Semiconductor device

Abstract

Provided is a semiconductor device comprising: a main transistor unit in which a main current flows; and a sense transistor unit that is provided in parallel with the main transistor unit and in which a sense current flows, wherein a gate resistance ratio obtained by dividing a resistance value of a sense gate resistance, which is a gate drive resistance of the sense transistor unit, by a resistance value of a main gate resistance, which is a gate drive resistance of the main transistor unit, is 0.015 times or more of a current ratio obtained by dividing the main current by the sense current.

Description

Semiconductor Devices

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

[0002] In semiconductor devices such as IGBTs (Insulated Gate Bipolar Transistors), a configuration is known in which a sense transistor is provided to detect a current flowing through a main transistor (see, for example, Patent Documents 1 to 3). Problem to be solved

[0003] To suppress oscillation of a current or voltage waveform when a sense transistor is turned on. General disclosure

[0004] One aspect of the present invention provides a semiconductor device. The semiconductor device may include a main transistor section that passes a main current in response to an applied gate signal. The semiconductor device may also include a sense transistor section that is provided in parallel with the main transistor section and passes a sense current in response to the gate signal that is common to the main transistor section. In the semiconductor device, a gate resistance ratio obtained by dividing a resistance value of a sense gate resistor that is a gate drive resistance of the sense transistor section by a resistance value of a main gate resistor that is a gate drive resistance of the main transistor section may be 0.015 or more times a current ratio obtained by dividing the main current by the sense current.

[0005] In any of the above semiconductor devices, the gate resistance ratio may be 0.5 times or more the current ratio.

[0006] In any of the above semiconductor devices, the gate resistance ratio may be equal to or greater than the current ratio.

[0007] In any of the above semiconductor devices, the gate resistance ratio may be 2.5 times or less the current ratio.

[0008] In any of the above semiconductor devices, the gate resistance ratio may be 30 or more.

[0009] In any of the above semiconductor devices, the gate resistance ratio may be 1000 or more.

[0010] In any of the above semiconductor devices, the gate resistance ratio may be 2000 or more.

[0011] In any of the above semiconductor devices, the gate resistance ratio may be 5000 or less.

[0012] In any of the above semiconductor devices, the resistance value of the sense gate resistor may be 300Ω or more.

[0013] In any of the above semiconductor devices, the resistance value of the sense gate resistor may be 10 kΩ or more.

[0014] In any of the above semiconductor devices, the resistance value of the sense gate resistor may be 20 kΩ or more.

[0015] In any of the above semiconductor devices, the resistance value of the sense gate resistor may be 50 kΩ or less.

[0016] Any of the above semiconductor devices may include a main gate transmission unit that transmits the gate signal to the main transistor unit. Any of the above semiconductor devices may include a sense gate transmission unit that is provided in parallel with the main gate transmission unit and transmits the gate signal to the sense transistor unit. In any of the above semiconductor devices, the sense gate transmission unit may have an ON path that includes the sense gate resistor and that passes a gate current to a gate terminal of the sense transistor unit in response to the gate signal. In any of the above semiconductor devices, the sense gate transmission unit may have an OFF path that is provided in parallel with the ON path and that draws charge from the gate terminal of the sense transistor unit in response to the gate signal. In any of the above semiconductor devices, the resistance value of the sense gate resistor may be 200 times or more the resistance value of the OFF path.

[0017] In any of the above semiconductor devices, the resistance value of the sense gate resistor may be 2000 times or more the resistance value of the off-path.

[0018] In any of the above semiconductor devices, the on-path may include a first diode having a cathode terminal connected to the gate terminal of the sense transistor portion. In any of the above semiconductor devices, the on-path may include the sense gate resistor provided in series with the first diode. In any of the above semiconductor devices, the off-path may include a second diode having an anode terminal connected to the gate terminal of the sense transistor portion. In any of the above semiconductor devices, the off-path may include a sense off-resistor provided in series with the second diode. In any of the above semiconductor devices, the resistance value of the sense gate resistor may be 200 times or more the resistance value of the sense off-resistor.

[0019] In any of the above semiconductor devices, the sense gate resistor and the sense transistor section may be provided on the same semiconductor chip.

[0020] In any of the above semiconductor devices, the sense gate resistor may be provided outside a semiconductor chip including the sense transistor portion.

[0021] Any of the above semiconductor devices may include a gate pad to which the gate signal is applied. Any of the above semiconductor devices may include a sense gate transmission unit that transmits the gate signal to the sense transistor unit. In any of the above semiconductor devices, the sense gate transmission unit may have a first pad connected to the gate pad. In any of the above semiconductor devices, the sense gate transmission unit may have a second pad connected to the sense transistor unit. In any of the above semiconductor devices, the sense gate resistor may be connected between the first pad and the second pad.

[0022] Any of the semiconductor devices described above may include a plurality of the sense gate resistors, and a switching unit configured to switch which of the sense gate resistors is connected between the first pad and the second pad.

[0023] The above summary of the invention does not list all of the necessary features of the present invention. In addition, subcombinations of these features may also constitute inventions.

[0024] 1 is a diagram showing an equivalent circuit of a semiconductor device 200 according to an embodiment of the present invention. FIG. 1 shows an example of a time waveform of the emitter voltage Vse of the sense transistor section 170 when the main transistor section 70 and the sense transistor section 170 are turned on. FIG. 2 shows an example of a time waveform of the emitter voltage Vse in the vicinity of a transient period. FIG. 3 shows another example of a time waveform of the emitter voltage Vse in the vicinity of a transient period. FIG. 4 shows another example of a time waveform of the emitter voltage Vse. FIG. 5 is a diagram showing an example of a waveform of the emitter voltage Vse when the absolute values ​​of the areas of the main transistor section 70 and the sense transistor section 170 are changed while the current ratio (Im / Is) and the gate resistance ratio (Rgs / Rgm) are fixed. FIG. 6 is a diagram showing another example of a waveform of the emitter voltage Vse when the absolute values ​​of the areas of the main transistor section 70 and the sense transistor section 170 are changed while the current ratio (Im / Is) and the gate resistance ratio (Rgs / Rgm) are fixed. FIG. 7 is a diagram showing another example of a configuration of the semiconductor chip 100. FIG. 8 is a diagram showing another example of a configuration of the semiconductor device 200. 11A and 11B are diagrams illustrating another example of the configuration of the semiconductor device 200. FIG. 11C is a top view showing an example of the semiconductor chip 100. FIG. 11D is a diagram showing an example of the AA' cross section in FIG. 11. FIG. 11E is a diagram showing an example of the semiconductor device 400 according to the comparative example. FIG. 11F is a diagram showing another example of the semiconductor device 400 according to the comparative example.

[0025] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. In this specification, the same parts in each drawing are given the same reference numerals, and their description may be omitted. Furthermore, for the sake of convenience, some components may not be illustrated.

[0026] In this specification, one side in a direction parallel to the depth direction of a semiconductor substrate is referred to as "upper" and the other side as "lower." Of the two main surfaces of a substrate, layer, or other member, one surface is referred to as the upper surface and the other surface is referred to as the lower surface. The directions of "upper" and "lower" are not limited to the direction of gravity or the directions when the semiconductor device is mounted.

[0027] In this specification, technical matters may be explained using an orthogonal coordinate system of X, Y, and Z axes. The orthogonal coordinate system merely specifies the relative positions of components and does not limit a specific direction. For example, the Z-axis direction does not limit the height direction relative to the ground. Note that the +Z-axis direction and the -Z-axis direction are opposite directions. When the Z-axis direction is written without specifying positive or negative, it means the direction parallel to the +Z-axis and -Z-axis.

