Semiconductor device

Abstract

To provide a semiconductor device capable of estimating a remaining life in the middle of operation even if a wire is disconnected in the middle of the device operation.SOLUTION: The semiconductor integrated circuit device 1A includes a semiconductor integrated circuit chip 2, a plurality of wires 8, a sensor 14, a storage unit 15, a calculation control unit 16, and an outputting unit 17. The plurality of wires 8 connect the semiconductor chip 2 to the outside. The sensor 14 measures a voltage and a current between one terminal and the other terminal of the semiconductor chip 2. The storage unit 15 stores an output characteristic table 151 representing a correspondence relationship between a voltage and a current according to a change in the number of wires 8, and a characteristic variation table 152 representing a correspondence relationship between the number of wires 8 and a voltage variation amount at the time of a change in the number of wires 8. The arithmetic control unit 16 calculates the number of disconnected wires 8 based on the measurement result by the sensor 14 during energization, the output characteristic table 151, and the characteristic fluctuation table 152. Output unit 17 outputs a calculation result obtained by calculation controller 16 to the outside.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device. [Background technology]

[0002] In recent years, semiconductor devices incorporating semiconductor chips such as IGBTs (insulated gate bipolar transistors) and MOSFETs (metal oxide semiconductor field effect transistors) have been widely used to drive the motors of moving objects such as trains and automobiles because they can efficiently supply power to loads such as motors. Such a semiconductor device is integrated by bonding a semiconductor chip, a wiring board to which the back surface of the semiconductor chip is fixed, and a copper base (heat sink plate) to the underside of the wiring board, and in addition, wires are used to connect the upper surface electrodes of the semiconductor chip and the patterns on the wiring board to form a current path.

[0003] The wiring of a semiconductor chip is electrically connected by bonding the electrodes on the lower main surface to a DCB (Direct Copper Bonding) substrate, while wire bonding is performed on the main and control electrodes on the top surface, and the other end of the wire is bonded to the substrate pattern. Multiple wires are usually connected to the main electrodes, which are the flow paths for large currents, and by sharing the current, the current burden of each wire is reduced, thereby ensuring connection reliability that can withstand long-term use.

[0004] As power converters become more powerful and their costs decrease, semiconductor chips are becoming increasingly high-current densities. However, converter systems must provide stable, long-term operation, and so must also improve their power cycle capability, which is closely related to operational reliability. However, as semiconductor chips become smaller, the bondable area on the chip shrinks, placing increasingly strict restrictions on the number of wires that can be bonded. For this reason, a small number of wires are bonded to a limited area on a miniaturized semiconductor chip. However, in applications requiring long-term operation, there is a concern that wire breakage may occur due to the increasing burden of wire wiring. As described in Patent Documents 1 and 2, the occurrence of such wire breakage can be statistically predicted to some extent.

[0005] The above-mentioned Patent Document 1 discloses a technique for detecting whether a wire has been peeled off from a pad by connecting a life prediction wire to the wire bonding pad in advance and checking whether a current flows to the wire bonding pad via the life prediction wire. Also, the above-mentioned Patent Document 2 discloses a technique for estimating the number of wires to be connected from a voltage rise at the wire junction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-4728 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-93289 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, power converters that use power semiconductor chips such as IGBTs must operate stably for a long period of time without interruption, so even if a wire breaks, they must continue operating using the remaining wires. For this reason, there is a demand for a technology that can detect the number of remaining wires even while the power converter is operating and estimate the remaining lifespan, i.e., how long the converter can continue operating. However, the technology disclosed in Patent Document 1 above is a technology that predicts the lifespan of power semiconductor chips such as IGBTs in advance using a lifespan prediction wire, but is not a technology that detects the number of wires that will break. Furthermore, the technology disclosed in Patent Document 2 above is a technology that predicts the current lifespan of a power semiconductor chip, but is not a technology that detects the number of wires that will break.

