CN110444584A - A kind of inverse conductivity type IGBT with superjunction - Google Patents

Abstract

The invention relates to power semiconductor technology, in particular to a reverse conduction IGBT with a superjunction. Compared with the traditional super junction reverse conduction IGBT, the present invention replaces a part of the P+ collector region in the collector region with an N+ collector region, and uses a P-type strip and a dielectric isolation layer to divide the N-type drift region into two different In the connected N-type drift region, the P+ collector region and the N+ collector region are each located in one of the N-type drift regions. When the device is conducting forward, since the left and right N-type drift regions are relatively isolated, the conduction state is similar to that of the left The superposition of the bipolar conduction state of the side IGBT and the unipolar conduction state of the right MOS does not have a snapback phenomenon. Due to the existence of the N+ collector region, the device can achieve reverse conduction. Beneficial results of the present invention: realizing reverse conduction capability, no snapback phenomenon, and optimizing current distribution during reverse conduction.

Description

A reverse conduction IGBT with superjunction

technical field

The invention belongs to the technical field of power semiconductors, and in particular relates to a superjunction inverse conduction IGBT (Insulated gate bipolar transistor, insulated gate bipolar transistor).

Background technique

The reverse conduction IGBT is an IGBT with reverse conduction capability. Ordinary IGBTs do not have reverse conduction capability, so a diode is often connected in reverse parallel for freewheeling protection in applications. However, this will increase the volume of the system and introduce parasitic effects that will affect the reliability of the system.

The traditional reverse conduction IGBT achieves the reverse conduction function by replacing a part of the P+ region of the collector region with an N+ region. This has certain requirements for the ratio of the N+ and P+ regions. If the N+ region is too large, it may cause the device to have a voltage snapback effect, and the smaller the N+ region, the more uneven the reverse current distribution will be.

Contents of the invention

The object of the present invention is to propose a reverse conduction IGBT with a superjunction to solve the above problems.

The technical solution of the present invention: a reverse conduction IGBT with a superjunction, its cell includes a collector structure, a voltage-resistant layer structure, an emitter structure and a gate structure, the voltage-resistant layer structure is located on the collector structure, and the emitter The electrode structure and the gate structure are located on the pressure-resistant layer structure;

The emitter structure includes a P-type well region 8 located on the upper surface of the pressure-resistant layer structure, an N+ emitter region 10 and a P+ body contact region 9 located on the upper surface of the P-type well region 8, and the N+ emitter region 10 is located on the P+ body contact region. On both sides of the region 9, the upper surface of the P+ body contact region 9 has an insulating layer 11, and the insulating layer 11 extends to both sides to contact the upper surface of the N+ emitter region 10. The common lead-out end of the N+ emitter region 10 and the P+ body contact region 9 is Emitter E;

The gate structure is a trench gate, and the trench gate is composed of a first insulating medium 11 and a first conductive material 12 located in the first insulating medium 11; the leading end of the first conductive material 12 is the gate of the device pole G; the trench gate is located at both ends of the device and vertically penetrates the P-type well region 8 from the device surface, and the side of the trench gate is in contact with the side surfaces of the P-type well region 8 and the N+ type emitter region 10;

The voltage-resistant layer structure includes an N-type drift region 5 and a P-type strip 6. The P-type strips 6 are distributed in the N-type drift region 5 at intervals. The upper surface of the P-type strip 6 is connected to the P-type well region 8. The lower surface is connected, the P-type strip 6 and the N-type drift region 5 form a super junction structure, the trench gate extends into the N-type drift region 5, and the upper surface of the N-type drift region 5 is also connected to the P-type well region 8 lower surface contact;

The collector structure includes a P+ collector region 2, an N+ collector region 1 and an N-type buffer layer 3, the upper surface of the N-type buffer layer 3 is connected to the withstand voltage layer, and the P+ collector region 2 and the N+ The upper surface of the collector region 1 is connected to the N-type buffer layer 3, and the common lead-out end of the P+ collector region 2 and the N+ collector region 1 is the collector C;

It is characterized in that the collector structure also includes an insulating dielectric isolation layer 4, which separates the P+ collector region 2 and the N+ collector region 1, and extends through the N-type buffer layer 3 into the P-type In the strip 6 , the side and upper surface of the insulating dielectric isolation layer 4 located in the P-type strip 6 are in contact with the N-type drift region 5 .

The beneficial effect of the present invention is that the reverse conduction IGBT of the present invention realizes the ability of reverse conduction. Compared with the traditional reverse conduction IGBT, the present invention eliminates the snapback phenomenon and can be realized at a smaller cell width Reverse conduction function, and the reverse conduction current is more uniform.

