A trench gate IGBT device with a floating structure and separate trenches

Abstract

This invention discloses a trench gate IGBT device with a separate floating structure and trench, comprising: a collector metal; a collector region of a first conductivity type located on the upper surface of the collector metal; a field cutoff layer of a second conductivity type located on the upper surface of the collector region of the first conductivity type; a drift region of the second conductivity type located on the upper surface of the field cutoff layer of the second conductivity type; a trench structure located within the drift region of the second conductivity type; a floating region of the first conductivity type located between the trench structures, and the floating region of the first conductivity type does not overlap with the trench structure; an emitter metal covering the entire device; and an isolation dielectric layer provided between the floating region of the first conductivity type and the emitter metal. This invention improves the dv / dt control capability of the IGBT during the turn-on process, reduces EMI interference during the switching process, and can also improve the device withstand voltage of the IGBT.

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 and a discrete trench. 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] During the turn-on process of the existing trench gate IGBT device, holes accumulate on the trench sidewalls, which reduces the dv / dt control capability of the IGBT during the turn-on process, fails to effectively suppress EMI interference, and is difficult to improve the device withstand voltage 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 and a discrete trench, which improves the dv / dt control capability of the IGBT during the opening process, reduces EMI interference during the switching process, and can also improve the device withstand voltage of the IGBT.

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

[0006] A trench gate IGBT device with a floating structure and a separate trench, 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 includes a trench, and a wide portion and a narrow portion located in the trench, and the wide portion is located below the narrow portion;

[0012] A floating region of the first conductivity type is located between the trench structures, and the floating region of the first conductivity type does not overlap with the trench structures; a minimum spacing between the wide portion and the floating region of the first conductivity type is smaller than a minimum spacing between the narrow portion and the floating region of the first conductivity type;

[0013] An emitter metal covers the entire device; an isolation dielectric layer is provided between the floating region of the first conductive type and the emitter metal.

[0014] Preferably, the groove structure is in an inverted T-shape, with the wide portion being located at the horizontal end of the inverted T-shape and the narrow portion being located at the vertical end of the inverted T-shape.

[0015] Preferably, the wide portion includes a wide portion electrode and a wide portion dielectric filled between the wide portion electrode and the inner wall of the groove; the narrow portion includes a narrow portion electrode and a narrow portion dielectric filled between the narrow portion electrode and the inner wall of the groove; and the wide portion electrode is connected to the narrow portion electrode.

[0016] Preferably, the junction depth of the floating region of the first conductivity type is not less than the depth of the narrow portion electrode.

[0017] Preferably, it also includes:

[0018] A body region of a second conductivity type, located outside the trench structure;

[0019] A body region of the first conductivity type, located on an upper surface of the body region of the second conductivity type;

[0020] An emitter region of the first conductivity type and an emitter region of the second conductivity type are arranged 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 trench structure.

[0021] Preferably, the isolation dielectric layer extends to cover the upper surface of the trench structure and a portion of the second conductivity type emitter region.

[0022] Preferably, the emitter metal is connected to an emitter region of the first conductivity type and an emitter region of the second conductivity type.

[0023] By adopting the above scheme, the beneficial effects of the present invention are:

[0024] The present invention effectively prevents a large amount of accumulation of holes on the sidewalls of the grooves during the IGBT opening process by designing the floating region of the first conductive type not to overlap with the groove structure, thereby reducing the displacement current, improving the dv / dt control capability during the IGBT opening process, and effectively reducing EMI noise. At the same time, through the wide portion of the inverted T-shaped groove structure, the distance between the groove structure and the floating region of the first conductive type is effectively reduced, thereby effectively reducing the electric field peak at the corner of the wide portion and improving the IGBT withstand voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention;

[0026] The accompanying drawings illustrate:

[0027] 1—Collector metal, 2—Collector region of the first conductivity type,

[0028] 3—field stop layer of the second conductivity type, 4—drift region of the second conductivity type,

[0029] 5—a floating region of the first conductivity type, 6—an emitter metal,

[0030] 7—wide part, 8—narrow part,

[0031] 9—a body region of the second conductivity type, 10—a body region of the first conductivity type,

[0032] 11—an emitter region of the first conductivity type, 12—an emitter region of the second conductivity type,

[0033] 13—isolation dielectric layer, 71—wide electrode,

[0034] 72—wide dielectric, 81—narrow electrode,

[0035] 82—Narrow medium. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0037] Reference Figure 1 As shown, the present invention provides a trench gate IGBT device with a floating structure and a discrete trench, comprising: 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 comprises a trench, and a A wide portion 7 and a narrow portion 8, and the wide portion 7 is located below the narrow portion 8; a floating region 5 of the first conductive type is located between the groove structures, and the floating region 5 of the first conductive type does not overlap with the groove structure; the minimum spacing between the wide portion 7 and the floating region 5 of the first conductive type is smaller than the minimum spacing between the narrow portion 8 and the floating region 5 of the first conductive type, that is, the design of the wide portion 7 reduces the distance between the groove structure and the floating region 5 of the first conductive type; an emitter metal 6 covers the top of the entire device; an isolation dielectric layer 13 is provided between the floating region 5 of the first conductive type and the emitter metal 6.