[0028] In this specification, orthogonal axes parallel to the upper and lower surfaces of the semiconductor substrate are referred to as the X-axis and Y-axis. Furthermore, an axis perpendicular to the upper and lower surfaces of the semiconductor substrate is referred to as the Z-axis. In this specification, the direction of the Z-axis may be referred to as the depth direction. Furthermore, in this specification, the direction parallel to the upper and lower surfaces of the semiconductor substrate, including the X-axis and Y-axis, may be referred to as the horizontal direction.

[0029] In this specification, when terms such as "same" or "equal" are used, it may include cases where there is an error due to manufacturing variations or the like. The error is, for example, within 10%. Furthermore, in this specification, when terms such as "parallel" or "perpendicular" are used, it may include an error of within 5°.

[0030] In this specification, the conductivity type of a doped region doped with an impurity is described as P-type or N-type. In this specification, the term "impurity" may particularly refer to either an N-type donor or a P-type acceptor, and may be referred to as a "dopant." In this specification, "doping" means introducing a donor or an acceptor into a semiconductor substrate to form a semiconductor exhibiting an N-type conductivity type or a P-type conductivity type. In this specification, the doping concentration of an N-type region may be referred to as a "donor concentration," and the doping concentration of a P-type region may be referred to as an "acceptor concentration."

[0031] In this specification, when P+ type or N+ type is described, it means that the doping concentration is higher than that of P type or N type, and when P- type or N- type is described, it means that the doping concentration is lower than that of P type or N type. The unit system in this specification is the SI unit system unless otherwise specified.

[0032] In describing a circuit diagram, when the arrangement of elements is described as "a third element is provided between a first element and a second element," the description describes the arrangement of electrical paths, i.e., the description does not describe the relative spatial positions of the first element, the second element, and the third element.

[0033] 1 is a diagram showing an equivalent circuit of a semiconductor device 200 according to an embodiment of the present invention. The semiconductor device 200 controls the power supply to a load 300. The semiconductor device 200 includes a semiconductor chip 100. The semiconductor device 200 may include only the semiconductor chip 100, or may be a semiconductor module including the semiconductor chip 100 and peripheral circuits. The semiconductor module may include a housing that houses the semiconductor chip 100 and the peripheral circuits. The housing may include an insulating material such as resin or ceramic.

[0034] The semiconductor device 200 may be connected to an external power supply 210. The semiconductor device 200 of this example controls the power supply from the external power supply 210 to the load 300.

[0035] The semiconductor chip 100 of this example is connected in series with the load 300. The semiconductor chip 100 of this example is a switch that controls whether or not to cut off the current flowing through the load 300. The semiconductor chip 100 may be capable of controlling the magnitude of the current flowing through the load 300.

[0036] The semiconductor chip 100 includes a main transistor section 70, a sense transistor section 170, a main gate resistor 57, and a sense gate resistor 59. The semiconductor chip 100 may further include a gate pad 116 to which a gate signal Vg is applied, a main gate transmission section 53, and a sense gate transmission section 55.

[0037] The main gate transmission unit 53 is connected to the gate pad 116 and transmits the gate signal Vg to the main transistor unit 70. The main gate transmission unit 53 may include at least one of a metal wiring and a polysilicon wiring provided on the semiconductor substrate.

[0038] The sense gate transmission unit 55 is provided in parallel with the main gate transmission unit 53 and transmits the gate signal Vg to the sense transistor unit 170. The sense gate transmission unit 55 may be provided from the gate pad 116 to the sense transistor unit 170, or may be branched from the main gate transmission unit 53 and provided to the sense transistor unit 170.

[0039] The main gate resistance 57 is the gate drive resistance of the main transistor section 70. In other words, the main gate resistance 57 is the resistance of the main gate transmission section 53 from the gate pad 116 to the gate terminal of the main transistor section 70. If no resistive element is provided in the main gate transmission section 53, the main gate resistance 57 is a parasitic resistance of the main gate transmission section 53. For example, the main gate resistance 57 may be 10 Ω or less, 5 Ω or less, or 2 Ω or less. The main gate resistance 57 is greater than 0 Ω.

[0040] The sense gate resistor 59 is a gate drive resistor of the sense transistor section 170. In other words, the sense gate resistor 59 is the resistance of the sense gate transmission section 55 from the gate pad 116 to the gate terminal of the sense transistor section 170. If the sense gate transmission section 55 branches off from the main gate transmission section 53, the resistance from the branch point to the gate terminal of the sense transistor section 170 may be the sense gate resistor 59.

[0041] The main transistor unit 70 passes a main current Im in response to an applied gate signal Vg. In the example of FIG. 1 , the main transistor unit 70 is an IGBT, but the main transistor unit 70 may be a MOSFET or another type of transistor. The main transistor unit 70 in this example is connected in series with the load 300. Therefore, the main current Im flowing through the main transistor unit 70 also flows through the load 300. In the example of FIG. 1 , the load 300 is connected between the main transistor unit 70 and the external power supply 210.

[0042] When the main transistor section 70 is turned off in response to the gate signal Vg, the current flowing from the load 300 to a reference potential such as the ground potential is cut off. When the main transistor section 70 is turned on in response to the gate signal Vg, a predetermined main current Im flows through the load 300.

[0043] The semiconductor device 200 may include a free wheel diode 230 provided in parallel with the load 300. The cathode terminal of the free wheel diode 230 is connected to the external power supply 210, and the anode terminal is connected to the collector terminal of the main transistor section 70. When the main transistor section 70 is turned off, the current flowing through the load 300 flows back to the free wheel diode 230.

[0044] The sense transistor section 170 is provided in parallel with the main transistor section 70. The sense transistor section 170 has a structure similar to that of the main transistor section 70. For example, the sense transistor section 170 may be a portion of the semiconductor chip 100 that functions as the main transistor section 70, separated from the other regions. In this example, the sense transistor section 170 is an IGBT, but it may also be a MOSFET or other transistor. The collector terminal of the sense transistor section 170 is connected to the collector terminal of the main transistor section 70. The emitter terminals of the main transistor section 70 and the sense transistor section 170 are each connected to a reference potential. However, a sense resistor 250 is provided between the emitter terminal of the sense transistor section 170 and the reference potential.

[0045] The sense transistor section 170 receives the same gate signal Vg as the main transistor section 70. The sense transistor section 170 passes a sense current Is in response to the applied gate signal Vg. The sense transistor section 170 has a similar structure to the main transistor section 70, and receives the same gate signal Vg as the main transistor section 70, so the sense current Is is proportional to the main current Im. The current ratio between the sense current Is and the main current Im is approximately equal to the ratio between the total channel width in the sense transistor section 170 and the total channel width in the main transistor section 70. Since the sense transistor section 170 in this example has a similar structure to the main transistor section 70, the area ratio between the sense transistor section 170 and the main transistor section 70 determines the ratio of the total channel widths, and therefore the current ratio.

[0046] In this specification, the value (Im / Is) obtained by dividing the current value of the main current Im by the current value of the sense current Is is referred to as the current ratio. The current ratio is greater than 1. The current ratio may be 100 or more, 1000 or more, or even 2000 or more. The current ratio in this example is the same as the area ratio obtained by dividing the area occupied by the main transistor section 70 on the semiconductor substrate by the area occupied by the sense transistor section 170. The value of this area ratio may be used as the value of the current ratio.

[0047] The sense current Is flows through the sense resistor 250. The magnitude of the sense current Is can be detected by measuring the voltage across the sense resistor 250. For example, the magnitude of the sense current Is can be calculated by dividing the voltage across the sense resistor 250 by the resistance value Rs of the sense resistor 250.

[0048] The semiconductor chip 100 may include a diode section 80 connected in anti-parallel to the main transistor section 70. The semiconductor chip 100 may include a diode section 180 connected in anti-parallel to the sense transistor section 170. The diode section 80 and the diode section 180 function as freewheeling diodes. The semiconductor chip 100 may be an RC-IGBT (reverse conducting IGBT). In this example, the cathode terminal of each freewheeling diode section is connected to the collector terminal of the transistor section, and the anode terminal is connected to the emitter terminal.

