Semiconductors are made in a very clean environment, and some processes are carried out in a vacuum. For example, many semiconductor components, such as optical disc drives (CD, VCD and DVD) and semiconductor lasers used in optical fiber communication, microwave integrated circuits used in radar or satellite communication equipment, and even many ordinary microelectronic integrated circuits, have a big part of the manufacturing process carried out in a vacuum chamber. The better the vacuum class, the better the performance of the device.