Withstand voltage adjustable SGT MOSFET terminal

Abstract

The utility model discloses a withstand voltage adjustable SGT MOSFET terminal comprising a source electrode metal and a drain electrode metal at two ends. A first conductive type substrate, a first epitaxial layer, a second epitaxial layer, a second conductive type body region, a first conductive type source region, a second conductive type heavily doped contact region and a fourth dielectric layer are sequentially arranged between the drain electrode metal and the source electrode metal; trench gate structures are arranged in the second epitaxial layer, the distance between the adjacent trench gate structures in the left terminal trench is fixed, and the distance between the trench gate structure in the right cellular trench and the nearest trench gate structure in the terminal trench is variable. Without increasing the cost, the withstand voltage of the terminal can be adjusted by adjusting the distance between the grooves, when the distance between the adjacent groove gate structures in the terminal groove is not changed, the electric field distribution of the grooves can be influenced by adjusting the distance between the groove gate structure in the cellular groove and the nearest groove gate structure in the terminal groove, and the voltage resistance of the terminal can be improved. Therefore, the withstand voltage of the terminal is adjustable.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor components, and more specifically, to a SGT MOSFET terminal with adjustable breakdown voltage. Background Art

[0002] SGT MOSFET, namely shield-gate trench MOSFET, is widely used in motor drive systems and inverter systems. It is a power semiconductor device adopting advanced process technology, with remarkable characteristics such as high power density, low switching loss and excellent EMI performance. In SGT MOSFET, a polysilicon field plate is used as a shield gate connected to the source potential, introducing a charge coupling effect to assist in depleting the drift region and optimizing the triangular electric field distribution into an approximately rectangular electric field distribution.

[0003] The SGT MOSFET terminal affects the breakdown voltage and stability of the device. In order to alleviate the phenomenon of reduced breakdown voltage of the device caused by the curvature effect at the edge of the cell, a reasonable terminal structure needs to be designed at the chip edge. Insufficient terminal breakdown voltage will result in a lower breakdown voltage of the device, affecting the performance of the device. Generally, the terminal breakdown voltage value is fixed. If the terminal breakdown voltage needs to be changed, the terminal structure needs to be redesigned, resulting in increased costs. Summary of the Utility Model

[0004] Aiming at the deficiencies of the prior art, the purpose of the utility model is to provide a SGT MOSFET terminal with adjustable breakdown voltage to solve one or more of the above problems.

[0005] To achieve the above purpose, the utility model provides the following technical solutions:

[0006] A SGT MOSFET terminal with adjustable breakdown voltage includes

[0007] Source metal and drain metal at both ends;

[0008] From the drain metal to the source metal, a first-conductivity-type substrate, a first epitaxial layer, a second epitaxial layer, a second-conductivity-type body region, a first-conductivity-type source region, a second-conductivity-type heavily doped contact region, and a fourth dielectric layer are sequentially arranged.

[0009] A trench gate structure is arranged in the second epitaxial layer. The distance between adjacent trench gate structures in the left terminal trench is fixed, and the distance between the trench gate structure in the right cell trench and the nearest trench gate structure in the terminal trench is variable.

[0010] Further, the trench gate structure in the terminal trench includes

[0011] A trench region, which is arranged in the second epitaxial layer;

[0012] A shielding gate, which is disposed in the trench region;

[0013] A first dielectric layer, which is disposed between the shielding gate and the trench region.

[0014] Further, the trench gate structure in the cell trench includes

[0015] A trench region, which is disposed in the second epitaxial layer;

[0016] A shielding gate and a polysilicon gate, both of which are disposed in the trench region, and there is a gap between the two;

[0017] A second dielectric layer, which is disposed between the shielding gate and the polysilicon gate;

[0018] A third dielectric layer, which is disposed between the polysilicon gate and the trench region.

[0019] Further, the source region of the first conductivity type and the heavily doped contact region of the second conductivity type are located in the body region of the second conductivity type, and the source metal is located on the heavily doped contact region of the second conductivity type and the fourth dielectric layer.

[0020] Further, the shielding gate is connected to the source potential.

[0021] In summary, the present invention has the following beneficial effects: Without increasing the cost, by adjusting the distance between the trenches, the breakdown voltage of the terminal can be adjusted. When the distance between adjacent trench gate structures in the terminal trench remains unchanged, adjusting the distance between the trench gate structure in the cell trench and the nearest trench gate structure in the terminal trench can affect the electric field distribution in the trench, and further affect the breakdown voltage, realizing adjustable terminal breakdown voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of an embodiment provided by the present invention;

[0023] Figure 2 is an electric field distribution diagram of the sidewall of the cell trench when the distance between the cell trench and the terminal trench changes in an embodiment provided by the present invention;

[0024] Figure 3 is a curve diagram of the breakdown voltage when the distance between the cell trench and the terminal trench changes in an embodiment provided by the present invention.