[0049] The semiconductor device 200 may further include a capacitor 220. The capacitor 220 is provided in parallel with the external power supply 210. The capacitor 220 can smooth the power supplied from the external power supply 210 to the load 300. Also, FIG. 1 shows a stray inductance 240 between the load 300 and the semiconductor chip 100.

[0050] When attempting to turn on the main transistor section 70 and the sense transistor section 170, the gate insulating film of each transistor section may be charged by carriers injected from the collector terminal. This phenomenon is called self-charging. When the gate insulating film is charged by self-charging, the voltage at the gate electrode becomes higher than the voltage of the gate signal Vg. This causes the transistor section to turn on before the gate signal Vg reaches the threshold voltage. This phenomenon is called self-on.

[0051] As described above, the area of ​​the sense transistor section 170 is smaller than the area of ​​the main transistor section 70. Therefore, the capacitance of the gate insulating film in the sense transistor section 170 is relatively small, and the voltage at the gate electrode is likely to rise due to self-charging. As a result, the sense transistor section 170 may turn on earlier than the main transistor section 70. If the sense transistor section 170 turns on first, carriers that should flow to the main transistor section 70 around the sense transistor section 170 will flow to the sense transistor section 170, causing a surge in the time waveform of the sense current Is or emitter voltage Vse of the sense transistor section 170.

[0052] In the semiconductor device 200, the turn-on of the sense transistor section 170 is delayed by adjusting the sense gate resistor 59. This suppresses the occurrence of a surge in the sense transistor section 170. More specifically, the gate resistance ratio (Rgs / Rgm) obtained by dividing the resistance value Rgs of the sense gate resistor 59 by the resistance value Rgm of the main gate resistor 57 is adjusted.

[0053] The main transistor section 70 is provided in a predetermined region of the semiconductor substrate. Therefore, the gate terminals of the main transistor section 70 are distributed within the predetermined region. Therefore, the length of the main gate transmission section 53 from the gate pad 116 to the gate terminal of the main transistor section 70 varies depending on the position within the predetermined region, and the size of the main gate resistor 57 also varies depending on the position within the predetermined region. If the size of the main gate resistor 57 varies, the minimum value of the main gate resistor 57 may be used as the value of the main gate resistor 57. The resistance value of the shortest main gate transmission section 53 from the gate pad 116 to the gate terminal of the main transistor section 70 may be used as the value of the main gate resistor 57.

[0054] The sense gate resistance 59 may also vary depending on the position on the semiconductor substrate, similar to the main gate resistance 57. The minimum value of the sense gate resistance 59 may be used as the value of the sense gate resistance 59.

[0055] 2 shows an example of the time waveform of the emitter voltage Vse of the sense transistor section 170 when the main transistor section 70 and the sense transistor section 170 are turned on. In FIG. 2, the emitter voltage of the main transistor section 70 is set to the reference voltage (0 V). In this example, the resistance value Rgm of the main gate resistor 57 is 10 Ω. The current ratio Im / Is is 2000. In this specification, when showing the time waveform of the emitter voltage Vse, Rgm = 10 Ω and Im / Is = 2000, unless otherwise specified.

[0056] 2 shows waveforms obtained when the resistance value of the sense gate resistor 59 is adjusted to 10Ω, 10 kΩ, 20 kΩ, and 50 kΩ. The resistance value of the sense gate resistor 59 may be adjusted by inserting a resistive element into the sense gate transmission section 55. In another example, a material with a higher resistivity than the main gate transmission section 53 may be used in at least a portion of the sense gate transmission section 55, the cross-sectional area of ​​the wiring may be smaller than that of the main gate transmission section 53, and the concentration of impurities implanted into the wiring, such as polysilicon, may be lower than that of the main gate transmission section 53.

[0057] The emitter voltage Vse of the sense transistor unit 170 converges to a voltage (e.g., Is × Rs) corresponding to the sense current Is, which is proportional to the main current Im. The period after the emitter voltage Vse converges is called the steady period. The period from when a gate signal Vg of a predetermined on-voltage is applied to the gate terminal of the sense transistor unit 170 until the steady period is reached is called the transient period. In FIG. 2 , the arrows indicate the transient period and steady period when the resistance value Rgs of the sense gate resistor 59 is equal to the resistance value Rgm of the main gate resistor 57 (i.e., Rgs = Rgm = 10Ω).

[0058] When the resistance value Rgs of the sense gate resistor 59 is equal to the resistance value Rgm of the main gate resistor 57, the sense transistor section 170 turns on due to self-on before the main transistor section 70. This causes a surge in the emitter voltage Vse during the transition period.

[0059] 2, increasing the resistance value of the sense gate resistor 59 reduces the surge in the emitter voltage Vse. Furthermore, in the examples where Rgs=10 kΩ and 20 kΩ, although the surge peak remains, the emitter voltage Vse converges more quickly than in the example where Rgs=10 Ω. In the example where Rgs=50 kΩ, the surge in the emitter voltage Vse is eliminated. Furthermore, compared to the example where Rgs=10 Ω, the emitter voltage Vse converges more quickly.

[0060] The control device of the semiconductor device 200 determines whether an overcurrent is flowing through the main transistor unit 70 based on the magnitude of the sense current (i.e., the magnitude of the emitter voltage Vse). If the control device determines that an overcurrent is flowing, it forcibly controls the main transistor unit 70 to an off state, thereby protecting the semiconductor device 200.

[0061] On the other hand, the magnitude of the emitter voltage Vse during the transient period does not reflect the magnitude of the main current Im of the main transistor section 70. Therefore, the control device does not use the emitter voltage Vse during the transient period to detect overcurrent. The period not used to detect overcurrent is preset in the control device as a mask period. However, since overcurrent cannot be detected during the mask period, the semiconductor device 200 cannot be protected. According to this example, the convergence of the emitter voltage Vse can be accelerated by adjusting the resistance value of the sense gate resistor 59. Therefore, the length of the mask period set in the control device can be shortened, and the period during which the semiconductor device 200 can be protected can be extended.

[0062] 3 shows an example of the time waveform of the emitter voltage Vse near the transient period. In this example, the waveforms are shown when the resistance value Rgs of the sense gate resistor 59 is adjusted to 10Ω, 20Ω, 40Ω, 60Ω, 80Ω, 100Ω, 300Ω, 500Ω, 700Ω, 900Ω, and 1 kΩ. While FIG. 3 only shows waveforms for Rgs=10Ω, 300Ω, and 1 kΩ, the surge becomes smaller as the resistance value Rgs increases.

[0063] As shown in FIG. 3 , when Rgs = 300Ω, the surge was reduced relatively significantly. The gate resistance ratio (Rgs / Rgm) at this time was 30. The gate resistance ratio (Rgs / Rgm) was also 0.015 times the current ratio (Im / Is). When the current ratio (Im / Is) was changed, the surge was also reduced relatively significantly in an example where the gate resistance ratio (Rgs / Rgm) was 0.015 times the current ratio (Im / Is). In the semiconductor device 200 of this example, the gate resistance ratio (Rgs / Rgm) was 0.015 times or more the current ratio (Im / Is). This suppresses surges in the emitter voltage Vse, as shown in FIG. 3 . Therefore, erroneous detection of the main current Im can be suppressed. The gate resistance ratio (Rgs / Rgm) may be 30 or more. The resistance value Rgs of the sense gate resistor 59 may be 300Ω or more.

[0064] In this example, the gate resistance ratio (Rgs / Rgm) is adjusted according to the current ratio (Im / Is). Since the current ratio (Im / Is) corresponds to the area ratio of the transistor section, the smaller the area of ​​the sense transistor section 170, the larger the sense gate resistance Rgs should be. As described above, the smaller the area of ​​the sense transistor section 170, the more likely the gate voltage will rise due to self-charge. In contrast, by adjusting the gate resistance ratio (Rgs / Rgm) according to the current ratio (Im / Is), it becomes easier to offset the rise in gate voltage due to self-charge. Therefore, the turn-on timing of the sense transistor section 170 can be appropriately adjusted.

