Prediction of stochastic behavior in differential charging of nanopatterned dielectric surfaces during plasma processing

We investigate differential charging of high aspect ratio dielectric trenches under plasma exposure using a two-dimensional computational model. Rather than considering average fluxes, we track individual ion and electron trajectories within the electric field arising from surface charges on the trench, updating the potentials within the computational domain after each particle. Our results show that, as the trench width shrinks to 100 nm and below, the potentials within the trench oscillate over an ever-wider range. The stochastic charging behavior in turn leads to noticeable changes in the flux and energies of ions passing through the trench.