Common deposition techniques for the metallization of ultra-large scale integrated circuits utilizes vapor (physical/chemical vapor deposition) or liquid (e.g. electro-chemical deposition). This paper reports the use of supercritical CO2 fluids as a new medium for depositing Cu thin films, where Cu is grown from a metalorganic precursor dissolved in the fluid. Hexafluoroacetylacetnatecopper (Cu-II (hfac)(2)) was used as the precursor, and depositions were carried out at pressures of 10-15 MPa and temperatures of 180-400 degrees C. We observed preferential growth of Cu on conductive substrates, a lower deposition temperature of 180 degrees C by about 100 degrees C than typical values reported for Cu chemical vapor deposition from Cu-II (hfac)(2). The temperature dependence of the deposition rate was further studied and the activation energy for the growth was determined at 0.42 +/- 0.12 eV Basic film characterization was also performed; X-ray photoelectron spectra of the films showed pronounced metallic Cu. peaks and trace level of impurity elements, and X-ray diffractometry showed (111) film texturing. Copper filling into nano high-aspect-ratio features was also demonstrated. Finally, a critical role of the solvent capability of supercritical CO2 on the film quality was discussed with comparative depositions using supercritical Ar. (c) 2005 Elsevier B.V All rights reserved.