THE PHOTOLYTIC LASER CHEMICAL VAPOR-DEPOSITION RATE OF PLATINUM, ITS DEPENDENCE ON WAVELENGTH, PRECURSOR VAPOR-PRESSURE, LIGHT-INTENSITY, AND LASER-BEAM DIAMETER

The rate of photolytic laser chemical vapor deposition (LCVD) of platinum from its bishexafluoroacetylacetonate precursor is measured as a function of the light intensity, the wavelength, the precursor pressure, and the laser beam diameter at the surface. The wavelength dependence of the deposition rate indicates that the photodissociation yield does not depend only on the absorption coefficient of the precursor, but may differ from one absorption band to another. This is indicative of the different photophysical processes associated with different absorption bands. Changing the precursor pressure strongly influences "gas-phase" LCVD, and hardly influences "adlayer" LCVD at the applied conditions. Effective quantum yields for the LCVD process are calculated using simple models for photolysis in the gas phase and in the adlayer. The magnitude of these quantum yields, as well as their dependence on light intensity and precursor vapor pressure is compared with experiment. A simple model is used to estimate the height above the surface which contributes effectively to gas-phase LCVD. © 1990.