JP2015128082A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which enables improvement of cooling performance while maintaining a device size and an on-resistance.SOLUTION: A semiconductor device (100) includes a semiconductor body (20) in which a gate electrode (17) having a trench structure is buried. The semiconductor device (100) is provided with a heat absorption part (30) connected with an end part of the gate electrode (17) which is exposed on a surface of the semiconductor body (20), the heat absorption part (30) which absorbs heat generated in the semiconductor body (20) through the gate electrode (17).

Description

  The present invention belongs to the technical field of semiconductor devices, in particular, trench gate type power semiconductor devices.

  In general, various power semiconductor devices are used in power control devices that control and supply electric power to electric devices depending on applications. Specifically, power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) are mainly used for high voltage applications, and IGBTs (Insulated Gate Bipolar Transistors) are mainly used for high-current applications. . This power semiconductor device is classified into a planar type and a trench gate type according to its structure. In recent years, there has been a demand for further reduction of On resistance, and in order to meet this demand, a trench gate type power semiconductor device capable of reducing On resistance by miniaturization in structure is used.

  On the other hand, in general, an electric vehicle such as a train, an electric vehicle, and a hybrid vehicle is provided with an electric motor for rotationally driving the drive wheels, and the electric power control that controls and supplies electric power stored in the battery to the electric motor. An inverter is provided as a device. In general, a power semiconductor device such as an IGBT is used for the inverter.

  Here, in an electric drive vehicle such as an electric vehicle or a hybrid vehicle, for example, during sudden acceleration or overstepping, there is a temporary load increase that is not expected in a train or the like. At this time, the semiconductor device in the inverter Is supplied with large power. If this large current exceeds the rated current of the inverter even for a moment, the semiconductor device may have a heat generation amount exceeding the compensation range and may be thermally destroyed. For this reason, a large-capacity semiconductor device must be used for the inverter for such a usage scene of several percent at most. As a result, the inverter is increased in size and the vehicle weight is increased, which affects fuel efficiency.

  In order to cope with the above-described problem, for example, in Patent Document 1, as shown in FIG. 7, in a trench gate type IGBT 300, a plate-like heat dissipation member 303 is provided between a plurality of gate electrodes 302 of the semiconductor body 301. A Peltier element 305 is configured by the embedded heat dissipation member 303 and the N-type or P-type thermoelectric semiconductor layer 304 bonded to the upper end surface. The Peltier element 305 is actively provided from the inside of the semiconductor body 301 via the heat dissipation member 303. Techniques for cooling are disclosed.

  However, in the technique of Patent Document 1, since the heat dissipating member 303 is separately provided, there is a concern that the device size increases accordingly. Further, since the heat dissipation member 303 is provided between the gate electrodes 302, there is a concern that the original current path between the gate electrodes 302 is limited, the periphery of the heat dissipation member 303 becomes resistance, and the On resistance increases. Further, in the case of this structure, the side wall portion of the gate electrode 302 having a high current density becomes a large heat generating portion, but since the heat generating portion and the heat radiating member 303 are separated from each other, there is a time delay in heat transfer between them. It occurred and affected the cooling performance.

JP 2007-227615 A

  The present invention has been made to solve the above-described problems, and provides a semiconductor device capable of improving the cooling performance while maintaining the device size and the low On resistance.

  In order to solve the above problems, the present invention is configured as follows.

First, the invention according to claim 1 of the present application is
A semiconductor device having a semiconductor body in which a gate electrode having a trench structure is embedded,
A heat absorption part is provided which is connected to an end of the gate electrode exposed on the surface of the semiconductor body and absorbs heat generated inside the semiconductor body through the gate electrode.

The invention according to claim 2 is the invention according to claim 1,
The heat absorption part is provided with a Peltier element formed of a P-type and / or an N-type semiconductor,
The Peltier element has a heat absorbing surface that absorbs the heat and a heat radiating surface that releases the absorbed heat.

The invention according to claim 3 is the invention according to claim 2,
The semiconductor device includes a plurality of the gate electrodes,
The end portion of each gate electrode exposed on the surface of the semiconductor body is directly connected to the heat absorbing surface of the Peltier element.

The invention according to claim 4 is the invention according to claim 2,
The semiconductor device includes a plurality of the gate electrodes,
An end portion of each gate electrode exposed on the surface of the semiconductor body is connected to a heat absorbing surface of the Peltier element through an insulating heat equalizing member that uniformly transmits the heat transmitted through each gate electrode. And

The invention according to claim 5 is the invention according to any one of claims 2 to 4,
The semiconductor device includes a heat radiating member that is connected to a heat radiating surface of the Peltier element and emits heat to the outside of the Peltier element.

