KINETICS OF LASER-ASSISTED CHEMICAL VAPOR-DEPOSITION OF TUNGSTEN MICROSTRUCTURES

Tungsten microstructures (dots, strips and films) have been deposited via H-2 reduction of WF6 on polycrystalline silicon-coated quartz substrates irradiated with a focused cw argon laser beam. The deposition rate of W dots, deduced from alpha-step measurements of the height of dots, was investigated as a function of irradiation time, composition of H-2-WF6 gas mixtures and laser-induced surface temperature. At a laser-induced surface temperature ranging from 340-degrees to 670-degrees-C with an H-2 partial pressure varying from 50 to 700 Torr, the reaction order with respect to H-2 was equal to one-half, whereas at higher temperatures (750-degrees-950-degrees-C) and lower H-2 partial pressures (20-80 Torr), the reaction order with respect to H-2 was found to be one. The reaction mechanism of the H-2 reduction of WF6 on substrates irradiated with the argon laser beam is discussed.