[0008] An object of the present invention is to provide a semiconductor device that makes it possible to estimate the remaining life during operation even if a wire breaks during operation of the device. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, a semiconductor device according to one embodiment of the present invention comprises a semiconductor chip having at least two or more terminals, at least two or more wire wirings each having a current path connecting from a chip surface electrode of the semiconductor chip to the outside, a sensor that measures the voltage between one terminal and the other terminal of the semiconductor chip and the current flowing between the one terminal and the other terminal, a memory unit that stores an output characteristic table that shows the correspondence between the voltage and the current in response to a change in the number of wire wirings, and a characteristic variation table that shows the correspondence between the number of wire wirings and the amount of voltage variation when the number of wire wirings changes, an arithmetic control unit that calculates the number of broken wire wirings based on the measurement results by the sensor when current is applied and the output characteristic table and the characteristic variation table stored in the memory unit, and an output unit that outputs the calculation results by the arithmetic control unit to the outside. [Effects of the Invention]

[0010] According to one aspect of the present invention, even if a wire breaks during device operation, it is possible to estimate the remaining life during operation. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a schematic configuration of a power semiconductor module according to a first embodiment. [Figure 2] 1 is a perspective view showing an external configuration of a power semiconductor module according to a first embodiment. [Figure 3] FIG. 3 is a characteristic diagram of an output characteristic table stored in a storage unit according to the first embodiment. [Figure 4] FIG. 10 is a circuit diagram showing an example of an equivalent circuit of a power semiconductor element used to calculate a voltage fluctuation amount according to the number of wires. [Figure 5] FIG. 4 is a characteristic diagram of a characteristic variation table stored in a storage unit according to the first embodiment. [Figure 6] FIG. 10 is a block diagram showing a schematic configuration of a power semiconductor module according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The embodiments of the present invention are merely examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0013] First Embodiment 1 is a block diagram showing a schematic configuration of a power semiconductor module according to the first embodiment. The power semiconductor module 1A (an example of a semiconductor device) roughly includes a power semiconductor element 2 (an example of a semiconductor chip), a sensor 14, a storage unit 15, an arithmetic and control unit 16, an output unit 17, and an input unit 18.

[0014] Here, an IGBT will be used as an example of the power semiconductor element 2. The power semiconductor element 2 includes a first voltage terminal 11, a gate terminal 12, and a second voltage terminal 13. As will be described later with reference to FIG. 2, an emitter electrode (E) of the power semiconductor element 2 is connected to earth via a plurality of wires 8 (an example of wire wiring) and a metal plate 3. Furthermore, a collector electrode (C) of the power semiconductor element 2 is connected to the second voltage terminal 13 via solder. The plurality of wires 8 each have a main current path formed from the emitter electrode (E) (an example of a chip surface electrode) of the power semiconductor element 2 to the outside.

[0015] The sensor 14 includes a voltage detection unit 141 and a current detection unit 142. The voltage detection unit 141 is connected to the first voltage terminal 11 and measures the voltage between the collector electrode (C) (an example of one terminal) and the emitter electrode (E) (an example of the other terminal) of the power semiconductor element 2. The current detection unit 142 is installed in a main current path from the emitter electrode (E) of the power semiconductor element 2 to the outside and measures the current flowing from the collector electrode (C) to the emitter electrode (E) of the power semiconductor element 2. In the embodiment of FIG. 1, a current transformer (CT) is used as the current detection unit 142, for example. The CT may be installed in the main current path from the emitter electrode (E) to the outside. If the power semiconductor element 2 has a built-in sense emitter for current detection, the sense emitter can be configured as the current detection unit instead of the CT (not shown).

[0016] The memory unit 15 stores an output characteristic table 151 that shows the correspondence between voltage and current when the number of wires 8 is changed, and a characteristic variation table 152 that shows the correspondence between the number of wires 8 and the amount of voltage variation when the number is changed. The calculation control unit 16 calculates the number of broken wires 8 or the number of remaining wires 8 based on the measurement results by the sensor 14 when current is applied and the output characteristic table 151 and characteristic fluctuation table 152 stored in the memory unit 15.

