JP2562854B2 - PNPN thyristor with control gate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a PNP with a control gate.
The present invention relates to an N thyristor and is particularly suitable for use in switching a large current at a high speed.

[0002]

2. Description of the Related Art Conventionally, a surface junction gate type electrostatic induction thyristor as shown in FIG. 3 has been known. In this electrostatic induction thyristor, a P-type gate region 5 and an N-type cathode region 4 are formed on the surface of an N-type semiconductor substrate 1,
A P-type anode region 7 is formed on the back surface of the semiconductor substrate 1. The anode electrode 1 is provided in the anode region 7.
7, the gate electrode 15 is connected to the gate region 5, and the cathode electrode 13 is connected to the cathode region 4. The electrostatic induction thyristor having such a structure has an advantage that it can be easily turned off at high speed by increasing the gate current at turn-off due to the characteristics of the device structure. In order to achieve the turn-off, there is also a drawback that the gate drive circuit needs to be devised in accordance with the magnitude of the gate current or the amount of gate extraction charge at the time of turn-off.

Therefore, while taking advantage of the advantage that the large current of the electrostatic induction thyristor having the above-mentioned structure can be switched at high speed, the amount of electric charge (current) for drawing out the gate at turn-off.
A semiconductor device as shown in FIG. 4 has been proposed as a structure for significantly reducing the noise (see Japanese Patent Application No. 3-110647). In this semiconductor device, a P-type gate region 5, an N-type source region 4, and a P-type cathode region 2 are formed on the surface of an N-type semiconductor substrate 1, and a P-type gate region 5 is formed on the back surface of the semiconductor substrate 1. The anode region 7 is formed. An anode electrode 17 is connected to the anode region 7, a gate electrode 15 is connected to the gate region 5, and a cathode electrode 13 is connected to the source region 4 and the cathode region 2. This device has a structure in which the base current of a vertical PNP transistor is controlled by an electrostatic induction gate,
The long storage time at turn-off, which is seen in the conventional electrostatic induction thyristor shown in FIG. 3, can be increased by one digit or more.

[0004]

In the semiconductor device shown in FIG. 4, the breakdown voltage between the gate and the cathode can be increased as compared with the conventional surface junction gate type electrostatic induction thyristor as shown in FIG. It was difficult. This is because in the semiconductor device shown in FIG. 4, the cathode electrode 13 has a depletion layer extending by the reverse voltage applied to the PN junction between the second conductivity type gate region 5 and the first conductivity type base region 1. The withstand voltage between the gate and the cathode is determined by the applied voltage between the gate and the cathode that reaches the connected second conductivity type cathode region 2. This is the electrostatic induction gate that controls the base current of the vertical PNP transistor. This is because it is difficult to design the electrical characteristics of both independently because it is the same part as the device structure that determines the threshold voltage. Therefore, for example, it has been difficult to realize a normally-off type electrostatic induction gate while maintaining a high gate-cathode breakdown voltage.

The present invention has been made in view of the above circumstances, and an object of the present invention is to control a control gate in a semiconductor device in which a gate drive current at turn-off is small and a large current can be controlled at high speed. It is to provide a structure capable of designing a high gate-cathode breakdown voltage independently of electrical characteristics.

[0006]

In a PNPN thyristor with a control gate according to claim 1, in order to solve the above-mentioned problems, as shown in FIG. 1, a semiconductor substrate of the first conductivity type is used as a base region. 1, a second conductivity type base region 2 is provided on the surface of the first conductivity type semiconductor substrate, and a first conductivity type emitter region 3 is provided on the surface of the second conductivity type base region 2. A second conductive type gate region 5 is provided spaced apart from the second conductive type base region 2, and a second conductive type gate region 5 is spaced apart from the second conductive type base region 2.
A second conductivity type collector region 6 is provided on the side opposite to the second conductivity type collector region, and a second conductivity type anode region 7 is provided on the back surface of the first conductivity type semiconductor substrate. A control gate 28 is provided at a portion sandwiched between the two-conductivity type base region 2 and the second-conductivity type collector region 6 with an insulating film 38 interposed therebetween, and the first-conductivity type emitter region 3 and the second-conductivity type The collector region 6 is connected to the cathode electrode 13, and the second conductivity type gate region 5 and the control gate 2 are connected.
8 is connected to the gate electrode 15, and the second conductivity type anode region 7 is connected to the anode electrode 17.

