Silicon dioxide, also known as silicic acid (from the Latin silex), is an oxide of silicon with the chemical formula SiO2, most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the main component of sand.

Silicic acid is one of the most complex and abundant families of materials, combining various minerals and synthetic products.
Examples include fused silica, fumed silica, silica gel, and aerogels.

It is used in structural materials, microelectronics, and components in the food and pharmaceutical industries.

Applications include Ferroelectric, Gate Dielectric, and For CMOS