Evolution of implanted carbon in silicon upon pulsed excimer laser annealing: epitaxial Si1−yCy alloy formation and SiC precipitation

Formation of epitaxial Si1−yCy alloy layers on monocrystalline silicon surfaces with y≈1 at% is reported. The preparation method was carbon ion implantation, followed by KrF excimer laser annealing in air. Results of Rutherford backscattering (RBS) measurements, secondary ion mass spectrometry (SIMS), Raman spectroscopy, infrared (IR) absorption analysis, and transmission electron microscopy (TEM) are compared. The evolution of the implanted carbon was affected by the implantation conditions, i.e., implantation energies, ion current, and implanted ion distribution (single-energy versus flat profile implantation), as well as by the laser annealing parameters. Up to approximately 1 at% carbon content, the dominant process was nonequilibrium trapping of carbon atoms in substitutional lattice sites upon fast resolidification, allowing perfect epitaxial recovery of the crystal lattice by laser annealing. Above this concentration, silicon carbide precipitates were formed, embedded into an otherwise well-ordered substitutional Si–C alloy matrix. Upon multipulse processing, the complex carbon redistribution processes were influenced by trapping of carbon in SiC precipitates, dissolution of SiC in the melt and segregation effects in the near-surface region.