A trench gate IGBT device with a floating structure

Abstract

The present invention discloses a trench gate IGBT device with a floating structure, comprising a collector metal; a collector region of a first conductivity type, located on the upper surface of the collector metal; a field stop layer of a second conductivity type, located on the upper surface of the collector region of the first conductivity type; a drift region of a second conductivity type, located on the upper surface of the field stop layer of the second conductivity type; a trench structure, located in the drift region of the second conductivity type, the trench structure comprising a trench, a wide portion, and a narrow portion, the wide portion comprising a wide portion electrode; a floating region of the first conductivity type, located between the trench structures; an emitter metal, covering the top of the entire device; the floating region of the first conductivity type and the emitter metal are isolated by a first dielectric layer; the wide portion electrode and the emitter metal have the same potential. The present invention reduces the Miller capacitance of the IGBT, reduces the switching time, improves the dv / dt control capability of the IGBT during the opening process, reduces the EMI interference during the switching process, and improves the withstand voltage of the IGBT device.

Description

Technical Field

[0001] The present invention relates to the technical field of power semiconductor devices, and in particular to a trench gate IGBT device with a floating structure. Background Art

[0002] Insulated gate bipolar transistor (IGBT) is a new type of power electronic device that combines MOS field effect and bipolar transistor. It not only has the advantages of MOSFET, large input resistance, easy to drive and simple control, but also has the advantages of bipolar transistor, such as low on-state voltage drop and large on-state current. It has become one of the core components in modern power electronic circuits and is widely used in transportation, energy, industry, household appliances and other fields.

[0003] At present, during the turn-on process of trench gate IGBT devices, holes accumulate on the sidewalls of the trench, which reduces the dv / dt control capability of the IGBT during the turn-on process, cannot effectively suppress EMI interference, and is difficult to improve the device withstand voltage of the IGBT. In addition, the greater the depth of the trench structure, the greater the Miller capacitance of the IGBT, which reduces the switching speed of the IGBT. Summary of the invention

[0004] The purpose of the present invention is to provide a trench gate IGBT device with a floating structure, reduce the Miller capacitance of the IGBT, shorten the switching time, improve the dv / dt control capability of the IGBT during the opening process, reduce EMI interference during the switching process, and improve the withstand voltage of the IGBT device.

[0005] In order to achieve the above purpose, the following technical solutions are adopted:

[0006] A trench gate IGBT device with a floating structure, comprising:

[0007] Collector metal;

[0008] A collector region of the first conductivity type, located on the upper surface of the collector metal;

[0009] A field stop layer of a second conductivity type is located on an upper surface of a collector region of the first conductivity type;

[0010] A drift region of the second conductivity type, located on an upper surface of the field stop layer of the second conductivity type;

[0011] A trench structure is located in the drift region of the second conductivity type and extends along the thickness direction of the drift region of the second conductivity type; the trench structure comprises a trench, and a wide portion and a narrow portion located in the trench, and the wide portion is located below the narrow portion; the wide portion comprises a wide portion electrode;

[0012] A floating region of the first conductivity type is located between the trench structures;

[0013] The emitter metal covers the entire device; the first conductive type floating region is isolated from the emitter metal by a first dielectric layer; and the wide portion electrode and the emitter metal have the same potential.

[0014] Preferably, the narrow portion includes a narrow portion electrode and a narrow portion dielectric filled between the narrow portion electrode and the inner sidewall of the trench; the narrow portion electrode and the wide portion electrode are isolated by a second dielectric layer.

[0015] Preferably, the floating region of the first conductivity type does not overlap with the narrow portion, and the two are separated by a body region of the second conductivity type.

[0016] Preferably, the floating region of the first conductivity type overlaps with the wide portion, and a junction depth of the floating region of the first conductivity type is greater than a depth of the narrow portion electrode.

[0017] Preferably, the wide portion further includes a wide portion dielectric filled between the wide portion electrode and the inner wall of the groove.

[0018] Preferably, a body region of the second conductivity type is further provided on the outside of the groove structure, and a body region of the first conductivity type is further provided on the upper surface of the body region of the second conductivity type; an emitter region of the first conductivity type and an emitter region of the second conductivity type are provided in parallel on the upper surface of the body region of the first conductivity type, and the emitter region of the second conductivity type is arranged close to the groove structure.

[0019] Preferably, the first dielectric layer extends to cover the upper surface of the trench structure and a portion of the second conductivity type emission region.

