A Novel Method For Determining Kinetic Rate Expressions During CVD Using a Combination of Step Coverage Measurements and Computer Simulation

摘要

While CVD tungsten remains an important film in IC manufacturing, there is still some debate of its rate mechanism. For instance, at high WF_6 flows, is the rate limiting step the dissociation of hydrogen or the desorption of HF? This question is difficult to answer because the gas concentrations near the wafer surface are generally unknown. In this paper, a method for distinguishing between competing mechanisms is suggested, based on using sticking coefficient data. The method is applied to the case of hydrogen reduced tungsten where it is found that HF desorption is is the rate limiting step at high WF_6 flows. At low flows the rate limiting step is WF_6 adsorption.