JPS62235782A - Semiconductor device - Google Patents

Abstract

PURPOSE:To simultaneously satisfy three conditions of a high speed switching, a low forward voltage drop and a high main electrode blocking voltage by forming local regions having relatively short charge carrier life on the vicinity of a gate region and a region depleted eventually in a main current interrupting step to an eventually depleted region. CONSTITUTION:A cathode region 11 and an anode region 12 made of opposite conductivity type high impurity density regions, a low impurity density region 14 formed at part between the regions 11 and 12, and a gate region 13 formed near the region 11 for controlling a main current are formed. in such a semicon ductor device, local regions 16, 15 having relatively short charge carrier life are formed on a region near the region 11, a region eventually depleted in a main current interrupting step and an eventually depleted region of the region 14. For example, after a P<+> type anode region 12, a P<+> type gate region 13 and an N<+> type cathode region 11 are respectively formed on an N-type silicon substrate, a photon beam is emitted from both side surfaces of an element to form regions 15, 16, thereby forming a static induction thyristor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in semiconductor devices such as electrostatic induction thyristors and gate turn-off thyristors that can handle large amounts of power. In particular, the present invention provides a semiconductor device for switching that is capable of high-speed switching of large currents, and has a low forward voltage drop and a high blocking voltage between main electrodes.

(Prior art) In applications such as motor control and switching power supplies using pulse width modulation, if the switching speed is not very fast and the control frequency is increased, switching loss will increase and the heat dissipation design of the equipment will become complicated. This will lead to an increase in size. The control frequency is lowered to the human audible frequency (2
0k)lz), the noise emitted by the equipment causes discomfort to the operator. If you try to implement soundproofing to avoid this, you will end up with a contradiction in terms of increasing the size.

Furthermore, it is said that the weight of an inductance device such as a transformer is inversely proportional to the 1/2 power of the frequency, and from this point of view as well, lowering the control frequency will lead to an increase in the size of the device.

Therefore, in the application of electric motor control and switching power supplies using this pulse width modulation method, it is necessary to increase the control frequency, and for this reason, high-speed switching is also required. In addition to the switching loss, it is also important to reduce on-loss, and to reduce this on-loss, it is necessary to realize a low forward voltage drop.

Furthermore, applications in high-voltage line systems require a high interelectrode blocking voltage of several kilovolts.

Semiconductor devices, typified by static induction thyristors and gate turn-off thyristors, have two main electrode regions, a cathode region and an anode region, each consisting of a high impurity density region of opposite conductivity type. It has a low impurity density region in part, and a gate region for controlling the main current near the cathode region.

In this type of conventional semiconductor device, it is generally known that a high blocking voltage between main electrodes can be achieved by increasing the thickness of the low impurity density region. Furthermore, in order to achieve high-speed switching in such semiconductor devices, attempts have been made to uniformly shorten the lifetime of charge carriers over the entire region of the low impurity density region, most commonly by gold diffusion. However, with this method, if the charge carrier lifetime is shortened enough to achieve sufficient speedup, the forward voltage drop becomes significantly high, making it impossible to achieve both high-speed switching and low forward voltage drop. .

In order to solve these problems and achieve both high-speed switching and low forward voltage drop, in the electrostatic induction thyristor, the charge carrier lifetime is reduced locally in the low impurity region with respect to the main current direction. A structure with a short region was proposed.

However, in this structure, only one region with a relatively short charge carrier life is provided, and when the low impurity density region is made thick in order to achieve a high main electrode blocking voltage, it is difficult to achieve sufficient high-speed switching and sufficient However, it was not possible to achieve both a low forward voltage drop and a low forward voltage drop.

(Problems to be Solved by the Invention) An object of the present invention is to provide two main electrode regions, a cathode region and an anode region, each consisting of a high impurity density region of opposite conductivity type, The object of the present invention is to solve the above-mentioned problems in a conventional semiconductor device having a low impurity density region in a part thereof and a gate region for controlling the main current in the vicinity of the cathode region.

That is, an object of the present invention is to provide a structure in a semiconductor device that satisfies three conditions: high-speed switching, low forward voltage drop, and high blocking voltage between main electrodes.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes two main electrode regions, a cathode region and an anode region, each consisting of a high impurity density region of opposite conductivity type. In a semiconductor device having a low impurity density region in a part between electrode regions and a gate region for controlling a main current near the cathode region, a region near the gate region and a main current in the low impurity density region This semiconductor device is characterized in that a local region with a relatively short charge carrier life is provided in a region that is depleted at the end of a current cutoff process or a region that is not depleted until the end.

