We measured electrical and plasma properties of a deep reactive ion etching Bosch process (Ar/SF6/C4F8) used for micromachining bulk silicon. The plasma-potential oscillations were measured by a glass-enclosed capacitive probe immersed in the plasma. We used rf-potential and current sensors installed at the output of the chuck's matching network and a calibrated equivalent circuit model to compute the chuck potential wave form. The plasma density and electron temperature were measured using a floating Langmuir double probe. Time-resolved measurements were made throughout the etch and deposition cycles of the Bosch process. Plasma densities in the reactor were quite nonuniform, with plasma densities close to the wafer chuck being more than a factor of 4 lower than densities in the center of the "bulk plasma" formed by the induction coil. Estimates of the ion energy distribution were obtained from a validated numerical model that employed the experimental data. For standard process conditions during the main etch part of the cycle, the chuck potential oscillations were in excess of 100 V-PP, but, because of the low plasma density near the wafer (>2 x 10(10) cm(-3)) and potential averaging across the resulting large sheath. width (600 mum), the width of the calculated argon ion energy distribution (IED) was. only 25 eV, for a double peaked IED centered about 80 eV The influence of rf-bias, plasma density,. and ion mass on the IEDs were also investigated. (C) 2003 American Vacuum Society.