Glow Discharge Sheath Electric Fields: Negative Ion, Power, and Frequency Effects.

For applications of plasmas to materials processing, e.g. thin film etching and deposition, the sheath, or boundary layer between the plasma and the surface, is of paramount importance. Ion and electron modification of deposition rates, etching rates, and electronic properties is a function of the charged particle energy and flux, which is governed by the shape and magnitude of the sheath electric field. Sheath electric fields in discharges through BCl sub 3 and Ar are measured in situ and non-intrusively as a function of concentration, power density (0.14 to 0.41 W cm sup -3), and frequency (dc to 10 MHz). Space-time color contour maps of the sheath electric field show double layers and oscillations resulting from non-linear ion and electron kinetics. These maps should prove useful as input for particle transport simulations and as tests for self- consistent sheath theories.