Investigation of laser-annealed antimony implanted Si by ion backscattering and channeling and structure analysis

Rutherford backscattering (RBS), ion channeling and surface studies were done to investigate diffusion of ion implanted Sb in Si. Clean and polished Si was implanted by 190KeV Sb⁺ ions to a dose of 2.3×10¹⁵cm^–2. Laser annealing was carried out by a single 10 J/cm² laser pulse from a Nd: glass (7 ns FWHM) laser. Concentration profiles of Sb as a function of depth and dopant substitutionalities were measured by helium-ion backscattering and channeling. The laser shot resulted in melting of the central portion of the spot. A honey comb type surface morphology was found by SEM analysis. Dektak surface profiles showed a crater of 600 nm depth. One-dimensional heating calculations show that dopant diffusion depths, after consideration of simultaneous evaporation, can be 400 nm, whereas experiments indicate larger depths (1 m). Calculated crater depth is roughly twice the experimental value. Measured depths are much larger than calculated by heat diffusion and indicate that regrowth and distribution of Sb has been modified by convection in the melt. We estimate good substitutionality up to 4 J/cm² and discuss energy density dependence for such high-energy density laser pulses.