The effect of topographical local charging on the etching of deep-submicron structures in SiO2 as a function of aspect ratio

Physical and electrical influences on plasma etching on the inside of a mic rotrench in SiO2 were numerically investigated using Monte Carlo simulation of ions and electrons with the aid of surface charge continuity and Poisso n's equation. When the aspect ratio is greater than seven, the bottom is ch arged up to a potential sufficient to prevent the influence of all the inci dent ions, with a realistic initial energy of 300 eV for SiO2 etching withi n the period required for monolayer stripping, resulting in etch stop. The cause of etch stop is purely the result of the electrical local charging du e to the topography of the trench, and of the initial conditions for incide nt charged particles. The etch stop caused by a cw plasma will be disorgani zed or prevented within a short time by the aid of ion-ion plasma in an aft erglow phase. (C) 2001 American Institute of Physics.