[en] The Chemical Vapor Deposition (CVD) of refractory metals from hexacarbonyl and halide sources is described; arguments for and against the use of solid sources are discussed. Constraints imposed on the gas manifold system are evaluated and approaches to obtain reproducible mass flows are described. The deposition of W and Mo from their hexacarbonyls in a hotwall LPCVD environment is presented in detail. As-deposited films are found to be amorphous and incorporate appreciable amounts of carbon and oxygen. Crystallization in subsequent anneal steps drastically reduces the impurity content and results in smooth films of near bulk resistivity