SIMS analysis of ultrathin implanted arsenic layers in silicon

A new regime of secondary ion mass spectrometry (SIMS) is proposed, which allows a depth resolution of λ=1.4 nm to be achieved. The profiles of arsenic implanted into silicon, measured using this regime on a Cameca IMS-4f microprobe, were close to the true distributions. SIMS profiling of the samples of silicon implanted with 30-keV As+ ions to a total dose of (1.25–3.13)×1013 cm−2 through a 20-nm-thick thermal oxide layer showed the presence of a sharp peak of arsenic accumulated at the oxide/silicon interface, which is explained by the diffusion of arsenic to this interface as a result of annealing.