JP2809896B2 - High-speed turn-on device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed turn-on device capable of high-speed turn-on using an insulated gate.

[0002]

2. Description of the Related Art A thyristor with an insulated gate is known as a high-speed turn-on element. The basic structure is such that a p-type emitter layer is formed on one surface of a high-resistance n-type base layer,
It has a pnpn structure in which a p-type base layer and an n-type emitter layer are selectively formed on the other surface, and a gate insulating film is formed in a region between the n-type emitter layer and the n-type base layer of the p-type base layer. A gate electrode is formed through the gate electrode. This thyristor with an insulated gate shifts from a MOSFET operation to an IGBT operation to a thyristor operation when turned on.

In this type of thyristor with an insulated gate, if high-speed repetitive pulse driving is performed, unless the peak current is set to a small value, there is a problem that false ignition occurs when the anode voltage rises after current decay. This is because there is residual carrier for a while in the high-resistance n-type base layer even after the current decay. When the frequency of the repetitive driving is about several hundred Hz or less, there is no problem since the residual carriers disappear before the anode voltage rises after the current decay, but there is no problem.
This is a major problem in applications requiring high-speed repetitive pulse driving. More specifically, this problem will be described using a case where a thyristor with an insulated gate is used as a switching element of an excimer laser power supply as an example.

FIG. 6 shows a laser power supply circuit in which an inductance L, a capacitance C, and a resistor R are connected in series to form an LCR.
When simulating the circuit is a diagram showing the waveform of the anode voltage V _A and the anode current I _A of the insulated gate with thyristor. The anode voltage V _A at the applied state to the device, a positive voltage is applied to the insulated gate electrode of the element is fast turned on, the anode current rise rate di / dt, peak anode current i _p, sinusoidal pulse width t _W Apply pulse current. In the case of an excimer laser power supply, di / dt is 1 k
A / μsec / cm ² Or more and a number peak current i _p thousand A / cm ²
The above values may be taken. The pulse width t _W is 0.1 to
Take a value of about 3.0 μsec. After the oscillating current is attenuated by the resistance R, the anode voltage is raised at a voltage rising rate dv / dt with the pause time Δt as a preparation period for applying the next pulse current. The pause time Δt is required to be about 20 μsec when the repetition rate is 5 kHz.

In the case where a high-speed turn-on element is used in such a circuit, it has been known that if the carrier lifetime of the element is shortened, the on-state voltage is increased, so that the carrier lifetime is not shortened so far. Was. Nevertheless, conventionally, since the repetition rate of the laser for one second is limited to several hundred Hz at most and Δt is sufficiently large at 1 msec or more, no carrier remains when the anode voltage is raised. But in recent years, become a laser with a repetition rate of several kHz is required, unless a smaller peak current i _p in the devices so far, a problem of false firing at a displacement current by rising the anode voltage Has come up.

[0006]

As described above, in the conventional thyristor with an insulated gate, there is a problem in that when the pulse current is driven at a high repetition rate, unless the peak current is set to a small value, false firing occurs when the anode voltage rises. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-speed turn-on element which solves the above-mentioned problem and turns on at a high speed with a low loss, and does not erroneously fire even if the anode voltage is raised in a short time after current decay. And

[0008]

SUMMARY OF THE INVENTION The present invention provides a first conductive type emitter layer, a second conductive type base layer provided in contact with the first conductive type emitter layer, and a selective diffusion formation on a surface portion of the second conductive type base layer. The first conductivity type base layer, the second conductivity type emitter layer selectively diffused on the surface of the first conductivity type base layer, the second conductivity type emitter layer of the first conductivity type base layer, and the second conductivity type emitter layer.
A region sandwiched between the conductive type base layers as a channel region, a gate electrode formed thereon with a gate insulating film interposed therebetween, a first main electrode provided on the first conductive type emitter layer,
In the high-speed turn-on device having the second main electrode provided on the conductive type emitter layer, the lifetime of the second conductive type carrier in the second conductive type base layer is determined by the pulse-like current flowing through the device. The time required to increase the current to 0.1 times the current value and the pulse applied to the element
The carrier is set to be longer than the time width of the pulse-shaped current, and the lifetimes of the first conductivity type and the second conductivity-type carriers are set to be shorter than the time interval from the application of the pulsed current to the application of the anode voltage. I do. Further, the present invention provides a first conductive type emitter layer, a second conductive type base layer provided in contact with the first conductive type emitter layer, and selectively diffusing into a surface portion of the second conductive type base layer. The formed first conductive type base layer, the second conductive type emitter layer selectively diffused on the surface of the first conductive type base layer, and the second conductive type emitter layer of the first conductive type base layer A gate electrode formed on a region between the base layer and the second conductivity type as a channel region via a gate insulating film, a first main electrode provided on the first conductivity type emitter layer, In the high-speed turn-on device including the second main electrode provided on the two-conductivity type emitter layer, the lifetime of the second conductivity-type carrier in the second conductivity-type base layer is determined by the pulse current flowing through the device. Increase to 0.1 times the current value Is set longer than the time width of the pulse current flowing through the element, and the lifetime of the first conductivity type carrier in the second conductivity type base layer is set longer than the time width of the pulse current flowing through the element. And the lifetime of the carriers of the first conductivity type and the second conductivity type is set shorter than the time interval between the application of the pulsed current and the application of the anode voltage .

