A novel silicon-based mosfet super junction structure
By introducing heat dissipation components and superjunction components into the silicon-based MOSFET superjunction structure, utilizing heat pipes for heat dissipation and forming conductive channels within the trench, the problem of charge balance disruption caused by dopant diffusion at high temperatures is solved, achieving high voltage withstand, low resistance, and high reliability of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU CHANGJING ELECTRONICS TECH CO LTD
- Filing Date
- 2025-08-18
- Publication Date
- 2026-06-19
AI Technical Summary
Existing silicon-based MOSFET superjunction structures suffer from charge balance disruption due to dopant diffusion at high temperatures, which affects long-term device reliability and increases leakage current.
The design employs heat dissipation components and superjunction components, including heat pipes and shielding gate oxide layers. The heat pipes dissipate heat to reduce the temperature, and the oxide layer and polysilicon in the trench form a conductive channel to restore N+ type characteristics and neutralize positively charged holes.
It effectively reduces high-temperature leakage current, improves the long-term reliability of devices, maintains high withstand voltage and low resistance characteristics, and enhances the oxidation resistance of devices.
Smart Images
Figure CN224386022U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of silicon-based MOSFETs, specifically a novel silicon-based MOSFET superjunction structure. Background Technology
[0002] Silicon-based MOSFET superjunction structures are a technology that overcomes the "silicon limit" of traditional silicon-based power devices by optimizing the internal electric field distribution. They are widely used in high-voltage, high-efficiency power conversion applications. Alternating P-type and N-type pillars, or N+ regions, are introduced into the drift region to form a built-in lateral electric field through a charge compensation mechanism. When the device is turned off, the depletion layers of the P- and N-pillars expand into each other, resulting in a more uniform electric field distribution. This significantly reduces the drift region thickness and on-resistance at the same breakdown voltage. High breakdown voltage and low on-resistance are achieved through charge compensation, significantly improving power conversion efficiency.
[0003] Patent CN210926026U discloses a superjunction MOSFET structure using a shielded gate. Specifically, the patent discloses a technical solution where "the traditional trench gate is transformed into a shielded gate structure in the X-direction, i.e., a thick oxide layer (shielded gate oxide layer) and a discrete shielded gate are used in the lower part of the first trench, thereby forming a MOS structure in the X-direction: shielded gate ←→ oxide layer ←→ epitaxial layer. This structure has the following advantages: it allows the device to simultaneously experience depletion in the Y-direction (P-type body region ←→ epitaxial layer), Z-direction (N-type epitaxial layer ←→ P-type epitaxial layer), and X-direction (shielded gate ←→ oxide layer ←→ epitaxial layer) during actual voltage withstand." This achieves the technical effect of "the device becoming a three-dimensional charge-balanced device, maximizing the concentration of the N-type epitaxial layer, and reducing the device resistance."
[0004] Existing silicon-based MOSFETs achieve the effect of becoming a three-dimensional charge-balanced device, which can maximize the concentration of the N-type epitaxial layer and reduce the device resistance. However, the dopants in the P-pillars and N-pillars may diffuse at high temperatures, disrupting the charge balance, leading to device performance degradation, increased leakage current at high temperatures, and affecting the long-term reliability of the device. Utility Model Content
[0005] The purpose of this invention is to provide a novel silicon-based MOSFET superjunction structure to solve the problems mentioned in the background art and overcome its technical defects.
[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a novel silicon-based MOSFET superjunction structure, including a silicon-based MOSFET body, a conductive epitaxial layer connected to the lower surface of the silicon-based MOSFET body, a heat dissipation component for heat dissipation of the structure provided on the outside of the silicon-based MOSFET body, and a superjunction component for superjunction of the silicon-based MOSFET body provided inside the silicon-based MOSFET body;
[0007] The heat dissipation assembly includes a packaging plate, which is fixed to the side wall of the silicon-based MOSFET body. An N-pillar is connected to the lower end of the silicon-based MOSFET body, and a P-pillar is provided on one side of the N-pillar and fixedly connected to the silicon-based MOSFET body. Heat pipes are installed on the side walls of both the N-pillar and the P-pillar.
