阅读说明：本技术 一种igbt器件 (IGBT device ) 是由 龚轶 刘伟 刘磊 毛振东 王鑫 于 2019-11-29 设计创作，主要内容包括：本发明实施例提供的一种IGBT器件,包括MOSFET单元阵列,每个MOSFET单元包括：位于n型漂移区顶部的p型体区,位于p型体区内的n型发射极区,位于p型体区之上栅介质层、栅极和n型浮栅,栅极位于栅介质层之上且靠近n型发射极区的一侧,n型浮栅位于栅介质层之上且靠近n型漂移区的一侧,栅极通过电容耦合作用于n型浮栅；至少有一个MOSFET单元的n型浮栅通过栅介质层与p型体区隔离,且至少有一个MOSFET单元的n型浮栅通过一个位于该n型浮栅下方的栅介质层中的开口与p型体区接触形成p-n结二极管。本发明可以方便的调节IGBT器件的反向恢复速度。(The embodiment of the invention provides an IGBT device, which comprises an array of MOSFET units, wherein each MOSFET unit comprises: the gate is positioned on the gate dielectric layer and close to one side of the n-type emitter region, the n-type floating gate is positioned on the gate dielectric layer and close to one side of the n-type drift region, and the gate acts on the n-type floating gate through capacitive coupling; the n-type floating gate of at least one MOSFET unit is separated from the p-type body region through the gate dielectric layer, and the n-type floating gate of at least one MOSFET unit is contacted with the p-type body region through an opening in the gate dielectric layer positioned below the n-type floating gate to form a p-n junction diode. The invention can conveniently adjust the reverse recovery speed of the IGBT device.)

1. An IGBT device, characterized by comprising:

an n-type collector region and a p-type collector region, an n-type drift region located above the n-type collector region and the p-type collector region, and a MOSFET cell array composed of a plurality of MOSFET cells, the MOSFET cells comprising:

the gate structure comprises a gate dielectric layer, a gate and an n-type floating gate, wherein the gate and the n-type floating gate are positioned on the gate dielectric layer, the gate is positioned at one side close to the n-type emitter region, the n-type floating gate is positioned at one side close to the n-type drift region, and the gate acts on the n-type floating gate through capacitive coupling;

in the MOSFET unit array, the n-type floating gate of at least one MOSFET unit is separated from the p-type body region through the gate dielectric layer, and the n-type floating gate of at least one MOSFET unit is contacted with the p-type body region through an opening in the gate dielectric layer positioned below the n-type floating gate to form a p-n junction diode.

2. The IGBT device of claim 1, further comprising an n-type field stop region located above the n-type collector region, the p-type collector region, the n-type field stop region located below the n-type drift region.

3. The IGBT device of claim 1, wherein the gate extends over the n-type floating gate.

4. The IGBT device of claim 1, wherein the gate extends over the n-type floating gate and covers sidewalls of the n-type floating gate on a side near the n-type drift region.

5. The IGBT device of claim 1, wherein the opening is located under the n-type floating gate and near a side of the n-type drift region.

6. The IGBT device of claim 1, wherein the gate of at least one of the MOSFET cells is electrically connected to the n-type emitter region.

Technical Field

The invention belongs to the technical field of IGBT devices, and particularly relates to an IGBT device with an adjustable reverse recovery speed.

Background

An IGBT (insulated gate bipolar transistor) device is a device formed by combining an MOS transistor and a bipolar transistor, and has an input electrode of the MOS transistor and an output electrode of the PNP transistor. The turn-on and turn-off of the prior art IGBT device is controlled by the gate-emitter voltage, and when the gate-emitter voltage is greater than the threshold voltage Vth of the MOS transistor, a current channel is formed inside the MOS transistor and a base current is supplied to the bipolar transistor, so that the IGBT device is turned on. When the gate-emitter voltage is less than the threshold voltage Vth of the MOS transistor, the current channel in the MOS transistor is turned off, the base current of the bipolar transistor is cut off, and the IGBT device is turned off. When the IGBT device in the prior art is turned off, when the voltage between a collector and an emitter is less than 0V, a parasitic body diode in the IGBT device is in a forward bias state, reverse current flows from the emitter to the collector through the body diode, the current of the body diode has the phenomenon of injecting minority carriers, and the minority carriers are subjected to reverse recovery when the IGBT device is turned on again, so that larger reverse recovery current is caused, and the reverse recovery time is long.