The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein
The semiconductor body is an insulated gate bipolar transistor or a power MOSFET.

  According to the invention according to the above claims, the following effects can be obtained.

  First, according to the first aspect of the present invention, there is provided an endothermic portion that is connected to an end portion of the gate electrode exposed on the surface of the semiconductor body and absorbs heat generated inside the semiconductor body through the gate electrode. ing. Therefore, the heat generating part inside the semiconductor body, in particular, the side wall part of the gate electrode having a high current density can be directly cooled, so that there is no time delay in heat transfer between the heat generating part and the gate electrode. Further, the cooling performance can be improved. Further, since the gate electrode itself also serves as a heat transfer member, there is no need to provide a separate heat transfer member, and there is no possibility that the device size will increase. Furthermore, since there is no need to provide a separate heat transfer member that becomes a new resistance, there is no concern that the On resistance will increase. Therefore, the cooling performance can be improved while maintaining the device size and On resistance.

  According to the second aspect of the present invention, since the Peltier element formed of the P-type and / or N-type semiconductor is provided, the Peltier element is stacked on the semiconductor body as a part of the semiconductor device. Can be formed. Therefore, a small semiconductor device provided with a cooling function integrally can be realized.

  According to the invention described in claim 3, a plurality of gate electrodes are provided, and an end portion exposed to the surface of the semiconductor body of each gate electrode is directly connected to a heat absorbing surface of the Peltier element. And the Peltier element are not separated from each other, there is no time delay in heat transfer between them. Therefore, the heat generated rapidly when a large current flows instantaneously can be transferred to the Peltier element and cooled quickly before it affects the surrounding members.

  According to the invention described in claim 4, the gate electrode is provided in plural, and the end portion exposed to the surface of the semiconductor body of each gate electrode has an insulation level that uniformly transmits the heat transmitted through each gate electrode. Since it is connected to the heat absorbing surface of the Peltier element via the heat member, the local heat transferred from the end of each gate electrode to the insulating heat equalizing member is equalized while being transmitted through the insulating heat equalizing member, Heat is transmitted to the endothermic surface of the Peltier element in an averaged state. Therefore, the amount of heat that can be transmitted by each Peltier element is increased compared to the case where heat is locally transmitted to the heat absorbing surface of the Peltier element without using an insulating heat equalizing member, and the cooling performance of the entire semiconductor device is improved. In addition, even when there is a bias in the amount of heat transmitted through each gate electrode, the amount of heat absorbed by each Peltier element is averaged by transferring heat to each Peltier element through the insulating heat equalizing member. Therefore, it is not necessary to select an expensive and large-sized Peltier element having a maximum rating that can absorb the maximum amount of heat transmitted through each gate electrode. Furthermore, since it is not always necessary to provide each Peltier element directly above the end of each gate electrode, the relative position of the Peltier element with respect to the gate electrode and the number of Peltier elements to be provided can be set relatively freely.

  In addition, according to the invention described in claim 5, since the heat dissipation member is connected to the heat dissipation surface of the Peltier element and releases heat to the outside of the Peltier element, the cooling performance is further improved as compared with natural heat dissipation from the Peltier element. Can be improved.

  According to the sixth aspect of the invention, the same effect as that of the first aspect of the invention can be realized in an insulated gate bipolar transistor or power MOSFET which is a typical power semiconductor device.

It is a schematic sectional drawing which shows the structure of the semiconductor device which concerns on 1st Example of this invention. FIG. 2 is an enlarged cross-sectional view illustrating a heat flow in the semiconductor device of FIG. 1. It is a schematic sectional drawing which shows the structure of the semiconductor device based on 2nd Example of this invention. It is a flowchart which shows the control method of the Peltier device in a semiconductor device at the time of start acceleration of a vehicle. It is a flowchart which shows the control method of the Peltier device in a semiconductor device at the time of the rapid regeneration of a vehicle. It is a time chart explaining operation | movement of the semiconductor device at the time of driving | running | working of a vehicle. It is a schematic sectional drawing which shows the structure of the conventional semiconductor device.

  Hereinafter, an embodiment in which the present invention is embodied in a semiconductor device including an n-channel MOSFET will be described with reference to FIGS. 1 to 6, but the present invention is not limited to the following embodiment.

