Characterization of Silane‐Reduced Tungsten Films Grown by CVD as a Function of Si Content

Tungsten (W) films grown by low‐pressure chemical vapor deposition using tungsten hexafluoride and silane are characterized as a function of the Si content ([Si]) in the films. The electrical resistance, stress, and composition of as‐deposited films showed a strong dependence on [Si] and could be classified into three groups: , , and . When , the electrical resistance is approximately proportional to [Si], and is mainly determined by impurity scattering of Si. In this [Si] region, W can be selectively deposited on Si. When , the temperature dependence of electrical resistance is characteristic of semiconductors, and a substantial increase in superconducting transition temperature is observed. When , microcrystals of begin to form. These results are discussed in terms of a model based on the solubility of Si in W.