[0020] Preferably, the emitter metal is connected to an emitter region of the first conductivity type and an emitter region of the second conductivity type.

[0021] By adopting the above scheme, the beneficial effects of the present invention are:

[0022] The wide electrode of the trench structure in the present invention is at the same potential as the emitter metal, which effectively shields the gate signal and reduces the Miller capacitance of the IGBT; the floating region of the first conductive type located between the trench structures does not overlap with the narrow portion, which effectively prevents a large amount of accumulation of holes on the trench sidewalls during the IGBT turn-on process, thereby improving the dv / dt control capability of the IGBT during the turn-on process; the floating region of the first conductive type overlaps with the wide portion, which effectively reduces the electric field peak at the corner of the wide portion and improves the withstand voltage of the IGBT. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention;

[0024] The accompanying drawings illustrate:

[0025] 1 - collector metal, 2 - collector region of the first conductivity type,

[0026] 3—field stop layer of the second conductivity type, 4—drift region of the second conductivity type,

[0027] 5 - wide part, 6 - narrow part,

[0028] 7—a floating region of the first conductivity type, 8—an emitter metal,

[0029] 9—first dielectric layer, 10—second dielectric layer,

[0030] 11—a body region of the second conductivity type, 12—a body region of the first conductivity type,

[0031] 13—an emitter region of the first conductivity type, 14—an emitter region of the second conductivity type,

[0032] 51 - wide part electrode, 52 - wide part dielectric,

[0033] 61—narrow portion electrode, 62—narrow portion dielectric. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0035] Reference Figure 1 As shown, the present invention provides a trench gate IGBT device with a floating structure, including a collector metal 1; a collector region 2 of a first conductivity type, located on the upper surface of the collector metal 1; a field stop layer 3 of a second conductivity type, located on the upper surface of the collector region 2 of the first conductivity type; a drift region 4 of a second conductivity type, located on the upper surface of the field stop layer 3 of the second conductivity type; a trench structure, located in the drift region 4 of the second conductivity type, and extending along the thickness direction of the drift region 4 of the second conductivity type; the trench structure includes a trench, and a wide portion 5 and a narrow portion 6 located in the trench, and the wide portion 5 is located below the narrow portion 6; the wide portion 5 includes a wide portion electrode 51, and a wide portion dielectric 52 filled between the wide portion electrode 51 and the inner wall of the trench; a floating region 7 of the first conductivity type, located between the trench structures; and an emitter metal 8, covering the entire device.

[0036] The first conductive type floating region 7 is isolated from the emitter metal 8 by the first dielectric layer 9. The potential of the first conductive type floating region 7 is floating, and the emitter metal 8 is isolated by the first dielectric layer 9. The wide portion electrode 51 has the same potential as the emitter metal 8, which effectively shields the gate signal, reduces the Miller capacitance of the IGBT, and improves the switching speed.

[0037] The narrow portion 6 includes a narrow portion electrode 61 and a narrow portion dielectric 62 filled between the narrow portion electrode 61 and the inner sidewall of the groove; the narrow portion electrode 61 is isolated from the wide portion electrode 51 by the second dielectric layer 10. The floating region 7 of the first conductivity type does not overlap with the narrow portion 6, and the two are isolated by the body region 11 of the second conductivity type. The narrow portion 6 is a gate structure, the narrow portion electrode 61 is a gate electrode, and the floating region 7 of the first conductivity type does not overlap with the gate structure, which enhances the dv / dt control capability during the IGBT turn-on process and reduces EMI noise.

[0038] Continue to refer to Figure 1 , point A is located at the side wall of the groove corresponding to the narrow portion 6. In the existing IGBT device structure, since point A overlaps with the floating region 7 of the first conductivity type, a large number of holes accumulate at point A on the groove side wall during the IGBT opening process, the potential at point A suddenly changes, and the gate displacement current increases, which leads to uncontrollable dv / dt during the IGBT opening process. In the present invention, at point A, the floating region 7 of the first conductivity type does not overlap with the groove structure, and point A is located at the body region 11 of the second conductivity type. Here, the body region 11 of the second conductivity type acts as a hole barrier, which effectively prevents the accumulation of holes at point A, thereby reducing the gate displacement current and effectively controlling the dv / dt during the IGBT opening process.

