A kind of superjunction mosfet device and its manufacturing method

Abstract

The invention discloses a super junction MOSFET device and a manufacturing method thereof. A first buffer layer of the first conductivity type adjacent to the body region of the second conductivity type and a second column of the second conductivity type are arranged in the drift layer of the first conductivity type. The second buffer layer of the first conductivity type; the body region of the second conductivity type and the drift layer of the first conductivity type are separated by the first buffer layer of the first conductivity type, and the second column of the second conductivity type is separated from the second column of the first conductivity type. A pillar is isolated by the second buffer layer of the first conductivity type; the impurity concentration of the first buffer layer of the first conductivity type and the second buffer layer of the first conductivity type is greater than that of the first conductivity type drift layer and the first conductivity type The impurity concentration of the first column. The invention has more optimized body diode reverse recovery characteristics, simple process, is compatible with the existing super junction MOSFET manufacturing process, and is suitable for mass production requirements.

Description

Technical field [0001] The invention relates to a semiconductor device and a manufacturing method thereof, in particular to a semiconductor device with a super junction structure and a manufacturing method thereof. Background technique [0002] In the field of medium and high voltage power semiconductor devices, the super junction structure (SuperJunction) has been widely adopted. Such as figure 1 As shown, in the drift region of the power MOSFET, a plurality of P-N column pairs formed by alternately adjacently arranged N columns and P columns form a super junction structure. When the MOSFET device with a super junction structure is turned off, the N pillars and P pillars in the super junction structure are respectively depleted, and the depletion layer extends from the PN junction interface between each N pillar and the P pillar. The mass is equal to the amount of impurities in the P column, so the depletion layer extends and completely depletes the N column and the P column, t...

AI Technical Summary

Problems solved by technology

Due to the poor reverse recovery characteristics of ordinary super-junction MOSFET devices T2 and T3, diodes D4 and D5 are respectively connected in parallel on T2 and T3, although this can solve the problem of T2 and T3 easily due to excessively high Irrm However, due to the addition of additional devices in the circuit, the power consumption of the entire circuit will also increase, and the efficacy of T2 and T3 will also decrease. This situation is constantly pursuing energy saving and consumption reduction. Under the direction of development, it is not a good choice

[0004] In order to solve the problem of reverse recovery characteristics of the body diode of super-junction MOSFET devices, three methods have been proposed or adopted at present: 1. Use electron irradiation to create defects in the drift layer, reduce the carrier lifetime during the reverse recovery process, and reduce the reverse recovery. To recover the charge, but this method will increase the leakage of the device, and the defects caused by irradiation will recover after high temperature and long-term work, affecting the reliability of the device; 2. Use heavy metal doping to form a recombination center in the device drift layer , to reduce the lifetime of carriers in the reverse recovery process. This method has a special manufacturing process, high process cost, and device leakage characteristics will also deteriorate; 3. A Schottky diode is connected in parallel to the super-junction MOSFET device to improve the device body. Diode reverse recovery characteristics. In addition to the special manufacturing process, the device leakage is uncontrollable, and it is hardly used in actual products at present.

Images