[0017] An external terminal or the like is connected to the input unit 18 via a terminal 19, and a command to output the number of broken wires 8 or the number of remaining wires 8 is input from the outside. An external display or the like is connected to the output unit 17 via a terminal 20. Then, in accordance with the external command input to the input unit 18, the output unit 17 outputs to the outside the number of broken wires 8 or the number of remaining wires 8 calculated by the arithmetic control unit 16. This allows the user to check the number of broken wires 8 displayed on the display and perform protection operations for the power semiconductor element 2, such as turning off an external gate drive circuit.

[0018] Next, the external configuration of the power semiconductor module 1A will be described with reference to FIG. 2 is a perspective view showing the external configuration of the power semiconductor module according to the first embodiment, in which the same reference numerals as in FIG. The power semiconductor module 1A comprises a power semiconductor element 2 having electrodes on its surface, a metal plate 3 for external electrodes, a metal plate 4 for heat dissipation, an insulating plate 5 having metal films 6 on both sides, and an insulating resin structural material 7 that supports these. The bottom surface of the power semiconductor element 2 is metal-bonded with solder 9 to the metal plate 4 for heat dissipation via the insulating plate 5 in order to dissipate heat generated during switching and steady current flow.

[0019] Furthermore, the upper surface of the power semiconductor element 2 and the metal plate 3 for the external electrode are joined by a plurality of wires 8. The metal plate 3 is grounded. As can be seen from the circuit diagram in FIG. 1 , a large current flows from the collector electrode (C) to the emitter electrode (E) of the power semiconductor element 2, so a plurality of wires 8 are used. A first voltage terminal 11, a gate terminal 12, and a second voltage terminal 13 of the power semiconductor element 2 are provided as respective voltage terminals. The gate terminal 12 is connected to the gate electrode (G) of the power semiconductor element 2. The second voltage terminal 13 is connected to the collector electrode (C) of the power semiconductor element 2.

[0020] Furthermore, in the first embodiment, the power semiconductor element 2 generates heat when energized, and the temperature repeatedly rises and falls. For example, the power semiconductor element 2 is mainly made of single crystal silicon, and has a linear expansion coefficient of approximately 4.2×10 -6 / °C, whereas the wire 8 is made of pure aluminum or aluminum containing a few ppm of nickel, and has a linear expansion coefficient of approximately 23 × 10 -6 / °C, which is a difference of about 5 times. For this reason, over long-term use, distortion occurs due to the difference in linear expansion coefficient, and cracks occur and grow in the joints of the wires 8 joined on the top surface of the power semiconductor element 2. Due to this cracking and growth, the joint area of ​​the wires 8 gradually decreases over long-term use, and the electrical resistance of this part gradually increases. In the above description, an IGBT is used as the power semiconductor element 2, but the same applies to the case where a MOSFET is used.

[0021] Next, the output characteristic table 151 stored in the storage unit 15 according to the first embodiment will be described with reference to FIG. 3 is a characteristic diagram of the output characteristic table 151 stored in the storage unit 15 according to the first embodiment. The output characteristic table 151 is measured in advance by, for example, an external measuring device. In FIG. 3, the horizontal axis represents the voltage V between the collector electrode (C) and the emitter electrode (E) of the power semiconductor element 2. CE The vertical axis represents the current I that flows from the collector electrode (C) to the emitter electrode (E) of the power semiconductor element 2. C Shows.

[0022] Also, in FIG. 3, curve W6 shows the output characteristics when, for example, one of seven wires 8 is broken, leaving six wires 8. Curve W5 shows the output characteristics when, for example, two wires 8 are broken, leaving five wires 8. Curve W4 shows the output characteristics when, for example, three wires 8 are broken, leaving four wires 8. Curve W3 shows the output characteristics when, for example, four wires 8 are broken, leaving three wires 8. Curve W2 shows the output characteristics when, for example, five wires 8 are broken, leaving two wires 8. Curve W1 shows the output characteristics when, for example, only one wire 8 remains. As shown in Figure 3, as the number of broken wires 8 increases, the voltage V CE This indicates that the number of wires 8 connecting the emitter electrode (E) of the power semiconductor element 2 and the metal plate 3 is reduced, and the electrical resistance value of each wire 8 is increased.

