In general, a chemical compound of an element with oxygen. In particular, short for silicon dioxide (silica). It is the most widely used insulating and/or passivating material in the construction of devices, components, and integrated circuits fabricated in silicon. Silicon dioxide can be readily grown on the surface of silicon and layers of varying thicknesses are grown during the fabrication of silicon devices and circuits.

Oxide acts as a barrier to the diffusion of impurities into the substrate material and is used as an ‘on-chip’ mask during the planar process. A thin oxide layer is used to form the insulator in the manufacture of MOS devices, such as MOSFETs and charge-coupled devices. An extra thick oxide layer can be formed by means of the coplanar process in order to prevent spurious MOST formation. A layer of oxide is formed over both bipolar and MOS integrated circuits and devices for passivation of the surface.