SiC Trench Technology
Introduction
From a macro perspective, the new generation of technologies and applications represented by AI and electric vehicles will inevitably exert tremendous pressure on the global energy supply. In the long run, "energy constraints" will inevitably become a key factor restricting the development of advanced technologies and their penetration into the field, leading to a huge demand to reshape the entire energy system structure.
As a wide bandgap material, SiC naturally has a higher voltage resistance. Compared with traditional Si-based devices, power devices made of it can handle high-voltage currents at higher frequencies and in a wider temperature range. At the module level, it can significantly reduce losses, weight and volume. SiC also has a longer-term roadmap. All of these make SiC materials extremely advantageous in future energy technology changes.
Material performance level:
1 Its dielectric breakdown field strength is 10 times that of silicon, which reduces power losses.
2 Its electron saturation speed is twice that of silicon, allowing the device to achieve faster switching speeds.
3 Its band gap width is three times that of silicon, so it does not require a large Ron to increase the withstand voltage, which can reduce the loss of high-power devices.
4 Its thermal conductivity is four times that of Si, and it is resistant to high temperatures, which improves the integration and power density of devices.
Cost is currently one of the major limitations affecting the application of this material, so using trench gates to reduce the surface area of the chip and allow a single wafer to produce more chips has become the main means of reducing costs in the industry. In addition to cost considerations, Trench-Gate can also avoid the additional body resistance caused by parasitic JFETs, and Infineon also uses trenches to select better crystal planes to improve the defect density of the gate oxide interface.
In the above context, how to deal with the ultra-high hardness of SiC (Mohs hardness 9.5), which is second only to diamond, in trench etching, and how to efficiently achieve the specific morphology requirements of the process, has become a major problem in the industry. In particular, the domestic market is at a critical stage of achieving technological breakthroughs and mass production of SiC-Trech-Gate, and local equipment manufacturers are required to provide more support for special processes to jointly achieve "overtaking on the curve" in semiconductor technology.
China has not yet completely overcome the difficulties of SIC-TRENCH
·High hardness, large stress problem, poor verticality, high sidewall roughness, bottom rouding control, difficult to ensure etching uniformity, substrate damage