[0065] 4 shows another example of the time waveform of the emitter voltage Vse near the transient period. In this example, the waveforms are shown when the resistance value Rgs of the sense gate resistor 59 is adjusted to 1 kΩ, 3 kΩ, 5 kΩ, 7 kΩ, 9 kΩ, 10 kΩ, and 30 kΩ. In the initial period T1 of the transient period, increasing the resistance value Rgs tended to increase the instantaneous peak of the surge waveform. In the intermediate period T2 after the initial period T1, increasing the resistance value Rgs tended to reduce the surge. In the latter period T3 after the intermediate period T2, increasing the resistance value Rgs significantly reduced the surge.

[0066] In particular, when Rgs=3 kΩ, the surge in the latter half period T3 was reduced relatively significantly compared to the example where Rgs=1 kΩ. The gate resistance ratio (Rgs / Rgm) when Rgs=3 kΩ is 300. The gate resistance ratio (Rgs / Rgm) is 0.15 times the current ratio (Im / Is). In the semiconductor device 200, the gate resistance ratio (Rgs / Rgm) may be 0.15 times or more the current ratio (Im / Is). The gate resistance ratio (Rgs / Rgm) may be 300 or more. The resistance value Rgs of the sense gate resistor 59 may be 3 kΩ or more.

[0067] When Rgs=9 kΩ, the surge waveform in the latter half period T3 becomes nearly flat. This allows the mask period set in the control device to be shortened. The gate resistance ratio (Rgs / Rgm) when Rgs=9 kΩ is 900. The gate resistance ratio (Rgs / Rgm) is also 0.45 times the current ratio (Im / Is). In the semiconductor device 200, the gate resistance ratio (Rgs / Rgm) may be 0.45 times or more the current ratio (Im / Is). The gate resistance ratio (Rgs / Rgm) may be 900 or more. The resistance value Rgs of the sense gate resistor 59 may be 9 kΩ or more.

[0068] When Rgs=10 kΩ, the surge waveform in the latter half period T3 becomes almost flat. Therefore, the mask period set in the control device can be further shortened. When Rgs=10 kΩ, the gate resistance ratio (Rgs / Rgm) is 1000. Furthermore, the gate resistance ratio (Rgs / Rgm) is 0.5 times the current ratio (Im / Is). In the semiconductor device 200, the gate resistance ratio (Rgs / Rgm) may be 0.5 times or more the current ratio (Im / Is). The gate resistance ratio (Rgs / Rgm) may be 1000 or more. The resistance value Rgs of the sense gate resistor 59 may be 10 kΩ or more.

[0069] When Rgs is set to 20 kΩ, the gate resistance ratio (Rgs / Rgm) becomes equal to the current ratio (Im / Is). In this case, the turn-on timing of the sense transistor section 170 and the turn-on timing of the main transistor section 70 can be made to approximately coincide. In this case, as shown in FIG. 2, the surge of the emitter voltage Vse becomes significantly smaller, and the transient period is also shortened.

[0070] If the resistance value Rgs is set to be greater than 20 kΩ, the turn-on timing of the sense transistor section 170 will begin to lag behind the turn-on timing of the main transistor section 70. However, since the main transistor section 70 has a larger area than the sense transistor section 170, even if carriers from the sense transistor section 170 flow to the main transistor section 70, there will be almost no effect on the emitter voltage waveform of the main transistor section 70. For this reason, the resistance value Rgs may be set to be greater than 20 kΩ.

[0071] The gate resistance ratio (Rgs / Rgm) may be equal to or greater than the current ratio (Im / Is) by a factor of 1. The gate resistance ratio (Rgs / Rgm) may be equal to or greater than 2000. The resistance value Rgs of the sense gate resistor 59 may be equal to or greater than 20 kΩ.

[0072] As shown in FIG. 4, when Rgs=30 kΩ, the level of the emitter voltage Vse during the transient period is equal to or lower than the level of the emitter voltage Vse during the steady period. Therefore, the mask period set in the control device can be set to approximately 0. The gate resistance ratio (Rgs / Rgm) may be 1.5 times or more the current ratio (Im / Is). The gate resistance ratio (Rgs / Rgm) may be 3000 or more. The resistance value Rgs of the sense gate resistor 59 may be 30 kΩ or more.

[0073] 5 shows another example of the time waveform of the emitter voltage Vse. In this example, the waveforms are shown when the resistance value Rgs of the sense gate resistor 59 is adjusted to 30 kΩ, 50 kΩ, 70 kΩ, 90 kΩ, 100 kΩ, and 300 kΩ. The transient period when Rgs=10 Ω is also shown.

[0074] 4, when the resistance value Rgs is set to 30 kΩ or more, the level of the emitter voltage Vse during the transient period can be set to the level of the emitter voltage Vse during the steady state period or less. On the other hand, the larger the resistance value Rgs is, the later the timing at which the emitter voltage Vse converges to the steady state value becomes.

[0075] As shown in FIGS. 2 and 5 , when Rgs=50 kΩ, the emitter voltage Vse converges to a steady-state value within the transient period when Rgs=10 Ω. Therefore, when Rgs=50 kΩ, the steady-state value of the emitter voltage Vse can be detected accurately even if the mask period is set shorter than when Rgs=10 Ω. On the other hand, when Rgs=70 kΩ, the emitter voltage Vse does not converge to a steady-state value within the transient period when Rgs=10 Ω. Therefore, the steady-state value of the emitter voltage Vse cannot be detected accurately until the transient period when Rgs=10 Ω has elapsed. Therefore, the mask period set in the control device cannot be set shorter than when Rgs=10 Ω.

[0076] The gate resistance ratio (Rgs / Rgm) may be 2.5 times or less the current ratio (Im / Is). The gate resistance ratio (Rgs / Rgm) may be 5000 or less. The resistance value Rgs of the sense gate resistor 59 may be 50 kΩ or less. The gate resistance ratio (Rgs / Rgm) may be twice or less the current ratio (Im / Is). The gate resistance ratio (Rgs / Rgm) may be 4000 or less. The resistance value Rgs of the sense gate resistor 59 may be 40 kΩ or less. The gate resistance ratio (Rgs / Rgm) may be 1.5 times or less the current ratio (Im / Is). The gate resistance ratio (Rgs / Rgm) may be 3000 or less. The resistance value Rgs of the sense gate resistor 59 may be 30 kΩ or less.

[0077] 6 is a diagram showing an example of the waveform of the emitter voltage Vse when the absolute values ​​of the areas of the main transistor section 70 and the sense transistor section 170 are changed while the current ratio (Im / Is) and gate resistance ratio (Rgs / Rgm) are fixed. In this example, Rgm=Rgs=10Ω. The current ratio (Im / Is) is 2000.

[0078] In this example, the absolute values ​​of the areas of the main transistor section 70 and the sense transistor section 170 are set to a reference value, the reference value + 5% (i.e., the reference value × 1.05), the reference value + 10%, the reference value + 20%, the reference value - 5%, the reference value - 10%, and the reference value - 20%. The emitter voltage Vse tends to increase as the areas of the main transistor section 70 and the sense transistor section 170 increase, but the length of the transient period remains almost unchanged. Furthermore, the magnitude of the emitter voltage Vse per unit area, calculated by dividing the magnitude of the emitter voltage Vse by the area of ​​the sense transistor section 170, remains almost unchanged.

[0079] 7 is a diagram showing another example of the waveform of the emitter voltage Vse when the absolute values ​​of the areas of the main transistor section 70 and the sense transistor section 170 are changed while the current ratio (Im / Is) and the gate resistance ratio (Rgs / Rgm) are fixed. In this example, the conditions are the same as those in the example of FIG. 6 except for Rgs=10 kΩ. In this example, the same tendency as in the example of FIG. 6 was observed.

