In semiconductor manufacturing, silicon on insulator (SOI) technology is fabrication of silicon semiconductor devices in a layered silicon–insulator–silicon substrate, to reduce parasitic capacitance within the device, thereby improving performance. SOI-based devices differ from conventional silicon-built devices in that the silicon junction is above an electrical insulator, typically silicon dioxide or sapphire (these types of devices are called silicon on sapphire, or SOS). The choice of insulator depends largely on intended application, with sapphire being used for high-performance radio frequency (RF) and radiation-sensitive applications, and silicon dioxide for diminished short-channel effects in other microelectronics devices. The insulating layer and topmost silicon layer also vary widely with application. Industry need SOI technology is one of several manufacturing strategies to allow the continued miniaturization of microelectronic devices, colloquially referred to as "extending Moore's Law" (or "More Moore", abbreviated "MM"). Reported benefits of SOI relative to conventional silicon (bulk CMOS) processing include: Lower parasitic capacitance due to isolation from the bulk silicon, which improves power consumption at matched performance Resistance to latchup due to complete isolation of the n- and p-well structures Higher performance at equivalent VDD. Can work at low VDD's Reduced temperature dependency due to no doping Better yield due to high density, better wafer utilization Reduced antenna issues No body or well taps are needed Lower leakage currents due to isolation thus higher power efficiency Inherently radiation hardened (resistant to soft errors), reducing the need for redundancy From a manufacturing perspective, SOI substrates are compatible with most conventional fabrication processes. In general, an SOI-based process may be implemented without special equipment or significant retooling of an existing factory. Among challenges unique to SOI are novel metrology requirements to account for the buried oxide layer and concerns about differential stress in the topmost silicon layer. The threshold voltage of the transistor depends on the history of operation and applied voltage to it, thus making modeling harder. The primary barrier to SOI implementation is the drastic increase in substrate cost, which contributes an estimated 10–15% increase to total manufacturing costs. SOI transistors An SOI MOSFET is a metal–oxide–semiconductor field-effect transistor (MOSFET) device in which a semiconductor layer such as silicon or germanium is formed on an insulator layer which may be a buried oxide (BOX) layer formed in a semiconductor substrate. SOI MOSFET devices are adapted for use by the computer industry. The buried oxide layer can be used in SRAM designs. There