DEPOSITION OF MICRON-SIZE NICKEL LINES BY ARGON-ION LASER-ASSISTED DECOMPOSITION OF NICKEL TETRACARBONYL

Nickel lines were deposited from the decomposition of Ni(CO)4 on silicon/silicon-dioxide/silicon substrates locally heated by means of a focused CW argon-ion laser operating at several wavelengths around 0.5 mum. Growth kinetics, morphology and electrical resistivity of the nickel microstructures were investigated at various scanning speeds of the laser Spot, laser beam powers and reactant gas pressures. Nickel lines as small as 1 mum in width were written. From the growth kinetics, the vertical deposition rate of nickel can be calculated. At low Ni(CO)4 pressures, typically below 0.3 mbar, deposition of flat-topped nickel lines occurs. The deposition rate is proportional to the Ni(CO)4 pressure and independent of the laser-induced temperature. At reactant gas pressures above 0.3 mbar, Gaussian nickel lines are obtained. The deposition rate is found to be independent of the Ni(CO)4 pressure and exhibits an activation energy of about 11.5 kcal mol-1. The measured electrical resistivity of the flat-topped lines is about 10 times higher than the bulk resistivity (7 muOMEGA . cm) while in the Gaussian regime this ratio falls below 1.5. The morphology and roughness of the deposited lines were investigated using both a scanning electron microscope (SEM) and an atomic force microscope (AFM). In the flat-topped regime, grains of about 100 nm are observed at the top of the nickel lines while in the Gaussian regime the surface is smooth.