[0080] 6 and 7, the magnitude of the surge in the emitter voltage Vse and the time until it converges do not improve much even if the absolute values ​​of the areas of the main transistor section 70 and the sense transistor section 170 are changed. On the other hand, as described with reference to FIGS. 1 to 5, at least one of the magnitude of the surge in the emitter voltage Vse and the time until it converges can be improved by adjusting the gate resistance ratio (Rgs / Rgm) in accordance with the current ratio (Im / Is).

[0081] 8 is a diagram showing another example of the configuration of the semiconductor chip 100. The sense gate transmission unit 55 of the semiconductor chip 100 of this example has an ON path 150 and an OFF path 160. The ON path 150 has a sense gate resistor 59, and passes a gate current to the gate terminal of the sense transistor unit 170 in response to a gate signal Vg.

[0082] The on-path 150 of this example includes a sense gate resistor 59 and a first diode 152. The cathode terminal of the first diode 152 is connected to the gate terminal of the sense transistor section 170. The sense gate resistor 59 is provided in series with the first diode 152. In the example of FIG. 8 , the first diode 152 is provided between the sense gate resistor 59 and the sense transistor section 170. In other examples, the sense gate resistor 59 may be provided between the first diode 152 and the sense transistor section 170. With this configuration, the on-path 150 allows a current to flow that charges the gate capacitance of the sense transistor section 170, but does not allow a current to flow that discharges it. Therefore, the sense gate resistor 59 functions as a gate resistor when charging the gate capacitance of the sense transistor section 170.

[0083] The off-path 160 is provided in parallel with the on-path 150 and extracts charge from the gate terminal of the sense transistor section 170 in response to the gate signal Vg. In this example, the off-path 160 includes a sense-off resistor 164 and a second diode 162. The anode terminal of the second diode 162 is connected to the gate terminal of the sense transistor section 170. The sense-off resistor 164 is provided in series with the second diode 162. In the example of FIG. 8 , the sense-off resistor 164 is provided between the second diode 162 and the sense transistor section 170. In other examples, the second diode 162 may be provided between the sense-off resistor 164 and the sense transistor section 170. With this configuration, the off-path 160 passes a current that discharges the charge of the gate capacitance of the sense transistor section 170, but does not pass a current that charges the gate capacitance. Therefore, the sense-off resistor 164 functions as a gate resistor when discharging the gate capacitance of the sense transistor section 170.

[0084] The resistance value Rgs of the sense gate resistor 59 may be 200 times or more the resistance value of the off path 160. In this example, the resistance value Rgs of the sense gate resistor 59 may be 200 times or more the resistance value Roff of the sense off resistor 164. The resistance value Rgs is set as described with reference to FIGS. 1 to 7. The sense off resistor 164 may be a parasitic resistance in the off path 160. In another example, the sense off resistor 164 may be a resistive element provided in the off path 160. The resistance value Roff may be the same value as the resistance value Rgm. The resistance value Roff may be a value smaller than the resistance value Rgm. The resistance value Roff may be 10 Ω or less.

[0085] In this example, the timing of turning on the sense transistor section 170 can be delayed by providing a relatively large sense gate resistor 59, and the timing of turning off can be advanced by providing a relatively small sense off resistor 164. This makes it possible to prevent the main transistor section 70 from being turned off and the sense transistor section 170 from being turned on, thereby preventing surges from occurring in the sense transistor section 170.

[0086] The resistance value Rgs of the sense gate resistor 59 may be 2000 times or more the resistance value of the OFF path 160. In this example, the resistance value Rgs of the sense gate resistor 59 may be 2000 times or more the resistance value Roff of the sense OFF resistor 164.

[0087] 9 is a diagram showing another example of the configuration of a semiconductor device 200. In the semiconductor device 200 shown in FIGS. 1 to 8, the sense gate resistor 59 and the sense transistor section 170 are provided on the same semiconductor chip 100. In the semiconductor device 200 of this example, the sense gate resistor 59 is provided outside the semiconductor chip 100 including the sense transistor section 170. The other structures are similar to those of the semiconductor device 200 of any of the examples described with reference to FIGS. 1 to 8.

[0088] The sense gate transmission unit 55 of the semiconductor chip 100 of this example has a first pad 101 and a second pad 102. The first pad 101 is connected to a gate pad 116. The first pad 101 may be connected to the gate pad 116 by the sense gate transmission unit 55, or may be connected to the gate pad 116 via the main gate transmission unit 53.

[0089] The second pad 102 is connected to the gate terminal of the sense transistor section 170. The second pad 102 may be connected to the sense transistor section 170 by a sense gate transmission section 55. The first pad 101 and the second pad 102 are separated from each other inside the semiconductor chip 100. In other words, the first pad 101 and the second pad 102 are not connected to each other by the wiring of the sense gate transmission section 55.

[0090] The sense gate resistor 59 in this example is connected between the first pad 101 and the second pad 102 outside the semiconductor chip 100. The sense gate resistor 59 may be connected to the first pad 101 and the second pad 102 by wiring such as a wire. The sense gate resistor 59 may be disposed on a circuit board provided in the semiconductor device 200.

[0091] 1 to 8 , this example also makes it possible to suppress the occurrence of surges in the sense transistor section 170. In this example, the sense gate resistor 59 selected by the user of the semiconductor device 200 or the like can be mounted on the semiconductor device 200. Therefore, a variety of sense gate resistors 59 can be used for the same type of semiconductor chip 100.

[0092] 10 is a diagram illustrating another configuration example of a semiconductor device 200. The semiconductor device 200 of this example differs from the semiconductor device 200 of FIG. 9 in that it includes a plurality of sense gate resistors 59 and a switching unit 103. The other structures are similar to those of the semiconductor device 200 described in FIG. 9. The plurality of sense gate resistors 59 and the switching unit 103 of this example are provided outside the semiconductor chip 100.

[0093] The plurality of sense gate resistors 59-1, 59-2, ... may have different resistance values ​​Rgs1, Rgs2, .... The switching unit 103 switches which of the sense gate resistors 59 is connected between the first pad 101 and the second pad 102. This makes it possible to select an appropriate resistance value Rgs depending on the characteristics that are to be achieved.

[0094] Fig. 11 is a top view showing an example of the semiconductor chip 100. Fig. 11 shows the positions of each component projected onto the top surface of the semiconductor substrate 10. Fig. 11 shows only some of the components of the semiconductor chip 100, and some components are omitted.

[0095] The semiconductor chip 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is a substrate made of a semiconductor material. As an example, the semiconductor substrate 10 is a silicon substrate. In this specification, the outer peripheral edge of the semiconductor substrate 10 in a top view is referred to as an outer peripheral edge 138. The top view refers to a view parallel to the Z axis from the top surface side of the semiconductor substrate 10. Furthermore, one of the edges of the outer peripheral edge 138 of the semiconductor substrate 10 in a top view is referred to as a first edge 139. In a top view, the direction parallel to the first edge 139 is referred to as the X-axis direction, and the direction perpendicular to the first edge 139 is referred to as the Y-axis direction.

[0096] An active portion 120 is provided on the semiconductor substrate 10. The active portion 120 is a region through which a main current flows in the depth direction between the upper and lower surfaces of the semiconductor substrate 10 when the semiconductor chip 100 is in operation. The active portion 120 may be a region in which the main transistor portion 70 is formed. A main emitter electrode is provided above the active portion 120, but is omitted in FIG. 11 .

[0097] The active section 120 is provided with at least one of a main transistor section 70 including a transistor element such as an IGBT and a diode section 80 including a diode element such as a free wheel diode (FWD). In the example of Fig. 11, the main transistor sections 70 and the diode sections 80 are alternately arranged along the X-axis direction. Note that the diode section 80 does not necessarily have to be provided.