A PN with a control gate according to claim 2
In the PN thyristor, as shown in FIG. 2, a first conductivity type semiconductor substrate is used as a base region 1, and a second conductivity type base region 2 is provided on the surface of the first conductivity type semiconductor substrate. A first conductivity type emitter region 3 is provided on the surface of the second conductivity type base region 2, a second conductivity type gate region 5 is provided apart from the second conductivity type base region 2, and the second conductivity type is provided. A collector region 6 of a second conductivity type on a side opposite to the gate region 5 of the second conductivity type and spaced apart from the base region 2 of the second conductivity type, and the base region 2 of the second conductivity type and the collector region 6 of the second conductivity type. A source region 4 of the first conductivity type is provided between the gate regions 5, an anode region 7 of the second conductivity type is provided on the back surface of the semiconductor substrate of the first conductivity type, and a surface region of the semiconductor substrate of the first conductivity type is provided. Second conductivity type base region 2 and the second conductivity type collector region A control gate 28 is provided at a portion sandwiched by the insulating film 38, and the first conductive type emitter region 3, the second conductive type collector region 6 and the first conductive type source region 4 are connected to the cathode electrode 13. The second conductive type gate region 5 and the control gate 28 are connected to the gate electrode 15, and the second conductive type anode region 7 is connected to the anode electrode 17. is there.

[0008]

The anode-cathode current, which is the main current of the semiconductor device shown in FIG. 1, is a current component flowing in the vertical PNPN thyristor formed between the back surface and the front surface of the semiconductor substrate. Since the main current is a current component of the vertical PNPN thyristor, the semiconductor element of the present invention has a low on-voltage and a low loss during conduction.

The operating mechanism of this semiconductor device for shifting to the ON state is that between the gate and the cathode by applying an appropriate positive voltage to the gate electrode 15 when the cathode electrode 13 is at the ground potential. When the lateral PNPN thyristor reaches the breakover condition and the gate-cathode becomes conductive, the main current between the anode and cathode is triggered to be conductive. The breakover condition of the lateral PNPN thyristor between the gate and the cathode is that the width of the second conductive type base region 2 is much larger than the width of the first conductive type base region 1 of the vertical PNPN thyristor between the anode and the cathode. Due to its narrow width, the lateral PNPN thyristor between the gate and the cathode is designed to break over at a voltage lower than the breakover voltage between the anode and the cathode.

On the other hand, the gate electrode 15 is turned off.
When a proper negative voltage is applied to the P-channel MOSFET, the P-channel MOSFET having the control gate 28 is turned on, and the source region of the P-channel MOSFET, that is, the second conductivity type collector region 6 is connected to the cathode electrode 13. Vertical PN between anode and cathode
The second conductivity type base region 2 of the PN thyristor is short-circuited with the cathode electrode 13 through the P-channel MOSFET,
The main current flowing between the anode and the cathode shifts to the turn-off state. Moreover, at this time, the gate turn-off current drawn from the second-conductivity-type base region 2 flows into the cathode electrode 13 via the P-channel MOSFET unlike the case of the conventional GTO, so that a large gate turn-off current is obtained. No drive current required. The gate drive current (charge amount) required at the time of turn-off is only the amount of charge accumulated in the control gate 28 necessary to bring the channel of the P-channel MOSFET into the conductive state, and the conventional static induction thyristor or GTO.
The gate extraction current (charge amount) at turn-off is much smaller than that of.

Next, the breakdown voltage between the gate and the cathode will be described. In the structure shown in FIG. 1, the gate region 5 and the control gate 28 are both connected to the gate electrode 15,
Further, both the emitter region 3 and the collector region 6 are connected to the cathode electrode 13. In this device structure, the depletion layer expands due to the reverse voltage applied to the PN junction between the second conductivity type gate region 5 and the first conductivity type base region 1 by the applied voltage between the gate and the cathode. Even if this depletion layer reaches the second conductivity type base region 2 as the applied voltage increases, the second conductivity type base region 2 is connected to the cathode electrode 13 unlike the conventional semiconductor device shown in FIG. Therefore, the breakdown voltage between the gate and the cathode is not controlled here. In the semiconductor device of the present invention shown in FIG. 1, a PN between a first conductivity type emitter region 3 and a second conductivity type base region 2 connected to a cathode electrode 13.
A depletion layer spread by the reverse voltage applied to the junction,
When the gate-cathode applied voltage is punched through due to both of the depletion layer from the PN junction between the gate region 5 and the first conductivity type base region 1, or when the emitter region 3 and the second conductivity type are reached. Between base regions 2 of
The breakdown voltage between the gate and the cathode is governed by the lower gate-cathode voltage, whichever is lower when the breakdown voltage is reached at the N-junction.

This is completely different from the gate-cathode breakdown voltage in the conventional semiconductor device shown in FIG. 4, and the semiconductor device of the present invention shown in FIG. Even if the voltage reaches, it does not correspond to the condition for the breakdown voltage between the gate and the cathode. In addition, the lateral PNPN between the gate and the cathode that triggers the turn-on of the main current between the anode and the cathode of the semiconductor device of the present invention.
It is possible to design the element independently of the breakover condition of the thyristor.

