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A shielding grid mosfet

A shielding gate and control gate technology, applied in semiconductor devices, electrical components, circuits, etc., can solve problems such as device damage, reliability problems, and device failure, so as to improve reliability, eliminate the possibility of conduction, and avoid secondary The effect of a breakdown

Active Publication Date: 2021-02-26
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the avalanche current is large, the forward voltage drop on the base resistance Rb of the parasitic BJT will be higher. If the generated voltage drop is greater than the forward conduction voltage drop of the parasitic BJT, the emitter of the parasitic BJT will be forward-biased and enter the positive To enlarge the working area, it may cause thermal burnout of the device, and the damage caused by the thermal burnout of the device is irreversible
Therefore, if the avalanche current is not limited or the device design is not optimized, once the avalanche capability is exceeded, reliability problems will occur, and may even cause device failure

Method used

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Examples

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Embodiment 1

[0026] This embodiment provides a shielded gate MOSFET, such as figure 2 As shown, it includes a metallized drain 1 and a semiconductor substrate 2 of the first conductivity type that are sequentially stacked from bottom to top. The first conductivity type semiconductor drift region 3 and the metallized source 12; characterized in that, the first conductivity type semiconductor drift region 3 is provided with a working cell region and a leakage cell region;

[0027]The working cell region includes: a second conductivity type semiconductor body region-4, a first conductivity type semiconductor heavily doped source region-5, a second conductivity type semiconductor heavily doped contact region-6, a first shielding gate structure and The first control gate structure; the second conductivity type semiconductor body region-4 is arranged on both sides of the top layer of the first conductivity type semiconductor drift region 3; the first conductivity type semiconductor heavily dope...

Embodiment 2

[0035] This embodiment provides a shielded gate MOSFET, such as image 3 As shown, the difference between this embodiment and Embodiment 1 is that the second shielding grid electrode 91 in the discharge cell can be designed as two mutually independent first split shielding grid electrodes 911 and second split shielding grid electrodes 912, The first split shielding gate electrode 911 is disposed above the second split shielding gate electrode 912 , and the depth of the first split shielding gate electrode 911 is greater than the junction depth of the second conductivity type semiconductor body region 2 41 . The first split shielding gate electrode 911 is structurally equivalent to the first control gate electrode 10 in the working cell region, but since there is no source region in the leakage cell region, the first split shielding gate electrode 911 does not have the function of turning on A dielectric layer may be used to isolate the first split shielding gate electrode 911 ...

Embodiment 3

[0038] This embodiment provides a shielded gate MOSFET, such as Figure 7 As shown, the difference between this embodiment and Embodiment 1 is that the second shielding grid electrode 91 of the discharge cell can be designed as two mutually independent first split shielding grid electrodes 911 and second split shielding grid electrodes 912, The first split shielding gate electrode 911 is disposed above the second split shielding gate electrode 912 , and the depth of the first split shielding gate electrode 911 is greater than the junction depth of the second conductivity type semiconductor body region 2 41 . The first split shielding gate electrode 911 is structurally equivalent to the first control gate electrode 10 in the working cell region, but since there is no source region in the leakage cell region, the first split shielding gate electrode 911 does not have the function of turning on , and precisely because of this, the first split shielding gate electrode 911 and the ...

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Abstract

A shielded gate MOSFET belongs to the technical field of semiconductor power devices. The device includes a drain, a substrate, a drift region and a metallized source stacked sequentially from bottom to top, and a working cell region and a leakage cell region are arranged in the drift region; the leakage cell region is located next to the working cell On the side, because it does not contain a source region and the side dielectric layer between the shielding gate electrode and the drift region is thicker, the lateral auxiliary depletion effect of the shielding gate on the N-type drift region is reduced, so that the leakage cell is compared with the working cell The static avalanche breakdown voltage is lower, so that the avalanche breakdown point is fixed at the discharge cell, so that the avalanche current will flow out through the source electrode above the discharge cell, and because there is no parasitic BJT, it completely eliminates parasitic Possibility of BJT conduction. Therefore, the present invention can avoid the secondary breakdown caused by parasitic BJT turning on, and effectively improve the reliability of the device.

Description

technical field [0001] The invention belongs to the technical field of power semiconductors, and in particular relates to a shielded gate MOSFET. Background technique [0002] DC / DC researchers are constantly challenged to increase efficiency and power density. Continuous advances in power MOSFET technology have helped them achieve this goal. Of the on-resistance Rds(on) and the gate charge Qg, one generally always decreases while the other increases, so the power MOSFET designer must consider the trade-off between the two. As an improved MOSFET based on the traditional trench MOSFET (U-MOSFET), the shielded gate MOSFET (Shielded Gate Trench MOSFET) can reduce Rds(on) without affecting Qg. Compared with U-MOSFET, the shielded gate MOSFET has faster switching speed and lower switching loss; at the same time, the shielded gate MOSFET uses its shielded gate polycrystalline layer as an "internal field plate" to reduce the electric field in the drift region, thus obtaining more...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L29/78H01L29/423
CPCH01L29/4236H01L29/7803H01L29/7813
Inventor 任敏杨梦琦胡玉芳李泽宏高巍张金平张波
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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