(Function) To make the explanation easier to understand, first, a cathode region and an anode region are provided, each having a high impurity density region of opposite conductivity type, and a low impurity density region is provided between these two regions. , a basic operation before implementing the present invention in a semiconductor device having a gate region for controlling a main current near the cathode region will be explained. For convenience of explanation, it is assumed that the upper sword region is an n+ region and the anode region is a p+ region.

In the semiconductor device having the above structure, in the cut-off state, a thick depletion layer spreads in the low impurity density region, so the maximum electric field strength in the semiconductor device is kept small, and a high blocking voltage between the main electrodes can be realized.

In the conductive state, electrons and holes are injected into the low impurity density region from the n+ cathode region and the p'' anode region, so the resistance of the low impurity density region decreases and a low forward voltage drop can be realized. , the longer the charge carrier lifetime in the low impurity density region, the higher the charge carrier density in the low impurity density region in the conductive state, and therefore the lower the forward voltage drop.

Switching from a blocked state to a conductive state is achieved by biasing the gate region to a positive voltage with respect to the n+ cathode region. Biasing the gate region to a positive voltage results in n
Electrons are injected from the cathode region to the low impurity density region. The injected electrons rapidly change to p due to the electric field in the depletion layer.
It reaches the vicinity of the + anode region and induces hole injection from the p+ anode region. The injected holes quickly reach the vicinity of the n+ cathode region due to the electric field in the depletion layer, and the
+ Promotes injection of electrons from the cathode region. Such repetition results in a positive feedback effect, and the low impurity density region is filled with electrons and holes, resulting in low resistance in the region and the semiconductor device becoming conductive. Therefore, the conduction process described above is fast.

Switching from a conductive state to a blocked state is accomplished by biasing the gate region to a negative voltage with respect to the n+ cathode region. When the gate region is biased to a negative voltage, injection of electrons from the n+ cathode region is stopped, and the positive feedback described above is stopped. Thereafter, as the electrons and holes in the low impurity density region recombine and disappear, the depletion layer spreads from the vicinity of the gate region into the low impurity density region.
The semiconductor device enters a cut-off state. In other words, this interruption
□The process strongly depends on the charge carrier lifetime in the low impurity density region. The charge carrier lifetime is long to achieve a low forward voltage drop, so the shutoff process is slow.

The basic operation of the semiconductor device that does not include the features of the present invention has been described above. Next, the operation of the improved semiconductor device according to the present invention will be described. That is,
The present invention is applied to the semiconductor device described above, and the charge carrier life span is increased in the vicinity of the cathode region in the low impurity density region and in the region that is depleted at the end of the main current cutoff process or the region that is not depleted until the end. The operation when a relatively short local area is provided will be explained.

The main interelectrode blocking voltage mainly depends on the impurity density in the low impurity density region, but since the impurity density does not change by providing the above-mentioned local region, which is a feature of the present invention, when no local region is provided. as well as high.

The forward voltage drop mainly depends on the charge carrier density distribution in the low impurity density region in the conductive state, but by providing the local region of the present invention, the charge carrier density distribution is only locally influenced. The increase in forward voltage drop is small.

Switching from the blocking state to the conducting state does not depend on the amount of recombination if the amount of charge carriers implanted into the low impurity density region is very large compared to the amount of recombination. Therefore, even if a local region, which is a feature of the present invention, is provided, the conduction process remains fast.

The switching from the conducting state to the blocking state mainly depends on the charge carrier lifetime of the low impurity density region and is very fast with the configuration of the present invention. The reason for this will be explained in detail below.