Regarding the operation of the semiconductor device shown in FIG. 2, the turn-on control gate is replaced by a lateral PNP thyristor, and a lateral PNP transistor is used.
The details will be described later in the description of the embodiments described below.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a PNP with a control gate according to claim 1.
It is a sectional view of an N thyristor. In this semiconductor device, N
P type gate region 5, collector region 6 and base region 2 are formed on the surface of a base region 1 made of a positive type semiconductor substrate, and N type emitter region 3 is formed on the surface of the base region 2.
And a P-type anode region 7 is formed on the back surface of the base region 1. And the anode region 7
Is connected to the anode electrode 17, the gate region 5 and the control gate 28 are connected to the gate electrode 15, and the emitter region 3 and the collector region 6 are connected to the cathode electrode 13. The cathode electrode 13 and the gate electrode 15 are connected to each other by the surface pattern of the electrodes, and the external electrode terminals of this semiconductor element are only the three terminals of the anode electrode 17, the cathode electrode 13 and the gate electrode 15.

The second functioning as the turn-on control gate of this device
Conductivity type gate region 5, first conductivity type base region 1, second conductivity type base region 2, first conductivity type emitter region 3
In a horizontal PNPN thyristor composed of
The width of the second conductivity type base region 2 governs the breakover voltage of the lateral PNPN thyristor, and the impurity profile of the second conductivity type base region 2 is determined so as to satisfy the desired turn-on trigger voltage of this device. To be done.
Here, the same second conductivity type gate region 5 and base region 2
The collector region 6 and the collector region 6 may be formed in the same manufacturing process or different manufacturing processes in the impurity diffusion region forming process of the present device. The impurity profile of the diffusion region of the second conductivity type may be the same in both the gate region 5 and the base region 2 or may be different impurity profiles.

Next, the thickness of the gate insulating film 38 of the P-channel MOSFET which becomes the turn-off control gate of this device,
The channel length between the second conductivity type base region 2 and the collector region 6 is appropriately selected depending on the manufacturing technique such as processing accuracy. However, the gate capacitance of the P-channel MOSFET is the same as it is when the device is turned off. And again,
Since the channel resistance (ON resistance of the P-channel MOSFET) governs the turn-off characteristics of this device, a thick gate oxide film thickness, a short channel length, and a short channel width are desirable, but the gate threshold voltage of the P-channel MOSFET is Since it is the gate turn-off voltage of this device, both are taken into consideration and set to an appropriate value.

In the embodiment of FIG. 1, the P channel MO
The SFET has a control gate 28 made of polysilicon and an insulating film 38 made of a silicon oxide film. However, another structure may be used as long as it has an insulating gate structure of a P channel MOSFET. Needless to say.

Next, the impurity profile of the second conductivity type base region 2 and the first conductivity type emitter region 3 forming the vertical PNPN thyristor which becomes the main current path between the anode and the cathode is the main profile between the anode and the cathode. Although it affects the current characteristics and the turn-on / off transient response characteristics, it is important to set the impurity profile of this portion in order to improve the breakdown voltage between the gate and the cathode. The breakdown voltage between the gate and the cathode of the present device is the depletion layer spread by the reverse voltage applied to the PN junction between the first conductivity type emitter region 3 and the second conductivity type base region 2, and the second conductivity type. When the gate-cathode applied voltage is punched through by the depletion layer from the PN junction between the gate region 5 and the first conductivity type base region 1 or the first conductivity type emitter region 3 is reached. And the second conductivity type base region 2 at the PN junction where the breakdown voltage is reached, whichever is lower.
The withstand voltage between the gate and the cathode is controlled by the applied voltage between the cathodes. Therefore, it is particularly necessary to set the impurity profile of the second conductivity type base region 2 so as to obtain desired electrical characteristics. Further, the impurity concentration and thickness of the semiconductor substrate forming the first conductivity type base region 1, particularly the distance between the second conductivity type base region 2 and the anode region 7, provides a desired breakdown voltage between the anode and the cathode. Is set as follows.

