CONTROL CIRCUIT FOR SEMICONDUCTOR DEVICE AND SEMICONDUCTOR DEVICE

Abstract

To provide a semiconductor device control circuit capable of detecting degradation of a bonding portion in a semiconductor device even during operation of a system, and provide a semiconductor device.SOLUTION: A control circuit 100 of a semiconductor device 200 includes a gate signal generation circuit 101 that drives a switching element 201 by applying a gate signal to a gate terminal 206 of the switching element 201, a constant current pulse generation circuit 103 that is connected between a first terminal 207 and a second terminal 208, and generates a pulse during the off period of the switching element 201, a voltage measurement circuit 104 that applies the pulse generated by the constant current pulse generation circuit 103, to a point between the first terminal 207 and the second terminal 208, and measures the voltage between the first terminal 207 and the second terminal 208, and a degradation state determination unit 105 that determines a bonding degradation state of a surface electrode of the semiconductor device 200 or a chip bonding conductor 204, on the basis of a voltage drop measurement result obtained by the voltage measurement circuit 104.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control circuit for a semiconductor device and a semiconductor device. [Background technology]

[0002] 2. Description of the Related Art There are semiconductor devices equipped with power semiconductor chips that handle large currents and are used, for example, to drive motors in electric vehicles and electric railways. This semiconductor device has a function of converting DC power supplied from a DC power source into AC power for supplying to an inductive load such as a motor, or a function of converting AC power generated by a motor into DC power for supplying to a DC power source. To perform this conversion function, the semiconductor device is provided with a power semiconductor chip with a switching function, and by repeating a conductive operation and an interruption operation, it converts DC power to AC power or AC power to DC power, and controls the power.

[0003] A typical semiconductor device is configured such that an insulating substrate with a wiring pattern formed thereon is bonded by solder or the like to a heat dissipation base, and a power semiconductor chip is mounted by solder or the like on the wiring pattern of the insulating substrate. The power semiconductor chip is provided with electrodes on its front and back sides, the back electrode being connected to the wiring pattern on the insulating substrate, and the front electrode being connected to the wiring pattern on the insulating substrate via a wire or the like. In semiconductor devices for high power applications such as railways, multiple power semiconductor chips are mounted on an insulating substrate, and multiple insulating substrates are further mounted to enable the device to handle large currents.

[0004] The power semiconductor chip mounted on the insulating substrate of the semiconductor device includes switching elements such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs), and free wheel diodes. A power semiconductor chip has a drain electrode (in the case of a unipolar transistor), a collector electrode (in the case of a bipolar transistor), or a cathode electrode (in the case of a freewheeling diode) as a back electrode through which the main current flows on the back side. Also, a power semiconductor chip has a gate electrode (in the case of a unipolar transistor or a unipolar transistor) through which a control current flows on the front side, and a source electrode (in the case of a unipolar transistor), an emitter electrode (in the case of a bipolar transistor), or an anode electrode (in the case of a freewheeling diode) as a front electrode through which the main current flows.

[0005] Conventionally, the back electrode has been bonded to the circuit board by lead solder or lead-free solder, and the front electrode is made of aluminum-based material, and aluminum-based wires or copper-based leads have been bonded to the front electrode as wiring. For example, semiconductor devices used to drive the motors of electric vehicles have a voltage resistance of 600V or more and a current capacity of 300A or more. In the case of electric railways, the voltage resistance is 3.3kV or more and the current capacity is 1200A or more. In order to handle such large currents, it is necessary to pass several hundred amperes of current per power semiconductor chip. For this reason, it is usually necessary to ultrasonically bond multiple thick wires with diameters of about 300μm to 550μm onto the surface electrodes, or to bond copper leads with solder or the like.

[0006] In recent years, solder has been replaced by sintered metal, which has excellent heat resistance and a long life, and copper wire, which has better heat resistance than aluminum. Demand for improved current capacity of semiconductor devices is increasing, and the current flowing per chip is increasing. This increases heat generation and exposes the joints around the chip to greater temperature fluctuations.

[0007] Patent Document 1 describes a degradation detection method for a semiconductor device having a semiconductor module connected in series between DC power sources, which detects degradation of the semiconductor elements by simultaneously applying an on-pulse to the semiconductor elements connected in series and detecting the short-circuit current value during the on-pulse period. The degradation detection method for a semiconductor device described in Patent Document 1 inputs an extremely short-time short-circuit pulse that does not exceed the short-circuit withstand capability from a control circuit to the upper and lower arm elements of the semiconductor power module, compares the current value flowing through the element at that time with a reference value, and detects the degradation of the solder joint if the value is other than the reference value, thereby making it possible to effectively and accurately detect degradation.

[0008] Patent Document 2 discloses a configuration in which a life prediction wire 14 is connected to one emitter wire bonding pad 2 in addition to the one for outputting the output current, and a life prediction circuit 17 passes a current from a constant current circuit 26 to a reference (ground) potential from the life prediction wire 14 via the emitter wire bonding pad 2 and other wires (emitter wire 8 and control emitter wire 15) connected to the emitter wire bonding pad 2.

