JP3248383B2 - Semiconductor device - Google Patents

Abstract

PURPOSE:To provide an IGBT module which allows low noise and has high breakdown strength. CONSTITUTION:An IGBT module is formed by incorporating the IGBT and a diode in reverse-parallel, the resistivity of the n-layer 1 of the IGBT is permitted to be larger than the resistivity of the n-layer 17 of the diode and the dynamic breakdown strength of the IGBT is permitted to be lower than the static breakdown strength of the diode and IGBT. Since the resistivity of the n-layer 13 of the IGBT is permitted to be lower than the resistivity of the n-layer 17 of the diode and the layers are integrated as the IBGT module, an IGBT jumping-up voltage, which is due to tail. current reduction when the IGBT is turned off with the increased resistivity of the n-layer 13 of the IGBT, and the cell structure are fined, a diode jumping-up voltage is reduced when the IGBT is turned on with a large current change rate. Thus, the IGBT module which does not generate noise with high breakdown strength is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which an insulated gate bipolar transistor and a diode are connected in anti-parallel (hereinafter referred to as an IGBT module).

[0002]

2. Description of the Related Art With the development of power electronics, it has become important for inverter devices to have higher performance, lower noise and smaller size. An insulated gate bipolar transistor (hereinafter, referred to as an IGBT) is a voltage-driven element having both the high-speed characteristics of a MOSFET and the high output characteristics of a bipolar transistor. The drive circuit can be downsized compared to a bipolar transistor which is a current drive type element.

[0003] This IGBT is usually used in the form of an IGBT module. The IGBT module is a semiconductor device in which an IGBT and a diode connected in anti-parallel are incorporated in one package, and an electrode terminal is taken out outside.
Mainly used in inverter circuits.

FIG. 3 shows an inverter circuit using an IGBT module. In FIG. 3, 100a to 100f are I
GBT, 101a to 101f are diodes, 110 is a motor, and 120 is a power supply. IGBT modules include one package that incorporates only one pair of IGBT and diode, one phase that has an upper arm and a lower arm, and three that have an upper arm and a lower arm that have three phases. Yes, depending on the application.

In FIG. 3, IGBTs 100a and 10g
When 0e is turned on, IGBT100a, motor 110, IG
Current flows through BT100e. At this time, the IGBTs 100b and 100d and the diodes 101b and
Since 1d is in the blocking state, the diode and the IGBT need to have the same blocking breakdown voltage. When the IGBT 100e is turned off, the current flowing to the motor up to that point by the energy of the motor is reduced to the IGBT 100a, the motor 110, the diode 101b.
To reflux. When the IGBT 100e is turned on again, the current flowing through the diode 101b flows through the IGBT 100e. FIG. 4 shows a switching waveform of the IGBT module at this time.
The anode current I _A and the anode-cathode voltage V of 1b
_AK waveform, a collector current I _C and the waveform of the collector-emitter voltage V _CE of IGBT100e the lower arm. When the IGBT is turned on, the current of the diode is turned off. When the IGBT is turned off, a current flows through the diode again.

To reduce the loss of the inverter circuit, I
It is necessary to reduce the loss of the GBT module. Therefore, in recent years, improvements have been made to reduce the switching loss of the IGBT and the loss due to the ON voltage. For example, after the collector current drops sharply at turn-off, which is the main cause of switching loss, the current (hereinafter referred to as the tail current), which gradually decreases in the tail, is reduced. It is known that the on-voltage is reduced by increasing the channel width per unit area by integrating the above.

As a technique for reducing the loss of the IGBT as described above, for example, as described in Japanese Patent Laid-Open No. 4-133355,
It is known to increase the specific resistance of the n-base layer of the GBT.

[0008]

As described above, the IG
The BT itself can be reduced in loss by reducing the tail current and the on-voltage. However, such a low-loss I
When the GBT is incorporated in the IGBT module, there is a problem that voltage noise occurs. As can be seen from the switching waveform of FIG. 4, the IGBT generates a jump voltage at the time of turn-off and generates noise. The diode is I
Similarly, when the GBT is turned on, a jump voltage is generated to generate noise.

The cause of the jump voltage at the time of turning off the IGBT is a sharp decrease in the collector current at the time of turning off. When the tail current is reduced to improve the switching loss, the collector current decreases more sharply at the time of turn-off, and the current change rate di / dt increases. Since there is always wiring inductance in the IGBT module, a jump voltage is generated by the current change rate and the wiring inductance, and the jump voltage is increased by an increase in the current change rate, thereby generating voltage noise.

