Millisecond Annealing for Semiconductor Device Applications

Abstract

AbstractOver the last decade millisecond annealing (MSA) has made the transition from a research tool to a key manufacturing technology for advanced complementary metal-oxide-semiconductor (CMOS) devices. MSA provides several unique process capabilities that have been very helpful for continued scaling of CMOS. One early application was for improving carrier activation in polysilicon gate electrodes, which reduces carrier depletion effects, providing increased gate capacitance. MSA also enables the formation of highly activated ultra-shallow junctions (USJ), which is essential for controlling short-channel effects while simultaneously minimizing the transistor’s parasitic resistance. New applications have emerged in silicide annealing, especially for NiSi contacts, where MSA can reduce the tendency for dopant deactivation, film agglomeration and for formation of “pipe defects”. As device scaling continues, the need to limit atomic diffusion and defect formation calls for ever-decreasing thermal budget, opening up new opportunities for MSA. Furthermore, the processing has to be compatible with new materials, including high-K dielectrics and metal gates, as well as the features needed for strain engineering and new channel materials. Millisecond annealing is usually performed through the use of pulsed high-power flash-lamps or scanned continuous wave laser beams. The paper describes the relative merits of these approaches, including flash-assisted RTP™ (fRTP™), where rapid wafer preheating is combined with pulsed surface heating to provide great flexibility in the design of thermal profiles. Such flexibility helps optimization in the trade-off between between dopant activation, diffusion, defect annealing and device integration requirements. Another important topic is process control, including issues of wafer temperature measurement and process uniformity. Finally the paper discusses emerging applications for millisecond annealing as a manufacturing technology for new types of semiconductor devices.KeywordsRapid Thermal AnnealingLaser AnnealingThermal BudgetCMOS DeviceSolid Phase EpitaxyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.