[0008] As a further embodiment of this invention: the outer surface of the silicon-based MOSFET body is fixed with a packaging shell, and a gate body is formed on the upper surface of the silicon-based MOSFET body.
[0009] As a further embodiment of this invention: the superjunction component includes trenches, and there are three trenches. All three trenches are formed inside the silicon-based MOSFET body, and the inner surface of each of the three trenches is provided with a shielding gate oxide layer.
[0010] As a further embodiment of this invention: the inner wall of the shielding gate oxide layer is connected to an oxide layer, and a superjunction fixed to the silicon-based MOSFET body is provided below the trench.
[0011] As a further improvement of this invention, the shielding gate oxide layer is internally connected to a polycrystalline silicon body.
[0012] As a further improvement of this invention: a gate polysilicon is connected to the upper end of the polysilicon body.
[0013] As a further embodiment of this invention: the upper surface of the gate polysilicon is connected to an insulating dielectric layer that is fixedly connected to the silicon-based MOSFET body.
[0014] As a further embodiment of this invention: the upper surface of the insulating dielectric layer is connected to a source metal layer that is fixedly connected to the silicon-based MOSFET body, and a conductive body is connected to one side of the trench.
[0015] Compared with the prior art, the beneficial effects of this utility model include:
[0016] 1. By setting up a heat dissipation component, the heat-absorbing end of the heat pipe is connected to the N-pillar and the P-pillar, so that the heat pipe can transfer heat through the evaporation and condensation of liquid, thereby effectively dissipating heat from the silicon-based MOSFET superjunction structure, reducing the increase in leakage current at high temperatures, and improving the long-term reliability of the device.
[0017] 2. By using the superjunction component, the electric fields of the gate and source invert the P-region under the gate, generating an N-type conductive channel in the P-region under the gate. Electrons from the source region enter the vertical N+ region through the conductive channel, neutralizing the positive charge holes in the N+ region and restoring the depleted N+ type characteristics. Thus, the conductive channel is formed. The vertical N+ region has a high doping concentration and low resistivity, thus exhibiting the high breakdown voltage of a planar structure and the low resistance of a trench structure. Attached Figure Description
[0018] The disclosure of this utility model is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:
[0019] Figure 1 The schematic diagram shows an overall structural schematic diagram according to one embodiment of the present invention;
[0020] Figure 2 The schematic diagram shows a three-dimensional structure of a silicon-based MOSFET according to one embodiment of the present invention;
[0021] Figure 3 The schematic diagram shows a packaging structure according to one embodiment of the present invention;
[0022] Figure 4 The schematic diagram shows a cross-sectional structure of a silicon-based MOSFET according to one embodiment of the present invention.
[0023] The diagram is labeled as follows: 1. Silicon MOSFET body; 2. Conductivity type epitaxial layer; 3. Package board; 31. Package shell; 32. N-pillar; 33. P-pillar; 34. Heat pipe; 4. Gate body; 5. Trench; 51. Oxide layer; 52. Superjunction; 53. Polysilicon body; 54. Gate polysilicon; 55. Insulating dielectric layer; 56. Source metal layer; 57. Conductivity type body; 58. Shielding gate oxide layer. Detailed Implementation
[0024] It is readily understood that, based on the technical solution of this utility model, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of this utility model. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative descriptions of the technical solution of this utility model and should not be considered as the entirety of this utility model or as limitations or restrictions on the technical solution of this utility model.
[0025] An embodiment of the present invention is shown in conjunction with the accompanying drawings.
[0026] Please see Figures 1 to 4 A novel silicon-based MOSFET superjunction structure includes a silicon-based MOSFET body 1, a conductive epitaxial layer 2 connected to the lower surface of the silicon-based MOSFET body 1, a heat dissipation component for heat dissipation of the structure on the outside of the silicon-based MOSFET body 1, and a superjunction component for superjunction of the silicon-based MOSFET inside the silicon-based MOSFET body 1.