On the other hand, noise at the time of diode recovery is caused by miniaturization of unit cells of the IGBT. Reducing the size of the unit cell and lowering the on-voltage means that more current can flow at the same gate voltage, and the transconductance gm at this time necessarily increases. When the IGBT is turned on during the operation of the inverter and the collector current increases, di / dt is proportional to gm. As gm increases, di / dt increases. Here, when gm of the IGBT increases, di / dt at turn-on increases, the turn-on time decreases, and the turn-on loss decreases. However, when the di / dt of the IGBT increases, the di / dt when the diode of the opposite arm recovers also increases. The jump voltage of the diode increases due to the increase of di / dt and the inductance of the wiring, and a noise voltage is generated. The generation of the voltage noise causes the breakdown voltage of the element to deteriorate, and also causes the IGBT of another arm or another phase to malfunction, thereby lowering the reliability of the IGBT module and the device such as the inverter.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is directed to an IG connected in antiparallel.
It is an object of the present invention to provide a semiconductor device having a pair of a BT and a diode, having low noise and high breakdown strength, in which reduction of voltage noise and reduction of loss are coordinated.

[0012]

According to a first aspect of the present invention, there is provided a semiconductor device having at least a pair of insulated gate bipolar transistors and a diode connected in anti-parallel, and a specific resistance of a base layer of the diode. Is lower than the specific resistance of the collector-side base layer of the insulated gate bipolar transistor, and the withstand voltage when the insulated gate bipolar transistor switches from the conducting state to the blocking state is lower than the withstand voltage of the insulated gate bipolar transistor and the diode in the blocking state. The present invention is a semiconductor device.

A second feature of the present invention is a semiconductor device having at least a pair of insulated gate bipolar transistors and a diode, the semiconductor device having a pair of main surfaces and having an exposed surface on one of the main surfaces. A first region of one conductivity type, a second region of a second conductivity type having a lower impurity concentration than the first region formed adjacent to the first region, and formed adjacent to the second region and exposed to the other main surface. A third region of a second conductivity type having a lower impurity concentration than the second region having a surface, and a first region of a first conductivity type having a higher impurity concentration than the third region selectively formed on the other main surface portion of the third region. A fourth region, a fifth region of the second conductivity type selectively formed on the other main surface side of the fourth region and having a higher impurity concentration than the fourth region, and the other of the third region, the fourth region, and the fifth region; An insulating gate provided on the exposed surface of the main surface of the An insulated gate bipolar transistor provided with a first main electrode having a low resistance contact with an exposed surface of the first region, and a second main electrode shorting the fourth and fifth regions on the other main surface; A sixth region of a second conductivity type having a pair of main surfaces and an exposed surface on one of the main surfaces;
A seventh region of the second conductivity type formed adjacent to the region and having a lower impurity concentration than the sixth region; and a higher impurity concentration than the seventh region formed adjacent to the seventh region and having an exposed surface on the other main surface. A third region having low resistance contact with the eighth and sixth regions of the first conductivity type;
A first main electrode and a third main electrode are connected to each other, and a second main electrode and a fourth main electrode are connected to each other. The electrode is connected, the specific resistance of the seventh region of the diode is lower than the specific resistance of the third region of the insulated gate bipolar transistor, and the withstand voltage when the insulated gate bipolar transistor switches from the conducting state to the blocking state is insulated. And a lower breakdown voltage than the blocking state of the diode.

[0014]

The structure of the IGBT, as shown in FIG. 2, forms a second region 12 adjacent to the first region 11, and further forms a third region 13 (collector-side base layer) adjacent to the second region 12. The fourth region 14 is selectively formed on the surface of the third region 13, and the fifth region 15 is selectively formed on the surface of the fourth region 14. And the third region 13 and the fifth
The surface of the fourth region 14 sandwiched by the regions 15 is used as a channel region, an insulating film 19 is provided thereon and an insulating gate 20 is further provided thereon, and the second region 14 is commonly connected to the fourth and fifth regions 14 and 15. , And a first main electrode 22 connected to the first region 11. On the other hand, in the structure of the diode, a seventh region (base layer) 17 is formed adjacent to the sixth region 16, an eighth region 18 is formed on the surface of the seventh region 17, and the seventh region (base layer) 17 is connected to the sixth region 16. It has a structure having three main electrodes 23 and a fourth main electrode 24 connected to the eighth region 18.

Here, the specific resistance of the seventh region (base layer) 17 is lower than the specific resistance of the third region (collector-side base layer) 13. In general, the depletion layer has a higher specific resistance and is easy to expand, and a low specific resistance has a difficulty in expanding. Therefore, when a IGBT is turned on, a diode having a low specific resistance performs soft recovery due to residual carriers in a region where a depletion layer does not extend, and a jump voltage is reduced. Furthermore, if the dynamic breakdown voltage when the IGBT switches from the conducting state to the blocking state is lower than the static breakdown voltage in the blocking state of the IGBT and the diode, avalanche breakdown occurs in the operating region of the IGBT at the time of turn-off, and a jump voltage is generated. The voltage can be suppressed to a constant value, and the diode can be protected from destruction. Thereby, the reliability and the breakdown strength of the semiconductor device can be improved.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an IGBT module to which the present invention is applied. An insulating plate 4 is provided on a metal heat sink plate 5, and a metal plate 3 is further provided thereon.
The IGBT 1 and the diode 2 are arranged on the metal plate 3. The collector electrode of the IGBT and the cathode electrode of the diode are both connected to the collector terminal 6 via the metal plate 3. Further, the wiring 25 allows the emitter electrode of the IGBT and the anode electrode of the diode to be connected to the emitter terminal 7.
, And the gate electrode of the IGBT is connected to the gate terminal 26. The above configuration is the plastic package 8
And each terminal is taken out of the plastic package 8.