A local region with a relatively short charge carrier lifetime provided near the gate reduces the hole density in front of the n+ cathode region and
This is effective in speeding up the first half of the blocking process by helping to stop the injection of electrons from the cathode region and by lowering the charge carrier density in the low impurity density region. However, during the blocking process, depletion of the low impurity density region from the vicinity of the gate region progresses, and when that local region becomes depleted, it is no longer effective for the disappearance of charge carriers.
Does not contribute to speeding up the shutoff process. On the other hand, a local region with a relatively short charge carrier life that is created in a region that is the last to be depleted in the main current cutoff process or a region that is not depleted to the end is a localized region that has a relatively short charge carrier life. It is clear from the above definition that it acts more effectively in the latter half of the blocking process. Therefore, the local area is mainly effective for speeding up the latter half of the blocking process. That is, only by jointly providing two local regions according to the invention with relatively short charge carrier lifetimes can a significant speed-up of the main current interruption process be achieved. If only one of them is used, only the first half or the second half of the shutoff process will be sped up, and the degree of speeding up will be low.

As explained above, the present invention applies to the region near the cathode region in the low impurity density region for obtaining the main interelectrode blocking voltage, and the region to be depleted at the end of the main current cutoff process. By providing a non-depleted region together with a localized region with a relatively short charge carrier lifetime, it is possible to simultaneously achieve a high inter-electrode blocking voltage, a low forward voltage drop, and high-speed switching.

(Example) Order 11 Circle 1 A first example in which the present invention is applied to a surface-gate n-channel static induction thyristor will be described. In the case of n-channel type, basically p4″n-nl or p”
It has a structure in which a p+ gate region is provided in a mekyu shape or a stripe shape near an n+ region which becomes a cathode of an nn-n+ diode.

FIG. 1 shows the cross-sectional structure of one unit of the electrostatic induction thyristor of the first embodiment.

Impurity density is about I x 10"cm", thickness is about 26
Boron is diffused over the entire surface of a 0 μm n-type silicon substrate from one surface to form a p + anode region 12 with a diffusion depth of 10 μm. Next, boron and arsenic are sequentially selectively diffused from the other surface to form a p + gate region 13 with a diffusion depth of 4 μm and an n + cathode region 11 with a diffusion depth of 0.5 μm. After that, the cathode region 11
, 6 μm thick aluminum electrode wirings 11' and 12' connected to the anode region 12 and gate region 13, respectively.
, 13' is applied. IO is an insulating film. Finally, a proton beam is emitted from both surfaces of the device at an energy of 1.1 MeV to approximately 1Xl.
Irradiated with a dose of 0" proton particle/cm2, area 15.1
6 to produce an electrostatic induction thyristor having the structure of the present invention shown in FIG. A proton beam with an energy of 1.1 MeV penetrates to a depth of about 20 μm from the element surface. The degree of damage to the crystal lattice due to proton beam irradiation is significantly greater in the region near the limit of the depth through which the proton beam can penetrate than in the region belonging to the proton beam passage path. Therefore, in this example, the local regions 15 and 16 in which the charge carrier lifetime is reduced are localized at a depth of approximately 20 μm from the element surface.

The main interelectrode blocking voltage is approximately IKV in both forward and reverse directions.
, and this value does not depend on the presence or absence of the local region 15.16.

The forward voltage drop is when the anode current ■A (main current) is 50
In the case of A, the voltage is 1.3V for the static induction thyristor that does not have local regions 15 and 16, and 2.95 V for the static induction thyristor of this embodiment that has both local regions 15 and 16, and the present invention. Even if this is adopted, the increase will only be about double.

In order to investigate the switching characteristics of this first embodiment,
The switching waveforms of various electrostatic induction thyristors were measured by applying a positive voltage in pulses to the gate at the timing when conduction was desired, and by applying a negative voltage in pulses to the gate at the timing when the gate was desired to be cut off.

Note that the voltage applied to the anode was 100V.

Figure 2 shows the results, and shows the switching waveform of the anode current I^ (main current) in the low impurity density region 1.
4, local regions of relatively short charge carrier lifetimes 15.
Waveform of a static induction thyristor that does not have 16 (a)
, Waveform (b) of one with only local area 15, Waveform (C) of one with only local area 16, Local area 15
．． The waveform (d) according to the invention with both 16 and 16 is shown.

As can be seen from Fig. 2, the turn-on time (the time required for the conduction process, the time from when the ON signal is input to the gate until the anode current 8 reaches 90%) is different for which of the above four types of electrostatic induction type. The same goes for the thyristor, about 0.2 μsec.
And it was fast. The turn-off time (the time required for the switching off process, the sum of the accumulation time t stg and the fall time 1.) is significantly influenced by the local area 15.16.

