The simplest method of producing silicon carbide involves melting silica sand and carbon, such as coal, at high temperatures - up to 2,500 degrees Celsius. Darker, more common versions of silicon carbide often contain iron and carbon impurities, but pure SiC crystals are colorless and are formed when silicon carbide is sublimated at 2,700 degrees Celsius. After heating, these crystals are deposited on graphite at a lower temperature in a process known as the Lely method.
Lely Method: In this process, a granite crucible is heated to a very high temperature, usually by induction, to sublimate the silicon carbide powder. The lower temperature graphite rod is in a gaseous mixture, allowing the pure silicon carbide to precipitate and form crystals.
Chemical vapor deposition: Alternatively, manufacturers grow cubic SiC using chemical vapor deposition, which is commonly used in carbon-based synthesis processes and is used in the semiconductor industry. In this method, a special chemical mixture of gases is introduced into a vacuum environment and combined before being deposited on a substrate.
Both methods of producing silicon carbide wafers require huge amounts of energy, equipment and knowledge to succeed.