[0038] The groove structure is in an inverted T-shaped structure, the wide portion 7 is located at the horizontal end of the inverted T-shape, and the narrow portion 8 is located at the vertical end of the inverted T-shape. The wide portion 7 includes a wide portion electrode 71 and a wide portion dielectric 72 filled between the wide portion electrode 71 and the inner wall of the groove; the narrow portion 8 includes a narrow portion electrode 81 and a narrow portion dielectric 82 filled between the narrow portion electrode 81 and the inner wall of the groove; the wide portion electrode 71 is connected to the narrow portion electrode 81.

[0039] Continue to refer to Figure 1 , point A is located at the trench sidewall corresponding to the narrow portion 8, and point B is located at the trench sidewall corresponding to the wide portion 7. In the existing IGBT device structure, since point A overlaps with the floating region 5 of the first conductivity type, a large number of holes accumulate at point A on the trench sidewall during the IGBT turn-on process, resulting in a sudden change in potential at point A and an increase in gate displacement current, so that the dv / dt during the IGBT turn-on process is uncontrollable.

[0040] In the present invention, at point A and point B, the floating region 5 of the first conductivity type does not overlap with the groove structure. Point A and point B are both located in the drift region 4 of the second conductivity type. The drift region 4 of the second conductivity type acts as a hole barrier, effectively preventing the accumulation of holes here, thereby reducing the gate displacement current, and effectively controlling the dv / dt during the IGBT opening process. At the same time, the groove structure is provided with a wide portion 7 below the narrow portion 8, and the spacing between point B and the floating region 5 of the first conductivity type is significantly smaller than the spacing between point A and the floating region 5 of the first conductivity type, effectively reducing the spacing between the groove structure and the floating region 5 of the first conductivity type, thereby effectively reducing the electric field peak at the corner of the wide portion 7 and improving the IGBT withstand voltage. Therefore, the present invention can improve the dv / dt control capability of the IGBT, reduce EMI interference during the switching process, and at the same time improve the withstand voltage of the IGBT device by setting an inverted T-shaped groove structure.

[0041] The junction depth of the floating region 5 of the first conductivity type is not less than the depth of the narrow portion electrode 81. The floating region 5 of the first conductivity type is floating in potential and is not connected to the emitter metal 6.

[0042] In addition, the trench gate IGBT device provided by the present invention further includes: a body region 9 of the second conductivity type, located outside the trench structure; a body region 10 of the first conductivity type, located on the upper surface of the body region 9 of the second conductivity type; an emitter region 11 of the first conductivity type and an emitter region 12 of the second conductivity type are arranged in parallel on the upper surface of the body region 10 of the first conductivity type, and the emitter region 12 of the second conductivity type is arranged close to the trench structure. The isolation dielectric layer 13 extends to cover the upper surface of the trench structure and part of the emitter region 12 of the second conductivity type. The emitter metal 6 is connected to the emitter region 11 of the first conductivity type and the emitter region 12 of the second conductivity type.

[0043] The first conductive type floating region 5 located between the groove structures of the present invention does not overlap with the groove structure, which effectively prevents the accumulation of a large number of holes on the groove sidewalls during the IGBT opening process, thereby reducing the displacement current, improving the dv / dt control capability during the IGBT opening process, and effectively reducing EMI noise. However, since the first conductive type floating region 5 does not overlap with the groove structure, the IGBT withstand voltage will be reduced. The larger the distance between the first conductive type floating region 5 and the groove structure, the lower the withstand voltage. The present invention effectively reduces the distance between the groove structure and the first conductive type floating region 5 through the wide portion 7 of the inverted T-shaped groove structure, thereby effectively reducing the electric field peak at the corner of the wide portion 7 and improving the IGBT withstand voltage.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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 and a separate trench, 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 includes a trench, and a wide portion and a narrow portion located in the trench, and the wide portion is located below the narrow portion; A floating region of the first conductivity type is located between the trench structures, and the floating region of the first conductivity type does not overlap with the trench structures; a minimum spacing between the wide portion and the floating region of the first conductivity type is smaller than a minimum spacing between the narrow portion and the floating region of the first conductivity type; An emitter metal covering the entire device; an isolation dielectric layer is provided between the floating region of the first conductivity type and the emitter metal; The groove structure is in an inverted T-shape, with the wide portion located at the horizontal end of the inverted T-shape and the narrow portion located at the vertical end of the inverted T-shape; The wide portion includes a wide portion electrode and a wide portion dielectric filled between the wide portion electrode and the inner wall of the groove; the narrow portion includes a narrow portion electrode and a narrow portion dielectric filled between the narrow portion electrode and the inner wall of the groove; the wide portion electrode is connected to the narrow portion electrode.

2. The trench gate IGBT device with a floating structure and separate trenches according to claim 1, characterized in that: The junction depth of the first conductive type floating region is not less than the depth of the narrow portion electrode.

3. The trench gate IGBT device with a floating structure and separate trenches according to claim 1, characterized in that: Also includes: A body region of a second conductivity type, located outside the trench structure; A body region of the first conductivity type, located on an 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 arranged 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 trench structure.

4. The trench gate IGBT device with a floating structure and separate trenches according to claim 3, characterized in that: The isolation dielectric layer extends to cover the upper surface of the trench structure and a portion of the second conductivity type emission region.

5. The trench gate IGBT device with a floating structure and separate trenches according to claim 3, 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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