[0009] In Patent Document 2, when the IGBT 1 is not degraded, the electrical resistance of the path from the life prediction wire 14 to the reference (ground) potential via the emitter wire bonding pad 2 and other wires (emitter wire 8 and control emitter wire 15) connected to the emitter wire bonding pad 2 is almost zero, and there is no current flowing through the detection resistor 27 connected in parallel, so no voltage drop occurs between the life prediction wire 14 and the reference (ground) potential, and the potential of the life prediction wire 14 is zero (ground level). However, when the IGBT 1 is used, cracks occur in the bonding portion of the life prediction wire 14 or in the vicinity of the bonding portion, and the life prediction wire 14 itself eventually peels off from the emitter wire bonding pad 2 or breaks, the current from the constant current circuit 26 cannot flow through the emitter wire bonding pad 2, and a voltage drop occurs in the detection resistor 27, raising the potential at the non-inverting input of the comparator 28. By comparing this with a detection reference voltage by the comparator 28, a life prediction can be performed. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2009-19953 A [Patent Document 2] JP 2008-4728 A Summary of the Invention [Problem to be solved by the invention]

[0011] The method of detecting deterioration of a semiconductor device described in Patent Document 1 has a problem in that since an on-pulse is simultaneously applied to semiconductor elements connected in series, the device must be shut down or disassembled. In addition, even when the current flowing per chip increases, increasing heat generation and exposing the joints around the chip to greater temperature fluctuations, it is still a challenge to detect deterioration of the joints due to repeated thermal stress without shutting down or disassembling the equipment.

[0012] The life prediction method described in Patent Document 2 has a problem that power consumption is large because a current is constantly applied from the constant current circuit 26. Also, there is a problem that only peeling or breakage of the life prediction wire 14 can be detected, and peeling or breakage of wires other than the life prediction wire 14 cannot be detected.

[0013] The present invention has been made in consideration of the above circumstances, and aims to provide a control circuit for a semiconductor device and a semiconductor device that are capable of detecting deterioration of the semiconductor device's joints even while the system is in operation. [Means for solving the problem]

[0014] In order to solve the above problems, a control circuit for a semiconductor device according to the present invention is a control circuit for driving a semiconductor device, the semiconductor device comprising: a switching element for passing a collector current or a drain current as a main current when the switching element is on; A tip joining conductor and a wire connected to both ends of the tip joining conductor the control circuit having a first terminal and a second terminal, the control circuit having a gate signal generating circuit that applies a gate signal to a gate terminal of the switching element to drive the switching element, a constant current pulse generating circuit that is connected between the first terminal and the second terminal and generates a pulse during a period when the switching element is off, a voltage measurement circuit that measures a voltage between the first terminal and the second terminal when the pulse generated by the constant current pulse generating circuit is applied between the first terminal and the second terminal, and a degradation state determination unit that determines a junction degradation state of the semiconductor device based on a voltage drop measurement result from the voltage measurement circuit. Effect of the Invention

[0015] According to the present invention, it is possible to provide a control circuit for a semiconductor device and a semiconductor device that are capable of detecting deterioration of a bonding portion of the semiconductor device even during operation of the system. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing a configuration of a control circuit for a semiconductor device according to a first embodiment of the present invention and a semiconductor device to which the control circuit is applied; [Diagram 2] 1 is a top view showing an example of a structure of a semiconductor device according to a first embodiment of the present invention. [Diagram 3] 3 is a cross-sectional view taken along the line AA' in FIG. 2. [Figure 4] 3 is a diagram illustrating a schematic flow of a main current and a constant current pulse for measurement in the semiconductor device according to the first embodiment of the present invention. FIG. [Diagram 5] 4 is a diagram showing a drive sequence of a control circuit in the semiconductor device according to the first embodiment of the present invention. [Figure 6] FIG. 4 is a top view showing an example of a structure of a semiconductor device according to a modified example of the first embodiment of the present invention. [Figure 7] 7 is a cross-sectional view taken along the line AA' in FIG. 6. [Figure 8] FIG. 11 is a diagram showing a configuration of a semiconductor device to which a control circuit of a semiconductor device according to a second embodiment of the present invention is applied; [Figure 9] 11 is a graph showing the relationship between the measured temperature and the detected voltage before deterioration, when an aluminum wire is used as a chip bonding conductor in a semiconductor device according to a second embodiment of the present invention, and when solder is used as a terminal bonding layer, and when the bonding area of ​​the aluminum wire is reduced by 20%, and when the solder bonding area is reduced by 80%. [Figure 10] FIG. 13 is a diagram illustrating a configuration of a control circuit for a semiconductor device according to a third embodiment of the present invention and a semiconductor device to which the control circuit is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. (First embodiment) 1 is a diagram showing the configuration of a semiconductor device control circuit according to a first embodiment of the present invention and a semiconductor device to which the same is applied. The control circuit of the semiconductor device according to this embodiment is applicable to an inverter system mounted on a semiconductor device having a power semiconductor chip that handles a large current used for driving the motors of electric vehicles and electric railways. As shown in FIG. 1, a control circuit 100 of the semiconductor device includes a gate signal generating circuit 101, a gate driving circuit 102, a constant current pulse generating circuit 103, a voltage measuring circuit 104, a deterioration state determination unit 105, and an alarm generating unit 106 (described in detail below), and drives a semiconductor device 200.

[0018] The semiconductor device 200 comprises a semiconductor chip 201 (switching element) that flows a collector current as a main current when on, a semiconductor chip 202 (diode element), a collector terminal 203, a chip junction conductor 204, an emitter terminal 205, a gate terminal 206, and a first emitter sense terminal (ES) 207 (first terminal) and a second emitter sense terminal (ES2) 208 (second terminal) connected to the emitter of the semiconductor chip 201 (switching element) (described in detail below).

[0019] Here, an example is shown in which the semiconductor chip 201 (switching element) uses a MOSFET as the switching element. However, the present invention is not limited to this, and a MOSFET may be used as the switching element. When a MOSFET is used as the switching element, the emitter may be replaced with the source, and the collector with the drain. Furthermore, when a MOSFET is used as the switching element, the semiconductor chip 202 (diode element) may be a body diode built into the MOSFET.