[0027] The heat dissipation assembly includes a package plate 3, which is fixed to the side wall of the silicon-based MOSFET body 1. An N-pillar 32 is connected to the lower end of the silicon-based MOSFET body 1. A P-pillar 33, which is fixedly connected to the silicon-based MOSFET body 1, is provided on one side of the N-pillar 32. Heat pipes 34 are installed on the side walls of both the N-pillar 32 and the P-pillar 33. A package shell 31 is fixed to the outer surface of the silicon-based MOSFET body 1. A gate body 4 is opened on the upper surface of the silicon-based MOSFET body 1.
[0028] By adopting the above technical solution, before using the novel silicon-based MOSFET superjunction structure, the silicon-based MOSFET body 1 is first encapsulated using packaging equipment, so that the packaging plate 3 and the packaging shell 31 are encapsulated outside the silicon-based MOSFET body 1 to protect the silicon-based MOSFET superjunction structure. The N-pillar 32 and P-pillar 33 provided on the silicon-based MOSFET body 1 facilitate connection with the circuit board, and the heat pipe 34 provided on the N-pillar 32 and P-pillar 33 can absorb the heat generated by the silicon-based MOSFET superjunction structure during operation. The heat-absorbing end of the heat pipe 34 is connected to the N-pillar 32 and P-pillar 33, so that the heat pipe 34 transfers heat through the evaporation and condensation of liquid. The heat pipe 34 is filled with a suitable working fluid. Under negative pressure, when one end of the heat pipe 34 is heated, the working fluid evaporates rapidly, forming vapor and moving towards the condensation section. In the condensation section, the vapor releases heat and condenses into liquid. The liquid then flows back to the evaporation section through capillary action, forming a cycle, thereby effectively dissipating heat from the silicon-based MOSFET superjunction structure, reducing the increase in leakage current at high temperatures, and improving the long-term reliability of the device.
[0029] Specifically, such as Figure 1 , Figure 2 and Figure 4As shown, the superjunction assembly includes trenches 5, and there are three trenches 5. All three trenches 5 are formed inside the silicon-based MOSFET body 1. The inner surface of each of the three trenches 5 is provided with a shielding gate oxide layer 58. The inner wall of the shielding gate oxide layer 58 is connected to an oxide layer 51. Below the trenches 5, there is a superjunction body 52 fixed to the silicon-based MOSFET body 1. The inside of the shielding gate oxide layer 58 is connected to a polysilicon body 53. The upper end of the polysilicon body 53 is connected to a gate polysilicon 54. The upper surface of the gate polysilicon 54 is connected to an insulating dielectric layer 55 fixedly connected to the silicon-based MOSFET body 1. The upper surface of the insulating dielectric layer 55 is connected to a source metal layer 56 fixedly connected to the silicon-based MOSFET body 1. A conductive body 57 is connected to one side of the trenches 5.
[0030] By adopting the above technical solution, a conductive epitaxial layer 2 and a gate body 4 are provided on the silicon-based MOSFET body 1. The oxide layer 51 and polysilicon body 53 in the trench 5 can achieve the effect of anti-oxidation. Through the superjunction body 52, when the MOSFET is turned on, the electric field of the gate and the source will invert the P region under the gate, and generate an N-type conductive channel in the P region under the gate. At the same time, electrons in the source region enter the vertical N+ region through the conductive channel, neutralizing the positive charge holes in the N+ region, thereby restoring the depleted N+ type characteristics. Therefore, the conductive channel is formed. The vertical N+ region has a high doping concentration and low resistivity. Therefore, it has the characteristics of high voltage withstand of planar structure and low resistance of trench 5 type structure, with a larger rated current value and avalanche energy. The gate polysilicon 54 and the insulating dielectric layer 55 can play an insulating role. The source metal layer 56 and the conductive body 57 facilitate the conduction of internal circuits. The shielding gate oxide layer 58 further improves the anti-oxidation effect.