(First embodiment)
As shown in FIG. 1, the semiconductor device 100 is provided with a drain electrode 11 on one side of a substrate made of silicon carbide, and an n-type drift layer 12 is provided on the surface of the drain electrode 11. A P-type body layer 13 that is a channel region forming layer is provided on the surface of the drift layer 12. An N + type source layer 14 is provided on a part of the surface of the body layer 13. A plurality of trenches 15 are provided so as to reach the drift layer 12 through the source layer 14 and the body layer 13. A gate insulating film 16 made of a predetermined material, which will be described later, is formed on the inner wall surface of the trench 15, and a predetermined material, which will be described later, is embedded in the trench 15 from above the gate insulating film 16 and protrudes to the outside of the trench 15. A gate electrode 17 is provided. That is, the lower portion of the gate electrode 17 is buried in the trench 15 via the gate insulating film 16. An insulating layer 18 is provided so as to cover the opening side end of the trench 15 of the gate insulating film 16 and a part of the source layer 14. A source electrode 19 is provided so as to cover the exposed surfaces of the body layer 13 and the source layer 14 and the insulating layer 18. A source terminal S and a drain terminal D are connected to the source electrode 19 and the drain electrode 11, respectively. A semiconductor body 20 that performs high-speed switching as a MOSFET includes the drain electrode 11, the drift layer 12, the body layer 13, the source layer 14, the gate insulating film 16, the gate electrode 17, the insulating layer 18, and the source electrode 19. .

  In the present embodiment, an insulating layer 21 is provided on the surface of the source electrode 19 so that the upper end face of the gate electrode 17 protruding outside the trench 15 is exposed. A gate layer 22 connected to the exposed end face of the gate electrode 17 is provided on the surface of the insulating layer 21. A gate terminal G is connected to the gate layer 22. A heat transfer layer 23 having an insulating property is provided on the surface of the gate layer 22. A Peltier element 30 is provided on the surface of the heat transfer layer 23.

  The Peltier element 30 has a plurality of heat absorbing surface portions 31 made of a conductor, a plurality of P-type and N-type semiconductor portions 32a and 32b, and a plurality of heat radiating surface portions 33 made of a conductor. The heat absorption surface portion 31 is provided so as to be in contact with the heat transfer layer 23, and the heat dissipation surface portion 33 is provided so as to be in contact with a heat dissipation layer 35, which will be described later, provided on the side opposite to the semiconductor body portion 20 via the insulating layer 34. Yes. The pair of P-type and N-type semiconductor portions 32a and 32b are provided such that one end thereof is in contact with the same heat-absorbing surface portion 31 and the other end is in contact with different adjacent heat-dissipating surface portions 33. The P-type semiconductor portion 32a and the N-type semiconductor portion 32b are connected in series as a whole. The heat radiating surface portion 33 in contact with the P-type semiconductor portion 32a and the N-type semiconductor portion 32b at both ends of the plurality of P-type and N-type semiconductor portions 32a and 32b connected in series is connected to the anode of the external DC power supply V. Each is connected to a cathode. The external DC power supply V is configured to be able to switch ON / OFF of power supply to the Peltier element 30 based on a control signal from the outside. Note that the number and size of the P-type and N-type semiconductor portions 32 a and 32 b may be determined according to the endothermic capacity per unit area required from the energy loss of the semiconductor device 100.

  A heat dissipation layer 35 for releasing heat to the outside of the Peltier element 30 is provided on the heat dissipation surface portion 33 of the Peltier element 30. The heat dissipation layer 35 is formed of a high heat conductive material such as aluminum, and is formed integrally with the semiconductor body 20 as a part of the semiconductor device 100. Note that the heat radiation layer 35 that is prepared separately from the semiconductor device 100 may be joined to the semiconductor device 100 later. As such a separate heat dissipation layer 35, a well-known cooling means can be used. For example, a heat sink for cooling with a separate air cooling fan or the like, and a flow path through which a refrigerant such as oil, water, or liquid nitrogen flows are provided, and the refrigerant stored in a separate tank is stored in the flow path. It may be a cooling device that is supplied by a separate pump, or is provided with a circular flow path and circulated by the pump. In addition, a part having a relatively large heat capacity constituting the vehicle may be used as the heat dissipation layer 35.

  It should be noted that the On resistance of the semiconductor device 100 is determined by the total resistance of the path along which carriers move from the source electrode 19 to the drain electrode 11. In particular, the ratio of the resistance of the drift layer 12 and the channel resistance of the body layer 13 to the total resistance between these electrodes is large. For this reason, the ratio of Joule heat generated by the resistance of the drift layer 12 and the channel resistance of the body layer 13 when energized between the electrodes occupies a large amount of heat generation of the entire semiconductor device 100.

  Here, in the conventional semiconductor device, materials as shown in Table 1 below are mainly used as the gate insulating film and the gate electrode.