FIG. 2 shows a cross-sectional structure and connection relationship between the IGBT 1 and the diode 2 in FIG. forming an n + layer 12 having a lower impurity concentration on the p + silicon substrate 11;
Further, an n @-layer 13 having a lower impurity concentration than the n @ + layer 12 is formed thereon, and ap @ + layer 14 having a higher impurity concentration is selectively formed on the surface of the n @ + layer 13; An n + layer 15 having a higher impurity concentration than the p + layer 14 is selectively formed on the surface of the + layer 14 region. And n-layer 13 and n
A gate insulating film 19 is disposed on the surface of the p + layer 14 sandwiched between the + layers 15 as a channel region, and a gate electrode 20 is further disposed thereon, and is commonly connected to the p + layer 14 and the n + layer 15. Emitter electrode 21, p + silicon substrate 1
1 has a collector electrode 22 connected thereto. On the other hand, in the structure of the diode, an n @-layer 17 having a lower impurity concentration is formed on an n @ + substrate 16 and a p @ + layer 18 having a higher impurity concentration is formed on the surface of the n @
The structure has a cathode electrode 23 connected to the substrate 16 and an anode electrode 24 connected to the p + layer 18. Here, the specific resistance of the n− layer 17 of the diode is equal to the n− layer 13 of the IGBT.
Is lower than the specific resistance. The collector electrode 22 of the IGBT is connected to the cathode electrode 23 of the diode.
The emitter electrode 21 of the GBT and the anode electrode 24 of the diode are connected, that is, the IGBT and the diode are connected in anti-parallel.

Hereinafter, the results of a study on the present invention performed by the present inventors will be described.

FIG. 5 shows the relationship between the specific resistance of the n − layer 13 of the IGBT and the n − layer 17 of the diode and the jump voltage. An example in which the rating of the IGBT module is 600 V and the power supply voltage is 300 V is shown. The thickness of the n− layer is IGB
Both T and the diode are 55 μm (note that if the specific resistance of the n − layer is 20 Ω · cm or less, a withstand voltage of 600 V cannot be obtained in the blocking state).

Here, the specific resistance of the n − layer of the IGBT and that of the diode are the same, and the voltage noise at the time of turn-on and the voltage noise at the time of turn-off will be compared.

First, the jump voltage at the time of turn-off is IGB
This is due to di / dt of the collector current of T, and is related to the magnitude of the tail current.

The turn-off and tail current of the IGBT will be described below.

When the IGBT is turned off, a reverse bias is applied between the n− layer 13 and the p + layer 14. The depletion layer is extended to the side of the n − layer 13 having a low impurity concentration to support the voltage. When the depletion layer extends, the n− layer 13 and the n + layer 12
The holes accumulated therein recombine with electrons and disappear. The tail current is a recombination current flowing until holes recombine with electrons and disappear.

As one index indicating the magnitude of the loss due to the tail current, there is a fall time of the collector current at the time of turn-off. Fig. 6 shows the rated voltage of 600V
The relationship between the specific resistance of the n − layer 13 and the fall time (Tf) in the IGBT of FIG. When the specific resistance of the n− layer 13 is large, the depletion layer is likely to be elongated at the time of turn-off, and the n− layer 1
Since few holes accumulate in 3, almost no tail current flows. Therefore, the fall time becomes shorter at this time. Conversely, when the specific resistance of n − layer 13 is small, the depletion layer is difficult to expand, so that holes accumulated in n − layer 13 increase and a tail current flows. At this time, the fall time becomes longer and the loss increases. Therefore, the n− layer 1 of the IGBT
The turn-off loss is reduced as the specific resistance of No. 3 is higher. According to the study results of the present inventors, when the rated voltage is nV, the specific resistance of the n − layer 13 of the IGBT is desirably n / 17 Ω · cm or more.

On the other hand, the jump voltage at turn-on is due to the recovery of the diode. This is determined by the diffusion current of the diode. Here, comparing the decay time of the recombination current with the diffusion current, the diffusion current is faster. Therefore, the current change rate at the time of recovery of the diode becomes larger than the current change rate of the tail current. Therefore, the maximum jump voltage as an IGBT module is determined by the turn-on voltage noise.

