Plasma-enhanced atomic layer deposition: Correlating O2 plasma parameters and species to blister formation and conformal film growth

Plasma-enhanced atomic layer deposition has gained a lot of attraction over the past few years. A myriad processes have been reported, several reviews written on this topic, and there is interest for industrial applications. Still, when developing new processes, often heuristic approaches are used, choosing plasma parameters that worked earlier processes. This can result in suboptimal process conditions. In order to rationally decide which use, we systematically studied an inductively coupled RF oxygen source (13.56 MHz) powers up 300 W, pressure range between 10?4 10?2 mbar, flow 10 400 sccm. We discerned chemically active “radical” species (atomic O excited, metastable O2) ionic particles (O2+, O+, O2?, O?), additional physical effect film. Optical emission spectroscopy (OES) was used study generation O2+ region. It shown concentration increases linear way with power atom-to-ion fraction both gas flow. To remote region, near sample position, electrostatic quadrupole analyzer gauge fluxes O2+, O?. Even moderate increase drastically reduce ion flux toward substrate. The formation bubbles or blisters films be linked ion-induced compressive stress, and, hence, it mitigated by pressure. Finally, Al2O3 deposited lateral high-aspect ratio structures investigate partial radical species. Simulated profiles were fitted experimental estimate trends pressure, relationship found. correlated density as observed OES measurements methods presented work also applicable characterize other reactor geometries, sources, mixtures.