the p-type collector layer. Therefore, latch-up occurs.

  However, if the main electrode has an electron current control unit, electrons escape to the main electrode without passing through the p-type semiconductor layer. That is, in the structure of FIG. 29, when the main electrode 142 is higher than the potential of the main electrode 141 and the electron is turned off when electrons flow from the main electrode 141 to the main electrode 142, the electron current control on the main electrode 142 side is performed. If the part is turned on, electrons can be discharged through the n-channel formed in the electron current controller without passing through the p-type semiconductor layer 134. As a result, injection of holes from the p-type semiconductor layer 134 connected to the main electrode 142 is suppressed, and the cause of latch-up can be reduced.

  26 can be safely turned off by turning on the control of the electron current on the main electrode side on the higher voltage side and turning off the control of the electron current on the lower voltage side. In the element shown in FIG. 26, the n-type semiconductor layer 133 and the p-type semiconductor layer 138 form a super junction structure. Further, the n-type semiconductor layer 137 and the p-type semiconductor layer 138, and the n-type semiconductor layer 139 and the p-type semiconductor 138 form a pn junction, and electrons are injected by holes. Therefore, a super junction structure and a double injection effect can be achieved, so that the resistance can be reduced.

  The second method is a method in which the control of the electron currents of the two main electrodes are both turned on by the hole current from the opposite side. Also in this case, the n-type and p-type may be inverted as they are in the structure of FIG.

  In FIG. 26, the control electrode is also on the n-type semiconductor layer 137 and the n-type semiconductor layer 139, but this portion is not involved in the control. Therefore, this portion is unnecessary, and it is preferable to remove this portion or to thicken the oxide film only in this portion. Then, only the channel formed on the surface of the p-type semiconductor layer 132 or the p-type semiconductor layer 134 needs to be controlled. In this case, there is an advantage that the gate capacitance is reduced.

(Embodiment 14)
The third method is a method in which the control of the electron current and the hole current of one main electrode is both turned on by the hole current and the electron current from the opposite side. This structure is shown in FIG. In addition, FIG. 32 shows a cross-sectional view at a position where the electron current control portion, the n-type semiconductor layer 153, and the p-type semiconductor layer 154 are aligned on the semiconductor surface in FIG. Similarly, FIG. 33 shows a cross-sectional view at the position where the hole current control portion, the p-type semiconductor layer 158, and the p-type semiconductor layer 159 are aligned on the semiconductor surface in FIG.

  The electron current control unit and the hole current control unit on the first main electrode 161 side are the same as the structure of FIG. In this structure, a first electron current control unit and a first hole current control unit are provided on the first main electrode 161 side. The first electronic current control unit includes an n-type semiconductor layer 151, a p-type semiconductor layer 152, and the like. The first hole current control unit includes a p-type semiconductor layer 156, an n-type semiconductor layer 157, and the like.

  The first electronic current control unit and the first Hall current control unit can be controlled by separate electrodes. However, control with the same control electrode simplifies the control circuit and process. The structure of FIG. 31 is a structure controlled by the same control electrode.

  The n-type semiconductor layer 153 through which the electron current flowing into and out of the first electron current control unit flows and the p-type semiconductor layer 158 through which the hole current flowing into and out of the first hole current control unit forms a super junction structure. .

  The second electron current control unit and the second hole current control unit on the second main electrode 162 side are pn junctions. It is isolated by an insulator 4. Electrons flow from the n-type semiconductor layer 159 on the main electrode 162 side. Holes flow from the p-type semiconductor layer 154 on the main electrode 162 side.

  When the potential of the main electrode 161 is higher than the potential of the main electrode 162 and current flows from the main electrode 161 to the main electrode 162, the potential of the control electrode 163 is made lower than the potential of the main electrode 161, and the first hole The current control unit may be turned on.