[0020] The first emitter sense terminal (ES) 207 (first terminal) is a first emitter auxiliary terminal, and the second emitter sense terminal (ES2) 208 (second terminal) is a second emitter auxiliary terminal. The first emitter sense terminal (ES) 207 (first terminal) is an auxiliary emitter terminal provided for precisely adjusting the potential difference of the gate-emitter voltage Vges of the semiconductor chip (switching element) 201. The on / off of the semiconductor chip 201 is determined by the potential difference of the gate-emitter voltage Vges, but there are individual differences and differences in the arrangement of each semiconductor chip 201, and therefore it is necessary to precisely adjust the potential difference. For this reason, a general semiconductor device is provided with the first emitter sense terminal (ES) 207. The gate-emitter voltage Vges of the semiconductor chip 201 is precisely adjusted by this first emitter sense terminal (ES) 207.

[0021] The second emitter sense terminal (ES2) 208 (second terminal) is an auxiliary emitter terminal for detecting a voltage drop in the chip bonding conductor 204 between the semiconductor chip 201 and the emitter terminal 205 when the semiconductor chip 201 is on, and grasping the conductive state of the chip bonding conductor 204. The second emitter sense terminal (ES2) 208 (second terminal) may not be provided in a general semiconductor device, in which case the emitter terminal 205 is used as the second terminal.

[0022] In addition, when the semiconductor chip 201 (switching element) is a MOSFET, the first emitter sense terminal (ES) 207 may be referred to as a first source sense terminal (first source auxiliary terminal), and the second emitter sense terminal (ES2) 208 may be referred to as a second source sense terminal (second source auxiliary terminal).

[0023] Also, as described above, the second terminal 208 can be the emitter terminal (E) 205. When the semiconductor chip 201 (switching element) is a MOSFET, the emitter terminal (E) 205 can be called a source terminal.

[0024] <Control circuit 100 of semiconductor device> The gate signal generating circuit 101 applies a gate signal S1 to a gate terminal 206 of a semiconductor chip 201 (switching element) to drive the semiconductor chip 201 (switching element). When the output of the voltage measurement circuit 104 is abnormal, the gate signal generating circuit 101 generates a gate signal different from that generated in the normal case. Here, the gate signal different from that generated in the normal case is a gate signal that drives the semiconductor chip 201 (switching element) in a low-load operation mode.

[0025] The gate drive circuit 102 is connected to a gate terminal 206 and a first emitter sense terminal 207 of the semiconductor device 200. The gate drive circuit 102 applies a voltage of +15V between the gate terminal 206 and the first emitter sense terminal 207.

[0026] The constant current pulse generating circuit 103 is connected between the first emitter sense terminal 207 (first terminal) and the second emitter sense terminal 208 (second terminal) of the semiconductor device 200, and generates a pulse during a period when the semiconductor chip 201 (switching element) is off. Specifically, the constant current pulse generating circuit 103 applies a constant current pulse for measurement from the first emitter sense terminal 207 to the second emitter sense terminal 208 based on a current on / off command signal S2 from the deterioration state determining unit 105 during a period when no main current or return current flows between the collector terminal 203 and the emitter terminal 205.

[0027] The voltage measurement circuit 104 measures the voltage between the first emitter sense terminal 207 (first terminal) and the second emitter sense terminal 208 (second terminal) when the pulse generated by the constant current pulse generation circuit 103 is applied between the first emitter sense terminal 207 (first terminal) and the second emitter sense terminal 208 (second terminal). Specifically, the voltage measurement circuit 104 measures the voltage drop caused by the resistance of the chip joint conductor 204 when the constant current pulse for measurement is applied. In order to detect the state of damage (deterioration) of the joints and solder of the chip joint 204 by comparing with the initial state, the voltage measurement circuit 104 outputs the voltage drop measurement result S3 to the deterioration state determination unit 105.

[0028] The degradation state determination unit 105 determines the degradation state of the bonding of the surface electrode of the semiconductor device 200 and the chip bonding conductor 204 based on the voltage drop measurement result S3 from the voltage measurement circuit 104. Specifically, the degradation state determination unit 105 determines the voltage drop measurement result (i.e., degradation of the bonding portion of the semiconductor device) caused by the increase in resistance due to cracks or lift-off of the emitter wire 204A (see FIGS. 2 and 3) or the emitter lead 204B (see FIGS. 6 and 7) through which the main current flows, based on the voltage between the first emitter sense terminal 207 (first terminal) and the second emitter sense terminal 208 (second terminal) when the pulse generated by the constant current pulse generation circuit 103 is applied between the first emitter sense terminal 207 (first terminal) and the second emitter sense terminal 208 (second terminal) during the period when the semiconductor chip 201 (switching element) is off.

[0029] The degradation state determination unit 105 determines the degradation state from the measurement result by the voltage measurement circuit 104, and if there is no problem, maintains the state as it is, and if there is a problem, outputs the degradation state determination result S4 to the alarm generation unit 106. The degradation state determination unit 105 determines the remaining life based on the degradation state, and transmits the remaining life determination result to a user or a maintenance company via the network 300. By transmitting the remaining life to a user or a maintenance company, the user or the maintenance company can perform maintenance at an appropriate time. In addition, the degradation state determination unit 105 and the gate signal generation circuit 101 can cooperate with each other to extend the life by driving the gate according to the degree of degradation. For example, when the degradation state determination unit 105 determines that the degradation state is in a degradation state, the gate signal generation circuit 101 outputs a gate signal for driving the switching element 201 in a low-load operation mode instead of the gate signal S1 in the normal case. The method of determining the remaining life is not limited to a specific method, and the remaining life can be determined by a known method.

[0030] The warning generation unit 106 issues an alarm when the output of the voltage measurement circuit 104 is abnormal. The alarm may be, for example, a warning display on a display unit, an audio announcement, sound emission, or the like, or a report to the network 300. By issuing an alarm, it is possible to prevent a breakdown from occurring.

