Plasma diagnostics in pulsed plasma doping (P2LAD) system

As semiconductor devices continue to shrink in size, demands for the formation of ultra-shallow junctions (USJ) are increasing. Pulsed plasma doping (P²LAD) has emerged as a scaleable and cost effective solution to dopant delivery, since it is capable of high dose rates at ultra-low energies (0.02-20 kV). In P²LAD, a pulsed plasma is generated adjacent to the silicon wafer using pulsed biases. Typical pulse widths range between 5 and 50 μs, and pulse repetition rates are between 100 and 10000 Hz. Time-resolved Langmuir probe measurements showed that cold plasma is present during the afterglow period, which may play an important role in process control. Probe measurements also showed the presence of primary electron and electron beams during the initial pulse-on stage in both Ar and BF₃ plasmas. Ion mass and energy analysis indicated that BF₂⁺ is the dominant ion species in the BF₃ plasmas, with BF⁺ as the second-most abundant ion species.