Note that the accumulation time t stg is the anode current after the off signal is input to the gate! The falling time t, which is the time it takes for the anode current I^ to drop from 90% to 10
This is the time it takes to drop to %.

In a static induction thyristor that does not have local regions 15°16 with relatively short charge carrier lifetimes, the accumulation time t st
g is relatively fast at 0.85 μsec, but the fall time tf is not very fast at 6 μsec.

In contrast, in the electrostatic induction thyristor with only the local region 15 added, the accumulation time t stg is 0.7μ
sec and does not change much, but the fall time tr
is 1.35 μsec, which is slightly faster.

On the other hand, in the electrostatic induction thyristor to which only the local region 16 is added, the accumulation time t stg is slightly faster at 0.2 μsec, but the fall time tf is not so fast at 4.7 μsec.

On the other hand, in the electrostatic induction thyristor of the present invention having both regions 15 and 18, t stg is slightly faster at 0.17, and tr is extremely faster at 0.05 μSec. In other words, by adopting the present invention, the switching time (total of turn-on time and turn-off time) is approximately 7μ.
sec to 0.4 μsec, which is very short. In other words, the switching speed was approximately 18 times faster than that of a static induction thyristor not implementing the present invention.

The above results are shown in the table below.

To summarize the above, the embodiment of the present invention simultaneously achieved a high forward and reverse blocking voltage of about IKV, a low forward voltage drop of about 3V, and high-speed switching of about 0.4V. It should be noted that the method for forming the 15° 160 region is not limited to proton beam irradiation; it is obvious that any method for locally reducing the charge carrier lifetime can be used, and the semiconductors can be used not only for silicon but also for germanium, gallium, arsenic, etc. It is also clear that other semiconductors may be used. Furthermore, it is also clear that a structure in which p-type and n-type are completely replaced is also possible. Further, the aluminum wiring is not limited to this, and other metal wiring (Ti, W) or metal silicide wiring may be used.

The above describes the first example in which the present invention is applied to a static induction thyristor.
Although the embodiment has been described, other semiconductor devices having the same basic operating mechanism can also have similar effects. A few examples will be explained below.

FIG. 3 shows a second embodiment in which the present invention is applied to a gate turn-off thyristor.

This second embodiment has a cathode region 31 made of a high impurity density region, an anode region 32 made of a high impurity density region of the conductivity type opposite to that of the cathode region 31, and a main current provided near the cathode region 31. a local region 36 with a relatively short charge carrier lifetime near the gate region in the low impurity density region 34 between the cathode region 31 and the anode region 32; In the low impurity density region 34 between the main current cutoff process and the main current cut-off process, there is a local region 36 with a relatively short charge carrier life, which is a region that is depleted at the end of the main current interruption process or a region that is not depleted until the end. The basic structure is the same as the first embodiment. In addition, 30
is an insulating film, and 31', 32', and 33' are metal or metal silicide wirings coupled to the cathode region 31, anode region 32, and gate region 33, respectively.

However, since the second embodiment is a gate turn-off thyristor and has a gate region 33 on the front surface of the sword region 31, a pattern as fine as that of an electrostatic induction thyristor is required to achieve a high blocking voltage between the main electrodes. do not need. Therefore, it is easy to increase the area, that is, increase the current. However, in this structure, when the impurity density of the gate region 33 is increased in order to lower the gate resistance, the forward voltage drop increases unlike in the case of a static induction thyristor. Therefore, the switching speed is slower than that of a static induction thyristor.

Other than these points, the basic operation is the same as that of the first embodiment, and similar actions and effects can be achieved.

Figure 4 shows a third embodiment in which the present invention is applied to a buried gate thyristor.

The third embodiment includes a cathode region 41 made of a high impurity density region, an anode region 42 made of a high impurity density region of a conductivity type opposite to that of the cathode region 41, and a main current provided near the cathode region 41. Gate region 43 to control
, the low impurity cloth 20 between the cathode region 41 and the anode region 42 , the local region 46 with a relatively short load body life near the gate region in the region 44 , and the region 46 between the cathode region 41 and the anode region 42 . A low impurity density region 44 in the main current cutoff process is depleted at the end of the main current cutoff process, and a local region 45 in which the charge carrier life is relatively short is located in a region that is not depleted to the end.This basic structure is as follows. This is similar to the first embodiment. Moreover, their basic functions and effects are also the same. Note that 40 is an insulating film and 41'.

