1György Hárs,1Hajnalka Csorbai, 1Péter Deák
2István Bársony, 2Csaba Dücső
1TU Budapest Surface Physics Laboratory
2HASI Research Institute for Technical Physics and Materials Science
The excellent mechanical and optical properties of diamond are well known but it shows extremely high dielectric breakdown, thermal conductivity and electron emissivity as well. In addition, diamond withstands any acid base or organic solvent up to ? 700°C. Chemical vapor deposition (CVD) of adherent polycristalline diamond films made practical applications economically feasible, but only in cases where coverage of small surfaces provide high added value. Such a possibility is the application of CVD diamond in micromachined silicon based sensors for highly corrosive environment. Diamond CVD is compatible this technology. The work carried out by the TUB and the RITPMS in this field will be presented.
Present work is intended to study
the dependence of the homogeneity, the contamination state and the
appearance of pinholes on various deposition parameters in diamond
films deposited on monocrystalline and polycrystalline substrates.
Such deposition parameters are the nucleation and the growing
temperature in the ranges of 850-950°C and
The compactness of diamond film on silicon monocrystalline substrate can readily be examined by means of chemical etching with basic solution. Regular rectangular etch patterns appear on the spots of the pinholes due to the anisotropy of Basic etching in (100) orientation crystal. These rectangles can readily be studied and counted by means of optical microscope.
The objective of the experiments is to find the technology of manufacturing graphite free diamond films with a pinhole density less than one in ten square centimetres. This can be used as an efficient chemical and mechanical protective coating on some micro sensor elements with surface area of 0,1-30 mm2, operating in extreme harsh environments.
This work is sponsored by OTKA # TT 025346
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