According to data from the China Academy of Commerce and Industry, the proportion of transistors represented by MOSFET and IGBT in power semiconductor discrete devices is about 28.8%. From the current market demand, silicon-based MOSFETs, silicon-based IGBTs, and silicon carbide are the main products of power semiconductor discrete devices. This article will also focus on the analysis and research of power discrete devices (including modules) such as silicon-based MOSFETs, IGBTs, and silicon carbide.
MOSFET， It has the advantages of high input impedance, low noise, good thermal stability, simple manufacturing process, and strong radiation, and is usually used in amplification circuits or switching circuits. MOSFETs can be divided into planar planar MOSFETs, trench MOSFETs, shielded gate SGT MOSFETs, and super junction SJ MOSFETs according to different processes. According to the conductive channel, it can be divided into N channel and P channel, namely N-MOSFET and PMOSFET. According to the amplitude of gate voltage, it can be divided into depletion type and enhancement type.
As MOSFET technology and processes continue to mature, costs will continue to decrease. Mid to high end products will gradually sink towards mid to low end products. For example, Trench MOSFETs will sink from the mid to low end, replacing some of the low-end market of planar MOSFETs. SGT MOSFET will partially replace Trench MOSFET in the low-voltage application market, sinking from the mid to high end to the mid end. SGT MOSFET, SJ MOSFET, and silicon carbide MOSFET are the three main products of MOSFET in the future. Since the birth of MOSFETs in the 1970s, power MOSFETs have evolved from planar MOSFETs to Trench MOSFETs, then to SGT MOSFETs and SJ MOSFETs, and finally to the current hot third-generation wide bandgap MOSFETs (silicon carbide, gallium nitride). The technological iteration direction of power MOSFETs mainly revolves around process, design (structural changes), process optimization, and material changes to achieve high performance of devices - high frequency, high power, and low loss.
IGBT, commonly known as the "CPU" of power electronic devices, is a core device for energy conversion and transmission. It is a fully controlled, voltage driven power semiconductor device composed of BJT and MOSFET. IGBT does not have the function of amplifying voltage. When conducting, it can be considered as a wire, and when disconnected, it can be considered as an open circuit. IGBT has the advantages of both BJT and MOSFET, including high input impedance, low conduction voltage drop, small driving power, and low saturation voltage drop. Compared with BJT or MOSFET, IGBT provides a larger power gain, higher operating voltage, and lower MOSFET input loss. Therefore, it is widely used in converter systems with DC voltage of 600V and above, such as AC motors, frequency converters, switching power supplies, lighting circuits, and traction drives.
Compared to MOSFETs, IGBT can operate continuously at higher voltages, while also taking into account factors such as high power density, low losses, high reliability, good heat dissipation, and low cost. A high-performance, highly reliable, and low-cost IGBT chip not only requires continuous optimization of device structure at the design end, but also raises higher requirements for wafer manufacturing and packaging.