Effect of image force on ion current density in plasma discharges

Ion current density at the bottom of narrow trenches has been calculated with a Monte Carlo method. It is found that in etching subquarter-micron trenches, the image force between the incident ions and the walls of the etched trench causes appreciable ion fluxes to the sidewalls and contributes to deviations from ideal etching anisotropy. The effect of the image force is particularly important in plasma etching discharges, which are characterized by low ion energies.