[0009]

When the carrier lifetime of the device is set within such a range, the second conductive type base layer is formed at the time of turn-on.
Since the carriers do not disappear until the conductivity type carriers are sufficiently accumulated, the resistance of the device can be rapidly reduced, and therefore, the turn-on loss does not increase. On the other hand, since the carriers disappear immediately after the current decay, erroneous firing does not occur even if the anode voltage is raised in a short time.

If the lifetime of the carrier of the second conductivity type is set longer than the time width of the pulse current flowing through the element, the turn-on loss can be further reduced.
When a larger current flows, the loss from the start of the thyristor operation becomes a problem. Therefore, it is necessary to set the lifetimes of the first conductivity type carrier and the second conductivity type carrier to be longer than the time width of the pulse current flowing through the element. As a result, the turn-on loss can be reduced.

[0011]

Embodiments of the present invention will be described below. In the following embodiments, the case where the first conductivity type is p-type and the second conductivity type is n-type is shown. Therefore, the first conductivity type carriers are holes, and the second conductivity type carriers are electrons.

FIG. 1 shows an element structure of a thyristor with an insulated gate according to one embodiment. The p ⁺ -type emitter layer 1 is formed on the back surface of the high-resistance n ⁻ -type base layer 3 via the n ⁺ -type buffer layer 2. The surface of the n ⁻ type base layer 3 is selectively p
A p-type base layer 4 is formed by diffusion, and n ⁺ The mold emitter layer 5 is formed by diffusion. p
N ^{+ of} mold base layer 4 Type emitter layer 5 and n ⁻ Mold base layer 3
A gate electrode 10 is formed on the channel region CH with a gate insulating film 9 interposed therebetween, with the surface of the region sandwiched between the channels as a channel region CH. p ⁺ An anode electrode 7 is formed on the mold emitter layer 1. n ⁺ A cathode electrode 8 is provided on the mold emitter layer 5 so as to be separated from the gate electrode 10 by an interlayer insulating film 11 so as to cover the gate electrode 10. The cathode electrode 8 is also in contact with the p-type base layer 4, and the contact portion has p ⁺ A mold layer 6 is formed. The reason why the cathode electrode 8 is electrically connected to the p-type base layer 4 is that the p-type base layer 4 becomes a well region of the insulated gate transistor, and its potential needs to be fixed.

The operation of this thyristor with an insulated gate is as follows. When a positive voltage is applied to the gate electrode 10,
The channel region CH of the p-type base layer 4 is inverted to n ⁺ Type emitter layer 5 to n ⁻ Electrons are injected into the mold base layer 3.
And the corresponding amount of holes is p ⁺ N from type emitter layer 1 ^- When injected into the mold base layer 3, the thyristor turns on.

In such a thyristor, electrons pass through the channel CH and n ⁻ The high-speed injection into the mold base layer 3 increases the electron concentration in a short time, so that high-speed turn-on is possible. However, in this structure, since the cathode electrode 8 is also in contact with the p-type base layer 4, n ⁺ Since electron injection does not occur from the end of the mold emitter layer 5, sufficient current driving capability cannot be obtained.

In order to solve such a problem, as shown in FIG. 2, the p ⁺ Mold layer 6
On the other hand, the control electrode 12 may be formed separately from the cathode electrode 8. With such a structure, the potential of the p-type base layer 4 can be fixed by the control electrode 14 separately from the potential of the cathode electrode 8. Therefore n ⁺ Electron injection can be performed over the entire area of the mold emitter layer 5, and a high current driving capability can be obtained in addition to a high-speed turn-on capability. Further, since the base current can be extracted from the control electrode 12, a high dV / dt resistance can be obtained.

