Hydrogen plasma chemical cleaning of metallic substrates and silicon wafers

The plasma chemical cleaning process based on an argon-hydro discharge differs from conventional plasma cleaning methods. Chemical reactions are used for the removal of surface contamination and the sputtering of material is avoided. Therefore no problems due to the redeposition of the sputtered material occur. The process chemistry is confirmed by in situ measurements of the plasma during the cleaning procedure using a plasma monitor. The process was investigated for bare copper lead frames and for silicon wafers. Volatile hydrogen compounds were formed during cleaning. An Auger spectrometer was attached to the cleaning chamber to investigate the substrate surfaces after each cleaning step. It was shown that the carbon and oxygen contamination at the substrate surface could be reduced below 0.5 at.% (noise limit of the measurement). The results clearly show that this simple and environmentally friendly process is an effective method for reducing organic and some inorganic contamination.