Internal stress reduction by nitrogen incorporation in hard amorphous carbon thin films

Abstract

Results of a study on internal stress, hardness, and structure of nitrogen-doped amorphous hydrogenated hard carbon films deposited by rf glow discharge from methane-nitrogen mixtures onto silicon substrate are presented. Films obtained for different N2 partial pressures (bias voltage Vb=−370 V and total pressure P=8 Pa) were characterized by infrared spectroscopy, Raman scattering, and nuclear techniques. The elemental composition, density, and structure are correlated with Vickers hardness and internal stress values, obtained from the substrate bending method. It has been observed that internal stress considerably decreases with increasing nitrogen content, in contrast to hardness, structure, and hydrogen concentration, which remain unchanged.

Influence of precursor gases on the structure of plasma deposited amorphous hydrogenated carbon–nitrogen films

“…8 Previous results on a-C͑N͒:H films 9 allude to an increase in the graphitic clustering (sp 2 bonding͒ upon nitrogen incorporation, which may be correlated to the observed internal stress reduction. 5 A similar reduction in stress is observed for highly tetrahedral C:N films 10,11 in which nitrogen incorporation above 1 at. % resulted in both stress reduction and increase in the sp 2 carbon fraction.…”

“…Research into the search for the proposed ␤-C 3 N 4 phase, which is predicted to be harder than diamond was initiated by Liu and Cohen. 1 As a result of nitrogen incorporation into carbon films it was found that both optical and electrical properties, 2-4 as well as their mechanical properties [5][6][7] can be modified. Particularly with respect to the mechanical properties, it was found that nitrogen incorporation results in a substantial reduction of the compressive internal stress of the films.…”

“…%. 2,3,[5][6][7]16,17 The hydrogen content as well as the atomic density show different behavior for the two series of samples. For the same amount of incorporated nitrogen, the hydrogen content is higher for the NH 3 -derived films.…”

Mechanical Properties of Amorphous Hard Carbon Films Prepared by Cathodic ARC Deposition

“…The stress in very hard amorphous carbon films can reach high values, larger than 10 GPa I1 11. Reducing the stress and containing the hardness at the same time was possible only by introducing additional chemical elements in the films as has been described for nitrogen incorporation [22]. The formation of multilayers offers an interesting alternative.…”

Tribological Characteristics of Diamond-Like Carbon Based Double-Layers Film Prepared by DC-Plasma Ionization Deposition

“…Some researchers successfully improved the durability through the reduction of the internal stress [7][8][9], although, a decrease of hardness was accompanied with it due to the coexistence of ductile metals.…”