Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuits (ICs) such as microprocessors, microcontrollers, and memories. It is a multiple-step photolithographic and physico-chemical process, with steps such as thermal oxidation, thin-film deposition, ion implantation, and etching, during which electronic circuits are gradually created on a wafer, typically made of pure single-crystal semiconducting material. Silicon is almost always used, but various compound semiconductors are used for specialized applications. Steps such as etching and photolithography can be used to manufacture other devices, such as LCD and OLED displays.