  In this embodiment, the gate insulating film 16 and the gate electrode 17 are formed using a material having a higher thermal conductivity than the conventional one. As for the gate insulating film 16, among materials having high thermal conductivity, the band gap is sufficiently higher than semiconductor materials such as silicon (Si 1.12 eV) and silicon carbide (4H—SiC 3.06 eV). A material having a higher relative dielectric constant than that of which a channel (inversion layer) is likely to occur is desirable. The gate insulating film 16 is preferably several hundred nm or more from the viewpoint of withstand voltage.

Specifically, the gate insulating film 16 includes, for example, alumina or sapphire (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), hexagonal boron nitride (h-BN), diamond, aluminum nitride (AlN), and the like. You may form using. The gate electrode 17 may be formed using, for example, aluminum, copper, polycrystalline silicon carbide (Poly-SiC), or the like. Table 2 below shows the material characteristics (thermal conductivity, band gap, dielectric constant) of the exemplified materials. The numerical values marked with * in Table 2 are based on the data described in Maruzen (2003), "Chemical Handbook Applied Chemistry 6th Edition".

  Next, the operation of the semiconductor device 100 configured as described above will be described with reference to FIG.

  When a gate voltage is applied so that the potential of the drain electrode 11 is higher than the potential of the source electrode 19 and the potential of the gate electrode 17 is higher than the potential of the source electrode 19, and the gate voltage exceeds the threshold voltage, FIG. As shown in FIG. 5), channels 13 a and 13 b through which electrons flow are formed on the inner surface portion of the body layer 13 that partially constitutes the side surface of the trench 15. The electrons flow from the source layer 14 to the drift layer 12 and the drain electrode 11 through the channels 13a and 13b, and the semiconductor device 100 is turned on. When the semiconductor device 100 is turned on, a large amount of Joule heat is generated in the drift layer 12 and the channels 13a and 13b.

  Heat generated in the drift layer 12 and the channels 13 a and 13 b is transmitted to the upper gate layer 22 and the heat transfer layer 23 through the gate insulating film 16 and the gate electrode 17. Since the heat transfer layer 23 is made of a high heat conductive material such as diamond-like carbon, the heat generated in the drift layer 12 and the channels 13a and 13b is made uniform in the heat transfer layer 23 in the upper direction. This is transmitted to the heat absorbing surface portion 31 of the Peltier element 30.

  Here, when a direct current is supplied to the Peltier element 30 from the external DC power source V, the heat transferred to the heat absorbing surface portion 31 is absorbed by the P-type and N-type semiconductor portions 32a and 32b due to the Peltier effect, and the heat radiating surface portion 33. The heat is dissipated. The heat radiated to the heat radiating surface portion 33 is transmitted to the heat radiating layer 35 in contact therewith and released from the heat radiating layer 35 to the outside of the semiconductor device 100.

  On the other hand, when the direct current is stopped from flowing to the Peltier element 30 by the external DC power source V, the heat transferred to the heat absorbing surface portion 31 does not have the Peltier effect, so that the P type and N type semiconductor portions 32a and 32b absorb the heat. Not. Therefore, only a very small amount of heat can be transferred to the heat radiating surface portion 33 through the P-type and N-type semiconductor portions 32a and 32b.

(Second embodiment)
As shown in FIG. 3, the semiconductor device 200 has the same configuration of the semiconductor body 20 as the MOSFET and the Peltier element 30 as compared with the semiconductor device 100 of the first embodiment described above, but the gate layer 22 and the heat transfer. The difference is that the layer 23 is not provided. In addition, the same code | symbol is attached | subjected about the member which has the same structure and function.

  In the present embodiment, an insulating layer 21 is provided on the surface of the source electrode 19 so that the upper end face of the gate electrode 17 protruding outside the trench 15 is exposed. The surface of the insulating layer 21 and the exposed end surface of the gate electrode 17 are formed to be the same surface, and a Peltier element 30 is provided on these surfaces. Each endothermic surface portion 31 of the Peltier element 30 is provided in contact with the exposed end surface of each gate electrode 17.

  Also in the case of this semiconductor device 200, Joule heat is generated in the drift layer 12 and the channels 13a and 13b, similarly to the semiconductor device 100 of the first embodiment. In the case of the second embodiment, the heat generated in the drift layer 12 and the channels 13a and 13b is directly transmitted from the end portion of the gate electrode 17 to the heat absorbing surface portion 31 of the Peltier element 30 in contact therewith. The subsequent heat absorption effect by the Peltier element 30 is the same as that of the semiconductor device 100 of the first embodiment.

  Next, a case where the semiconductor device 100 (or 200) of the above-described embodiment is specifically applied to an electric vehicle will be described.