In the above-described device structure shown in FIG. 1 or FIG. 2, in this embodiment, n ⁻ The carrier lifetime in the mold base layer 3 is set so as to satisfy the following condition. First,
The lifetime of the electrons is set to be longer than the time required for the pulse current flowing through the element to increase to a current value 0.1 times the peak value. In particular, in order to make the turn-on loss sufficiently small, the lifetime of electrons is set to be longer than the time width of the pulse current flowing through the element. Second
In addition, the lifetime of electrons and holes is set shorter than the time interval between the application of the anode current and the application of the pulsed current. The control of the carrier lifetime in the device as described above can be performed, for example, by irradiating the device with an electron beam. Next, the effect of this embodiment will be described based on specific data.

FIG. 3 is a diagram showing a change in element resistance when the thyristor with an insulated gate of the embodiment is turned on at a high speed. The change in element resistance is caused by the MOSFET mode in which electrons passing through the channel region CH contribute to conduction, and the IG in which holes start to be injected.
BT mode, n ⁺ The thyristor mode in which electron injection occurs from the mold emitter layer 5 is divided into three modes. When a positive voltage is applied to the gate electrode 10, the channel region CH of the p-type base layer 4 is inverted and n ⁺ Type emitter layer 5 to n ⁻
Electrons are injected into the mold base layer 3. Element resistance is first n ^-
Rapidly decreases due to the accumulation of electrons in the mold base layer 3 (M
OSFET mode). Then p ⁺ N from type emitter layer 1 ^- The injection of holes into the mold base layer 3 starts, but a large amount of holes are injected and the element resistance starts to decrease again only after the anode current starts to rise (IGBT mode).
Large amount of n holes ^- When implanted into the mold base layer 3, the n ⁺ Electron injection from the type emitter layer 5 to the p-type base layer 4 starts, and the thyristor turns on. After that, n
^- The carrier concentration in the mold base layer 3 increases and the element resistance gradually decreases (thyristor mode).

As is apparent from FIG. 3, the element resistance is rapidly reduced in the high-speed turn-on operation because n ⁻ from the channel region CH. These are electrons injected into the mold base layer 3. Therefore, in the IGBT mode, the anode current starts to rise and a large amount of holes are n ⁻ If electrons do not disappear until they are injected into the mold base layer 3, electrons can be efficiently accumulated and the element resistance can be rapidly reduced. The starting point of the rise of the anode current is set at 0.
It is appropriate to take the time point when the current value reaches about one time.
If the lifetime of the electrons is set longer than the time width of the pulsed current flowing through the element, the element resistance after entering the thyristor mode can be reduced. When a larger current flows, the element resistance in the thyristor mode can be further reduced by setting the lifetime of the holes longer than the time width of the pulsed current.

FIG. 4 shows dv / dt after the pulsed current is applied.
FIG. 4 is a diagram showing the dependence of the withstand amount on the amount of electron beam irradiation. i _p = 6
00A / cm ² , A pulse current of t _W = 0.7 μsec was applied, and after the current attenuated, the anode voltage was applied when the pause time Δt passed 5 μsec, and the dv / dt resistance was measured. As the electron beam irradiation amount increases, the dv / dt resistance increases. This is presumably because irradiation with an electron beam reduces the carrier lifetime, and the carriers inside the element disappear immediately after the pulsed current is applied.

FIG. 5 is a diagram showing the dependence of the turn-on loss on the amount of electron beam irradiation. It can be seen that there is no change in the turn-on loss even when the electron beam irradiation amount is increased. The actually measured amount of electron beam irradiation and ^{(× 10 13 cm -2) n} - Electrons in the base layer 3,
The relationship of the lifetime (μsec) of the holes is as follows.

The amount of electron beam irradiation 1 2 3 4 5 8 Electron lifetime 1.19 0.80 0.58 0.47 0.38 0.25 Hole lifetime 0.22 0.12 0.08 0.06 0.05 0.03

As described above, in the range of the electron beam irradiation amount shown in FIGS. 4 and 5, the lifetime of the electron is が of the conduction width t _W = 0.7 μsec of the pulse-like current, ie, the sinusoidal pulse current Is set to be longer than the time until the peak is reached, so that the turn-on loss does not increase.
On the other hand, the lifetime of the electron and the hole is the pause time Δt
= 5μsec, which is a sufficiently small value.
High dv / dt resistance is obtained. Therefore, a great effect can be obtained when used in high-speed pulse drive applications such as an excimer laser power supply.

