Silicon Carbide Power Devices
The difference between silicon carbide epitaxy and traditional silicon power devices is that silicon carbide power devices can not be directly fabricated on silicon carbide single crystal materials, so an active layer needs to be fabricated
Epitaxial growth is used to produce active layers of silicon carbide (SiC)-based device structures with designed doping density and thickness, because control of doping and thickness in bulk growth is difficult.
The epitaxial process of silicon carbide is basically the same as that of silicon, and the temperature design and equipment structure design are different.
In the aspect of device preparation, due to the particularity of materials, the processing of devices is different from that of silicon, which adopts high-temperature processes, including high-temperature ion implantation, high-temperature oxidation and high-temperature annealing.
Epitaxy process is a very key process in the whole industry. Since all devices are basically realized on epitaxy, the quality of epitaxy has a great impact on the performance of devices. However, the quality of epitaxy is affected by crystal and substrate processing. It is in the middle of an industry and plays a very key role in the development of the industry.
SiC material has the following advantages,
1. Material properties, i.e. physical properties: large band gap, high saturated electron drift speed, high-speed two-dimensional electron gas and high breakdown field strength. These material properties will affect the performance of later devices.
2. Device performance: high temperature resistance, fast switching speed, low on resistance and high voltage resistance. Superior to ordinary silicon materials. Reflected in electronic and electrical systems and device products.
3. System performance: small volume, light weight, high energy efficiency and strong driving force.
The high-pressure resistance of silicon carbide is 10 times that of silicon, the high-temperature resistance is 2 times that of silicon, and the high-frequency capacity is 2 times that of silicon; For products with the same electrical parameters, using silicon carbide material can reduce the volume by 50% and the energy loss by 80%.
This is also the reason why semiconductor giants continue to add weight to the research and development of silicon carbide: they hope to make the device volume smaller and smaller and the energy density larger and larger.
With the increase of voltage, the high-frequency performance and energy density of silicon materials are declining, and their advantages are becoming smaller and smaller compared with silicon carbide and gallium nitride.
Silicon carbide is mainly used in high-voltage environment, and gallium nitride is mainly concentrated in medium and low voltage fields. The two key development directions overlap, but each has its own route. Generally, 650V is used as a boundary: above 650V is usually the application of silicon carbide materials, and below 650V, for example, gallium nitride has more obvious advantages in some consumer electronics.