  First, the configuration of an electric vehicle to which the semiconductor device of this embodiment is applied will be briefly described. The electric vehicle includes an electric motor for rotating the drive wheels, and an inverter that controls and supplies electric power stored in a battery to the electric motor. In this inverter, a semiconductor device 100 is used for high-speed switching. The electric motor is an alternator that also functions as a generator, and regenerative energy generated during deceleration can be stored in the battery via the alternator. The electric vehicle further includes a vehicle controller that controls the vehicle in an integrated manner.

  This vehicle controller includes a Peltier element control unit for switching ON / OFF the power supply by the external DC power source V to the Peltier element 30 in the inverter. The Peltier element control unit includes a signal indicating the temperature of the semiconductor body 20 (hereinafter referred to as “power element temperature”) from the temperature sensor, and an accelerator pedal operation angle (hereinafter referred to as “accelerator angle”) from the accelerator pedal operation amount sensor. ), A signal indicating the brake pedal operation angle (hereinafter referred to as “brake angle”), a signal indicating the vehicle speed from the vehicle speed sensor, and a semiconductor device 100 from the current sensor. And a signal indicating an input current (hereinafter referred to as “power element current”). Further, based on these input signals, the Peltier element control unit outputs an ON / OFF signal for energization of the Peltier element 30 to the external DC power supply V. Further, the Peltier element control unit includes an internal timer that measures the energization time of the Peltier element 30.

  The Peltier element control unit switches on / off the power supply by the external DC power source V to the Peltier element 30 according to the usage scene of the electric vehicle. While the Peltier element 30 is energized, the semiconductor body 20 that is a heat generating part is cooled by the Peltier element 30, so that the entire semiconductor device 100 can be controlled to a desired temperature or lower.

  Here, in the above-described electric vehicle, a use scene in which the amount of heat generated in the semiconductor body 20 rapidly increases due to a temporary increase in load on the electric motor and supply of large power to the semiconductor device 100 in the inverter, For example, a method for controlling the Peltier element 30 when overcoming a step, at the start of high-speed traveling, etc. will be described according to each step of the flowchart of FIG. 3 with reference to the time chart of FIG. 5 as appropriate.

  First, when the electric motor is operated from the stopped state (when the start switch is ON), the Peltier element 30 is not energized (step S1).

  Next, it is determined whether or not the power element temperature is higher than a predetermined temperature (step S2).

  If it is determined in step S2 that the power element temperature is not higher than the predetermined temperature, that is, not higher than the predetermined temperature, the accelerator angle is then changed rapidly, that is, the accelerator angle changes per unit time. It is determined whether or not the amount is larger than a predetermined value (step S3).

  If it is determined in step S3 that the accelerator angle is not a sudden change, it is next determined whether or not the accelerator angle is equal to or greater than a predetermined value (step S4).

  If it is determined in step S4 that the accelerator angle is smaller than a predetermined value, it is next determined whether the increase rate of the power element current is larger than a predetermined value (step S5).

  If it is determined in step S5 that the increase rate of the power element current is equal to or less than a predetermined value, it is determined whether or not the power element current is larger than the predetermined value (step S6).

  If it is determined in step S6 that the power element current is equal to or smaller than the predetermined value, the process returns to step S1.

On the other hand, if one of the determinations is YES in steps S2 to S6, that is, the power element current is higher than the predetermined temperature, the accelerator angle is abruptly changed, and the accelerator angle is greater than or equal to a predetermined value. Is determined to be greater than a predetermined value or the power element current is greater than a predetermined value, energization to the Peltier element 30 is started (ON), and the energization time to the Peltier element 30 is measured by an internal timer. (Step S7). For example, as shown in FIG. 6, when the vehicle gets over the step at time t <b> 1, if it is determined in step S <b> 3 that the accelerator angle is suddenly changed (see arrow a in the figure), energization to the Peltier element 30 starts. Is done. Further, when the automobile starts traveling at high speed at time t3 and it is determined in step S4 that the accelerator angle is equal to or _larger than the predetermined value θ _ON (see arrow c in the figure), energization to the Peltier element 30 is started.

  Next, it is determined whether or not the power element temperature has returned to normal, that is, is equal to or lower than a predetermined normal temperature (step S8).

  If it is determined in step S8 that the power element temperature has returned to normal, it is next determined whether or not the sudden change in the accelerator angle has disappeared, that is, whether or not the amount of change in the accelerator angle per unit time is equal to or less than a predetermined value. (Step S9).

  If it is determined in step S9 that there is no sudden change in the accelerator angle, it is next determined whether or not the accelerator angle is equal to or smaller than a predetermined value (step S10).

