Production and application of SiC epitaxial wafers

      SiC silicon carbide is a compound semiconductor material composed of carbon and silicon elements, which is one of the ideal materials for making high-temperature, high-frequency, high-power, and high-voltage devices.

      Compared to traditional silicon materials (Si), the bandgap width of silicon carbide (SiC) is three times that of silicon; The thermal conductivity is 4-5 times that of silicon; The breakdown voltage is 8-10 times that of silicon; The electron saturation drift rate is 2-3 times that of silicon.

    The core advantages of silicon carbide raw materials are reflected in:
1) High voltage resistance characteristics: lower impedance, wider bandgap, able to withstand larger currents and voltages, resulting in smaller product designs and higher efficiency;
2) High frequency resistance characteristics: SiC devices do not have current trailing during the shutdown process, which can effectively improve the switching speed of the component (approximately 3-10 times that of Si), suitable for higher frequencies and faster switching speeds;
3) High temperature resistance: SiC has higher thermal conductivity compared to silicon and can operate at higher temperatures.

     From the perspective of process flow; SiC powder undergoes crystallization, processing, cutting, grinding, polishing, and cleaning processes to ultimately form a substrate. The substrate undergoes epitaxial growth to obtain an epitaxial wafer. Epitaxial wafers are manufactured into devices through steps such as photolithography, etching, ion implantation, and deposition.

    Cut the wafer into dies, package the devices, and assemble them into modules in a special casing. The industrial chain includes upstream substrate and epitaxial, midstream device and module manufacturing, and downstream terminal applications.

     Power devices made of silicon carbide are divided into two categories based on their electrical performance differences, and are widely used in fields such as new energy vehicles, photovoltaic power generation, rail transit, and 5G communication. According to the different electrical properties, devices made of silicon carbide materials are divided into conductive silicon carbide power devices and semi insulating silicon carbide devices, with different terminal application fields for the two types of silicon carbide devices.

     Conductive silicon carbide power devices are mainly made by growing silicon carbide epitaxial layers on conductive substrates, obtaining silicon carbide epitaxial wafers and further processing them. The varieties include Schottky diodes, MOSFETs, IGBTs, etc. They are mainly used in infrastructure construction such as electric vehicles, photovoltaic power generation, rail transit, data centers, and charging.

Semi insulating silicon carbide based RF devices are made by growing gallium nitride epitaxial layers on semi insulating silicon carbide substrates to obtain silicon carbide based gallium nitride epitaxial wafers. These devices include HEMT and other gallium nitride RF devices, mainly used for 5G communication, vehicle communication, national defense applications, data transmission, and aerospace.