Initial nucleation and succeeding coalescence in supercritical fluid deposition (SCFD) of Cu was studied in situ by using our devised monitoring technique, i.e. surface reflectivity measurement of visible white light. Fabrication of 10nm-thick smooth and continuous Cu film required by ULSI metallization, was succeeded. Complete filling without any seems and voids into various via patterns of 50 - 200 nm in diameter and 1 μm in depth was also achieved, which was revealed through angled polishing of patterned substrate.

We study new deposition chemistry in Cu-SCFD (supercritical fluid deposition), especially effect of acetone is investigated as reducing agent and additives into H2 reducing Cu-SCFD. Acetone reduction yields Cu film deposition onto Ru coated Si substrate, because Ru has catalytic effect to generate reducing agent from acetone. When acetone is added into H2 reducing chemistry, the solubility of precursor is enhanced approximately 50 %, which is so-called “entrainer effect”. Ethanol can enhance the deposition of Cu in H2 reduction chemistry, which is a solvent effect. Two effects of entrainer effect by acetone and solvent effect by ethanol works independently, without interfering each other.