BYH3413_STN4822 Introduction

The power mos used on electric vehicles is a three-dimensional structure. The mos tube we have seen is actually composed of thousands of small mos tubes in parallel. You may think that one or a few bad moss should easily appear in thousands of small mos. In fact, it is not that easy. , the current manufacturing process basically guarantees the high consistency of various parameters of these small units. Low-power mos is a planar structure.

Assuming that the carriers of the conductive channel are electrons, it is called an N-channel; assuming that the carriers are holes, it is called a P-channel. According to the carrier of the conduction channel, it can be divided into N channel and P channel. A MOS tube is a semiconductor device in which unipolar carriers participate in conduction.

BYH3413_STN4822

BYT6230

NCE30H11K NCE3402B NCE30H10AK NCE2304 NCE3404.

However, in terms of structure, there is a big difference between them. In order to better understand the mechanism of power MOSFET, we must first recall the mechanism of low-power FET. . The following describes the principle of the MOS transistor with the structure of an N-channel enhancement type low-power MOSFET. Working principle of power MOS tube Power MOS tube is developed from low-power MOS tube.

Barrier capacitance: In power semiconductors, when the N-type and P-type semiconductors are combined, the electrons of the N-type semiconductor will partially diffuse into the holes of the P-type semiconductor due to the concentration difference, so they will form on both sides of the junction surface. Space charge area (the electric field formed by the space charge area will resist the diffusion movement, and finally make the diffusion movement reach equilibrium);

BYP31538 BYP31510 BYP31575 BYH31574 BYD31523A BYH31532 BYM31580 BYH31519 BYS31535 BYM31545 .

BYH3413_STN4822

SI4622DY-T1-E3

Diffusion capacitance: When a forward voltage is applied, the non-equilibrium minority carrier concentration near the interface of the depletion layer is high, far from the non-equilibrium minority carrier concentration is low, and the concentration gradually decays from high to 0 until it reaches zero. The process of charge accumulation and release in this phenomenon is the same as that of capacitor charging and discharging, which is called diffusion capacitance. When the applied forward voltage increases, the concentration of unbalanced minority carriers increases and the concentration gradient also increases, and when the applied voltage decreases, the change is opposite.

The N-channel enhancement mode MOS transistor uses a low-doped P-type semiconductor as the substrate, and forms two heavily doped N+ regions on the substrate by a dispersed method, and then generates a very thin one on the P-type semiconductor. A silicon dioxide insulating layer, and then photolithography is used to etch away the silicon dioxide layer on the upper end of the two heavily doped N+ regions, exposing the N+ regions, and finally on the outer surface of the two N+ regions and the two between them. The surface of silicon oxide is sprayed with a layer of metal film by evaporation or sputtering. These three metal films constitute the three electrodes of the MOS tube, which are called source (S), gate (G) and drain (D) respectively. .

When the low UDS separate pinch off voltage is large, the MOS tube is equivalent to a resistance, and this resistance decreases with the increase of UGS. Cut-off area (UGS). Growth slows as the conduction channel approaches pinch off. Figure 1. Drain output characteristics of MOS transistors The output characteristics of field effect transistors can be divided into four regions: variable resistance region, cut-off region, breakdown region and constant current region. Variable resistance region (UDS In this region, ID increases linearly as UDS increases.

Another technique is to intermittently improve the structure of the MOSFET and use a straight V-groove structure. In order to avoid the problems of too small current-carrying capacity and large on-resistance of MOSFET, two techniques are generally used in high-power MOSFETs. One is to connect millions of low-power MOSFET unit cells in parallel to improve the current-carrying capacity of MOSFET. . FIG. 3 is a cross-sectional view of the structure of a V-channel MOSFET.

BYH3413_STN4822

NCE25TD135LP NCE1608N NCE18ND11U NCE3134 NCE20ND07U.

NCE25TD135LT NCE15TD135LT NCE15TD120LP NCE15TD135LP NCE25TD120LP.

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