Computer Simulation of Metal Ions Transport to Uneven Substrates during Ionized Plasma Vapour Deposition

Abstract

We present a computational study of processes taking place in a sheath region formed near a negatively biased uneven substrate during ionized plasma vapour deposition. The sputtered metal atoms are ionized on their way to substrate and they are accelerated in the sheath near the substrate. They are able to penetrate to high-aspect-ratio structures, for example, trenches, which can be, therefore, effectively coated. The main technique used was a two-dimensional particle simulation. The results of our model predict the energy and angular distributions of impinging ions in low-pressure conditions which are characteristic for this method and where typical continuous models fail due to unfulfilled assumptions. Input bulk plasma properties were computed by a "zero dimensional" global model which took into account more physical processes important on a scale of the whole magnetron chamber. Output parameters, such as electrostatic potential, energy of ions, and ion fluxes, were computed for wide range of conditions (electron density and substrate bias) to show the influence of these conditions on observed phenomena, penetration of sheath inside the trench, deceleration of argon and copper ions inside the trench, and local maxima of ion fluxes near the trench opening.