FIG. 7 shows the relationship between the specific resistance of the n− layer 17 and the current change rate (di / dt) when the diode recovers due to turn-on in a diode having a rated voltage of 600 V. When the specific resistance of the n − layer 17 of the diode is low, the depletion layer does not extend sufficiently, so that the sweeping out of carriers is delayed, and the current change rate can be suppressed low. However, when the specific resistance of the n @-layer 17 increases, the sweeping out of carriers becomes faster, and the current change rate increases as the specific resistance increases. Therefore, the specific resistance of the n − layer 17 of the diode is preferably low.
However, when the specific resistance is reduced, the static withstand voltage also decreases. Therefore, the specific resistance of the n − layer 17 of the diode is preferably low as long as the static withstand voltage can maintain the rated voltage. According to the study results of the present inventors, when the rated voltage is nV, the specific resistance of the n − layer 17 of the diode is (n / 25) to (n / 1).
0) It is desirable to be Ω · cm. As described above and as shown in FIG. 5, assuming that the specific resistances of the IGBT and the n − layer of the diode are the same, the maximum jump voltage is determined by the turn-on voltage noise. Therefore, when suppressing the maximum jump voltage to a certain constant voltage (for example, 600 V in FIG. 5),
The specific resistance of the diode is higher than the specific resistance of the n − layer 13 of the IGBT.
The specific resistance of the layer 17 can be reduced. In other words, the specific resistance of the n − layer 13 of the IGBT can be increased. Therefore, in the present embodiment, the turn-off loss of the IGBT can be reduced while suppressing the maximum jump voltage to a certain constant voltage.

Next, the dynamic breakdown voltage of the IGBT will be described.

FIG. 8 shows the relationship between the power supply voltage and the jump voltage of the IGBT. The specific resistance of the n− layer 13 is 40Ω.
・ It is cm. The inventor has found that when the power supply voltage is low, the jump voltage increases with an increase in the power supply voltage, but when the power supply voltage exceeds 300 V, the jump voltage hardly increases. This is due to the IGB
This is because avalanche breakdown occurs in the operation region of T.
Generally, in the blocking state, avalanche breakdown occurs in the termination region to determine the breakdown voltage. This is called a static withstand voltage. However, in the conductive state, the n − layer 13 of the IGBT is subjected to conductivity modulation and has a low resistance, so that when turned off, the depletion layer is less likely to extend than in the blocking state. For this reason, the electric field applied to the depletion layer increases, and avalanche breakdown occurs in the operation region at a voltage lower than the blocking voltage of the termination region, that is, a voltage lower than the static withstand voltage. The voltage at which avalanche breakdown occurs at the time of turn-off is referred to as dynamic withstand voltage. Dynamic withstand voltage is n
The present inventors have discovered that the higher the specific resistance of the layer 13 is, the higher the specific resistance of the n − layer 13 is in order to reduce the tail current.

The dynamic breakdown voltage of the IGBT is a diode or I
When the dynamic breakdown voltage is lower than the static breakdown voltage of the GBT, the IGB
Since the current is dispersed throughout the operation region of T, the IGBT has a high withstand voltage and the IGBT module does not break down even when avalanche is performed. Conversely, if the dynamic breakdown voltage of the IGBT is higher than the static breakdown voltage of the IGBT or diode, the jump voltage
The GBT or the diode is destroyed, and the IGBT module is destroyed. When the specific resistance of the n − layer 17 of the diode is lower than the specific resistance of the n − layer 13 of the IGBT, the withstand voltage of the diode is apt to decrease. However, by making the dynamic withstand voltage of the IGBT lower than the static withstand voltage of the diode. In addition, the diode can be protected from a jump voltage at the time of turn-off. Therefore, destruction of the diode and the IGBT in the termination region can be prevented by setting the dynamic withstand voltage to be equal to or lower than the rated voltage of the IGBT module. According to the study results of the inventor, when the rated voltage is nV, IGB
The specific resistance of the n − layer 13 of T is desirably (n / 6) Ω · cm or less.

Each of the above-mentioned examination results relates to an IGBT and a diode having a rated voltage of 600 V or 1200 V. In general, how the depletion layer extends depends on the applied voltage and the specific resistance (impurity concentration). Specifically, the width of the depletion layer is proportional to the half of the applied voltage and the half of the reciprocal of the impurity concentration. Therefore, even at other rated voltages, the relationship between the elongation of the depletion layer and the specific resistance is the same as that at the rated voltages of 600 V and 1200 V.

FIG. 9 summarizes the results of the above study. The specific resistance of the n − layer of the IGBT and the diode, the static breakdown voltage (IGBT and diode), and the dynamic breakdown voltage (IGB
T). The lower limit of the specific resistance of the n @-layer of the diode is determined by the rated voltage (n (V)), and the upper limit is determined by the turn-on noise. The preferred range of the specific resistance is n / 25 Ω · cm or more and n / 10 Ω · cm or less. Also, regarding the specific resistance of the n − layer of the IGBT,
The lower limit is determined by the turn-off loss, and the upper limit is determined by the rated voltage. The preferred range of the specific resistance is n
/ 17Ω · cm or more and n / 6Ω · cm or less. If the specific resistance of the diode is set to be equal to or less than the specific resistance of the IGBT in these specific resistance ranges, the loss and noise of the IGBT module can be reduced, and the breakdown strength can be improved. In addition, if it is within the range of each of the above specific resistances, I
When the specific resistance of the GBT is equal to or smaller than the specific resistance of the diode, at least the effect of improving the breakdown strength can be obtained.