[0098] In this example, the main transistor section 70 and the diode section 80 each have a longitudinal direction in the Y-axis direction. That is, the length of the main transistor section 70 in the Y-axis direction is greater than its width in the X-axis direction. Similarly, the length of the diode section 80 in the Y-axis direction is greater than its width in the X-axis direction. The longitudinal direction of the main transistor section 70 and the diode section 80 may be the same as the longitudinal direction of each trench section, which will be described later.

[0099] The diode section 80 has an N+ type cathode region in a region that contacts the lower surface of the semiconductor substrate 10. In this specification, the region in which the cathode region is provided is referred to as the diode section 80. In other words, the diode section 80 is a region that overlaps with the cathode region in a top view. A P+ type collector region may be provided in a region other than the cathode region on the lower surface of the semiconductor substrate 10. In this specification, the region in which the diode section 80 is extended in the Y-axis direction to an active well region, which will be described later, may also be included in the diode section 80. A collector region is provided on the lower surface of the extended region.

[0100] A plurality of pad portions are provided above the upper surface of the semiconductor substrate 10. In the example of Fig. 11, a sense pad 114, an auxiliary emitter pad 115, a gate pad 116, a cathode pad 117, and an anode pad 118 are provided above the upper surface of the semiconductor substrate 10.

[0101] The sense pad 114 is connected to the sense transistor section 170. The sense transistor section 170 has the same structure as the main transistor section 70, and has a smaller area (corresponding to the area of ​​the channel) in a top view than the main transistor section 70. By detecting the current flowing in the sense transistor section 170, the current flowing throughout the entire semiconductor chip 100 can be estimated.

[0102] The auxiliary emitter pad 115 is connected to a main emitter electrode disposed above the upper surface of the semiconductor substrate 10. The wiring extending from the sense pad 114 may be connected to the main emitter electrode at the auxiliary emitter pad 115 by wire bonding so as to have the same potential as the main emitter electrode.

[0103] A gate signal Vg is sent from a gate driver circuit of the control device to the gate pad 116. The gate pad 116 is connected to the gates of the main transistor section 70 and the sense transistor section 170 via gate wiring.

[0104] The cathode pad 117 and the anode pad 118 are connected to the temperature sensing unit 111 via the temperature sensing wiring 112. The temperature sensing unit 111 measures the temperature of the semiconductor chip 100. The temperature sensing unit 111 is, for example, a diode for temperature measurement. The temperature sensing wiring 112 extends from the temperature sensing unit 111 to a region between the active unit 120 and the outer peripheral edge 138 on the upper surface of the semiconductor substrate 10, and is connected to the cathode pad 117 and the anode pad 118. The temperature sensing wiring 112 may be polysilicon. Note that the number and types of pads provided on the semiconductor substrate 10 are not limited to the example shown in FIG. 11 .

[0105] Each pad portion is made of a metal material such as aluminum. The pad portions may be arranged in a predetermined direction between the active portion 120 and a first edge 139 on the upper surface of the semiconductor substrate 10. In this example, the pad portions are arranged in the X-axis direction and are sandwiched between the active portion 120 and the first edge 139 in the Y-axis direction.

[0106] In the arrangement direction of the pad sections, the sense transistor section 170 may be provided between any two pad sections. In this example, the sense transistor section 170 is disposed between the sense pad 114 and the auxiliary emitter pad 115 in the X-axis direction.

[0107] As will be described later, the sense transistor section 170 has a sense gate trench section with a trench structure. The sense gate trench section has a sense gate conductive section to which a gate voltage is applied. As will be described later, the main transistor section 70 also has a gate trench section with a trench structure. The gate trench section has a gate conductive section to which a gate voltage is applied.

[0108] The semiconductor substrate 10 has a main gate wiring 48 and a sense gate wiring 148. The main gate wiring 48 is an example of a main gate transmission unit 53. The sense gate wiring 148 is an example of a sense gate transmission unit 55. The main gate wiring 48 is provided on the upper surface of the semiconductor substrate 10, and surrounds the active unit 120 and at least one of the multiple pad units. The main gate wiring 48 is also provided so as to cross the active unit 120. The main gate wiring 48 is connected to the gate conductive unit of the main transistor unit 70. That is, the main gate wiring 48 extends from the gate pad 116 to the gate conductive unit.

[0109] The main gate wiring 48 is a wiring that transmits a gate signal Vg to the gate conductive portion. The main gate wiring 48 may be a wiring through which a charging current flows to charge the gate conductive portion. The main gate wiring 48 may be a gate wiring other than the sense gate wiring 148 described later. In FIG. 11, the main gate wiring 48 is indicated by a dotted line.

[0110] The sense gate wiring 148 is provided above the upper surface of the semiconductor substrate 10 and is arranged along the sense transistor section 170. In this example, the sense gate wiring 148 surrounds the sense transistor section 170. The sense gate wiring 148 is connected to the sense gate conductive portion of the sense transistor section 170. "Arranged along the sense transistor section 170" may refer to being arranged parallel to one of the sides of the sense transistor section 170. The distance between the sense gate wiring 148 and the sense transistor section 170 may be smaller than the distance between the sense transistor section 170 and the sense pad 114. For example, if the sense transistor section 170 is rectangular, the sense gate wiring 148 may be arranged parallel to two or more sides of the sense transistor section 170, or may be arranged parallel to three or more sides. If there are multiple gate wirings arranged parallel to one of the sides of the sense transistor section 170, the sense gate wiring 148 may refer to the gate wiring closest to the sense transistor section 170.

[0111] The sense gate wiring 148 is a wiring that transmits a gate signal to the sense gate conductive portion. The sense gate wiring 148 may be a wiring that is arranged along the outer shape of the sense transistor portion 170, among the wirings through which a charging current flows to charge the sense gate conductive portion. The sense gate wiring 148 does not have to include a wiring through which a charging current flows to charge the gate conductive portion.

[0112] 11, the sense gate wiring 148 is indicated by a thick solid line. In this example, the sense gate wiring 148 is arranged in a closed loop surrounding the sense transistor section 170. At least a portion of the main gate wiring 48 and the sense gate wiring 148 may have a laminated structure of metal and polysilicon. An insulating film may be provided between the metal wiring and the polysilicon wiring. The metal wiring and the polysilicon wiring may be electrically connected via a contact hole provided in the insulating film. The main gate wiring 48 and the sense gate wiring 148 are insulated from the upper surface of the semiconductor substrate 10 by an interlayer insulating film.

[0113] The semiconductor substrate 10 has a gate wiring connection portion 50 that connects the main gate wiring 48 and the sense gate wiring 148. In this example, the gate wiring connection portion 50 is disposed between the sense transistor portion 170 and the auxiliary emitter pad 115. The gate wiring connection portion 50 is a wiring that transmits a gate signal Vg to the sense gate conductive portion, and is a wiring through which a charging current flows that charges the sense gate conductive portion.

[0114] The gate wiring connection portion 50 may function as the sense gate resistor 59. The gate wiring connection portion 50 may be a wiring formed of polysilicon. The resistance value Rgs of the gate wiring connection portion 50 can be adjusted by adjusting the cross-sectional area of ​​the gate wiring connection portion 50 perpendicular to the direction in which the gate current flows. The resistance value Rgs of the gate wiring connection portion 50 can also be adjusted by adjusting the length of the gate wiring connection portion 50 in the direction in which the gate current flows. The resistance value Rgs can also be adjusted by adjusting the concentration of impurities added to the polysilicon of the gate wiring connection portion 50. The gate wiring connection portion 50 may be a high-resistance wiring formed of a high-resistance material other than polysilicon.

[0115] 9 and the like may be provided instead of the gate wiring connection portion 50. The first pad 101 is connected to the main gate wiring 48, and the second pad 102 is connected to the sense gate wiring 148.

