INVESTIGATIONS ON PLASMA-ASSISTED SURFACE CLEANING OF ALUMINUM CONTAMINATED WITH LUBRICANTS

Aluminum and silicon plates contaminated with hydrocarbon-containing l ubricants were treated with Ar, O-2 and H-2 plasma at different discha rge modes (d.c.: anomalous glow regime, hollow cathode regime, r.f., a nd silent discharge). During the plasma process the discharge was moni tored by means of optical emission spectroscopy. Simultaneously, the r emoval of the contamination layers was observed by means of in situ el lipsometry. The temporal change of the spectral line intensities and o f the ellipsometric parameters psi and Delta during the cleaning proce ss were taken as a measure for the state of the surface. Because the t hermal stress of the material is an important parameter in technologic al application, the energy inflow towards the substrate surface during plasma treatment has also been studied carefully.