  At this time, the hole current flowing through the p-type semiconductor layer 158 from the first hole current control unit overcomes the diffusion potential of the pn junction formed by the p-type semiconductor layer 158 and the n-type semiconductor layer 159, and It flows to the electrode 162. This is the same as passing a current in the forward direction of the pn diode.

  Accordingly, at the same time, electrons flow from the n-type semiconductor layer 159 to the p-type semiconductor layer 158. That is, the pn junction formed by the p-type semiconductor layer 158 and the n-type semiconductor layer 159 functions as a second electron current control unit on the main electrode 162 side. The electrons flowing to the p-type semiconductor layer 158 pass through the p-type semiconductor layer 158 as they are to reach the n-type semiconductor layer 157 or pass through to the n-type semiconductor layer 153.

  The electrons passing through the n-type semiconductor layer 153 flow over the diffusion potential existing between the n-type semiconductor layer 153 and the p-type semiconductor layer 152 and flow to the p-type semiconductor layer 152. At the same time, holes flow from the p-type semiconductor layer 152 to the n-type semiconductor layer 153. This is the same operation as a pn diode. This causes double injection and low resistance.

  On the other hand, in order to turn it off, the potential of the control electrode 163 is made higher than the potential of the main electrode 161, the first hole current control unit is turned off, and the first electron current control unit is turned on. Electrons flow through the n-type semiconductor layer 153 to the n-type semiconductor layer 151 through an n-channel formed between the p-type semiconductor layer 152 and the insulating film 165. As a result, holes are not supplied from the p-type semiconductor layer 152, and the off operation is performed safely.

  When the potential of the main electrode 162 is higher than the potential of the main electrode 161 and current flows from the main electrode 162 to the main electrode 161, the potential of the control electrode 163 is set higher than the potential of the main electrode 161, and the first electrons The current control unit may be turned on.

  At this time, the electron current flowing through the n-type semiconductor layer 153 from the first electron current control unit overcomes the diffusion potential of the pn junction formed by the n-type semiconductor layer 153 and the p-type semiconductor layer 154, and mainly It flows to the electrode 162. This is the same as passing a current in the forward direction of the pn diode.

  Accordingly, holes also flow from the p-type semiconductor layer 154 to the n-type semiconductor layer 153 at the same time. That is, the pn junction formed by the p-type semiconductor layer 154 and the n-type semiconductor layer 153 functions as a second hole current control unit on the main electrode 162 side. The holes flowing to the n-type semiconductor layer 153 pass through the n-type semiconductor layer 153 as they are to reach the p-type semiconductor layer 152 or pass through to the p-type semiconductor layer 158.

  The holes passing through the p-type semiconductor layer 158 flow over the diffusion potential existing between the p-type semiconductor layer 158 and the n-type semiconductor layer 157 and flow to the n-type semiconductor layer 157. At the same time, electrons flow from the n-type semiconductor layer 157 to the p-type semiconductor layer 158. This is the same operation as a pn diode. This causes double injection and low resistance.

  On the other hand, when turning off, the potential of the control electrode 163 is made lower than the potential of the main electrode 161, the first electron current controller is turned off, and the first hole current controller is turned on. Through the p-type semiconductor layer 158, holes flow to the p-type semiconductor layer 156 through a p-channel formed between the n-type semiconductor layer 157 and the insulating film 165. As a result, electrons are not supplied from the n-type semiconductor layer 157, and the off operation is performed safely.

  With this structure, it is also possible to provide a threshold voltage control layer in the current control unit on the main electrode 161 side and operate as a diode in a normal state. For example, if the first electronic current control unit is normally on, it operates as a diode through which current flows when the potential of the main electrode 162 is higher than the potential of the main electrode 161 during normal operation.

  A vertical device structure is also possible. The structure is shown in FIG. In this case, a heat sink can be formed on the main electrode 162 side, which is suitable for a large current.