[0025] In the figure: 1. Substrate of the first conduction type; 2. First epitaxial layer; 3. Second epitaxial layer; 4. Trench region; 5. First dielectric layer; 6. Shielding gate; 7. Second dielectric layer; 8. Third dielectric layer; 9. Polysilicon gate; 10. Body region of the second conduction type; 11. Source region of the first conduction type; 12. Fourth dielectric layer; 13. Heavily doped contact region of the second conduction type; 14. Source metal; 15. Drain metal. Detailed implementation mode

[0026] The following is further detailed description of the present utility model in conjunction with the attached Figures 1-3 drawings.

[0027] A breakdown voltage adjustable SGT MOSFET terminal, as Figure 1 shown, includes a drain metal 15. On the drain metal 15, there is a substrate of the first conduction type 1. On the substrate of the first conduction type 1, there is a first epitaxial layer 2. On the first epitaxial layer 2, there is a second epitaxial layer 3. On the second epitaxial layer 3, there is a body region of the second conduction type 10. On the body region of the second conduction type 10, there are a parallel and adjacent source region of the first conduction type 11 and a heavily doped contact region of the second conduction type 13. On the source region of the first conduction type 11 and the heavily doped contact region of the second conduction type 13, there is a fourth dielectric layer 12. On the heavily doped contact region of the second conduction type 13 and the fourth dielectric layer 12, there is a source metal 14.

[0028] A trench gate structure is provided in the second epitaxial layer 3. The main body of the breakdown voltage adjustable SGT MOSFET terminal is Figure 1 the left part except for the cell trenches in

[0029] it. The distance between adjacent trench gate structures in the terminal trench is denoted as d2, and the distance between the trench gate structure in the cell trench and the closest trench gate structure in the terminal trench is denoted as d1. Among them, d2 remains unchanged, and the breakdown voltage is adjustable by adjusting d1.

[0030] The trench gate structure in the terminal trench includes a trench region 4, a shielding gate 6, and a first dielectric layer 5. The trench region 4 is located in the second epitaxial layer 3. In the trench region 4, there is a shielding gate 6. Between the shielding gate 6 and the trench region 4, there is a first dielectric layer 5. The shielding gate 6 is connected to the source potential.

[0031] The cell trench and the terminal trench are formed simultaneously, and the shielding gates 6 in the cell trench and the shielding gates 6 in the terminal trench are also formed simultaneously. The terminal preparation can be achieved by using the cell process flow without additional process steps. The first conductive type substrate 1 can be made of semiconductor materials such as bulk silicon, silicon carbide, and gallium arsenide. The first dielectric layer 5, the second dielectric layer 7, the third dielectric layer 8, and the fourth dielectric layer 12 can be oxide layers or other dielectric layers.

[0032] As Figure 2 shown, the electric field distribution on the sidewalls of the cell trench at different spacings d1. When d2 is kept constant, as d1 increases, the electric field at the bottom of the cell trench is gradually lifted, the electric field distribution is closer to a rectangle, and the breakdown voltage increases.

[0033] As Figure 3 shown, the breakdown voltage curve distribution. When d2 is kept constant, as d1 increases, the breakdown voltage increases.

[0034] When the trench spacing d2 is constant, adjusting the spacing d1 will affect the electric field distribution in the trench, and thus affect the breakdown voltage, so as to achieve adjustable terminal breakdown voltage. The purpose of adjustable breakdown voltage can be achieved without increasing costs.

[0035] It should be noted that this specific embodiment is only an explanation of the present invention, and it does not limit the present invention. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. SGT MOSFET terminal with adjustable withstand voltage, characterized by: include Source metal (14) and drain metal (15) at both ends; A first conductive type substrate (1), a first epitaxial layer (2), a second epitaxial layer (3), a second conductive type body region (10), a first conductive type source region (11), a second conductive type heavily doped contact region (13), and a fourth dielectric layer (12) are sequentially provided between the drain metal (15) and the source metal (14); The second epitaxial layer (3) is provided with a trench gate structure, wherein the spacing between adjacent trench gate structures in the left terminal trench is fixed, and the spacing between the trench gate structure in the right cell trench and the nearest trench gate structure in the terminal trench is variable.

2. The SGT MOSFET terminal with adjustable withstand voltage according to claim 1, characterized in that: The trench gate structure in the terminal trench includes A trench region (4) disposed in the second epitaxial layer (3); A shielding gate (6) disposed in the trench region (4); A first dielectric layer (5) is provided between the shielding gate (6) and the trench region (4).

3. The SGT MOSFET terminal with adjustable withstand voltage according to claim 1, characterized in that: The trench gate structure in the cell trench includes A trench region (4) disposed in the second epitaxial layer (3); A shielding gate (6) and a polysilicon gate (9), both of which are arranged in the trench region (4), with a gap left between the two; a second dielectric layer (7) disposed between the shielding gate (6) and the polysilicon gate (9); A third dielectric layer (8) is provided between the polysilicon gate (9) and the trench region (4).

4. The SGT MOSFET terminal with adjustable withstand voltage according to claim 1, characterized in that: The first conductive type source region (11) and the second conductive type heavily doped contact region (13) are located in the second conductive type body region (10), and the source metal (14) is located on the second conductive type heavily doped contact region (13) and the fourth dielectric layer (12).

5. The SGT MOSFET terminal with adjustable withstand voltage according to claim 3, characterized in that: The shielding gate (6) is connected to the source potential.

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