Real time optical profilometry as a probe of rates of laser-induced chemical vapor deposition

Abstract

An optical method for the measurement of rates of laser induced chemical vapor deposition processes is described. Vertical growth rates are obtained from measurements of the power attenuation by a growing deposit of a probe beam of known diameter directed parallel to the substrate and intersecting the axis of the deposit. A theoretical analysis is presented that relates the growth rate of deposits with various geometries to the attenuation of the probe beam as a function of time and the probe laser beam diameter. The method can be used to obtain growth rates for deposits as small as a few μm in height, as long as the surface of the deposit is smooth relative to the diameter of the probe beam. The method is used to determine rates of photothermal gold deposition as a function of gold precursor partial pressure. Measured deposition rates ranged from 0.2 to 5.5 μm/s for dimethyl gold hexafluoroacetylacetonate partial pressures from 0.03 to 0.62 Torr.