[0031] <Semiconductor device 200> A gate electrode of the semiconductor chip 201 (switching element) is connected to a gate terminal 206, and a collector electrode is connected to a collector terminal 203. An emitter electrode of the semiconductor chip 201 (switching element) is connected to a first emitter sense terminal 207, and is further connected to a second emitter sense terminal 208 and an emitter terminal 205 via a chip junction conductor 204.

[0032] When a voltage of +15V is applied between the gate terminal 206 and the first emitter sense terminal 207 from the gate drive circuit 102 of the control circuit 100, the semiconductor chip 201 (switching element) is turned on and a main current flows between the collector terminal 203 and the emitter terminal 205. When a voltage of -5V is applied between the gate terminal 206 and the first emitter sense terminal 207, the semiconductor chip 201 (switching element) is turned off, and no main current flows between the collector terminal 203 and the emitter terminal 205, or a reflux current from a load such as a motor may flow from the emitter terminal 205 to the collector terminal 203 via the semiconductor chip 202 (diode element).

[0033] The constant current pulse generating circuit 103 of the control circuit 100 flows a constant current pulse for measurement from the first emitter sense terminal 207 to the second emitter sense terminal 208 during a period when no main current or return current flows between the collector terminal 203 and the emitter terminal 205. At this time, a voltage drop occurs due to the resistance of the tip bonding conductor 204 due to the constant current pulse. If the current of the constant current pulse in the on state is Itest and the resistance of the tip bonding conductor 204 is R, a voltage drop of Vtest = R × Itest occurs. The voltage measurement circuit 104 measures this voltage drop and outputs the measurement result to the deterioration state determination unit 105.

[0034] The chip bonding conductor 204 is an emitter wire 204A or an emitter lead 204B (see the modified examples in Figs. 6 and 7) through which a main current flows and which is bonded to a surface electrode of the semiconductor chip 201. In the case of the emitter wire 204A, it is generally bonded directly to the surface electrode of the semiconductor chip 201 by ultrasonic bonding, while in the case of the emitter lead 204B (see the modified examples in Figs. 6 and 7), it is generally bonded to the surface electrode of the chip by soldering.

[0035] The joint and solder of the emitter wire 204A are gradually damaged by repeated application of thermal stress, etc., and the joint area is reduced. The reduction in the joint area causes an increase in the resistance of the tip joint conductor 204. Therefore, by measuring the voltage drop caused by a constant current pulse with the voltage measurement circuit 104, the deterioration state determination unit 105 can detect the state of damage (deterioration of the joint) by comparing it with the initial state.

[0036] In addition, by passing a constant current pulse for measurement from the first emitter sense terminal 207 to the second emitter sense terminal 208 (second terminal) during a period when no main current or return current flows between the collector terminal 203 and the emitter terminal 205, the state of deterioration can be detected with high accuracy without being affected by the main current or return current.

[0037] [Structure of semiconductor device] Fig. 2 is a top view showing an example of the structure of the semiconductor device 200. Fig. 3 is a cross-sectional view taken along the line AA' in Fig. 2. 2 and 3, a semiconductor device 200 includes a semiconductor chip (switching element) 201, a semiconductor chip (diode element) 202, a collector terminal 203, an emitter wire 204A as a chip bonding conductor 204, an emitter terminal 205 (see FIG. 2), a gate terminal 206 (see FIG. 2), a first emitter sense terminal 207, a second emitter sense terminal 208, an emitter surface electrode 211 of the switching element, a surface electrode 212 of the diode element, a gate surface electrode 213 of the switching element (see FIG. 2), and an emitter terminal 214 of the switching element. The insulating substrate includes a terminal sense wire 214, a gate wire 215 of the switching element (see FIG. 2), a back electrode 216 of the switching element (see FIG. 3), a back electrode 217 of the diode element (see FIG. 3), a bonding layer 218 of the switching element (see FIG. 3), a bonding layer 219 of the diode element, a wiring layer 220 of the insulating substrate, an insulating layer 221 of the insulating substrate, a back metal layer 222 of the insulating substrate (see FIG. 3), a bonding layer 223 of the insulating substrate (see FIG. 3), a heat dissipation base 224, a case 225, an insulating filler 226 (see FIG. 3), and a terminal bonding layer 227 (see FIG. 3).

[0038] 2 and 3, an insulating substrate having a wiring layer 220 of the insulating substrate, an insulating layer 221 of the insulating substrate, and a back surface metal layer 222 of the insulating substrate is bonded on a heat dissipation base 224 by a bonding layer 223 of the insulating substrate. A semiconductor chip (switching element) 201 and a semiconductor chip (diode element) 202 are mounted on the wiring layer 220 of the insulating substrate. A back surface electrode 216 of the switching element and a back surface electrode 217 of the diode element are provided on the back surfaces of the semiconductor chip (switching element) 201 and the semiconductor chip (diode element) 202, respectively, and are bonded to the wiring layer 220 of the insulating substrate by a bonding layer 218 of the switching element and a bonding layer 219 of the diode element, respectively.

[0039] The surfaces of the semiconductor chip 201 (switching element) and the semiconductor chip 202 (diode element) are respectively provided with an emitter surface electrode 211 of the switching element and a surface electrode 212 of the diode element, and on the emitter surface electrode 211 of the switching element and the surface electrode 212 of the diode element are joined an emitter wire 204A connected to an emitter terminal 205 through which a main current flows, and an emitter sense wire 214 of the switching element connected to a first emitter sense terminal 207 through which a main current does not flow.