[0116] The semiconductor substrate 10 has an active main well region 29 formed to surround the active section 120 in a top view. The active main well region 29 surrounds the main transistor section 70 and the diode section 80 in a top view. The active main well region 29 is a second conductivity type region provided from the top surface of the semiconductor substrate 10 to the interior. The active main well region 29 may surround the active section 120 along the main gate wiring 48. The active main well region 29 is also provided around the pad section, but the periphery of the pad section is not shown in FIG. 11 .

[0117] The edge termination structure 90 is provided on the top surface of the semiconductor substrate 10 between the active well region and the outer periphery edge 138 of the semiconductor substrate 10. The edge termination structure 90 may be arranged in an annular shape to surround the active well region on the top surface of the semiconductor substrate 10. In this example, the edge termination structure 90 is arranged along the outer periphery edge 138 of the semiconductor substrate 10. The edge termination structure 90 reduces electric field concentration on the top surface side of the semiconductor substrate 10. The edge termination structure 90 may have, for example, a guard ring, a field plate, a resurf structure, or a structure combining these.

[0118] FIG. 12 is a diagram showing an example of the AA' cross section in FIG. 11. The AA' cross section is an XZ cross section passing through the emitter region 12 and the diode section 80 of the main transistor section 70. The sense transistor section 170 may also have the structure shown in FIG. 12. However, the main transistor section 70 and the sense transistor section 170 may be separated by a P+ type well region. The well region has a higher P+ concentration than the base region 14, and is formed from the upper surface 21 of the semiconductor substrate 10 to a position deeper than the lower end of the gate trench section 40. The well region may be provided to surround the sense transistor section 170 in a top view.

[0119] In the AA' cross section, the semiconductor chip 100 includes a semiconductor substrate 10, a collector electrode 24, an interlayer insulating film 38, and a main emitter electrode 52. The semiconductor substrate 10 has an upper surface 21 and a lower surface 23. The upper surface 21 and the lower surface 23 are the two main surfaces of the semiconductor substrate 10.

[0120] The interlayer insulating film 38 is provided on the upper surface 21 of the semiconductor substrate 10. The main emitter electrode 52 is provided above the interlayer insulating film 38. The main emitter electrode 52 passes through a contact hole 54 in the interlayer insulating film 38 and is in contact with the upper surface 21 of the semiconductor substrate 10. The collector electrode 24 is provided on the lower surface 23 of the semiconductor substrate 10. The main emitter electrode 52 and the collector electrode 24 are formed of a metal material such as aluminum.

[0121] The main transistor section 70 and the diode section 80 have a drift region 18 of a first conductivity type and a base region 14 of a second conductivity type provided between the drift region 18 and the upper surface 21 of the semiconductor substrate 10. In this example, the drift region 18 is N-type, and the base region 14 is P-type.

[0122] The main transistor section 70 has a plurality of gate trench sections 40 and a plurality of dummy trench sections 30 extending inward from the upper surface 21 of the semiconductor substrate 10. In this example, the gate trench sections 40 and dummy trench sections 30 are arranged along the X-axis direction and extend longitudinally in the Y-axis direction. The gate trench section 40 has a trench, a gate insulating film 42, and a gate conductive section 44. The gate insulating film 42 is provided to cover the inner wall of the trench. The gate insulating film 42 may be formed by oxidizing or nitriding the semiconductor on the inner wall of the trench. The gate conductive section 44 is provided inside the trench, further inward than the gate insulating film 42. In other words, the gate insulating film 42 insulates the gate conductive section 44 from the semiconductor substrate 10. The gate conductive section 44 is formed of a conductive material such as polysilicon.

[0123] The dummy trench portion 30 has a trench, a dummy insulating film 32, and a dummy conductive portion 34. The structure of the dummy trench portion 30 may be similar to that of the gate trench portion 40. However, although the gate conductive portion 44 is connected to the main gate wiring 48, the dummy trench portion 30 does not have to be connected to the main gate wiring 48. The dummy conductive portion 34 may be connected to the main emitter electrode 52 in a cross section different from the A-A' cross section. The diode portion 80 also has a plurality of dummy trench portions 30.

[0124] The main transistor section 70 has a mesa section 60 which is a region between the gate trench sections 40 or the dummy trench sections 30. Similarly, the diode section 80 has a mesa section 72 which is a region between the dummy trench sections 30. A base region 14 is provided in each mesa section.

[0125] The main transistor section 70 has a first conductivity type emitter region 12 provided on the upper surface 21. The emitter region 12 is exposed at the upper surface 21 of the semiconductor substrate 10, and is provided in contact with the gate trench portion 40 or the dummy trench portion 30. The emitter region 12 may be in contact with the gate trench portion 40 or the dummy trench portion 30 on both sides of the mesa portion 60.

[0126] The base region 14 is provided below the emitter region 12. In this example, the base region 14 is provided in contact with the emitter region 12. The base region 14 may be in contact with the gate trench portions 40 or the dummy trench portions 30 on both sides of the mesa portion 60.

[0127] The accumulation region 16 is provided below the base region 14. The accumulation region 16 is an N+ type region with a higher doping concentration than the drift region 18. By providing the high-concentration accumulation region 16 between the drift region 18 and the base region 14, the carrier injection enhancement effect (IE effect) can be enhanced and the on-voltage can be reduced. The accumulation region 16 may be provided so as to cover the entire lower surface of the base region 14 in each mesa portion 60.

[0128] A P-type base region 14 is provided in the mesa portion 72 of the diode portion 80 in contact with the upper surface 21 of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. No emitter region 12 is provided in the mesa portion 72 of the diode portion 80.

[0129] The main transistor section 70 has a collector region 22 of the second conductivity type provided on the lower surface 23 of the semiconductor substrate 10. In this example, the collector region 22 is of P+ type. The acceptor concentration of the collector region 22 is higher than the acceptor concentration of the base region 14. The collector region 22 may contain the same acceptor as the base region 14, or may contain a different acceptor. The acceptor of the collector region 22 is, for example, boron.

[0130] The diode section 80 has a cathode region 82 of a first conductivity type provided on the lower surface 23 of the semiconductor substrate 10. In this example, the cathode region 82 is N+ type. The donor concentration of the cathode region 82 is higher than the donor concentration of the drift region 18. The donor of the cathode region 82 is, for example, hydrogen or phosphorus. Note that the elements that serve as donors and acceptors in each region are not limited to the above-mentioned examples.

[0131] The collector region 22 and the cathode region 82 are exposed on the lower surface 23 of the semiconductor substrate 10 and are connected to the collector electrode 24. The collector electrode 24 may be in contact with the entire lower surface 23 of the semiconductor substrate 10.

[0132] The main transistor section 70 may be a region in which a collector region 22 is provided on the lower surface 23. The diode section 80 may be a region in which a cathode region 82 is provided on the lower surface 23. The boundary between the main transistor section 70 and the diode section 80 may be the boundary between the cathode region 82 and the collector region 22.

[0133] An N+ type buffer region 20 may be provided between the drift region 18 and the collector region 22 and the cathode region 82. The doping concentration of the buffer region 20 is higher than the doping concentration of the drift region 18. The buffer region 20 may function as a field stop layer that prevents a depletion layer extending from the lower end of the base region 14 from reaching the P+ type collector region 22.

[0134] In a cross section different from the A-A' cross section, a second conductivity type contact region may be provided in the main transistor section 70 and the diode section 80. The contact region may be provided between the base region 14 and the upper surface 21. The contact region may be a P+ type region having a higher doping concentration than the base region 14.

[0135] The gate trench portion 40 and the dummy trench portion 30 extend from the upper surface 21 of the semiconductor substrate 10 through the base region 14 to reach the drift region 18. In regions where at least one of the emitter region 12, the contact region, and the accumulation region 16 is provided, the gate trench portion 40 and the dummy trench portion 30 also penetrate these doped regions to reach the drift region 18. The trench portion penetrating the doped region does not necessarily mean that the trench portion is formed after the doped region is formed. Forming the doped region between the trench portions after the trench portion is also included in the trench portion penetrating the doped region. The bottom of the trench portion may have a downwardly convex curved shape (curved in cross section).