(Embodiment 15)
In this structure, the horizontal element shown in FIG. The current control unit on the first main electrode 161 side uses a trench structure. The current control unit simultaneously isolates the first electronic current control unit and the first hall current control unit.

  The first electronic current controller on the first main electrode 161 side includes an n-type semiconductor layer 151 and a p-type semiconductor layer 152, a control electrode 163, and an oxide film 165 between the control electrode 163 and the p-type semiconductor layer 152. Become. The first hole current control unit on the first main electrode 161 side includes a p-type semiconductor layer 156 and an n-type semiconductor layer 157, a control electrode 163, and an oxide film 165 between the control electrode 163 and the n-type semiconductor layer 157. Become.

  The main electrode 161 is electrically connected to the n-type semiconductor layer 151, the p-type semiconductor layer 152, the n-type semiconductor layer 157, and the p-type semiconductor layer 156. The n-type semiconductor layer 153 and the p-type semiconductor layer 158 form a super junction structure. The n-type semiconductor layer 153 is electrically connected to the second main electrode through the p-type semiconductor layer 154. The p-type semiconductor layer 158 is electrically connected to the second main electrode through the n-type semiconductor layer 159. The p-type semiconductor layer 154 and the n-type semiconductor layer 159 are separated by the insulator 4. The second main electrode is formed on the bottom surface of the element. The operation principle of the element shown in FIG. 34 is the same as the operation principle of the element shown in FIG.

  It can be used as a matrix converter for driving small motors. Further, since integration is possible, an inexpensive and highly functional matrix converter can be realized. It can also be used for inverters, converters, etc. for household power supplies. Integration with other electronic components is also possible, and the AC-DC conversion unit of the household DC power supply can be miniaturized. In addition, high-speed operation is possible, which is effective for energy saving.

Bidirectional switch with current injection controller Semiconductor surface view of bidirectional switch with current injection controller Sectional view of the element in the direction AB in FIG. Device sectional view in the CD direction of FIG. Bidirectional switch with electric field control type controller Semiconductor surface view of bidirectional switch with electric field control type controller Cross-sectional view of the element in the AB direction of FIG. Device sectional view in the CD direction of FIG. Semiconductor structure diagram of field effect bidirectional switch capable of threshold control Cross section of field effect bidirectional switch capable of threshold control Cross section of field effect bidirectional switch capable of threshold control Field-effect bidirectional switch that is difficult to latch up Semiconductor surface of a field-effect bidirectional switch that is difficult to latch up Sectional view in the AB direction of FIG. Sectional view of CD direction of FIG. Field effect bidirectional switch without insulator Semiconductor surface of field effect bidirectional switch without insulator A sectional view in the direction of AB in FIG. Sectional view in the CD direction of FIG. Semiconductor structure of field effect bidirectional switch Semiconductor structure of field effect bidirectional switch Bi-directional switch using n-type substrate Cross-sectional view of bidirectional switch element using n-type substrate Cross-sectional view of bidirectional switch element using n-type substrate Bidirectional switch with superjunction structure of laminated structure Bidirectional switch using pn junction Semiconductor structure diagram of bidirectional switch using pn junction Semiconductor surface of bidirectional switch using pn junction 28 is a cross-sectional view in the direction AB of FIG. 28 is a cross-sectional view in the CD direction of FIG. Bidirectional switch that can be controlled by one electrode Cross-sectional view of bidirectional switch controllable with one electrode Cross-sectional view of bidirectional switch controllable with one electrode Vertical bidirectional switch that can be controlled by a single electrode