[0040] A gate wire 215 of the switching element connected to a gate terminal 206 is bonded to the gate surface electrode 213 of the switching element. The first emitter sense terminal 207 and the second emitter sense terminal 208 are bonded to a wiring layer 220 of the insulating substrate by a terminal bonding layer 227. All except for a part of the heat dissipation base 224, a part of the collector terminal 203, a part of the emitter terminal 205, a part of the gate terminal 206, a part of the first emitter sense terminal 207, and a part of the second emitter sense terminal 208 are contained in a case 225, and the inside of the case 225 is filled with an insulating filler 226.

[0041] The first emitter sense terminal 207 (first terminal) and the surface electrode of the semiconductor chip 201 (switching element) are connected via an emitter sense wire 214 through which no main current flows, and the second emitter sense terminal 208 (second terminal) and the surface electrode of the semiconductor chip 201 (switching element) are connected via an emitter wire 204A through which the main current flows.

[0042] The main current flows from collector terminal 203 through wiring layer 220 of the insulating substrate, semiconductor chip 201 (switching element), emitter surface electrode 211 of the switching element, emitter wire 204A, to emitter terminal 205. The return current flows in the opposite direction, that is, through emitter terminal 205 and emitter wire 204A, to surface electrode 212 of the diode element, semiconductor chip 202 (diode element), wiring layer 220 of the insulating substrate, and collector terminal 203. A constant current pulse for measurement flows from the first emitter sense terminal 207 through the emitter surface electrode 211 of the switching element and the emitter wire 204A to the second emitter sense terminal 208.

[0043] The emitter sense wire 214 of the switching element is joined to the end of the wire on the semiconductor chip 201 (switching element) that is the furthest from the center of the semiconductor chip 201. This minimizes deterioration of the bond between the emitter sense wire 214 of the switching element and the emitter surface electrode 211 of the switching element. This is because, when the semiconductor chip 201 (switching element) generates heat, the temperature is highest at the center and decreases toward the end, resulting in lower thermal stress. It is preferable to join the emitter sense wire 214 of the switching element to a corner of the semiconductor chip 201 (switching element).

[0044] By minimizing the deterioration of the bond between the emitter sense wire 214 of the switching element and the emitter surface electrode 211 of the switching element, the deterioration of the bond of the emitter wire 204A can be detected more accurately.

[0045] [Operation of the control circuit 100 of the semiconductor device] The operation of the control circuit 100 of the semiconductor device configured as above will now be described. <Principle> Fig. 4 is a diagram showing a schematic diagram of the flow of the main current Ic and the measurement constant current pulse Itest in the semiconductor device 200. Fig. 4 shows the route of the current flow by simplifying the cross-sectional view of Fig. 3. 4 flows from the collector terminal 203 through the wiring layer 220 (not shown) of the insulating substrate, the semiconductor chip 201 (switching element), the emitter surface electrode 211 of the switching element, and the emitter wire 204A to the second emitter terminal 204.

[0046] The measurement constant current pulse Itest, indicated by the thin dashed arrow in Figure 4, flows from the emitter sense wire 214 of the switching element, which is connected to the first emitter sense terminal 207 (not shown), through which no main current flows, through the emitter surface electrode 211 of the switching element and the emitter wire 204A, to the second emitter sense terminal 204. That is, the main current Ic flows from the collector terminal 203, through the wiring layer 220 of the insulating substrate, the semiconductor chip 201 (switching element), the emitter surface electrode 211 of the switching element, and the emitter wire 204A to the second emitter terminal 204, while the constant current pulse Itest flows from the emitter sense wire 214 of the switching element, through the emitter surface electrode 211 of the switching element, and through the emitter wire 204A to the second emitter sense terminal 204.

[0047] The emitter wire 204A is a wire for a main current, and the wire bond is deteriorated by the flow of the main current Ic. When the wire bond is deteriorated, the resistance of the emitter wire 204A as the tip bond conductor 204 increases, and the voltage drop of the tip bond conductor 204 including the emitter wire 204A increases, so that the deterioration of the bonded surface of the emitter wire 204A can be detected.

[0048] The emitter sense wire 214 is a wire for sensing, through which only a weak measurement current flows.

[0049] <Drive sequence> FIG. 5 is a diagram showing a drive sequence of the control circuit 100 of the semiconductor device. Vges shown in Fig. 5 is the gate-emitter voltage of the semiconductor chip (switching element) 201 in Fig. 1. Vce shown in Fig. 5 is the collector-emitter voltage of the semiconductor chip (switching element) 201 in Fig. 1. A gate drive signal is output from a gate signal generating circuit 101 (see FIG. 1) to a gate driver 102 (see FIG. 1), and when the gate driver 102 amplifies this gate drive signal and supplies it to a gate terminal 206 of a semiconductor chip (switching element) 201, the semiconductor chip (switching element) 201 turns on due to the potential difference of the gate-emitter voltage Vges (see Vges in FIG. 5). When the semiconductor chip (switching element) 201 turns on, the collector-emitter voltage Vce drops (see Vce in FIG. 5), and a collector current (main current) Ic flows (see Ic in FIG. 5). Note that a transient overshoot may occur in Ic when the switching element turns on.

[0050] When the gate drive signal from the gate signal generating circuit 101 (see FIG. 1) is turned off, the potential difference of the gate-emitter voltage Vges disappears and the semiconductor chip (switching element) 201 is turned off (see Vges in FIG. 5). When the semiconductor chip (switching element) 201 is turned off, a collector-emitter voltage Vce is generated (see Vce in FIG. 5), and the collector current (main current) Ic does not flow (see Ic in FIG. 5). Note that when the switching element is turned off, a transient overshoot may occur in Vce.

[0051] When the main current Ic stops flowing, the “on period of the switching element” (see symbol c in FIG. 5) ends and the “off period of the switching element” (see symbol d in FIG. 5) begins, as delimited by the dashed line in FIG. 5.

