Silicon nitride (Si3N4) is a hard, solid substance, that can be obtained by direct reaction between
silicon and
nitrogen at high temperatures. Silicon nitride is the main component in silicon nitride
ceramics, which have relatively good
shock resistance compared to other ceramics.Rollers made of silicon nitride ceramic are sometimes used in high-end skateboard
bearings, due to the material's shock and heat-resistant characteristics. It is also used as an ignition source for domestic gas appliances, hot surface ignition.In
microelectronics, silicon nitride is usually formed using
chemical vapor deposition (CVD) method, or one of its variants, such as
plasma-enhanced chemical vapor deposition (PECVD). It is usually used either as an
insulator layer to electrically isolate different structures or as an
etch mask in
bulk micromachining. As a passivation layer for microchips, it is superior to
silicon dioxide, as it is a significantly better
diffusion barrier against water molecules and
sodium ions, two major sources of corrosion and instability in microelectronics. It is also used as a
dielectric between
polysilicon layers in
capacitors in analog chips.
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chemical formula Si3N4, silicon nitride is a good insulator with a dielectric constant of 7.5, a breakdown strength of 107 V/cm, and is an excellent barrier against moisture and other contaminants. Silicon nitride is highly stressed in direct contact with silicon and so an intervening stress relief layer is typically used.