Rapid thermal processing  ( RTP ) is a  semiconductor,  manufacturing process that heats silicon wafers to high temperatures (over 1,000 °C) on a timescale of several seconds or less. During cooling, however, wafer temperatures must be brought down slowly to prevent dislocations and wafer breakage due to thermal shock. Such rapid heating rates are often attained by high intensity lamps or lasers. These processes are used for a wide variety of applications in  semiconductor  manufacturing including  dopant activation ,  thermal oxidation , metal reflow and chemical vapor deposition One of the key challenges in rapid thermal processing is accurate measurement and control of the wafer temperature. Monitoring the ambient with a thermocouple has only recently become feasible, in that the high temperature ramp rates prevent the wafer from coming to  thermal equilibrium  with the process chamber. One temperature control strategy involves  in situ   pyrometry  to effect real time control. Used for melting iron for welding purposes