[0052] The constant current pulse generating circuit 103 (see FIG. 1) flows a constant current pulse Itest for measurement from the first emitter sense terminal 207 to the second emitter sense terminal 208 (see symbol a in FIG. 5) during the period when the main current Ic is not flowing (see "switching element off period" in FIG. 5).

[0053] The voltage measurement circuit 104 (see FIG. 1) measures the voltage drop caused by the resistance of the tip bonding conductor 204 when a constant current pulse Itest for measurement is applied, and measures the detection voltage (see symbol b in FIG. 5).

[0054] [Variations] In the first embodiment, an example in which a wire is used as the chip bonding conductor 204 is shown, but the present invention is not limited to this. For example, when a larger current is to be handled, a semiconductor device 200A shown in the following modified example is used. Fig. 6 is a top view showing an example of the structure of a semiconductor device 200A of a modified example. Fig. 7 is a cross-sectional view taken along the line A-A' in Fig. 6. The same components as those in Fig. 2 and Fig. 3 are designated by the same reference numerals, and explanations of overlapping parts will be omitted. As shown in Figures 6 and 7, semiconductor device 200A differs from semiconductor device 200 in Figures 2 and 3 in that emitter wire 204A as chip bonding conductor 204 is changed to emitter lead 204B, and that emitter sense wire 214 of the switching element is changed to emitter sense lead 214B.

[0055] As shown in FIG. 7, the emitter lead 204B and the emitter sense lead 214B of the switching element are joined by an emitter lead joining layer 204C. Other than these, the semiconductor device is the same as the semiconductor device 200 in FIG. 2 and FIG. 3, so a description thereof will be omitted.

[0056] It is also possible to use the emitter lead 204B in combination with the emitter sense wire 214 shown in FIGS.

[0057] [effect] As described above, in the control circuit 100 that drives the semiconductor device 200 (or 200A, the same applies below) according to this embodiment, the semiconductor device 200 has a switching element 201 that flows a collector current or a drain current as a main current when turned on, and a first terminal 207 and a second terminal 208 connected to the emitter or source of the switching element 201. The first terminal 207 is a first emitter sense terminal (ES) 207 or a first source sense terminal, and the second terminal 208 is a second emitter sense terminal (ES2) 208 or a second source sense terminal. The second terminal 208 may be an emitter terminal (E) 205 or a source terminal.

[0058] The first emitter sense terminal 207 (first terminal) and the surface electrode of the semiconductor chip 201 (switching element) are connected via an emitter sense wire 214 (see Figures 2 and 3) or an emitter sense lead 214B (see Figures 6 and 7) through which no main current flows, and the second emitter sense terminal 208 (second terminal) and the surface electrode of the semiconductor chip 201 (switching element) are connected via an emitter wire 204A (see Figures 2 and 3) or an emitter lead 204B (see Figures 6 and 7) through which a main current flows.

[0059] The control circuit 100 (see FIG. 1) of the semiconductor device 200 includes a gate signal generating circuit 101 that applies a gate signal to a gate terminal 206 of the switching element 201 to drive the switching element 201, a constant current pulse generating circuit 103 that is connected between a first terminal 207 and a second terminal 208 and generates a pulse during a period when the switching element 201 is off, a voltage measurement circuit 104 that measures a voltage between the first terminal 207 and the second terminal 208 when a pulse generated by the constant current pulse generating circuit 103 is applied between the first terminal 207 and the second terminal 208, and a deterioration state determination unit 105 that determines a deterioration state of the bonding of the surface electrode of the semiconductor device 200 and the chip bonding conductor 204 based on a voltage drop measurement result from the voltage measurement circuit 104.

[0060] The constant current pulse generating circuit 103 flows a constant current pulse Itest for measurement from the first emitter sense terminal 207 to the second emitter sense terminal 208 during a period when the main current Ic is not flowing (see “switching element off period” (d) in FIG. 5).

[0061] The voltage measurement circuit 104 measures the voltage drop that occurs due to the resistance of the tip bonding conductor 204 when a constant current pulse Itest for measurement is applied, and measures the detected voltage.

[0062] With this configuration, a constant current pulse Itest for measurement is applied during the period (d) when the switching element 201 is off (see FIG. 5), so that deterioration of the junctions of the semiconductor device 200 can be detected even when the switching element 201 has the period (c) when it is on, i.e., when the system is in operation.

[0063] In particular, the power density has increased due to the miniaturization of inverters, and the risk of wire life shortening due to heat cycles has increased. In this embodiment, crack growth and lift-off of bonding wires and the like can be detected during operation. Since the deterioration of bonding wires and the like can be detected in real time, a destruction warning alarm can be issued or the operation mode can be switched to a low-load operation mode to extend the life of the wires.

[0064] In addition, by adopting a configuration that monitors the voltage drop of the bonding wire, the amount of deterioration can be diagnosed by the increase in resistance due to cracks or lift-off, making it possible to diagnose the degree of deterioration and remaining life of the bonding wire. This is expected to be useful for maintenance services of power devices.

[0065] Second embodiment 8 is a diagram showing the configuration of a semiconductor device to which the control circuit of the semiconductor device according to the second embodiment of the present invention is applied, in which the same components as those in FIG.

[0066] <Temperature sensor 209> 8, semiconductor device 200B further includes a temperature sensor 209 that measures the temperature of semiconductor chip (switching element) 201, and a temperature sensor terminal 210 that extracts the output of temperature sensor 209, in addition to the semiconductor device 200 in FIG 1. A temperature measurement result S5 of temperature sensor 209 is inputted to deterioration state determination unit 105 of control circuit 100B of the semiconductor device via temperature sensor terminal 210.