As described above, the specific resistance of the n − layer of the IGBT is made larger than the specific resistance of the n − layer of the diode, and
By making the dynamic breakdown voltage of the GBT lower than the static breakdown voltage of the IGBT and the diode, an IGBT module having small noise and turn-off loss and having a high breakdown strength can be obtained.

More preferably, the n- layer 17 of the diode
May be made thicker than the thickness of the n − layer 13 of the IGBT. As a result, carriers remaining in the n − layer 17 in a region where the depletion layer does not extend cause di /
dt will be smaller. As a result, the jump voltage of the diode when the IGBT is turned on is further reduced, which is more effective. Therefore, the result of the study by the present inventors regarding the thickness of the n − layer will be described.

FIG. 10 shows the relationship between the thickness of the n − layer 13 and the fall time (Tf) in an IGBT having a rated voltage of 600 V. When the n − layer 13 in the IGBT is thin, the depletion layer extends completely at the time of turn-off, so that almost no tail current flows and the fall time has a substantially constant value. However, when the n − layer 13 is thick, the depletion layer cannot be fully extended, so that a tail current is generated, and the thickness of the n − layer 13 increases, the fall time increases, and the loss increases. However, a certain thickness is required to secure a static withstand voltage higher than the rated voltage. Therefore, the thickness of n − layer 13 in the IGBT is preferably equal to or greater than a thickness that can ensure a static breakdown voltage equal to or higher than the rated voltage, and equal to or less than a thickness that reduces tail loss. According to the study results of the present inventors, when the rated voltage is nV, the thickness of the n − layer 13 in the IGBT is desirably (n / 10.5) to (n / 7.5) μm.

FIG. 11 shows rated voltages of 1200 V and 600 V.
In a V diode, the relationship between the thickness of the n − layer 17 and the current change rate (di / dt) when the diode recovers by turn-on is shown. When the thickness of n − layer 17 is large, the same effect as when the specific resistance is low is obtained. In other words, since the depletion layer does not extend sufficiently during recovery, the sweeping out of carriers is delayed, and the current change rate can be kept low. Conversely, when the thickness of the n− layer 17 is small,
The current change rate increases. Therefore, it is preferable that the thickness of the n @-layer 17 of the diode is large.

Therefore, in order to reduce the turn-on jump voltage and the noise, the specific resistance of the n − layer 17 of the diode is low as long as the rated voltage can be secured, and the thicker the n − layer 17 is, the more effective. is there. According to the study results of the present inventors, when the rated voltage is nV, it is desirable that the thickness of the n − layer 17 of the diode is (n / 10) μm or more. According to the results of the study by the present inventors, the thickness of the n − layer 17 of the diode is 1.2 times the thickness of the n − layer 3 of the IGBT.
It is preferable that the number be twice or more.

Further, the rated voltage of the IGBT module is n
In volts, the n− layer 13 of the IGBT is (n / 2)
The specific resistance and thickness of the diode depleted by volts
-An IGBT incorporating an IGBT and a diode whose layer 17 has a specific resistance and thickness that does not deplete at (n / 2) volts.
The T module has the same effect. The IGBT is usually used at half the rated voltage in consideration of the jump voltage.
Here, when the n − layer 13 of the IGBT is depleted at (n / 2) volts, the voltage noise at the time of turn-off is suppressed, and the depletion layer can reach the n + layer 12 more quickly, thereby reducing the tail current. Switching loss can be reduced. On the other hand, the diode is n @-
Is not depleted, di / dt at the time of recovery can be reduced, and the jump voltage of the diode can be suppressed.

The present invention can be applied not only to an IGBT module but also to a case where a single IGBT and a diode are connected in anti-parallel to form a circuit. further,
Even if the conductivity type of each semiconductor layer of the IGBT and the diode shown in FIG. 2 is reversed, that is, it can be applied to a semiconductor device in which p is changed to n and n is changed to p.

Hereinafter, a power converter embodying the present invention will be described.

FIG. 12 shows an example of a main circuit of a power inverter device embodying the present invention. The present invention is applied to a portion surrounded by a broken line in the drawing, that is, an anti-parallel circuit portion of the IGBT and the diode. The present inverter device has a pair of DC terminals 543 and 544, and three terminals equal to the number of AC phases.
A plurality of AC terminals 557 to 559 are provided, a DC power supply is connected to the DC terminals, and the IGBTs 545 to 550 are switched to convert DC power into AC power and output the AC power to the AC terminals. A set of IGBTs 54 connected in series is connected between the DC terminals.
5, 546, 547 and 548, and 549 and 550 are connected to both ends. Two IGBTs in each IGBT set
An AC terminal is taken out from the series connection point. A diode is connected to each IGBT in anti-parallel to circulate the load current.