Explanation of symbols

1: insulating substrate 2: semiconductor substrate 3: buried insulating film 4: insulators 11, 31, 51, 69, 71, 91, 111, 131, 137, 151: n-type semiconductor layer connected to the first main electrode 12, 32, 52, 132, 152: p-type semiconductor base layers 13, 33, 53, 73, 93, 113, 133, 153 of the first electronic current control unit: n-type semiconductor layers constituting a super junction 14, 34, 54, 134: p-type semiconductor base layers 15, 35, 55, 70, 75, 95, 115, 135, 139, 159 of the second electronic current control unit: connected to the second main electrode N-type semiconductor layers 16, 36, 56, 67, 76, 96, 116, 156: p-type semiconductor layers 17, 37, 57, 77, 117, 157 connected to the first main electrode: first Hall current controller n-type half Body base layers 18, 38, 58, 78, 98, 118, 138, 158: p-type semiconductor layers 19, 39, 59, 79 constituting super junction: n-type semiconductor base of second hole current control unit Layers 20, 40, 60, 68, 80, 100, 120, 154: p-type semiconductor layers 21, 41, 61, 81, 101, 121, 141, 161 connected to the second main electrode: first main Electrodes 22, 42, 62, 82, 102, 122, 142, 162: second main electrodes 23, 43, 63, 83, 103, 123, 143, 163: first control electrodes 24, 44, 64, 84 104, 124, 144: second control electrodes 45, 65, 85, 105, 125, 145, 165: oxide films 46, 66, 86, 106, 126, 146 of the first current control unit: second Current regulation Oxide film parts 47, 48, 49, 50: the threshold voltage control layer

Claims (9)

In a semiconductor bidirectional switching device configured on an insulating substrate and controlling a current flowing bidirectionally between a first main electrode and a second main electrode,
A first current control unit that controls a current flowing into and out of the first main electrode, and a second current control unit that controls a current flowing into and out of the second main electrode are connected to the first main electrode and the second main electrode. Between the electrodes,
Both the first current controller second current control unit, respectively, have a structure for controlling both the electron current and hole current,
The structure for controlling both the electron current and the hall current includes an n-type semiconductor in which an electron current flows between the first current control unit and the second current control unit, and the first current control unit and the second current. A p-type semiconductor in which a hole current flows between the control units, and the n-type semiconductor and the p-type semiconductor have a super junction structure,
The first current control unit includes a first electronic current control unit and a first Hall current control unit, and the second current control unit includes the second electronic current control unit and the second Hall current. It consists of a control unit,
The first electronic current control unit and the second electronic current control unit are connected by an n-type semiconductor layer constituting a super junction structure, and the first Hall current control unit and the second Hall current control unit are super junctions. A semiconductor bidirectional switching device connected by a p-type semiconductor layer constituting the structure . According to claim 1, the electronic current control unit and the hole current control unit that controls the respective currents into and out of the same main electrode of the first main electrode and the second main electrode, characterized in that it is separated by an insulator Semiconductor bidirectional switching device. 3. The semiconductor bidirectional switching device according to claim 1, wherein the electronic current control unit and the Hall current control unit are of a current injection type. Claims the first main electrode and the control electrode of the electron current control unit and the hole current control unit for controlling the current into and out of the respective same main electrode of the second main electrode, characterized in that it is electrically connected Item 4. The semiconductor bidirectional switching device according to Item 3 . 3. The semiconductor bidirectional switching device according to claim 1, wherein the electronic current control unit and the Hall current control unit are field effect type. Claims the first main electrode and the control electrode of each electron current control unit for controlling the current into and out of the same main electrode and the hole current controller of the second main electrode, characterized in that it is electrically connected 5. The semiconductor bidirectional switching device according to 5. Has a threshold voltage control layer to the electron current control unit and the hole current control unit, typically operates as a diode when, according to claim 6, characterized in that to control the current control unit in the control voltage of two voltage levels Semiconductor bidirectional switching device. The electronic current control unit and the hall current control unit have a threshold voltage control layer, operate as a diode during normal operation, and have an operation mode for conducting without a diffusion potential, and control the current control unit with control voltages of three voltage levels. The semiconductor bidirectional switching device according to claim 6 . 7. The semiconductor bidirectional switching device according to claim 5 , wherein a base layer in which a channel is formed by a field effect is floating.

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