[0067] <Amplification circuit 107> The control circuit 100B of the semiconductor device further includes an amplifier circuit 107 in addition to the components of the control circuit 100 of the semiconductor device of FIG. The amplifier circuit 107 amplifies the voltage drop across the tip junction conductor 204 between the first emitter sense terminal (ES) 207 and the second emitter sense terminal (ES2) 208. The amplifier circuit 107 amplifies the voltage drop in the tip joint conductor 204 caused by the constant current pulse for measurement, and the voltage measurement circuit 104 measures the voltage amplified by the amplifier circuit 107 .

[0068] The control circuit 100B of the semiconductor device includes the amplifier circuit 107, so that it is possible to detect with high accuracy a minute voltage drop in the tip bonding conductor 204. This makes it possible to improve the accuracy of degradation detection.

[0069] <Deterioration state determination unit 105> (1) The deterioration state determining unit 105 of the semiconductor device control circuit 100B determines the bonding deterioration state of the front surface electrodes of the semiconductor device 200B based on the temperature measurement result from the temperature sensor 209 and the voltage drop measurement result from the voltage measurement circuit 104.

[0070] By inputting both the temperature measurement result by the temperature sensor 209 and the voltage drop measurement result by the voltage measurement circuit 104 to the degradation state determination unit 105, degradation can be detected with higher accuracy.

[0071] (2) When the temperature measurement result from the temperature sensor 209 is predetermined, the deterioration state determining unit 105 of the semiconductor device control circuit 100B determines the bonding deterioration state of the front surface electrodes of the semiconductor device 200B based on the voltage drop measurement result from the voltage measurement circuit 104.

[0072] The chip bonding conductor 204 is a metal, and thus has the characteristic that its electrical resistance varies with an increase in temperature. Therefore, it affects the voltage drop along with the decrease in bonding area due to bonding degradation. Therefore, for example, the voltage drop is detected when the temperature measurement result of the temperature sensor 209 is a predetermined temperature. That is, when the temperature measurement result is a predetermined temperature, the voltage drop at that temperature is detected (the voltage drop is detected when the temperature change is within a predetermined range), thereby eliminating the effect of temperature change. This makes it possible to detect the change in voltage drop due to bonding degradation without being affected by temperature fluctuations. This improves the accuracy of determining the degradation state.

[0073] (3) Temperature sensor 209 of semiconductor device 200B measures multiple temperatures of switching element 201, and inputs the measured temperatures to deterioration state determination unit 105 of control circuit 100B of the semiconductor device. Based on the voltage drop measurement results for multiple temperatures measured by temperature sensor 209, deterioration state determination unit 105 derives a temperature coefficient according to the relationship between this voltage drop and temperature, and compares the derived temperature coefficient with the temperature coefficient of the conductive material used for emitter wire 204A (see FIGS. 2 and 3) or emitter lead 204B (see FIGS. 6 and 7) through which the main current flows, to determine the location where junction deterioration has occurred.

[0074] By detecting the voltage drop for multiple temperatures, it becomes possible to identify the location of deterioration by taking into account the temperature coefficient of the chip bonding conductor 204 (a coefficient that determines the relationship between temperature and electrical resistance and has a different value depending on the material).

[0075] 9 is a graph showing the measurement results V1, V2, and V3 when an aluminum wire is used as the chip bonding conductor 204 and solder is used as the terminal bonding layer 227. The horizontal axis represents the measured temperature T (°C), and the vertical axis represents the detected voltage V (mV). V1 shows the measurement result before degradation, V2 shows the measurement result when the solder bonding area of ​​the terminal bonding layer 227 is reduced by 80%, and V3 shows the measurement result when the bonding area of ​​the aluminum wire of the chip bonding conductor 204 is reduced by 20%. As shown in Figure 9, when the relationship between multiple measured temperatures and detected voltages is obtained, if the obtained results are points A, B, and C, it can be determined that the aluminum wire joint of the chip bonding conductor 204 has deteriorated, and if the results are points D, E, and F, it can be determined that the solder joint of the terminal bonding layer 227 that bonds the emitter sense terminal 207 has deteriorated.

[0076] (Third embodiment) 10 is a diagram showing the configuration of a semiconductor device to which the control circuit of the semiconductor device according to the third embodiment of the present invention is applied, in which the same components as those in FIG. As shown in Fig. 10, a control circuit 100C of a semiconductor device is obtained by removing the constant current pulse generating circuit 103 and the voltage measuring circuit 104 from the control circuit 100 of the semiconductor device of Fig. 1. A semiconductor device 200C is obtained by adding the constant current pulse generating circuit 103 and the voltage measuring circuit 104 to the semiconductor device 200 of Fig. 1. In the third embodiment, a constant current pulse generating circuit 103 and a voltage measuring circuit 104 are built into a semiconductor device 200C.

[0077] The semiconductor device 200C incorporates a constant current pulse generating circuit 103 and a voltage measuring circuit 104. As a result, the constant current pulse for measurement is generated and the voltage drop is measured within the semiconductor device 200C, which reduces an error in the voltage drop of the chip bonding conductor 204 caused by noise superimposed on a signal line connecting the semiconductor device's control circuit 100C and the semiconductor device 200C, enabling more accurate deterioration detection.

[0078] Furthermore, since the semiconductor device 200C has the constant current pulse generating circuit 103 and the voltage measuring circuit 104 built therein, the control circuit 100C of the semiconductor device does not need to have the constant current pulse generating circuit 103 and the voltage measuring circuit 104, and the control circuit 100C of the semiconductor device can be realized with a simple configuration. For the same reason, the control circuit 100C of the semiconductor device can be easily realized by using a general-purpose control circuit device (system).