As described above, according to the present invention, the pulse-like current flowing through the element for the lifetime of the second conductivity type carrier in the second conductivity type base layer has a peak value of 0.
The time required to increase the current to 1 times and the element
Set it longer than the time width of the pulsed current
Or the second conductive type carrier in the second conductive type base layer.
The pulse current that passes the lifetime through the element is
Time required to increase to a current value 0.1 times the
Set longer than the time width of the pulsed current flowing through the element
And the carrier of the first conductivity type in the second conductivity type base layer.
The lifetime is determined by the time width of the pulsed current flowing through the element.
By setting the lifetime of the first conductivity type carrier and the second conductivity type carrier shorter than the time interval between the application of the pulse current and the application of the anode voltage, a high-speed turn-on with a small turn-on loss, and A thyristor with an insulated gate that can raise the anode voltage in a short time after the current decay can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a thyristor with an insulated gate according to an embodiment.

FIG. 2 is a diagram showing a thyristor with an insulated gate according to another embodiment.

FIG. 3 is a diagram showing a change in element resistance at the time of high-speed turn-on.

FIG. 4 is a diagram showing the dependence of dv / dt resistance after irradiation of a pulsed current on the amount of electron beam irradiation.

FIG. 5 is a diagram showing the dependence of the turn-on loss on the amount of electron beam irradiation.

FIG. 6 is a switching waveform diagram when an excimer laser power supply is simulated.

[Explanation of symbols]

1 ... p ⁺ Type emitter layer, 2 ... n ⁺ Type buffer layer, 3 ... n ^- Mold base layer, 4 ... p-type base layer, 5 ... n ⁺ Type emitter layer, 6 ... p ⁺ Mold layer, 7: anode electrode, 8: cathode electrode, 9: gate insulating film, 10: gate electrode, 11: interlayer insulating film, 12: control electrode, CH: channel region.

Claims (2)

(57) [Claims] A first conductivity type emitter layer; a second conductivity type base layer provided in contact with the first conductivity type emitter layer;
A first conductivity type base layer selectively diffused on the surface of the second conductivity type base layer; a second conductivity type emitter layer selectively diffused on the surface of the first conductivity type base layer; A gate electrode formed on a region of the first conductive type base layer between the second conductive type emitter layer and the second conductive type base layer as a channel region with a gate insulating film interposed therebetween; A first main electrode provided on the one conductivity type emitter layer; and a second main electrode provided on the second conductivity type emitter layer.
In the high-speed turn-on element having the main electrode of the above, the lifetime of the carrier of the second conductivity type in the base layer of the second conductivity type is such that the pulse current flowing through the element is a current value of 0.1 times the peak value. Time to increase
And the lifetime of the carrier of the first conductivity type and the carrier of the second conductivity type is set to be longer than the time width of the pulse current flowing through the element , and is set to be shorter than the time interval between the application of the anode current and the application of the pulse current. A high-speed turn-on device. (2)A first conductivity type emitter layer and the first conductivity type
A second conductivity type base layer provided in contact with the emitter layer;
The second conductive type base layer is selectively diffused and formed on the surface.
First conductive type base layer, and the first conductive type base layer
Second conductivity type emitter layer selectively diffused on the surface
And the second conductivity type emitter of the first conductivity type base layer
A region sandwiched between the layer and the second conductivity type base layer as a channel region
As a gate formed on this via a gate insulating film
An electrode; and a first conductive type emitter layer provided on the first conductive type emitter layer.
A main electrode; and a second electrode provided on the second conductivity type emitter layer.
In a high-speed turn-on device having a main electrode of A second conductive type carrier in the second conductive type base layer;
The lifetime is determined by the pulse current flowing through the element.
Time required to increase to a current value 0.1 times the peak value
Longer than the time width of the pulsed current
And the first conductivity type key in the second conductivity type base layer.
The lifetime of the carrier Pulse current
And the first conductivity type and the second
The lifetime of the conductivity type carrier is after the pulse current
Set shorter than the time interval until the anode voltage is applied.
Have been Characterized by High-speed turn-on device.