Carbon Incorporation into Substitutional Silicon Site by Molecular Carbon Ion Implantation and Recrystallization Annealing as Stress Technique in n-Metal–Oxide–Semiconductor Field-Effect Transistor

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Since the lattice constant of silicon-carbon (Si:C) is smaller than that of Si, Si:C embedded in the source and drain (e-Si:C S/D) can induce tensile stress in the channel and improve the electron mobility of n-metal–oxide–semiconductor field-effect transistor (nMOSFETs). In this research, molecular carbon (C) ion implantation and recrystallization schemes employed to achieve strained Si:C films with a high substitutionally incorporated carbon concentration ([C]sub) and a high ratio of substitution were studied. Several recrystallization techniques including rapid-thermal-annealing (RTA)-based solid phase epitaxy (SPE), spike annealing, and nonmelt laser annealing have been used to optimize C incorporation into Si and strain application. Results of these different implantation and annealing techniques are compared and discussed. Furthermore, we proposed the first recrystallization by nonmelt laser annealing and the co-incorporation of a dopant that increases the rate of Si regrowth and has a covalent radius slightly different from that of Si. These processes markedly promoted the recrystallization of C densely incorporated in an amorphous Si layer and improved the crystallinity of strained Si:C films while maintaining a high [C]sub at a high ratio of substitution.
2010-04-25