Study of pulsed plasma doping by Langmuir probe diagnostics and ion mass-energy analyzer

Summary form only given. Pulsed plasma diagnostics in a plasma doping system for semiconductor device fabrication have been carried out. Pulsed plasma was generated adjacent to the silicon wafer using pulsed biases. The source gases were BF/sub 3/ and N/sub 2/. An ion mass and energy analyzer was mounted with a small aperture open to the plasma. Bias voltages between 0 and -5.0 kV were applied to the aperture to measure the ion species and ion energy distribution during the plasma doping. Time-resolved Langmuir probe measurements were used to determine the doping plasma conditions such as plasma density and electron temperature. Preliminary ion mass analysis results show that BF/sup 2+/ is the dominant ion species in the BF/sub 3/ plasmas, and BF/sup +/ is the second most abundant dopant species. The time-resolved Langmuir probe data indicate that during a 20 ps long implant pulse the plasma density is in the order of 10/sup 8/ - 10/sup 10/ cm/sup -3/ and the electron temperature is 2-15 eV. Between the pulses, the density decays exponentially at first and then reaches a non-zero value, which demonstrates the existence of residual plasma between pulses. The effects of electron beams, primary electron bombardment, secondary electron emission, and the fast decay of electron temperature during the afterglow period were observed. Increase of plasma density with cathode voltage and pressure, and decay with time were also observed.