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A shielded gate mosfet

A shielding gate and control gate technology, applied in semiconductor devices, electrical components, circuits, etc., can solve problems such as device thermal burnout, drain-source PN junction avalanche breakdown, etc., to achieve improved reliability, low avalanche breakdown voltage, and eliminate The effect of the possibility of conduction

Active Publication Date: 2021-03-30
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 drain voltage overshoot is too high, avalanche breakdown of the drain-source PN junction may occur, and the avalanche current and C DS The superposition of charge and discharge currents will make the forward voltage drop on the parasitic BJT base resistance Rb 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 forward voltage. To enlarge the working area, it may cause thermal burnout of the device

Method used

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Examples

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Embodiment 1

[0029] 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 stacked sequentially 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;

[0030] 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 dop...

Embodiment 2

[0039] 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 . At this time, the resistance between the second shielding gate electrode 91 of the discharge cell and the metallized source 12 is realized through device layout design, and the specific method is to connect the polycrystalline trace end of the shield gate electrode 91 of the discharge cell with the metal A polycrystalline region 13 or a metal resistor is added between the s...

Embodiment 3

[0042] 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 on the upper surface of 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 elec...

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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 side, because it does not contain a source region, and there is a resistance R between the shielded gate electrode and the metallized source in the discharge cell, so that the shielded gate electrode and the drift region of the discharge cell region form a capacitance C during the dynamic process of the device DS1 Form an RC loop with the resistor R to generate a displacement current, so that the static avalanche breakdown voltage of the discharge cell is lower than that of the working cell, thereby fixing the avalanche breakdown point at the discharge cell, so that the avalanche current It will flow out through the source electrode above the discharge cell, and at the same time, because there is no parasitic BJT, the possibility of parasitic BJT conduction is completely eliminated. 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. The continuous advancement of power MOSFET technology has helped them achieve this goal. In the on-resistance Rds(on) and the gate charge Qg, one generally always decreases while the other increases, so power MOSFET designers must consider the trade-off between the two. The Shielded Gate Trench MOSFET (Shielded Gate Trench MOSFET), as an improved MOSFET based on the traditional trench MOSFET (U-MOSFET), can reduce Rds(on) without affecting Qg. Compared with U-MOSFET, shielded gate MOSFET has faster switching speed and lower switching loss; at the same time, 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 m...

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 任敏杨梦琦马怡宁李泽宏高巍张金平张波
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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