Disclosure of Invention

In view of this, the present invention provides an IGBT device with an adjustable reverse recovery speed, so as to solve the technical problem of long reverse recovery time of the IGBT device in the prior art due to the injection of minority carrier.

An IGBT device provided in an embodiment of the present invention includes:

an n-type collector region and a p-type collector region, an n-type drift region located above the n-type collector region and the p-type collector region, and a MOSFET cell array composed of a plurality of MOSFET cells, the MOSFET cells comprising:

the gate structure comprises a gate dielectric layer, a gate and an n-type floating gate, wherein the gate and the n-type floating gate are positioned on the gate dielectric layer, the gate is positioned at one side close to the n-type emitter region, the n-type floating gate is positioned at one side close to the n-type drift region, and the gate acts on the n-type floating gate through capacitive coupling;

in the MOSFET unit array, the n-type floating gate of at least one MOSFET unit is separated from the p-type body region through the gate dielectric layer, and the n-type floating gate of at least one MOSFET unit is contacted with the p-type body region through an opening in the gate dielectric layer positioned below the n-type floating gate to form a p-n junction diode.

Optionally, the IGBT device of the present invention further includes an n-type field stop region located above the n-type collector region and the p-type collector region, and the n-type field stop region is located below the n-type drift region.

Optionally, in the IGBT device of the present invention, the gate extends over the n-type floating gate.

Optionally, in the IGBT device of the present invention, the gate extends to the n-type floating gate and covers a sidewall of the n-type floating gate near one side of the n-type drift region.

Optionally, in the IGBT device of the present invention, the opening is located below the n-type floating gate and near one side of the n-type drift region.

Optionally, in the IGBT device according to the present invention, the gate of at least one of the MOSFET cells is electrically connected to the n-type emitter region.

According to the IGBT device provided by the embodiment of the invention, the reverse recovery speed of the IGBT device can be conveniently and accurately adjusted by controlling the number of the MOSFET units with the p-n junction diodes, so that the IGBT device has wider application; meanwhile, when the number of MOSFET units formed with p-n junction diodes is adjusted, only one mask for forming openings in the gate dielectric layer needs to be modified, so that the manufacturing cost of the IGBT device can be effectively controlled.

Drawings

In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, a brief description is given below of the drawings used in describing the embodiments.

Fig. 1 is a schematic cross-sectional structure diagram of a first embodiment of an IGBT device according to the present invention;

fig. 2 is a schematic cross-sectional structure diagram of a second embodiment of an IGBT device according to the present invention.

Detailed Description

The technical solution of the present invention will be fully described by the following detailed description with reference to the accompanying drawings in the embodiments of the present invention. Meanwhile, in order to clearly illustrate the embodiments of the present invention, the schematic drawings listed in the drawings of the specification enlarge the sizes of the layers and regions of the present invention, and the listed sizes of the figures do not represent actual sizes. The examples listed in the specification should not be limited to the specific shapes of the regions shown in the drawings of the specification, but include the resulting shapes such as deviations due to production and the like.

Fig. 1 is a schematic cross-sectional structure diagram of a first embodiment of an IGBT device according to the present invention, and as shown in fig. 1, the IGBT device according to the present invention includes an n-type collector region 20 and a p-type collector region 30, an n-type field stop region 29 located above the n-type collector region 20 and the p-type collector region 30, an n-type drift region 21 located above the n-type field stop region 29, and a MOSFET cell array composed of a plurality of MOSFET cells, and fig. 1 exemplarily shows two MOSFET cells (a MOSFET cell 200 and a MOSFET cell 201).

The MOSFET cell of the embodiment of the invention comprises: a p-type body region 22 located on top of the n-type drift region 21, an n-type emitter region 23 located within the p-type body region 22; and a gate structure located above the p-type body region 22, the gate structure including a gate dielectric layer 24, an n-type floating gate 25 and a gate 26, the gate 26 being located above the gate dielectric layer 24 and near one side of the n-type emitter region 23 and the gate 26 extending to above the n-type floating gate 25 toward one side of the n-type drift region 21, the n-type floating gate 25 being located above the gate dielectric layer 24 and near one side of the n-type drift region 21, the gate 26 and the n-type floating gate 25 being separated by an insulating dielectric layer 27, the gate 26 acting on the n-type floating gate 25 through capacitive coupling. The insulating dielectric layer 27 is typically silicon dioxide.