  If it is determined in step S10 that the accelerator angle is equal to or smaller than a predetermined value, it is next determined whether or not the increasing rate of the power element current is smaller than the predetermined value (step S11).

  If it is determined in step S11 that the increase rate of the power element current is smaller than a predetermined value, it is next determined whether or not the power element current is smaller than a predetermined value (step S12).

In this step S12, as shown in FIG. 6 (see arrow b at time t2), the power device current is determined to be smaller than the predetermined value I _ON, then, a predetermined time after the start of energization to the Peltier element 30 It is determined whether Δt (several seconds) has passed (step S13).

  If it is determined in step S13 that a predetermined time Δt has elapsed since the start of energization of the Peltier element 30, the process returns to step S1 and the energization of the Peltier element 30 is cut off (OFF). On the other hand, if it is determined that the predetermined time Δt has not elapsed since the start of energization of the Peltier element 30, the process returns to step S7, and energization of the Peltier element 30 is continued (ON).

  On the other hand, if any determination is NO in steps S8 to S12, that is, the power element temperature has not returned to normal, there is a sudden change in the accelerator angle, the accelerator angle is greater than a predetermined value, If the increase rate is greater than a predetermined value or the power element current is greater than a predetermined value, it is next determined whether or not a certain time has elapsed since the start of energization of the Peltier element 30 (step S14).

  If it is determined in step S14 that a certain time has not elapsed since the start of energization of the Peltier element 30, the process returns to step S7 and energization of the Peltier element 30 is continued (ON). On the other hand, if it is determined that a certain time has elapsed since the start of energization of the Peltier element 30, then fail-safe control is executed (step S15). As the fail-safe control, for example, the current flowing from the battery to the inverter may be limited to limit the power element current to reduce the heat generation.

  After executing step S15, it is determined whether or not the power element temperature has returned to the normal value (step S16). If it is determined that the power element temperature has not returned to the normal value, the process returns to step S15 to execute fail-safe control. On the other hand, if it determines with having returned to the normal value, it will return to step S1 and will interrupt | block the electricity supply to the Peltier device 30 (OFF).

  The above-described flow ends when the electric motor is stopped (when the start switch is OFF).

  Further, in the above-described electric vehicle, the amount of heat generated by the electric motor temporarily increases, and a large amount of power is supplied to the semiconductor device 100 in the inverter, so that the amount of heat generated in the semiconductor body 20 rapidly increases. For example, a method for controlling the Peltier element 30 at the end of high-speed running and during sudden regeneration will be described according to each step of the flowchart of FIG. 4 with appropriate reference to the time chart of FIG.

  First, when the electric motor is operated from a stopped state (when the start switch is ON), the Peltier element 30 is not energized (step S21).

  Next, it is determined whether or not the power element temperature is higher than a predetermined temperature (step S22).

  If it is determined in step S22 that the power element temperature is not higher than the predetermined temperature, that is, not higher than the predetermined temperature, then the brake angle is suddenly changed, that is, the brake angle changes per unit time. It is determined whether or not the amount is greater than a predetermined value (step S23).

  If it is determined in step S23 that the brake angle is not suddenly changed, it is next determined whether or not the vehicle speed is suddenly changed, that is, whether or not the vehicle acceleration is equal to or greater than a predetermined value (step S24).

  If it is determined in this step S24 that the vehicle speed is suddenly changed, it is next determined whether or not the increasing rate of the power element current is larger than a predetermined value (step S25).

  If it is determined in step S25 that the increase rate of the power element current is equal to or less than a predetermined value, it is determined whether or not the power element current is larger than the predetermined value (step S26).

  If it is determined in step S26 that the power element current is equal to or smaller than the predetermined value, the process returns to step S21.

  On the other hand, if any determination is YES in steps S22 to S26, that is, the power element temperature is higher than the predetermined temperature, as shown in FIG. 6 (see arrow e at time t5), the brake angle suddenly increases. If it is determined that the vehicle speed is a rapid change, the increase rate of the power element current is greater than a predetermined value, or the power element current is greater than a predetermined value, energization to the Peltier element 30 is started (ON). Then, the energization time to the Peltier element 30 is measured by the internal timer (step S27).

  Next, it is determined whether or not the power element temperature has returned to normal, that is, is equal to or lower than a predetermined normal temperature (step S28).

  If it is determined in step S28 that the power element temperature has returned to normal, it is next determined whether or not the sudden change in the brake angle has disappeared, that is, whether or not the amount of change in the brake angle per unit time is less than or equal to a predetermined value. (Step S29).

  If it is determined in step S29 that the sudden change in the brake angle has disappeared, it is next determined whether or not the sudden change in the vehicle speed has disappeared (step S30).

