The process of SiC device manufacturing is basically similar to that of silicon-based devices, including gluing, development, lithography, thinning, annealing, doping, etching, oxidation, cleaning and other front-end processes. However, due to the different characteristics of silicon carbide materials, manufacturers need specific equipment and develop specific processes in the wafer manufacturing process, which cannot be completely common with the past silicon process equipment and processes, so the current SiC wafer manufacturing capacity is in short supply.
Some of the differences between the SIC wafer fabrication specific process and the SI process are mainly in lithography alignment. Since the SiC wafer is transparent, CD-SEM and metrology measurements are complex, making it difficult to align lithography and transfer the piece from the device.
The etching process, since SiC is inert in chemical solvents, dry etching is used with the same light. The masking material, the choice of mask etching, the gas mixture, the control of the sidewall slope, etching rate, the sidewall roughness, etc., all need to be redeveloped.
Due to the characteristics of SiC devices, the diffusion temperature of SiC is much higher than that of silicon, and the traditional thermal diffusion is not practical in silicon carbide, and high-temperature ion implantation can only be used for doping. Ultra-high temperature annealing process.
High-temperature ion implantation will destroy the lattice structure of the material itself, so it is necessary to anneal at high temperature in an inert gas to restore the structure, usually at annealing temperatures up to 1600-1700 degrees, to recrystallize the SiC surface and electrically activate the dopant.
High-quality gate oxide growth. Poor SiO interface quality will reduce the mobility of the MOSFET inversion layer, resulting in unstable threshold voltage, so passivation techniques need to be developed to improve SiC SiOxide interface quality.
The specific process of SiC wafer manufacturing brings the need for specific equipment, which mainly includes high-temperature ion implanters, high-temperature annealing furnaces, SIC thinning equipment, backside metal deposition equipment, backside laser annealing equipment, SIC substrates and epitaxial wafer surface defect detection and metrology. Among them, whether there is a high-temperature ion implanter is one of the important criteria to measure the silicon carbide production line. Semiconductors