Description of drawings

Fig. 1 is the schematic diagram of the reverse conduction type IGBT with superjunction of the present invention;

Figure 2 is a schematic diagram of a conventional super-junction IGBT;

Detailed ways

The present invention is described in detail below in conjunction with accompanying drawing

As shown in FIG. 1 , it is a reverse conduction IGBT with a superjunction of the present invention. It works as follows:

When conducting forward conduction, the gate is connected to positive voltage, the collector is connected to positive voltage, and the emitter is grounded. The voltage on the gate opens the channel, and electrons are injected into the n-type drift region. Due to the blocking effect of the P-type strip and the insulating dielectric isolation layer, the injected electrons move to the collector region on both sides of the P-type strip, and the right side The electrons on the left are collected by the N-type collector, while the electrons on the left will accumulate on the N-type buffer layer on the P+ collector region. With the gradual increase of the collector voltage, the P+ collector region and the N-type buffer layer will The formed PN junction is opened and holes are injected into the drift region. Therefore, when the collector voltage of the device is low, the left side of the device is not conducting and the right side is in a unipolar conduction state. As the collector voltage increases, the PN junction of the left anode of the device is opened, and the P+ anode begins to drift toward the drift region. When holes are injected, the left side of the device enters the bipolar conduction state, and most of the holes injected into the drift region flow directly along the P-type strip to the cathode, so most of the right side is still in the unipolar conduction mode. Therefore, the forward conduction curve is the superposition of unipolar and bipolar conduction states on the left and right sides, so there is no snapback phenomenon caused by the sudden change of resistance in the drift region from unipolar conduction to bipolar conduction.

During reverse conduction, the gate is grounded, the collector is grounded, and the emitter is connected to positive voltage. The P-type well region, P-type strip, N-type drift region and N+ collector form a super junction diode, and the reverse conduction power consumption is small, and because the ratio between the N+ collector/P+ collector is high, the reverse conduction , the reverse conduction current distribution is uniform.

Claims (1)

1. A reverse conduction type IGBT with a superjunction, its cell includes a collector structure, a voltage-resistant layer structure, an emitter structure and a gate structure, the voltage-resistant layer structure is located on the collector structure, the emitter structure and the grid The pole structure is located on the pressure-resistant layer structure; The emitter structure includes a P-type well region (8) located on the upper surface of the pressure-resistant layer structure, an N+ emitter region (10) and a P+ body contact region (9) located on the upper surface of the P-type well region (8), and the N+ The emitter region (10) is located on both sides of the P+ body contact region (9), the upper surface of the P+ body contact region (9) has an insulating layer (11), and the insulating layer (11) extends to both sides to be connected with the N+ emitter region (10) The upper surface is contacted, and the common terminal of the N+ emitter region (10) and the P+ body contact region (9) is the emitter; The gate structure is a trench gate, and the trench gate is composed of a first insulating medium (11) and a first conductive material (12) located in the first insulating medium (11); the first conductive material (12) ) is the gate of the device; the trench gate is located at both ends of the device and vertically penetrates the P-type well region (8) from the device surface, and the side of the trench gate is connected to the P-type well region (8) and the N+ type emitter side contact of the polar region (10); The pressure-resistant layer structure includes an N-type drift region (5) and a P-type strip (6), the P-type strips (6) are distributed at intervals in the N-type drift region (5), and the P-type strips (6) The upper surface of the upper surface is connected to the lower surface of the P-type well region (8), the P-type strip (6) and the N-type drift region (5) form a super junction structure, and the trench gate extends into the N-type drift region ( In 5), the upper surface of the N-type drift region (5) is also in contact with the lower surface of the P-type well region (8); The collector structure includes a P+ collector region (2), an N+ collector region (1) and an N-type buffer layer (3), and the upper surface of the N-type buffer layer (3) is connected to the withstand voltage layer, so The upper surfaces of the P+ collector region (2) and the N+ collector region (1) are connected to the N-type buffer layer (3), and the common leads of the P+ collector region (2) and the N+ collector region (1) The terminal is the collector; It is characterized in that the collector structure further includes an insulating dielectric isolation layer (4), the insulating dielectric isolation layer (4) separates the P+ collector region (2) and the N+ collector region (1), and runs through the N-type The buffer layer (3) extends into the P-type strip (6), and the side and upper surface of the insulating dielectric isolation layer (4) in the P-type strip (6) are in contact with the N-type drift region (5).