  If it is determined in step S30 that there is no sudden change in the vehicle speed, it is next determined whether or not the increasing rate of the power element current is smaller than a predetermined value (step S31).

  If it is determined in step S31 that the increase rate of the power element current is smaller than a predetermined value, it is next determined whether or not the power element current is smaller than a predetermined value (step S32).

In this step S32, FIG. 6 as shown in (arrow d at time t4, see arrow f in time t6), the power device current (absolute value) is determined to be smaller than the predetermined value I _ON, then the Peltier It is determined whether or not a predetermined time Δt (several seconds) has elapsed since the start of energization of the element 30 (step S33).

  If it is determined in step S33 that a predetermined time Δt has elapsed since the start of energization of the Peltier element 30, the process returns to step S21, and the energization of the Peltier element 30 is cut off (OFF). On the other hand, if it is determined that the predetermined time Δt has not elapsed since the start of energization of the Peltier element 30, the process returns to step S27, and energization of the Peltier element 30 is continued (ON).

  On the other hand, if any determination is NO in steps S28 to S32, that is, the power element temperature has not returned to normal, there is a sudden change in the brake angle, there is a sudden change in the vehicle speed, and the power element current increases. If the rate is greater than a predetermined value or the power element current is greater than a predetermined value, it is next determined whether or not a certain time has elapsed since the start of energization of the Peltier element (step S34).

  If it is determined in step S34 that a certain time has not elapsed since the start of energization of the Peltier element 30, the process returns to step S27 and energization of the Peltier element 30 is continued (ON). On the other hand, if it is determined that a certain period of time has elapsed since the start of energization of the Peltier element 30, then fail-safe control is executed (step S35). As this fail-safe control, for example, the current flowing from the electric motor to the inverter may be limited to limit the power element current to reduce the heat generation.

  After executing step S35, it is determined whether or not the power element temperature has returned to the normal value (step S36). If it is determined that the power element temperature has not returned to the normal value, the process returns to step S35, and fail-safe control is executed. On the other hand, if it determines with having returned to the normal value, it will return to step S21 and will interrupt | block the electricity supply to the Peltier device 30 (OFF).

  The above-described flow ends when the electric motor is stopped (when the start switch is OFF).

  As described above, according to these embodiments, the Peltier element is connected to the end of the gate electrode 17 exposed on the surface of the semiconductor body 20 and absorbs heat generated in the semiconductor body 20 via the gate electrode 17. 30 is provided. Therefore, the heat generating part inside the semiconductor body 20, particularly the side wall part of the gate electrode 17 having a high current density can be directly cooled, so that a time delay occurs in heat transfer between the heat generating part and the gate electrode 17. In addition, the cooling performance can be further improved as compared with the prior art. Further, since the gate electrode 17 itself also serves as a heat transfer member, there is no need to provide a separate heat transfer member, and there is no possibility that the device size will increase. Furthermore, since there is no need to provide a separate heat transfer member that becomes a new resistance, there is no concern that the On resistance will increase. Therefore, the cooling performance can be improved while maintaining the device size and On resistance.

  Further, according to these embodiments, since the Peltier element 30 formed of the P-type and / or N-type semiconductor portions 32a and 32b is provided, the Peltier element 30 is a semiconductor as a part of the semiconductor device 100 (200). The main body portion 20 can be laminated and formed. Therefore, a small semiconductor device 100 (200) provided with a cooling function can be realized.

  Further, according to the second embodiment, a plurality of gate electrodes 17 are provided, and the end portions exposed to the surface of the semiconductor body 20 of each gate electrode 17 are directly connected to the heat absorbing surface portion 31 of the Peltier element 30. Since the gate electrode 17 and the Peltier element 30 are not separated from each other, there is no time delay in heat transfer between them. Therefore, heat generated rapidly when a large current flows instantaneously can be quickly transferred to the Peltier element 30 and cooled before the surrounding members are affected.