In the figure, the antiparallel circuit portion of the IGBT and the diode surrounded by the broken line is constituted by the IGBT module embodying the present invention as shown in FIG.
Therefore, the efficiency of the inverter device is improved because the loss of the module is reduced. Further, since the module does not easily malfunction, the reliability of the inverter device is improved. In addition, since the breakdown resistance of the module is improved, the protection circuit can be omitted or simplified. Therefore, the size of the inverter device can be reduced.

[0043]

As can be seen from the above description, according to the present invention, the specific resistance of the base layer of the diode is made lower than the specific resistance of the base layer on the collector side of the IGBT, and the dynamic breakdown voltage of the IGBT is reduced by the diode and the IGBT. Lowering the static breakdown voltage of the semiconductor device, such as an IGBT module having a circuit in which they are connected in anti-parallel, enables low noise and low loss, and increases the reliability and breakdown strength of the IGBT module and the like. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing an IGBT module embodying the present invention.

FIG. 2 is a sectional view of an IGBT and a diode in the IGBT module.

FIG. 3 is an inverter circuit diagram using an IGBT module.

FIG. 4 is a switching waveform of the IGBT module.

FIG. 5 shows a change in jump voltage when the specific resistance of the n − layer is changed.

FIG. 6 is a graph showing the relationship between the specific resistance of the n − layer and the fall time in the IGBT.

FIG. 7 shows the relationship between the specific resistance of the n − layer and the current change rate (di / dt) at the time of recovery in a diode.

FIG. 8 shows a change in jump voltage when the power supply voltage is changed.

FIG. 9 shows the specific resistance of the n− layer of the IGBT and the diode,
Static breakdown voltage (IGBT and diode) and dynamic breakdown voltage (I
GBT).

FIG. 10 shows the relationship between the thickness of the n − layer and the fall time (Tf) in the IGBT.

FIG. 11 is a graph showing a relationship between a thickness of an n − layer and a current change rate (di / dt) during recovery in a diode.

FIG. 12 is an example of a main circuit of a power inverter device embodying the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... IGBT, 2 ... diode, 3 ... metal plate, 4 ... insulating plate, 5 ... heat sink, 6 ... collector terminal, 7 ... emitter terminal, 8 ... plastic package, 9 ... power supply, 10
... motor, 11 ... p + substrate, 12, 15 ... n + layer, 1
3,17 ... n- layer, 14,18 ... p + layer, 16 ... n + substrate, 19 ... gate insulating film, 20 ... gate electrode, 21 ... emitter electrode, 22 ... collector electrode, 23 ... cathode electrode, 24 ... Anode electrode, 25 wiring, 26 gate terminal.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-300568 (JP, A) JP-A-6-1223771 (JP, A) JP-A-59-132671 (JP, A) JP-A-59-13767 98557 (JP, A) JP-A-2-112285 (JP, A) JP-A-5-259462 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 29/78

Claims (18)

