Overview

Silicon Carbide (SiC), also called Moissanite, is a compound that is known to be the third hardest material, only after diamond and boron carbide. Naturally almost nonexistent, they are only found in very small amounts in meteorites. Refining method of synthetic silicon carbide was discovered by accident by Edison's assistant, Edward Goodrich Acheson, while he was performing experiments on synthetic diamond production. With its comparable reflectivity and transparency to that of diamond and significantly cheaper costs, it is also widely used in jewelry.

Elements, Chemical Composition and Structure

Silicon Carbide is a compound that consists of carbon (C) and silicon (Si) elements in 1:1 ratio. While its components are always the same, it can have various crystal structures depending on the location of the silicon elements in the matrix. Each polymorphous crystal structure is designated with a letter; "C" for cubic, "H" for hexadecimal and "R" for rhombohedral. The most common polymorphous crystalline structures for SiC are 3C, 4H, 6H and 15R. SiC with 4H crystal structure is commonly used in automobiles, household appliances and power electronics.

Properties

Silicon carbide is an extremely hard material; along with boron carbide, it has a Mohs hardness between 9-10, compared to diamond, the hardest known material, which is 10. This makes it extremely wear-resistant. It has a higher dielectric strength than other silicon containing materials, has wide bandgap and high thermal conductivity, heat and corrosion resistant. Due to these properties, they are very suitable for semiconductor applications for use in extreme environments.

Production

Silicon carbide is generally made by using an Acheson graphite electric resistance furnace. Silica and carbon are combined in the furnace at 2200℃ into an ingot. Main steps of the process is "Putting the raw materials into the furnace", "Passing electric current", "Cooldown of the product" and "Taking silicon carbide ingot out of the furnace", each of which can take up to several days. The ingot is then further refined, pulverized, refined again and finally sifted to the desired grain size and made into the final product.

Practical Applications

Due to its higher dielectric strength, band gap and wider doping range, SiC has been replacing silicon as the raw material in power semiconductors. It is also being used as the substrate material in high luminance blue LEDs, high speed, high dielectric strength, on-resistance Schottky barrier diodes and MOSFETs. They can also be found in nuclear power applications due to their high heat resistance and thermal conductivity and durability.

DISCO's processing solutions

DISCO's grinders, dicing and laser saws can be used when cutting and grinding substrate materials.