[0031] Working Principle: The N-pillars 32 and P-pillars 33 on the silicon-based MOSFET body 1 facilitate connection to the circuit board. Heat pipes 34 on the N-pillars 32 and P-pillars 33 absorb the heat generated during operation of the silicon-based MOSFET superjunction structure. The heat-absorbing ends of the heat pipes 34 are connected to the N-pillars 32 and P-pillars 33, allowing heat transfer through the evaporation and condensation of liquids. This effectively dissipates heat from the silicon-based MOSFET superjunction structure, reducing leakage current increases at high temperatures and improving long-term device reliability. The silicon-based MOSFET body 1 has a conductive epitaxial layer 2 and a gate body 4. The oxide layer 51 and polysilicon body 53 within the trench 5 provide oxidation resistance. When the MOS is turned on, the electric field between the gate and the source inverts the P-region under the gate, generating an N-type conductive channel in the P-region under the gate. At the same time, electrons from the source region enter the vertical N+ region through the conductive channel, neutralizing the positive charge holes in the N+ region, thereby restoring the depleted N+ type characteristics. Thus, the conductive channel is formed. The vertical N+ region has a high doping concentration and low resistivity, thus exhibiting the high breakdown voltage of a planar structure and the low resistance of a trench type structure. It also has a larger rated current value and avalanche energy. The gate polysilicon 54 and the insulating dielectric layer 55 provide insulation. The source metal layer 56 and the conductive body 57 facilitate the conduction of internal circuits, and the shielding gate oxide layer 58 further enhances the oxidation resistance.
[0032] The technical scope of this utility model is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this utility model, and all such modifications and variations should fall within the protection scope of this utility model.
Claims
1. A novel silicon-based MOSFET super junction structure, characterized in that, The device includes a silicon-based MOSFET body (1), the lower surface of which is connected to a conductive epitaxial layer (2), the exterior of which is provided with a heat dissipation component for heat dissipation of the structure, and the interior of which is provided with a superjunction component for superjunction of the silicon-based MOSFET. The heat dissipation assembly includes a package plate (3), which is fixed to the side wall of the silicon MOSFET body (1). The lower end of the silicon MOSFET body (1) is connected to an N-pillar (32), and a P-pillar (33) is provided on one side of the N-pillar (32) and fixedly connected to the silicon MOSFET body (1). Heat pipes (34) are installed on the side walls of both the N-pillar (32) and the P-pillar (33).
2. A novel silicon-based MOSFET super junction structure according to claim 1, characterized in that, The outer surface of the silicon-based MOSFET body (1) is fixed with a package shell (31), and a gate body (4) is formed on the upper surface of the silicon-based MOSFET body (1).
3. A novel super junction structure of silicon-based MOSFET according to claim 2, characterized in that, The superjunction assembly includes trenches (5), and there are three trenches (5). All three trenches (5) are formed inside the silicon-based MOSFET body (1), and the inner surface of each of the three trenches (5) is provided with a shielding gate oxide layer (58).
4. The novel silicon-based MOSFET super junction structure of claim 3, wherein, The inner wall of the shielding gate oxide layer (58) is connected to an oxide layer (51), and a superjunction (52) fixed to the silicon MOSFET body (1) is provided below the trench (5).
5. A novel super junction structure of silicon-based MOSFET according to claim 4, characterized in that, The shielding gate oxide layer (58) is internally connected to a polysilicon body (53).
6. A novel silicon-based MOSFET superjunction structure according to claim 5, characterized in that, The upper end of the polysilicon body (53) is connected to a gate polysilicon (54).
7. A novel silicon-based MOSFET superjunction structure according to claim 6, characterized in that, The upper surface of the gate polysilicon (54) is connected to an insulating dielectric layer (55) that is fixedly connected to the silicon-based MOSFET body (1).
8. A novel silicon-based MOSFET superjunction structure according to claim 7, characterized in that, The upper surface of the insulating dielectric layer (55) is connected to a source metal layer (56) that is fixedly connected to the silicon MOSFET body (1), and a conductive body (57) is connected to one side of the trench (5).