Low temperature metalorganic chemical vapor deposition of conformal silver coatings for applications in high aspect ratio structures

A low temperature metalorganic chemical vapor deposition process has been developed for the growth of conformal silver coatings for applications in reflective mirror arrays, computer chip metallization, and superconducting wire and cable technologies. The process employed the silver source precursor Ag(COD)hfac, where COD=1,5-cyclooctadiene and hfac=1,1,1,5,5,5-hexafluoro 2,4-pentanedionate. Silver films were deposited at wafer temperature, source temperature, and processing pressure in the range of, respectively, 160–240 °C, 80–150 °C, and 0.5–5 Torr. Experiments were carried out in the presence of either argon or hydrogen as coreactant. The resulting films were characterized by Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, x-ray diffraction, and cross-section scanning electron microscopy. These investigations indicated that the silver films were pure, highly specular, and exhibited excellent conformality in 180 nm wide trench structures with 7:1 aspect rati