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Groove silicon carbide MOSFET integrated with high-speed fly-wheel diode and preparation method

A freewheeling diode, silicon carbide technology, applied in semiconductor/solid-state device manufacturing, semiconductor devices, electrical components, etc., can solve the problems of high conduction voltage drop of SiC body diode, high density of JFET area, and increased dynamic loss of devices, etc. Achieve the effect of improving long-term reliability, reducing on-voltage and reducing Miller capacitance

Active Publication Date: 2022-07-29
NOVUS SEMICON CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, there are two problems in the planar SiC VDMOS. One is that the density of the JFET area is relatively high, which introduces a large Miller capacitance, which increases the dynamic loss of the device; the other is that the parasitic SiC body diode conduction voltage drop is too high. , and it is a bipolar device, which has a large reverse recovery current. In addition, the bipolar degradation phenomenon caused by the silicon carbide BPD defect makes the conduction voltage drop of the body diode continue to increase with the growth of service time. Therefore, The body diode of SiC VDMOS cannot be directly used as a freewheeling diode

Method used

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  • Groove silicon carbide MOSFET integrated with high-speed fly-wheel diode and preparation method
  • Groove silicon carbide MOSFET integrated with high-speed fly-wheel diode and preparation method
  • Groove silicon carbide MOSFET integrated with high-speed fly-wheel diode and preparation method

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Embodiment 1

[0042] like figure 1 As shown, this embodiment provides a trench silicon carbide MOSFET with integrated high-speed freewheeling diode, including a backside ohmic contact alloy 1, an N-type doped silicon carbide substrate 2, an N-type doped silicon carbide epitaxial layer 3, a first P-type doped buried layer 41, second P-type doped buried layer 42, third P-type doped buried layer 43, first gate oxide layer 51, second gate oxide layer 52, first polysilicon 61, Two polysilicon 62, a first P-type doped well region 71, a second P-type doped well region 72, a third P-type doped well region 73, a first N-type doped source region 81, a second N-type doped well region 81 Doping source region 82, P-type doping source region 9, interlayer dielectric 10, front ohmic contact alloy 11;

[0043] On the plane formed by the x-axis and the y-axis, the N-type doped silicon carbide substrate 2 is located above the backside ohmic contact alloy 1; the N-type doped silicon carbide epitaxial layer 3...

Embodiment 2

[0050] like Figure 2 to Figure 9 As shown, this embodiment provides a method for fabricating a trench silicon carbide MOSFET integrated with a high-speed freewheeling diode, including the following steps:

[0051] Step 1: An oxide layer is deposited on the N-type silicon carbide epitaxial wafer. After photolithography, an ion-implanted P-well ion-implantation mask layer 101 is formed, and then Al ion implantation is performed at a temperature of 300K~1000K to form a second P-type dopant. In the miscellaneous well region 72, at the same time, since the Al ion implantation in silicon carbide will cause lateral scattering, P-type doping scattering regions with laterally graded concentration will be simultaneously formed on the left and right sides of the second P-type doping well region 72, respectively. For the first P-type doped well region 71 and the third P-type doped well region 73, the following figure 2 structure. After the injection is completed, the mask layer is rem...

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Abstract

The invention discloses a trench silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) integrated with a high-speed fly-wheel diode and a preparation method, and belongs to the technical field of power semiconductor devices, the MOSFET is of a trench structure, in order to solve the problem of electric field concentration at the corner of the bottom of a trench, a trench-type gate-controlled diode is added beside the MOSFET, a P-type buried layer is added to the bottom of the trench, and a gate-controlled diode is added to the bottom of the trench. Therefore, the electric field intensity of each other is weakened. In addition, the grid-control diode is connected in parallel with the original body diode of the device, so that the conduction voltage drop of the body diode is greatly reduced, and the loss in a reverse follow current working mode is reduced. In addition, the grid-control diode is a monopole type device and does not have a minority carrier storage effect, reverse recovery current of a body diode can be completely eliminated, and therefore dynamic loss is reduced.

Description

technical field [0001] The invention belongs to the technical field of power semiconductor devices, and in particular relates to a trench silicon carbide MOSFET integrated with a high-speed freewheeling diode and a preparation method thereof. Background technique [0002] The wide-bandgap semiconductor material SiC is an ideal material for the preparation of high-voltage power electronic devices. Compared with Si material, SiC material has a high breakdown electric field strength (4×10 6 V / cm), high carrier saturation drift velocity (2×10 7 cm / s), high thermal conductivity, good thermal stability, etc., so it is especially suitable for high-power, high-voltage, high-temperature and radiation-resistant electronic devices. [0003] SiC VDMOS is a commonly used device in SiC power devices. Compared with bipolar devices, since SiCVDMOS has no charge storage effect, it has better frequency characteristics and lower switching losses. At the same time, the wide band gap of SiC ma...

Claims

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Application Information

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IPC IPC(8): H01L29/78H01L29/06H01L21/336
CPCH01L29/0623H01L29/7804H01L29/7813H01L29/66068H01L29/7805H01L29/7391H01L29/1608H01L29/739
Inventor 顾航高巍戴茂州
Owner NOVUS SEMICON CO LTD
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