[0023] Next, an example of calculating the amount of voltage fluctuation according to the number of wires 8 will be described with reference to FIG. FIG. 4 is a circuit diagram showing an example of an equivalent circuit of the power semiconductor element 2 used to calculate the amount of voltage fluctuation corresponding to the number of wires 8. As shown in FIG. First, in order to calculate the voltage fluctuation amount according to the number of wires 8, the electrical resistance value R of each wire 8 is calculated. WB Calculate the electrical resistance value R WB is obtained from the relational expression (Equation 1) of the amount of voltage drop when the number of wires 8 changes.

[0024]

number

[0025] Note that N is the number of wires 8 and is an integer of 2 or more. C is the current flowing from the collector electrode (C) to the emitter electrode (E) of the power semiconductor element 2. ΔV WB is the voltage fluctuation amount. The above (Equation 1) is the electrical resistance value R when changing from N wires to N-1 wires. WB This is the calculation formula. Next, the electrical resistance value R WB Using this, the voltage fluctuation amount ΔV according to the number of wires 8 WB Calculate the voltage fluctuation amount ΔV WB is calculated by the relation (Equation 2).

[0026]

number

[0027] Voltage fluctuation ΔV WB is a known quantity in the characteristic fluctuation table 152.

[0028] Next, the characteristic variation table 152 stored in the storage unit 15 according to the first embodiment will be described with reference to FIG. 5 is a characteristic diagram of the characteristic variation table 152 stored in the storage unit 15 according to the first embodiment. The characteristic variation table 152 is measured in advance by, for example, an external measuring device. 5, the horizontal axis represents the ratio of the number of wires 8 to the initial number of 7, and the vertical axis represents the voltage fluctuation amount ΔV WB Shows.

[0029] Also, in Figure 5, point D0 is the voltage fluctuation ΔV in the initial state (7 wires, 8 connections). WB The point D1 indicates the voltage fluctuation ΔV when, for example, one wire 8 is broken (the remaining six wires). WB Point D2 indicates the voltage fluctuation ΔV when, for example, two wires 8 are broken (five wires remaining). WB The point D3 indicates the voltage fluctuation ΔV when, for example, three wires 8 are broken (four remaining). WB The point D4 indicates the voltage fluctuation ΔV when, for example, four wires 8 are broken (the remaining three wires). WB The point D5 indicates the voltage fluctuation ΔV when, for example, five wires 8 are broken (two remaining wires). WB Shows. As shown in FIG. 5, as the number of broken wires 8 increases, the voltage fluctuation amount ΔV WB gradually increases.

[0030] Next, the operation of the arithmetic control unit 16 will be described. The arithmetic and control unit 16 performs the following operations as required in response to an external command. (Step 1) The output characteristic table 151 (initial output characteristic) stored in the storage unit 15 and the voltage V measured by the sensor 14 are used. CE (voltage drop amount) and based on the comparison result, the voltage fluctuation amount ΔV when power is applied WB Calculate. (Step 2) Calculated voltage fluctuation ΔV WBis compared with the characteristic fluctuation table 152 stored in the storage unit 15, and the number of broken wires 8 or the number of remaining wires 8 is calculated based on the comparison result.

[0031] The output unit 17 outputs to the outside the number of broken wires 8 or the number of remaining wires 8 calculated by the calculation control unit 16. This allows the user to check the number of broken wires 8 displayed on an external display and perform protection operations for the power semiconductor element 2, such as turning off an external gate drive circuit.

[0032] <Effects of the First Embodiment> As described above, according to the first embodiment, the output characteristics depending on the number of wires 8 are measured in advance, and the amount of voltage fluctuation that occurs is calculated. This allows the relationship between the number of broken wires 8 in the power semiconductor element 2 and the amount of voltage fluctuation to be derived in advance and stored in the storage unit 15. Then, when current is applied, the sensor 14 measures the current I C -Voltage V CE By measuring this, it is possible to determine the initial state in which all wires 8 are connected in a healthy state, and the number of wires 8 that have broken as a result of deterioration due to current flow. Therefore, by detecting and outputting the number of remaining wires 8 that break during the deterioration process associated with the operation of the power semiconductor module 1A, it is possible to estimate the remaining lifespan during operation, and further realize the function of protecting the power semiconductor module 1A from current loads.

