Diagnostics of plasma for metal-organic chemical vapour deposition of Cu and fabrication of Cu thin films using the plasma

Effects of hydrogen dilution on properties of Cu films deposited using the metal-organic plasma chemical vapour deposition method were examined. On increasing the H₂ dilution from 70 to 88%, the Cu concentration and gram size of the films increase from about 75 to 99% and from about 10 nm to above 100 nm respectively; also their resistivity decreases concomitantly to about 2 μΩ cm. Films of high quality are obtained in the high H₂ dilution range above 80% H₂, for which the emission intensity of H is high, suggesting that hydrogen atoms may play an important role in eliminating impurities from the films. The density of Cu atoms in the plasma measured by a light-absorption method is of the order of 10⁹ cm^-3, which is lower by two orders of magnitude than the density necessary to explain the deposition rate of 5 nm min^-1 typical in our experiments.