FIG. 2 shows a PN with a control gate according to claim 2.
It is a sectional view of a PN thyristor. With this structure, in the semiconductor device of FIG. 1, a source region 4 of the first conductivity type is provided between the base region 2 of the second conductivity type and the gate region 5 of the second conductivity type, and the source region 4 is used as the cathode. Electrode 13
Connected to. This semiconductor device has an operating mechanism of transition to the ON state, in which, when the cathode electrode 13 is at the ground potential, an appropriate positive voltage is applied to the gate electrode 15 and the second conductivity type gate region 5 and By turning on the lateral PNP transistor formed between the first conductivity type base region 1 and the second conductivity type base region 2,
A collector current flows through this lateral PNP transistor,
This current becomes a turn-on trigger current of the vertical PNPN thyristor, so that conduction is established between the anode and the cathode. In the present device, the base width of the lateral PNP transistor constituted by the second conductivity type gate region 5 serving as the turn-on control gate, the first conductivity type base region 1 and the second conductivity type base region 2, that is, the gate region. The distance between 5 and the second conductivity type base region 2 depends on the current injection efficiency of the lateral PNP transistor and the threshold voltage of the static induction gate formed by the gate region 5 and the second conductivity type base region 2. Determined by Other configurations and operations are similar to those of the embodiment shown in FIG.

In the illustrated embodiment, the first conductivity type is N
Although the type and the second conductivity type are P-type, conversely, the first conductivity type may be P-type and the second conductivity type may be N-type.

[0021]

The PNPN with the control gate according to claim 1
In the thyristor, the main current path between the anode and the cathode is composed of a vertical PNPN thyristor, and the turn-on control gate of this thyristor is composed of a lateral PNPN thyristor.
Since the turn-off control gate which is constituted by an insulated gate transistor, only a small gate drive current at the turn-off time can be controlled a large current at a high speed, turn
Switching characteristics of off and turn-on can be designed independently
It is possible to obtain a high gate structure and to design a high gate-cathode breakdown voltage independently of the electrical characteristics of the control gate.

A PN with a control gate according to claim 2
In the PN thyristor, the main current path between the anode and the cathode is composed of a vertical PNPN thyristor, the turn-on control gate of this thyristor is composed of a lateral PNP transistor, and the turn-off control gate is composed of an insulated gate transistor. Therefore, the gate drive current at turn-off is small, and large current can be controlled at high speed .
Independent design of turn-off and turn-on switching characteristics
There is an effect that it is possible to have a possible gate structure and, moreover, the withstand voltage between the gate and the cathode can be designed to be high independently of the electrical characteristics of the control gate.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of another embodiment of the present invention.

FIG. 3 is a sectional view of a conventional example.

FIG. 4 is a sectional view of another conventional example.

[Explanation of symbols]

 1 N-type base region 2 P-type base region 3 Emitter region 4 Source region 5 Gate region 6 Collector region 7 Anode region 13 Cathode electrode 15 Gate electrode 17 Anode electrode 28 Control gate

Claims (2)

(57) [Claims] 1. A first conductivity type semiconductor substrate is used as a base region, a second conductivity type base region is provided on a surface of the first conductivity type semiconductor substrate, and a second conductivity type base region is provided on a surface of the second conductivity type base region. A first-conductivity-type emitter region is provided, a second-conductivity-type gate region is provided separately from the second-conductivity-type base region, and a second-conductivity-type base region is provided separately from the second-conductivity-type base region.
A second conductivity type collector region is provided on the side opposite to the conductivity type gate region, and a second conductivity type collector region is provided on the back surface of the first conductivity type semiconductor substrate.
A conductive type anode region is provided, and the second conductive type base region and the second conductive type base region on the surface of the first conductive type semiconductor substrate are provided.
A control gate is provided in a portion sandwiched between conductive type collector regions via an insulating film, the first conductive type emitter region and the second conductive type collector region are connected to a cathode electrode, and the second conductive type A PNPN thyristor with a control gate, wherein a gate region and the control gate are connected to a gate electrode, and the second conductivity type anode region is connected to an anode electrode. 2. A first conductivity type semiconductor substrate is used as a base region, a second conductivity type base region is provided on a surface of the first conductivity type semiconductor substrate, and a second conductivity type base region is formed on a surface of the second conductivity type base region. A first-conductivity-type emitter region is provided, a second-conductivity-type gate region is provided separately from the second-conductivity-type base region, and a second-conductivity-type base region is provided separately from the second-conductivity-type base region.
A second conductivity type collector region is provided on the side opposite to the conductivity type gate region, and a first conductivity type source region is provided between the second conductivity type base region and the second conductivity type gate region. A second conductivity type anode region is provided on the back surface of the first conductivity type semiconductor substrate, and is sandwiched between a second conductivity type base region and the second conductivity type collector region on the surface of the first conductivity type semiconductor substrate. A control gate is provided in an isolated portion through an insulating film, and the first conductive type emitter region, the second conductive type collector region, and the first conductive type source region are connected to a cathode electrode, and the second conductive type is formed. The PNPN thyristor with a control gate, wherein the gate region and the control gate are connected to a gate electrode, and the anode region of the second conductivity type is connected to the anode electrode.