[0033] <Second embodiment> Fig. 6 is a block diagram showing a schematic configuration of a power semiconductor module according to the second embodiment. In Fig. 6, the same parts as those in Fig. 1 are given the same reference numerals and detailed description thereof will be omitted. The power semiconductor module 1B includes a free wheel diode 30. The free wheel diode 30 is connected in parallel to the power semiconductor element 2. A cathode electrode (K) of the free wheel diode 30 is connected to a collector electrode (C) of the power semiconductor element 2. An anode electrode (A) of the free wheel diode 30 is connected to an emitter electrode (E) of the power semiconductor element 2. The free wheel diode 30 is mainly made of single crystal silicon.

[0034] The voltage detection unit 141 of the sensor 14 measures the voltage between the collector electrode (C) and the emitter electrode (E) of the power semiconductor element 2, and also measures the voltage between the cathode electrode (K) and the anode electrode (A) of the freewheeling diode 30. The current detection unit 142 of the sensor 14 measures the current flowing from the collector electrode (C) to the emitter electrode (E) of the power semiconductor element 2, and also measures the current flowing from the anode electrode (A) to the cathode electrode (K) of the freewheeling diode 30.

[0035] <Effects of the second embodiment> As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained.

[0036] <Other embodiments> In the first and second embodiments, the power semiconductor element 2 is primarily made of single-crystal silicon. However, other semiconductor materials, such as silicon carbide, gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide, or diamond, each having a wider bandgap than silicon (1.1 eV), can be used for the power semiconductor element 2. Furthermore, the power semiconductor element 2 may be made of a combination of silicon, silicon carbide, gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide, or diamond. The freewheel diode 30 may also be made of other materials, such as silicon carbide, gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide, or diamond, or a combination thereof.

[0037] The technical scope of the present invention is not limited to the exemplary embodiments shown and described, but also includes all embodiments that achieve equivalent effects to the object of the present invention. Furthermore, the technical scope of the present invention is not limited to the combination of inventive features defined by the claims, but can be defined by any desired combination of specific features from among all the respective disclosed features. [Explanation of symbols]

[0038] 1A, 1B Power Semiconductor Module 2. Power semiconductor elements 3 metal plate 4. Heat dissipation metal plate 5. Insulating plate 6 Metal Film 7. Insulating resin structural material 8 Multiple Wires 9 Solder 11 First voltage terminal 12 Gate terminal 13 Second voltage terminal 14 Sensors 15 Storage section 16 Calculation control unit 17 Output section 18 Input section 19,20 terminals 30 Freewheeling diode 141 Voltage detection unit 142 Current detection unit 151 Output characteristics table 152 Characteristics Variation Table

Claims

1. a semiconductor chip having at least two or more terminals; at least two or more wires each having a current path connecting the chip surface electrode of the semiconductor chip to an external device; a sensor that measures a voltage between one terminal and another terminal of the semiconductor chip and a current flowing between the one terminal and the other terminal; a storage unit that stores an output characteristics table that indicates a correspondence relationship between the voltage and the current according to a change in the number of wires, and a characteristics variation table that indicates a correspondence relationship between the number of wires and a voltage variation amount when the number of wires changes; an arithmetic control unit that calculates the number of broken wires based on the measurement results of the sensor when current is applied, and the output characteristic table and the characteristic fluctuation table stored in the storage unit; an output unit that outputs the calculation result by the calculation control unit to the outside; A semiconductor device comprising:

2. 2. The semiconductor device according to claim 1, wherein the calculation control unit calculates a fluctuation amount of the voltage when current is applied based on a comparison between the voltage measured by the sensor and the output characteristic table, and calculates the number of broken wires based on the calculated fluctuation amount of the voltage and the characteristic variation table.

3. 2. The semiconductor device according to claim 1, wherein the semiconductor chip is at least one of an insulated gate bipolar transistor, a MOSFET, and a diode.

4. 4. The semiconductor device according to claim 1, wherein the material of said semiconductor chip is one of silicon, silicon carbide, gallium arsenide, gallium nitride, gallium oxide, and diamond, or a combination of two or more of these.

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