[0039] In the existing IGBT device structure, if the junction depth of the floating region 7 of the first conductivity type is less than the depth of the narrow electrode 61, or if an N-type storage layer is provided below the floating region 7 of the first conductivity type, an electric field peak will appear at the corner of the groove, thereby reducing the withstand voltage of the IGBT. However, the junction depth of the floating region 7 of the first conductivity type of the present invention is greater than the depth of the narrow electrode 61, and the floating region 7 of the first conductivity type overlaps with the wide portion 5 of the groove structure. The floating region 7 of the first conductivity type effectively reduces the electric field peak at the corner of the wide portion 5. Therefore, the IGBT device provided by the present invention can reduce the Miller capacitance of the IGBT, reduce the switching time, improve the dv / dt control capability of the IGBT turn-on process, reduce the EMI interference of the switching process, and improve the withstand voltage of the IGBT device. When the spacing between the floating region 7 of the first conductivity type and the groove structure is larger, the withstand voltage is lower. The present invention improves the withstand voltage of the IGBT device by overlapping the floating region 7 of the first conductivity type with the wide portion 5.

[0040] A body region 11 of the second conductivity type is also provided on the outside of the groove structure, and a body region 12 of the first conductivity type is also provided on the upper surface of the body region 11 of the second conductivity type; an emitter region 13 of the first conductivity type and an emitter region 14 of the second conductivity type are provided in parallel on the upper surface of the body region 12 of the first conductivity type, and the emitter region 14 of the second conductivity type is arranged close to the groove structure.

[0041] The first dielectric layer 9 extends to cover the upper surface of the trench structure and a portion of the second conductivity type emitter region 14. The emitter metal 8 is connected to the first conductivity type emitter region 13 and the second conductivity type emitter region 14.

[0042] In one embodiment, the first conductive type may include a P type, and in this case, the second conductive type may include an N type.

[0043] In another embodiment, the first conductive type may include an N type, and in this case, the second conductive type may include a P type.

[0044] The semiconductor involved in the IGBT device of the present invention can be made of semiconductor materials such as bulk silicon, silicon carbide, gallium arsenide, indium phosphide or silicon germanium.

[0045] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A trench gate IGBT device with a floating structure, characterized in that: include: Collector metal; A collector region of the first conductivity type, located on the upper surface of the collector metal; A field stop layer of a second conductivity type is located on an upper surface of a collector region of the first conductivity type; A drift region of the second conductivity type, located on an upper surface of the field stop layer of the second conductivity type; A trench structure is located in the drift region of the second conductivity type and extends along the thickness direction of the drift region of the second conductivity type; the trench structure comprises a trench, and a wide portion and a narrow portion located in the trench, and the wide portion is located below the narrow portion; the wide portion comprises a wide portion electrode; A floating region of the first conductivity type is located between the trench structures; The emitter metal covers the entire device; the floating region of the first conductive type is isolated from the emitter metal by a first dielectric layer; the wide portion electrode and the emitter metal have the same potential; The narrow portion includes a narrow portion electrode and a narrow portion dielectric filled between the narrow portion electrode and the inner sidewall of the trench; the narrow portion electrode and the wide portion electrode are isolated by a second dielectric layer; The floating region of the first conductivity type does not overlap with the narrow portion, and the two are separated by a body region of the second conductivity type.

2. The trench gate IGBT device with a floating structure according to claim 1, characterized in that: The floating region of the first conductivity type overlaps with the wide portion, and a junction depth of the floating region of the first conductivity type is greater than a depth of the narrow portion electrode.

3. The trench gate IGBT device with a floating structure according to claim 1, characterized in that: The wide portion further includes a wide portion dielectric filled between the wide portion electrode and the inner wall of the trench.

4. The trench gate IGBT device with a floating structure according to claim 1, characterized in that: A body region of the second conductivity type is also provided on the outside of the groove structure, and a body region of the first conductivity type is also provided on the upper surface of the body region of the second conductivity type; an emitter region of the first conductivity type and an emitter region of the second conductivity type are provided in parallel on the upper surface of the body region of the first conductivity type, and the emitter region of the second conductivity type is arranged close to the groove structure.

5. The trench gate IGBT device with a floating structure according to claim 4, characterized in that: The first dielectric layer extends to cover the upper surface of the trench structure and a portion of the second conductive type emission region.

6. The trench gate IGBT device with a floating structure according to claim 4, characterized in that: The emitter metal is connected to an emitter region of the first conductivity type and an emitter region of the second conductivity type.

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