[0136] The gate conductive portion 44 may be provided longer in the depth direction than the base region 14. The gate trench portion 40 is covered with an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The gate conductive portion 44 is electrically connected to a main gate wiring 48. When a predetermined gate voltage is applied to the gate conductive portion 44, a channel is formed by an electron inversion layer in the surface layer of the interface of the base region 14 that contacts the gate trench portion 40. As a result, a main current flows between the main emitter electrode 52 and the collector electrode 24 in the main transistor portion 70.

[0137] As described above, when a predetermined gate voltage is applied to the gate conductive portion of each transistor portion, carriers are injected from the collector region 22. These carriers are charged into the gate insulating film 42 of the gate trench portion 40, causing self-charging and self-turning on of the transistor portion. The gate insulating film 42 of the sense transistor portion 170 can also be charged by carriers injected from the collector region 22 of the surrounding main transistor portion 70. Similarly, the gate insulating film 42 of the main transistor portion 70 can also be charged by carriers injected from the collector region 22 of the surrounding sense transistor portion 170. However, the area of ​​the sense transistor portion 170 is much smaller than the area of ​​the main transistor portion 70. Therefore, the sense transistor portion 170 is more susceptible to carriers from the main transistor portion 70 and is more likely to self-turn on earlier than the main transistor portion 70.

[0138] As described above, the semiconductor device 200 can delay the timing of turning on the sense transistor section 170. This makes it possible to suppress the occurrence of surges in the sense transistor section 170.

[0139] 13 is a diagram showing an example of a semiconductor device 400 according to a comparative example. The semiconductor device 400 does not have a sense gate resistor 59, and the sense transistor section 170 is not an RC-IGBT. In the structure of the semiconductor device 400, the ESD tolerance (tolerance against electrostatic discharge) of the sense transistor section 170 is low.

[0140] FIG. 14 is a diagram showing another example of a semiconductor device 400 according to a comparative example. The semiconductor device 400 of this example does not have a sense gate resistor 59. However, the sense transistor section 170 is an RC-IGBT. With this configuration, the S-E withstand capability can be improved. The S-E withstand capability is the withstand capability between the sense pad 114 and the main emitter electrode 52. On the other hand, the S-G withstand capability is not improved. The S-G withstand capability is the withstand capability between the sense pad 114 and the gate pad 116. In contrast, with the semiconductor device 200 described with reference to FIG. 1 and other figures, the S-G withstand capability can also be improved by providing a relatively large sense gate resistor 59.

[0141] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0142] 10...Semiconductor substrate, 12...Emitter region, 14...Base region, 16...Accumulation region, 18...Drift region, 20...Buffer region, 21...Upper surface, 22...Collector region, 23...Lower surface, 24...Collector electrode, 29...Active main well region, 30...Dummy trench portion, 32...Dummy insulating film, 34...Dummy conductive portion, 38...Interlayer insulating film, 40...Gate trench portion, 42...Gate insulating film, 44...Gate conductive portion, 48...Main gate wiring, 50...Gate wiring connection portion, 52...Main emitter electrode, 53...Main gate transmission portion, 54...Contact hole, 55...Sense gate transmission portion, 57...Main gate resistor, 59...Sense gate resistor, 60...Mesa portion, 70...Main transistor portion, 72...Mesa portion, 80...Diode portion, 82...Cathode region, 90... Edge termination structure, 100...semiconductor chip, 101...first pad, 102...second pad, 103...switching section, 111...temperature sensing section, 112...temperature sensing wiring, 114...sense pad, 115...auxiliary emitter pad, 116...gate pad, 117...cathode pad, 118...anode pad, 120...active section, 138...outer peripheral edge, 139...first edge, 148...sense gate wiring, 150...on path, 152...first diode, 160...off path, 162...second diode, 164...sense off resistor, 170...sense transistor section, 180...diode section, 200...semiconductor device, 210...external power supply, 220...capacitor, 230...diode, 240...stray inductance, 250...sense resistor, 300...load, 400...semiconductor device

Claims

1. A semiconductor device comprising: a main transistor section that passes a main current in response to an applied gate signal; and a sense transistor section that is provided in parallel with the main transistor section and passes a sense current in response to the gate signal that is common to the main transistor section; wherein a gate resistance ratio obtained by dividing the resistance value of a sense gate resistor that is the gate drive resistor of the sense transistor section by the resistance value of a main gate resistor that is the gate drive resistor of the main transistor section is 0.015 times or more of a current ratio obtained by dividing the main current by the sense current.

2. The semiconductor device according to claim 1, wherein the gate resistance ratio is 0.5 times or more the current ratio.

3. The semiconductor device according to claim 1, wherein the gate resistance ratio is equal to or greater than 1 time the current ratio.

4. The semiconductor device according to claim 1, wherein the gate resistance ratio is 2.5 times or less the current ratio.

5. The semiconductor device according to any one of claims 1 to 4, wherein the gate resistance ratio is 30 or more.

6. The semiconductor device according to any one of claims 1 to 4, wherein the gate resistance ratio is 1000 or more.

7. The semiconductor device according to any one of claims 1 to 4, wherein the gate resistance ratio is 2000 or more.

8. The semiconductor device according to claim 5, wherein the gate resistance ratio is 5000 or less.

9. The semiconductor device according to any one of claims 1 to 4, wherein the resistance value of the sense gate resistor is 300 Ω or more.

10. The semiconductor device according to any one of claims 1 to 4, wherein the resistance value of the sense gate resistor is 10 kΩ or more.

11. The semiconductor device according to any one of claims 1 to 4, wherein the resistance value of the sense gate resistor is 20 kΩ or more.

12. The semiconductor device according to claim 9, wherein the resistance value of the sense gate resistor is 50 kΩ or less.

13. A semiconductor device according to any one of claims 1 to 4, further comprising: a main gate transmission section which transmits the gate signal to the main transistor section; and a sense gate transmission section which is provided in parallel with the main gate transmission section and which transmits the gate signal to the sense transistor section, wherein the sense gate transmission section has: an on path which has the sense gate resistor and which passes a gate current to a gate terminal of the sense transistor section in response to the gate signal; and an off path which is provided in parallel with the on path and which draws charge from the gate terminal of the sense transistor section in response to the gate signal, wherein the resistance value of the sense gate resistor is 200 times or more the resistance value of the off path.

14. The semiconductor device according to claim 13, wherein the resistance value of the sense gate resistor is 2000 times or more the resistance value of the off-path.

15. The semiconductor device according to claim 13, wherein the on path comprises a first diode having a cathode terminal connected to the gate terminal of the sense transistor portion and the sense gate resistor arranged in series with the first diode; the off path comprises a second diode having an anode terminal connected to the gate terminal of the sense transistor portion and a sense off resistor arranged in series with the second diode; and the resistance value of the sense gate resistor is 200 times or more the resistance value of the sense off resistor.

16. The semiconductor device according to any one of claims 1 to 4, wherein the sense gate resistor and the sense transistor section are provided on the same semiconductor chip.

17. The semiconductor device according to any one of claims 1 to 4, wherein the sense gate resistor is provided outside a semiconductor chip including the sense transistor section.

18. The semiconductor device according to claim 17, further comprising: a gate pad to which the gate signal is applied; and a sense gate transmission section that transmits the gate signal to the sense transistor section, wherein the sense gate transmission section has a first pad connected to the gate pad and a second pad connected to the sense transistor section, and the sense gate resistor is connected between the first pad and the second pad.

19. The semiconductor device according to claim 18, comprising: a plurality of sense gate resistors; and a switching unit that switches which of the sense gate resistors is connected between the first pad and the second pad.