In the MOSFET cell array according to the embodiment of the invention, the n-type floating gate 25 of at least one MOSFET cell is isolated from the p-type body region 22 by a gate dielectric layer 24 (e.g., the MOSFET cell 201 in fig. 1), and the n-type floating gate 25 of at least one MOSFET cell is in contact with the p-type body region 22 through an opening 28 in the gate dielectric layer 24 under the n-type floating gate 25 to form a p-n junction diode (e.g., the MOSFET cell 200 in fig. 1).

The gate 26 of the MOSFET cell in the embodiment of the present invention may be located only on one side close to the n-type emitter region 23, i.e., in the lateral direction, the gate 26 and the n-type floating gate 25 are disposed left and right (not shown in the embodiment of the present invention), or the gate 26 is located on one side close to the n-type emitter region 23 and extends to one side of the n-type drift region 21 to be above the n-type floating gate 25 (as shown in fig. 2), and the gate 26 extends to be above the n-type floating gate 25, so as to increase the area of the n-type floating gate 25 covered by the gate 26 and increase the capacitive coupling ratio of the gate 26 to the n.

In an IGBT device according to an embodiment of the present invention, in a forward blocking state, a high voltage is applied to the n-type collector region 20 and the p-type collector region 30, a p-n junction diode formed by the n-type floating gate 25 and the p-type body region 22 in the MOSFET cell 200 is forward biased, and the n-type floating gate 25 in the MOSFET cell 200 is charged with positive charge, which lowers the threshold voltage Vht1 of the current channel under the n-type floating gate 25 in the MOSFET cell 200. The voltage of the n-type floating gate 25 in the MOSFET cell 200 is related to the position of the opening 28 in the gate dielectric layer 24. optionally, the opening 28 in the gate dielectric layer 24 is located under the n-type floating gate 25 and near one side of the n-type drift region 21, thereby making it easier for the n-type floating gate 25 to be charged with positive charges.

When the IGBT device according to the embodiment of the present invention is in the forward blocking state and the forward turning-on state, the collector-emitter voltage Vce is greater than 0V, the influence of the threshold voltage Vht1 of the current channel under the n-type floating gate 25 in the MOSFET cell 200 on the threshold voltage Vth of the entire MOSFET cell 200 is low, and the MOSFET cell 200 still has the high threshold voltage Vth. When the IGBT device according to the embodiment of the present invention is turned off, when the emitter-collector voltage Vec is greater than 0V, the threshold voltage Vht1 of the current channel under the n-type floating gate 25 in the MOSFET cell 200 greatly affects the threshold voltage Vth of the entire MOSFET cell 200, so that the MOSFET cell 200 has a low threshold voltage Vth, and thus the current channel of the MOSFET cell 200 is turned on at a low gate voltage (or 0V voltage), and thus the reverse current flowing through the MOSFET cell 200 can be increased, the current flowing through the parasitic body diode in the IGBT device is reduced, and the reverse recovery speed of the entire IGBT device is increased.

According to the IGBT device provided by the embodiment of the invention, the reverse recovery speed of the IGBT device can be conveniently and accurately adjusted by controlling the number of the MOSFET units with the p-n junction diodes formed in the MOSFET unit array, so that the IGBT device has wider application; meanwhile, when the number of MOSFET units formed with p-n junction diodes is adjusted, only one mask for forming openings in the gate dielectric layer needs to be modified, so that the manufacturing cost of the IGBT device can be effectively controlled.

In the MOSFET cell array of the IGBT device according to the embodiment of the invention, the gate electrode 26 of at least one MOSFET cell can be electrically connected to the n-type emitter region 23, i.e., the part of the gate electrode 26 receives the emitter voltage, which can reduce the gate charge of the IGBT device.

Fig. 2 is a schematic cross-sectional structure diagram of a second embodiment of the IGBT device according to the present invention, and unlike the IGBT device structure of the embodiment of the present invention shown in fig. 1, in the IGBT device according to the present embodiment, the gate 26 of the MOSFET cell extends to a side of the n-type drift region 21 to be above the n-type floating gate 25 and covers a sidewall of the n-type floating gate 25 close to the n-type drift region 21, so that an area of the gate 26 covering the n-type floating gate 25 can be further increased, and a capacitive coupling ratio of the gate 26 to the n-type floating gate 25 can be further increased.

The above embodiments and examples are specific supports for the technical ideas of the present invention, and the protection scope of the present invention should not be limited thereby, and any equivalent changes or equivalent modifications made on the basis of the technical solutions according to the technical ideas proposed by the present invention still belong to the protection scope of the technical solutions of the present invention.