Thin film deposition with hot-filament activated CVD

The activation of low pressure gas phases by hot filaments for chemical vapour deposition (CVD) of thin films differs considerably from that of plasma activation. The absence of electric fields and energetic particles in the case of hot filament CVD avoids any physical impact thereby resulting in gentle and conformal processes. Thus hot-filament CVD processes can also be applied to sensitive and structured substrates, respectively. We report on hot-filament CVD equipment for deposition areas of up to 0.5 m by 1.0 m and for 3-dimensional film deposition. Additionally, deposition processes for polycrystalline diamond and for silicon and silicon nitride coatings are presented. Equipment and process development are discussed in the light of applications in such different fields as tools and wear parts, electrochemistry and electronics. The technology has been transferred to industry for CVD diamond tools, for the production of diamond-coated electrodes for electrochemistry and for diamond-coated ceramic face seals. Currently we are focussing on deposition rates, deposition uniformity and material properties of amorphous silicon, nanocrystalline silicon and silicon nitride films deposited on glass, silicon and polymers for different purposes. The results of these investigations are promising to enable large-area hotfilament CVD processes for new fields of applications such as insulating films and diffusion barrier coatings