AbstractThe reaction mechanism of blanket chemical vapor deposition of WSixfrom WF6/Si2H6mixture was modeled based on the data of a tubular reactor. In this reaction, film deposition is initiated by radical chain reaction and the silicon concentration in the film can be increased easily. The model is as follows. During radical chain reaction, reaction between WF6and Si2H6takes place, Si‐rich intermediary product with Si/W = 2 is formed and reaction between the product and Si2H6causes an increase of Si concentration. The Si concentration profile in the film in the reactor could be simulated by using the reaction speed constant as a fitting parameter and the validity of this model was confirmed. The activation energy of this reaction was 23.5 kJ/mol. Using this model, the Si concentration in the film formed in the substrate‐heating‐type reactor could be pred