Kinetics of the initial stages of film formation during low pressure chemical vapour deposition of polysilicon by pyrolysis of silane

A kinetic model for description of the process of silicon film formation on silica by thermal decomposition of silane at reduced pressure has been proposed. The model is based on the concept of kinetic interdependence between heterogeneous catalytic chemical reaction and fundamental structure forming phenomena - nucleation and nuclei growth. A number of experimental data for deposition rates and polysilicon grains sizes have been mathematically processed in order to derive kinetic equations for the rates of nucleation and nuclei growth as functions of reactor operating conditions (pressure and temperature) as well as process duration. Furthermore, based on both the good correspondence achieved between the experimental results and the model, and the deductions of thermodynamic theory of nucleation, the kinetic equations derived were analysed in regard to the general description of silicon film structure evolution. The analysis of the model, by confïrming the general trends established between the arrival and the surface diffusion rates of silicon adspecies, contributes to clarify the mechanism of the initial stages of film microstructure formation. The results obtained show that kinetics of structure evolution can be successfully described by developing the existing CVD phenomenological kinetic models further to an atomistic level

Low pressure chemical vapour deposition of CNx layers by interaction between tetramethylguanidine and cyanurchloride

Possibilities are demonstrated for synthesis of CNx layers in a LPCVD reactor, using liquid and solid state source organic compounds. The influence of pressure and deposition temperature on the composition, structure and physico-chemical properties of the films is investigated. It is found that at a temperature range of 400 +600 °C, the layers obtained are transparent, colored on silicon, with good adhesion, homogeneous in morphology and uniform in thickness. Peculiar features of coatings are their amorphous nature, nitrogen to carbon relation 0.76 as well as possible hydrogen incorporation