42' are a cathode region 41 and an anode region 42, respectively.
It is a metal or metal silicide interconnect connected to the

However, this embodiment is a buried gate type static induction type thyristor, and as the name suggests, the gate region 43 is buried.
This embodiment differs from the surface-gate electrostatic induction thyristor of the first embodiment in that it has a structure in which the thyristor is embedded in a low impurity density region 44.

The third embodiment can achieve a higher gate-cathode breakdown voltage than the surface gate type of the first embodiment. Therefore, it is easy to realize a high blocking voltage between the main electrodes. Another advantage is that the drive power supply capacitor for each gate can be small.

By the way, if the distance between the gate and the cathode is made large with emphasis on the withstand voltage between the gate and the cathode, the charge carriers existing between the gate and cathode will not be effectively eliminated. It is also possible to include short local regions.

"L Practical" 1st Example - FIG. 5 shows a fourth embodiment in which the present invention is applied to an insulated gate thyristor.

The fourth embodiment includes a cathode region 51 made of a high impurity density region, an anode region 52 made of a high impurity density region of a conductivity type opposite to that of the cathode region 51, and a main current provided near the cathode region 51. Gate region 53 to control
, a local region 56 with a relatively short load body life near the gate region in the low impurity density region 54 between the cathode region 51 and the anode region 52 , and a local region 56 between the cathode region 51 and the anode region 52 . The low impurity density region 54 includes a local region 55 with a relatively short charge carrier life, which is a region that is depleted at the end of the main current cutoff process or a region that is not depleted until the end, and the charge carrier life is compared. The basic structure of providing short local areas 55 and 56 is similar to that of the first embodiment. Moreover, their basic functions and effects are also the same.

However, this fourth embodiment is an insulated gate type electrostatic induction thyristor, and as the name suggests, it is not a normal junction type thyristor like the first embodiment, but the gate region 53 is formed by an insulating film 50. This embodiment differs from the junction type surface gate type static induction thyristor like the first embodiment in that it has a separate structure.

Note that 51' and 52' are metal or metal silicide electrode wirings.

The electrostatic induction thyristor of the fourth embodiment does not have a low input impedance like the junction type electrostatic induction thyristor of the first embodiment, but has a high input impedance. Therefore, there is an advantage that the gate drive circuit becomes simple.

Although this fourth embodiment is of the surface gate type, it is obvious that it can be configured as a buried gate type like the third embodiment.

Example 1 of "L Practical Example" FIG. 6 shows a fifth example having a structure in which a thin layer region 67 having a relatively high impurity density is provided in front of the anode region in the first example.

That is, the fifth embodiment has a cannide region 61 made of a high impurity density region, an anode region 62 made of a high impurity density region of a conductivity type opposite to that of the cathode region 61, and a main region provided near the cathode region 61. a gate region 63 for controlling current; a local region 66 with a relatively short load body life located near the gate region in a low impurity density region 64 between the cathode region 61 and the anode region 62;
A local region with a relatively short charge carrier life in a region that is depleted at the end of the main current interruption process or a region that is not depleted until the end in the thin layer region 67 with a relatively high impurity density.
65, and the pole-and-line fishing structure of this base 24 is similar to that of the first embodiment. Moreover, their basic functions and effects are also the same.

The feature different from the first embodiment is that, as described above, a thin layer region 67 with a relatively high impurity density is provided on the front surface of the anode region 62, and a local region 65 is arranged within the thin layer region 67.
With this structure, the anode region 6
The maximum blocking voltage applied to gate region 6
The electric field distribution between the anode region 1 and the anode region 62 has a quadrilateral shape, and the thin layer region 67 having a relatively high impurity density remains as a region that will not be depleted.

Therefore, the electrostatic induction thyristor of this fifth embodiment is
Compared to the electrostatic induction thyristor of the embodiment, there is an advantage that a higher blocking voltage between the main electrodes can be realized by using a low impurity density region of the same thickness.

The structure in which the thin layer region 67 of the fifth embodiment is provided is also applicable to the second, third, and fourth embodiments.

7 shows an impurity density region 79 of the same conductivity type as the cathode region in a part of the anode region in the first embodiment.
The sixth region has a structure in which the anode region is provided with the same potential as the anode region.
This is an example.