[0079] The semiconductor device 200C may have either the constant current pulse generating circuit 103 or the voltage measuring circuit 104 built therein. Furthermore, the semiconductor device 200C may have a configuration including a temperature sensor 209 and a temperature sensor terminal 210 shown in FIG.

[0080] The present invention is not limited to the above-described embodiments, and includes other modifications and applications without departing from the spirit of the present invention as described in the claims. For example, although IGBTs (Insulated Gate Bipolar Transistors) are used as switching elements, the present invention is not limited to these, and other types of elements such as MOSFETs can also be used.

[0081] The above embodiments can be applied to, for example, main power conversion devices for railway vehicles, but can also be applied to power conversion devices for automobiles and trucks, power conversion devices for ships and aircraft, industrial power conversion devices used as control devices for electric motors that drive factory equipment, and household power conversion devices used in home solar power generation systems and control devices for electric motors that drive home electrical appliances. The present invention provides a safe and secure inverter system that prevents damage to a power module by diagnosing deterioration and predicting remaining life through status detection.

[0082] The above-mentioned embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0083] 100, 100B, 100C Control circuit 101 Gate signal generating circuit 102 Gate drive circuit 103 Constant current pulse generating circuit 104 Voltage measurement circuit 105 Deterioration state determination unit 106 Alarm generation unit 107 Amplification circuit 200, 200A, 200B, 200C Semiconductor device 201 Semiconductor chips (switching elements) 202 Semiconductor chip (diode element) 203 Collector terminal 204 Chip-bonded conductor 204A emitter wire 204B Emitter lead 204C Emitter lead bonding layer 205 Emitter terminal (second terminal) 206 Gate terminal 207 First emitter sense terminal (ES) (first terminal) 208 Second emitter sense terminal (ES2) (Second terminal) 209 Temperature Sensor 210 Temperature sensor terminal 211 Emitter surface electrode of switching element 212 Surface electrode of diode element 213 Gate surface electrode of switching element 214 Emitter sense wire of switching element 214B Emitter sense lead of switching element 215 Gate wire of switching element 216 Back electrode of switching element 217 Back electrode of diode element 218 Junction layer of switching element 219 Junction layer of diode element 220 Wiring layer of insulating substrate 221 Insulating layer of insulating substrate 222 Back metal layer of insulating substrate 223 Bonding layer of insulating substrate 224 Heat dissipation base 225 cases 226 Insulating filler 227 Terminal bonding layer 300 Network

Claims

1. A control circuit for driving a semiconductor device, comprising: The semiconductor device includes: a switching element that flows a collector current or a drain current as a main current when the switching element is on, a tip junction conductor connected to an emitter or a source of the switching element, and a first terminal and a second terminal connected to both ends of the tip junction conductor; The control circuit includes: a gate signal generating circuit that applies a gate signal to a gate terminal of the switching element to drive the switching element; a constant current pulse generating circuit connected between the first terminal and the second terminal, the constant current pulse generating circuit generating a pulse during a period when the switching element is off; a voltage measurement circuit that measures a voltage between the first terminal and the second terminal when the pulse generated by the constant current pulse generation circuit is applied between the first terminal and the second terminal; a degradation state determination unit that determines a bonding degradation state of the semiconductor device based on a voltage drop measurement result from the voltage measurement circuit. 2 is a block diagram showing a semiconductor device according to the first embodiment of the present invention;

2. A control circuit for driving a semiconductor device, comprising: The semiconductor device includes: a switching element that flows a collector current or a drain current as a main current when the switching element is on, a tip junction conductor connected to an emitter or a source of the switching element, and a first terminal and a second terminal connected to both ends of the tip junction conductor; a constant current pulse generating circuit connected between the first terminal and the second terminal, the constant current pulse generating circuit generating a pulse during a period when the switching element is off; a voltage measurement circuit that measures a voltage between the first terminal and the second terminal when the pulse generated by the constant current pulse generation circuit is applied between the first terminal and the second terminal, The control circuit includes: a gate signal generating circuit that applies a gate signal to a gate terminal of the switching element to drive the switching element; a degradation state determination unit that determines a bonding degradation state of the semiconductor device based on a voltage drop measurement result from the voltage measurement circuit. 2 is a block diagram showing a semiconductor device according to the first embodiment of the present invention;

3. The first terminal is a first emitter sense terminal or a first source sense terminal, and the second terminal is a second emitter sense terminal or a second source sense terminal.

3. The control circuit for a semiconductor device according to claim 1.

4. The first terminal is a first emitter sense terminal or a first source sense terminal, and the second terminal is an emitter terminal or a source terminal.

3. The control circuit for a semiconductor device according to claim 1.

5. The first terminal and the surface electrode of the switching element are connected via a wire or lead through which the main current does not flow, and the second terminal and the surface electrode of the switching element are connected via a wire or lead through which the main current flows.

3. The control circuit for a semiconductor device according to claim 1.

6. When the output of the voltage measurement circuit is abnormal, the gate signal generation circuit outputs a signal different from the normal signal. Generates a gate signal that 3. The control circuit for a semiconductor device according to claim 1.

7. The gate signal different from the normal case is a gate signal for driving the switching element in a low load operation mode.

7. The control circuit for a semiconductor device according to claim 6.

8. a temperature sensor for measuring a temperature of the switching element; The deterioration state determining unit determines a bonding deterioration state of the front electrode of the semiconductor device based on a temperature measurement result from the temperature sensor and a voltage drop measurement result from the voltage measurement circuit.

3. The control circuit for a semiconductor device according to claim 1.

9. An alarm generating unit is provided that generates an alarm when the output of the voltage measuring circuit is abnormal.

3. The control circuit for a semiconductor device according to claim 1.

10. 3. A semiconductor device comprising the control circuit of the semiconductor device according to claim 1.

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