(57) [Claims] An insulated gate bipolar transistor having at least a pair of insulated gate bipolar transistors and a diode connected in anti-parallel, wherein a specific resistance of a base layer of the diode is lower than a specific resistance of a collector side base layer of the insulated gate bipolar transistor. A semiconductor device characterized in that the withstand voltage when the transistor switches from the conductive state to the blocking state is lower than the withstand voltage of the insulated gate bipolar transistor and the diode in the blocking state. In one module, at least a pair of insulated gate bipolar transistors and a diode connected in antiparallel are built in, and the specific resistance of the base layer of the diode is higher than the specific resistance of the collector-side base layer of the insulated gate bipolar transistor. A semiconductor device characterized by having a low withstand voltage when the insulated gate bipolar transistor switches from the conductive state to the blocking state, lower than the withstand voltage of the insulated gate bipolar transistor and the diode in the blocking state. 3. The semiconductor device according to claim 1, wherein a thickness of a base layer of the diode is larger than a thickness of a collector-side base layer of the insulated gate bipolar transistor. Semiconductor device. 4. The semiconductor device according to claim 1, wherein the rated voltage is n volts, and the collector-side base layer of the insulated gate bipolar transistor is depleted by (n / 2) volts. A semiconductor device having a specific resistance and a thickness, wherein the base layer of the diode has a specific resistance and a thickness that does not cause depletion at (n / 2) volts. 5. The semiconductor device according to claim 1, wherein the rated resistance is n volts, and the specific resistance of the collector-side base layer of the insulated gate bipolar transistor is (n / 17) Ω ·. A semiconductor device, wherein a specific resistance of the base layer of the diode ranges from (n / 25) Ω · cm to (n / 10) Ω · cm. 6. The semiconductor device according to claim 1, wherein the rated voltage is n volts, and the thickness of the collector-side base layer of the insulated gate bipolar transistor is (n / 10.5). A semiconductor device, characterized in that the thickness of the base layer of the diode is (n / 10) μm or more from μm to (n / 7.5) μm. 7. The semiconductor device according to claim 1, wherein the specific resistance of the collector-side base layer of the insulated gate bipolar transistor is at least 1.5 times the specific resistance of the base layer of the diode. A semiconductor device, characterized in that: 8. An insulated gate bipolar transistor having at least a pair of insulated gate bipolar transistors and a diode connected in anti-parallel, rated at n volts, and having a collector-side base layer of the insulated gate bipolar transistor having a specific resistance of (n / 17) Ω · cm. From (n / 6) Ω · cm
And the specific resistance of the base layer of the diode is (n / 25) Ω ·
cm to (n / 10) Ω · cm, the thickness of the collector-side base layer of the insulated gate bipolar transistor is (n / 10.5) μm to (n / 7.5) μm, and the thickness of the diode base layer is (n / 10) A semiconductor device characterized in that it is not less than μm. 9. A semiconductor device having at least a pair of insulated gate bipolar transistors and a diode, comprising: a first region of a first conductivity type having a pair of main surfaces and an exposed surface on one of the main surfaces. A second conductivity type second region having a lower impurity concentration than the first region formed adjacent to the first region;
A third region of a second conductivity type having a lower impurity concentration than the second region formed adjacent to the second region and having an exposed surface on the other main surface, and selectively formed on the other main surface portion of the third region. And the fourth region of the first conductivity type having a higher impurity concentration than the third region.
A fifth region of a second conductivity type selectively formed on the other main surface side of the region and having a higher impurity concentration than the fourth region, and exposing the third region, the fourth region, and the fifth region on the other main surface; An insulating gate provided on the surface via an insulating film;
A first main electrode having a low resistance contact with an exposed surface of the region, an insulated gate bipolar transistor provided with a second main electrode for short-circuiting the fourth region and the fifth region on the other main surface, A sixth region of a second conductivity type having a surface and an exposed surface on one main surface; a sixth region formed adjacent to the sixth region;
A seventh region of the second conductivity type having a lower impurity concentration than the region, an eighth region of the first conductivity type having a higher impurity concentration than the seventh region formed adjacent to the seventh region and having an exposed surface on the other main surface, Sixth
A third electrode having a low resistance contact with the region and a diode having a fourth main electrode having a low resistance contact with the eighth region, wherein the first main electrode and the third main electrode are connected, and And the fourth main electrode are connected, the specific resistance of the seventh region of the diode is lower than the specific resistance of the third region of the insulated gate bipolar transistor, and the insulated gate bipolar transistor switches from the conducting state to the blocking state. A semiconductor device having a breakdown voltage lower than a breakdown voltage in a blocking state of the insulated gate bipolar transistor and the diode. 10. A semiconductor device having at least a pair of anti-parallel insulated gate bipolar transistors and a diode connected in anti-parallel in one module, having a pair of main surfaces, one of which has an exposed surface. A first region of the first conductivity type, a second region of the second conductivity type having a lower impurity concentration than the first region formed adjacent to the first region,
A third region of a second conductivity type having a lower impurity concentration than the second region formed adjacent to the second region and having an exposed surface on the other main surface, and selectively formed on the other main surface portion of the third region. And the fourth region of the first conductivity type having a higher impurity concentration than the third region.
A fifth region of a second conductivity type selectively formed on the other main surface side of the region and having a higher impurity concentration than the fourth region, and exposing the third region, the fourth region, and the fifth region on the other main surface; An insulating gate provided on the surface via an insulating film;
A first main electrode having a low resistance contact with an exposed surface of the region, an insulated gate bipolar transistor provided with a second main electrode for short-circuiting the fourth region and the fifth region on the other main surface, A sixth region of a second conductivity type having a surface and an exposed surface on one main surface; a sixth region formed adjacent to the sixth region;
A seventh region of the second conductivity type having a lower impurity concentration than the region, an eighth region of the first conductivity type having a higher impurity concentration than the seventh region formed adjacent to the seventh region and having an exposed surface on the other main surface, Sixth