That is, the sixth embodiment has a cathode region 71 made of a high impurity density region, an anode region 72 made of a high impurity density region of a conductivity type opposite to that of the cathode region 71, and a main region provided near the cathode region 71. a gate region 73 for controlling current; a local region 76 with a relatively short charged body life near the gate region 73 in a low impurity density region 74 between the cathode region 71 and the anode region 72;
In the low impurity density region 74 between the cathode region 71 and the anode region 72, there is a local region 76 with a relatively short charge carrier life, which is a region that is depleted at the end of the main current cutoff process or a region that is not depleted until the end. It is equipped with

In addition, 70 is an insulating film, 71', ? 2' and 73' are metal or metal silicide electrode wirings. This basic structure is similar to the first embodiment. Moreover, their basic functions and effects are also the same.

A feature different from the first embodiment is that in the basic structure, an impurity density region 79 of the same conductivity type as the cathode region is provided in a part of the anode region 72, and this
The reason is that it is used at the same potential as the With this structure, since the region 79 has the same conductivity type as the cathode region 71, charge carriers injected from the cathode region 71 into the low impurity density region 74 can be easily swept away, which has the advantage of shortening the turn-off time.

Note that the structure in which the impurity density region 79 of the same conductivity type as the cathode region 71 is provided in a part of the anode region 72 of the sixth embodiment is different from that of the second, third, fourth, and fifth embodiments. It is also applicable.

IL Imaging 1 FIG. 8 shows a seventh embodiment in which the present invention is applied to a double-sided gate type static induction thyristor.

This double-sided gate type electrostatic induction thyristor is characterized in that gates for controlling the main current are provided both near the cathode region and near the anode region.

That is, this seventh embodiment has a cathode region 81 made of a high impurity density region, an anode region 82 made of a high impurity density region of the opposite conductivity type to that of the cathode region 81, and a cathode region 82 provided near the cathode region 81. a first gate region 83 for controlling the main current, a second gate region 88 for controlling the main current provided near the anode region 82, and a low impurity density region between the cathode region 81 and the anode region 82. first and second gate regions 8 in 84 respectively;
The main current interruption process is located near the first and third local regions @ 86 and 89 with relatively short charged body lifetimes located near 3 and 88 and the center between the cathode region 81 and the anode region 82. A second local region 85 having a relatively short charge carrier lifetime is provided in a region that is depleted at the end or a region that is not depleted until the end. Note that 80 is an insulating film, and 81', 82', and 83' are metal or metal silicide electrode wirings. The seventh embodiment with such a structure is characterized by the structure and effect of adding the second gate region 88 and third local region 89 to the first embodiment, but the basic function and effect are the same as those of the first embodiment. - Column 1 is the same as the example.

In the seventh embodiment, a first gate region 83 near the cathode region 81 controls the injection of charge carriers from the cathode region 81, and a second gate region 88 near the anode region 82 controls the injection of charge carriers from the anode region 82. control. Therefore, compared to the electrostatic induction thyristor of the first embodiment, which controls only the injection of charge carriers from the cathode region 81, there is an advantage that faster switching can be realized.

Note that the gate structure of the double-sided gate type static induction thyristor of this example can be implemented in any combination with the surface gate type, buried gate type, junction gate type, or insulated gate type shown in each of the above-mentioned examples. can do.

In the various embodiments shown above, the distance between the two or three local regions where the charge carrier lifetime is relatively short is within the diffusion length of the charge carrier in the low impurity density region. If the interval between two or three local regions is equal to or greater than the diffusion length, the effect of recombination of charge carriers will be reduced, so one or more additional locations will be added between the two or three local regions. It is advantageous to provide additional local regions with relatively short charge carrier lifetimes.

Also, for the same reason, when the gap between the gate region and the cathode region is longer than the diffusion length of charge carriers in the low impurity density region, the charge carrier life is relatively short in the low impurity density region near the cathode region. It is also effective to provide additional local areas.

(Effects of the Invention) As explained above, according to the present invention, the region near the cathode region in the low impurity density region for obtaining the main inter-electrode blocking voltage and the end of the main current cutoff process. By providing a depleted region or a region that is not fully depleted together with a localized region with a relatively short charge carrier lifetime, a high main electrode blocking voltage, low forward voltage drop, and high speed switching can be achieved. A semiconductor device with excellent characteristics can be realized.

