CHEMICAL-VAPOR-DEPOSITION OF THICK TUNGSTEN COATINGS - MASS-TRANSPORTMODELING AND EXPERIMENTS

Thick tungsten coatings have been produced by chemical vapor depositio n (CVD) from H-2-WF6 at a temperature in the range 773-1073 K under a reduced pressure. The experimental set-up was designed for in situ Ram an analysis of the gas phase (temperature and WF6 concentration) durin g the growth of tungsten coatings. A two dimensional mass transport mo del was proposed. It assumes a simple chemical pathway. Only the H-2 r eduction of WF6 on the substrate was taken into account. The major obj ective of the present paper is to report on (i) the experimental depos ition rates and the rate values calculated by the model, (ii) the valu es of temperature and gas phase composition deduced from Raman spectro scopy measurements and the values of these quantities obtained by nume rical calculations. Within the range of process parameters investigate d, the predictive capabilities of the numerical modelling are demonstr ated; in addition the temperature and WF6 partial pressure measurement s can be recorded by a Raman equipment during the deposition process.