A third electrode having a low resistance contact with the region and a diode provided with a fourth main electrode having a low resistance contact with the eighth region, wherein the first main electrode and the third main electrode are connected, and And the fourth main electrode are connected, the specific resistance of the seventh region of the diode is lower than the specific resistance of the third region of the insulated gate bipolar transistor, and the insulated gate bipolar transistor switches from the conducting state to the blocking state. A semiconductor device having a breakdown voltage lower than a breakdown voltage in a blocking state of the insulated gate bipolar transistor and the diode. 11. The method according to claim 9 or claim 10.
Item 7. The semiconductor device according to Item 1, wherein the thickness of the seventh region of the diode is larger than the thickness of the third region of the insulated gate bipolar transistor. 12. The method according to claim 9, wherein
In the semiconductor device according to the item, the rated n volts,
The third region of the insulated gate bipolar transistor is (n /
2) A semiconductor device having a specific resistance and a thickness depleted by volts, and a seventh region of the diode having a specific resistance and a thickness not depleted by (n / 2) volts. 13. The method according to claim 9, wherein
In the semiconductor device according to the item, the rated n volts,
The specific resistance of the third region of the insulated gate bipolar transistor is (n / 17) Ω · cm to (n / 6) Ω · cm, and the specific resistance of the seventh region of the diode is (n / 25) Ω · cm to (n).
/ 10) A semiconductor device characterized by Ω · cm. 14. The method according to claim 9, wherein
In the semiconductor device according to the item, the rated n volts,
The thickness of the third region of the insulated gate bipolar transistor is (n / 10.5) μm to (n / 7.5) μm, and the thickness of the seventh region of the diode is (n / 10) μm or more. Characteristic semiconductor device. 15. The method according to claim 9, wherein:
9. The semiconductor device according to item 6, wherein the specific resistance of the third region of the insulated gate bipolar transistor is at least 1.5 times the specific resistance of the seventh region of the diode. 16. A semiconductor device having at least a pair of insulated gate bipolar transistors and a diode, comprising: a first region of a first conductivity type having a pair of main surfaces and an exposed surface on one of the main surfaces. A second conductivity type second region having a lower impurity concentration than the first region formed adjacent to the first region;
A third region of a second conductivity type having a lower impurity concentration than the second region formed adjacent to the second region and having an exposed surface on the other main surface, and selectively formed on the other main surface portion of the third region. And the fourth region of the first conductivity type having a higher impurity concentration than the third region.
A fifth region of a second conductivity type selectively formed on the other main surface side of the region and having a higher impurity concentration than the fourth region, and exposing the third region, the fourth region, and the fifth region on the other main surface; An insulating gate provided on the surface via an insulating film;
A first main electrode having a low resistance contact with an exposed surface of the region, an insulated gate bipolar transistor provided with a second main electrode for short-circuiting the fourth region and the fifth region on the other main surface, A sixth region of a second conductivity type having a surface and an exposed surface on one main surface; a sixth region formed adjacent to the sixth region;
A seventh region of the second conductivity type having a lower impurity concentration than the region, an eighth region of the first conductivity type having a higher impurity concentration than the seventh region formed adjacent to the seventh region and having an exposed surface on the other main surface, Sixth
A third electrode having a low resistance contact with the region and a diode provided with a fourth main electrode having a low resistance contact with the eighth region, wherein the first main electrode and the third main electrode are connected, and The main electrode and the fourth main electrode are connected to each other, the rated voltage is n volts, the specific resistance of the third region of the insulated gate bipolar transistor is (n / 17) Ω · cm to (n / 6) Ω · cm, and the diode is Has a specific resistance of (n / 25) Ω · cm to (n
/ 10) Ω · cm, the thickness of the third region of the insulated gate bipolar transistor is
A semiconductor device, wherein (n / 10.5) μm to (n / 7.5) μm, and the thickness of the seventh region of the diode is (n / 10) μm or more. 17. A semiconductor device having at least a pair of insulated gate bipolar transistors and a diode, comprising: a first region of a first conductivity type having a pair of main surfaces and an exposed surface on one of the main surfaces. A second conductivity type second region having a lower impurity concentration than the first region formed adjacent to the first region;
A third region of a second conductivity type having a lower impurity concentration than the second region formed adjacent to the second region and having an exposed surface on the other main surface, and selectively formed on the other main surface portion of the third region. And the fourth region of the first conductivity type having a higher impurity concentration than the third region.
A fifth region of a second conductivity type selectively formed on the other main surface side of the region and having a higher impurity concentration than the fourth region, and exposing the third region, the fourth region, and the fifth region on the other main surface; An insulating gate provided on the surface via an insulating film;
A first main electrode having a low resistance contact with an exposed surface of the region, an insulated gate bipolar transistor provided with a second main electrode for short-circuiting the fourth region and the fifth region on the other main surface, A sixth region of a second conductivity type having a surface and an exposed surface on one main surface; a sixth region formed adjacent to the sixth region;
A seventh region of the second conductivity type having a lower impurity concentration than the region, an eighth region of the first conductivity type having a higher impurity concentration than the seventh region formed adjacent to the seventh region and having an exposed surface on the other main surface, Sixth
A third electrode having a low resistance contact with the region and a diode having a fourth main electrode having a low resistance contact with the eighth region, wherein the depletion layer of the insulated gate bipolar transistor is located at the second region at the maximum applied voltage. And a depletion layer of the diode is in the seventh region and does not reach the sixth region. 18. A power inverter device having an anti-parallel circuit of an insulated gate bipolar transistor and a diode and converting DC power to AC power by switching the insulated gate bipolar transistor, wherein the anti-parallel circuit is 18. A power inverter device comprising the semiconductor device according to any one of 1 to 17.