Characterisation of copper thin films deposited on machinable glass-ceramic and glass by DC magnetron sputtering

Thin film metallisation of machinable glass-ceramic is a technique used for industrial applications. Data of copper thin films on machinable glass-ceramic, realised by using a magnetron sputtering system in an extensive pressure range, are uncommon. Aim of this study is to obtain and analyse these data, and to use as comparison the same copper depositions performed on glass. Surface analyses of materials used as substrates have been performed, and treatments prior to depositions are reported. Films with thicknesses of some hundreds of nanometres have been obtained by DC magnetron sputtering, varying the gas discharge pressure in the range 0.13-6.6 Pa. The films have been analysed, and the mechanical and structural data have been determined by profilometer, X-ray diffraction and atomic force measurements, whereas electrical resistivity has been derived from sheet resistance measurement. The analyses have shown that the films obtained on glass and machinable glass-ceramic have similar structural (crystallite sizes and preferred orientation) and electrical (resistivity) characteristics. The resistivity data obtained from coatings realised at the highest pressures present an increase of more than one order of magnitude with respect to the values measured at the lowest pressures, and this result may be related to film 'intra-grain' size effect.