Rapid thermal annealing of shallow Sb-implanted Si

Abstract

Rapid thermal annealing (RTA) of low-energy Sb-implanted Si has been studied with Rutherford backscattering spectrometry (RBS) and sheet-resistance measurements. For comparison, some samples were also analyzed with secondary ion mass spectrometry (SIMS). Si wafers were implanted with Sb at energies of 16, 32, and 48 keV and doses of 5×1014 and 1×1015/cm2. Samples were annealed in a nitrogen atmosphere with an AG Associates 410 Heatpulse system. RTA cycles ranged from 10 to 30 s at temperatures of 1000–1150 °C. Some samples were furnace annealed at 930 °C for 30 min. RBS experimental mean projected range and range straggle values did not differ significantly from trim code calculations. However, SIMS experimental range straggle values were ∼30% greater than RBS values. With RBS, a broadening of the Sb depth distribution and Sb accumulation in the near-surface region (<5 nm) were observed for furnace-annealed samples and, to a lesser extent, for those subjected to RTA. The relative retained SB dose decreased as RTA temperature and/or time increased. No loss of Sb was observed for furnace-annealed samples. For a dose of 5×1014/cm2, lower sheet-resistance values were obtained following RTA of a 32-keV Sb implant compared to a 30-keV As implant. The opposite was true for a dose of 1×1015/cm2.