Therefore, according to the present invention, the control frequency can be raised to allow use in a region outside of the audible frequency range, so that the noise generated by the device can be significantly reduced.

Further, since switching loss is small even when used at high frequencies, heat dissipation design becomes easier and the device can be made smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment in which the present invention is applied to a surface gate type electrostatic induction thyristor. FIG. 2 shows the switching waveforms of the first embodiment and the conventional example. FIG. 3 is a sectional view showing a second embodiment in which the present invention is applied to a gate turn-off thyristor. FIG. 4 is a sectional view showing a third embodiment in which the present invention is applied to a buried gate thyristor. FIG. 5 is a sectional view showing a fourth embodiment in which the present invention is applied to an insulated gate electrostatic induction thyristor. FIG. 6 is a sectional view showing a fifth embodiment of the present invention having a structure in which a thin layer region with relatively high impurity density is provided in front of the anode region in the first embodiment of the present invention. FIG. 7 shows a sixth embodiment of the present invention in which, in the first embodiment, an impurity density region of the same conductivity type as the cathode region is provided in a part of the anode region, and the potential is the same as that of the anode region. FIG. FIG. 8 is a sectional view showing a seventh embodiment in which the present invention is applied to a double-sided gate type electrostatic induction thyristor. 10.30,40,50,60. To, 80... Insulating film, 11.31, 41, 51, 61, 71.81-11
0 cathode area, 12.32, 42, 52, 62, 72
．． 82... Anode region, 13.33, 43, 53,
63, 73, 83φ...gate region, 14.34, 44
, 54, 64, 74.84...low impurity density region, +
5.35, 45.55, 65, 75.85... A local region with a relatively short charge carrier life in a region that is the last to be depleted or a region that is not depleted to the end in the main current interruption process, +6. 36, 46, 56, 66. 76. 866 Φ Local region with relatively short charge carrier lifetime near gate region, 67... Region with relatively high impurity density, 79...
A region having the same conductivity type as the fist cathode region and the same potential as the anode region, 88...Second gate region, 89φ...A local region with a relatively short charge carrier life in the vicinity of the second gate region. Patent applicant Toyota Central Research Institute Co., Ltd. Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 72' Figure 8

Claims (9)

[Claims] (1) A cathode region and an anode region consisting of high impurity density regions of mutually opposite conductivity types, a low impurity density region located in a part between these two regions, and a main current provided near the cathode region are controlled. In a semiconductor device having a gate region, a charge carrier life span exists in a region near the gate region in the low impurity density region and a region that is depleted at the end of the main current cutoff process or a region that is not depleted until the end. A semiconductor device characterized in that a relatively short local region is provided. (2) The semiconductor device according to claim (1), characterized in that the semiconductor device is configured as a surface-gate electrostatic induction thyristor in which the gate region is provided in the vicinity of the cathode region in the form of a mesh or stripe. (3) The semiconductor device according to claim (1), further comprising a gate region in front of the cathode region, and configured as a gate turn-off thyristor. (4) The semiconductor device according to claim (1), wherein the semiconductor device is configured as a buried electrostatic induction thyristor in which the gate region is buried in a low impurity density region. (5) Any one of claims (1), (2), or (4), characterized in that the gate region is surrounded by an insulating film to constitute an insulated gate electrostatic induction thyristor. The semiconductor device according to item 1. (6) Claims characterized in that a thin layer region with relatively high impurity density is provided in front of the anode region, and one local region with a relatively short charge carrier life is provided in the thin layer region. The semiconductor device according to any one of items (1) to (5). (7) Claim (1) characterized in that an impurity density region of the same conductivity type as the cathode region is provided in a part of the anode region, and this region is used at the same potential as the anode region.
The semiconductor device according to any one of paragraphs to (6). (8) The gate region is located near the cathode region.
It consists of two regions: a gate region and a second gate region provided near the anode region. Any one of claims (1) to (7), characterized in that a region with a relatively short charge carrier life is provided in a region that is depleted until the end or a region that is not depleted to the end. The semiconductor device described in . (9) Three or more of the local regions are provided so that the distance between the local regions having relatively short charge carrier lifetimes is no longer than the diffusion length of the charge carriers in the low impurity density region. Claims (1) to (8)
The semiconductor device according to any one of the preceding items.