  Further, according to the first embodiment, a plurality of gate electrodes 17 are provided, and the end portions exposed to the surface of the semiconductor body 20 of each gate electrode 17 transmit the heat transmitted through each gate electrode 17 in a uniform manner. Since it is connected to the heat absorbing surface portion 31 of the Peltier element 30 via the heat transfer layer 23, the local heat transferred from the end of each gate electrode 17 to the heat transfer layer 23 is transmitted through the heat transfer layer 23. The heat is equalized and heat is transmitted to the heat absorbing surface portion 31 of the Peltier element 30 in an averaged state. Therefore, the amount of heat that can be transferred by each Peltier element 30 is increased compared to the case where heat is locally transmitted to the heat absorbing surface portion 31 of the Peltier element 30 without passing through the heat transfer layer 23, and the cooling performance of the semiconductor device 200 as a whole is increased. Will improve. Further, even when the amount of heat transmitted through each gate electrode 17 is uneven, the amount of heat absorbed by each Peltier element 30 is averaged by transferring heat to each Peltier element 30 through the heat transfer layer 23. . Therefore, it is not necessary to select an expensive and large-sized Peltier element 30 having a maximum rating capable of absorbing the maximum amount of heat transmitted through each gate electrode 17. Furthermore, since it is not always necessary to provide each Peltier element 30 directly above the end of each gate electrode 17, the relative position of the Peltier element 30 with respect to the gate electrode 17 and the number of Peltier elements 30 to be provided are set relatively freely. be able to.

  In addition, according to these embodiments, since the heat dissipation layer 35 that is connected to the heat dissipation surface portion 33 of the Peltier element 30 and releases heat to the outside of the Peltier element 30 is provided, the cooling is further reduced as compared with natural heat dissipation from the Peltier element 30. Performance can be improved.

  Note that the present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes are possible without departing from the scope of the present invention.

  For example, in this embodiment, an N-channel type MOSFET has been described, but a P-channel type may be used. Moreover, not only MOSFET but IGBT which has a trench structure may be sufficient.

  In the present embodiment, the Peltier element 30 is formed integrally with the semiconductor body 20, but it may be prepared in advance as a separate member and joined later. Further, although the Peltier element 30 is used to absorb heat from the gate electrode 17, the heat transfer layer 23 or the insulating layer 21 is directly cooled using a known refrigerant such as liquid nitrogen, oil, or water. May be. Alternatively, the gate electrode 17 may be configured to have a heat sink shape extending to the outside of the semiconductor device and may be subjected to forced heat cooling using natural heat dissipation or a separate air cooling fan.

  Moreover, although the power semiconductor device applied to the inverter of the electric vehicle has been described as the present embodiment, in the inverter of the hybrid vehicle that can be driven by a motor, and further in the power control device in general that requires high-speed high-speed switching. Similarly, the present invention can be applied and the same effects can be obtained. For example, the utility value is particularly high in power converters having a rapid current fluctuation such as DC / AC for solar power generation and DC / DC for wind power generation.

  As described above, according to the present invention, in the semiconductor device, the cooling performance can be improved while maintaining the device size and the On resistance. Therefore, an automobile (EV, EV) equipped with an inverter to which this type of semiconductor device is applied. Not only HEV etc.), but also power generation / transmission / distribution systems (smart grids, etc.), transport equipment other than automobiles (railroads, ships, aircraft), industrial equipment (FA equipment, elevators, etc.), IT related equipment (computers, mobile phones, etc.) ), And may be suitably used in the manufacturing technology field of consumer / home appliances (air conditioners, FPDs, AV devices, etc.).

100, 200 Semiconductor device 16 Gate insulating film 17 Gate electrode 20 Semiconductor body (semiconductor body)
23 Heat transfer layer (insulating soaking member)
30 Peltier element (heat absorption part)
31 Endothermic surface (endothermic surface)
33 Heat dissipation surface (heat dissipation surface)
35 Heat dissipation layer (heat dissipation member)

Claims (6)

A semiconductor device having a semiconductor body in which a gate electrode having a trench structure is embedded,
A semiconductor device comprising: a heat absorbing portion connected to an end portion of the gate electrode exposed on the surface of the semiconductor body and configured to absorb heat generated inside the semiconductor body through the gate electrode. The heat absorption part is provided with a Peltier element formed of a P-type and / or an N-type semiconductor,
The semiconductor device according to claim 1, wherein the Peltier element has a heat absorption surface that absorbs the heat and a heat dissipation surface that releases the absorbed heat. The semiconductor device includes a plurality of the gate electrodes,
The semiconductor device according to claim 2, wherein an end portion of each gate electrode exposed on the surface of the semiconductor body is directly connected to a heat absorption surface of the Peltier element. The semiconductor device includes a plurality of the gate electrodes,
An end portion of each gate electrode exposed on the surface of the semiconductor body is connected to a heat absorbing surface of the Peltier element through an insulating heat equalizing member that uniformly transmits the heat transmitted through each gate electrode. The semiconductor device according to claim 2. 5. The semiconductor according to claim 2, wherein the semiconductor device includes a heat dissipation member that is connected to a heat dissipation surface of the Peltier element and emits heat to the outside of the Peltier element. apparatus. The semiconductor device according to claim 1, wherein the semiconductor body is an insulated gate bipolar transistor or a power MOSFET.

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