Rapid Thermal Processing (RTP) has been a key technology for semiconductor manufacturing. The ability to rapidly change wafer-processing temperature in a well-controlled way is a distinguishing characteristic of RTP. Today’s state of the art single wafer RTP equipment is used for a wide range of thermal processes for the manufacturing of advanced semiconductor devices. Two different designs of halogen lamp based RTP equipment dominate the applications. The two equipment designs can be traced back to the early development of the semiconductor industry before there was wide acceptance of RTP. Two junctures in the evolutions of these designs resulted in the growth of RTP. The first juncture occurred when the conventional batch diffusion furnace could not satisfy some of the thermal budget and ambient control process requirements for semiconductor devices. A second juncture occurred with breakthrough developments in RTP equipment that enabled better control and repeatability of the process temperature. Developments of alternatives to tungsten halogen lamp based RTP will likely be seen in the future.