Characterisation of CVD Tungsten Deposited by Silane Reduction

摘要

CVD tungsten layers of equal thickness were deposited under various SiH_4/WF_6 ratios and deposition temperatures. It was found that at a constant SiH_4/WF_6 ratio of 1, as the temperature increased, the resistivity of the layer decreased. The layers were found to be highly stress, with the stress decreasing at higher temperatures. The roughness and the average grain size increased as the deposition temperature increased. When the SiH_4/WF_6 ratio was increased at a constant temperature of 450℃, it was found that there was little change in the resistivity until the layer changed from alpha phase to beta phase, at which point the resistivity increased dramatically. The stress of the deposited tungsten layer increased until SiH_4/WF_6 reached a value of 1 then decreased. The roughness and average grain size followed a very similar trend.