Plasma Diagnostics in Pulsed Plasma Doping (P<tex>$^2$</tex>LAD) System

Abstract

As semiconductor devices continue to shrink in size, demands for the formation of ultra-shallow junctions (USJ) are increasing. Pulsed plasma doping (P/sup 2/LAD) 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 P/sup 2/LAD, a pulsed plasma is generated adjacent to the silicon wafer using pulsed biases. Typical pulse widths range between 5 and 50 /spl mu/s, 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 BF/sub 3/ plasmas. Ion mass and energy analysis indicated that BF/sub 2//sup +/ is the dominant ion species in the BF/sub 3/ plasmas, with BF/sup +/ as the second-most abundant ion species.