Investigation of boron implantation into silicon by quantitative energy-filtered transmission electron microscopy

High-resolution electron microscopy (HREM), chemical mapping by energy-filtered transmission electron microscopy (EFTEM), electron energy-loss spectroscopy (EELS) and energy-loss spectroscopic profiling (ELSP), also called spectroscopic transverse image profiling by EFTEM (stripeTEM) have been combined to study the distribution of boron after implantation into silicon at low energy (0.5keV) and rapid thermal annealing. The key to the experiments is that stripeTEM combines both ∼1nm spatial resolution and sub-at% sensitivity. It is shown that the near-surface spike of boron visible in secondary ion mass spectrometry (SIMS) profiles is an artefact of surface profiling. The real distribution of boron is several nm deeper into the specimen, in agreement with both Monte Carlo simulations and shoulders apparent in the SIMS profile. Quantification of the experimental stripeTEM data shows that the B concentration is approximately ∼2at% in the SiO2 and ∼4at% in the Si, with statistical errors of about ±0.2at% due to noise and background fitting and systematic errors of ±0.6at% due to uncertainties in the scattering cross-sections.