AVS 47th International Symposium
    Surface Engineering Monday Sessions
       Session SE+TF-MoM

Paper SE+TF-MoM1
Plasma Deposition of Hard and Thermal Resistant Coatings in the System Si-B-C-N

Monday, October 2, 2000, 8:20 am, Room 201

Session: Hard and Superhard Coatings
Presenter: D. Hegemann, Fraunhofer Institute for Interfacial Engineering and Biotechnology, Germany
Authors: D. Hegemann, Fraunhofer Institute for Interfacial Engineering and Biotechnology, Germany
C. Oehr, Fraunhofer Institute for Interfacial Engineering and Biotechnology, Germany
R. Riedel, Technical University Darmstadt, Germany
H. Brunner, Fraunhofer Institute for Interfacial Engineering and Biotechnology, Germany
Correspondent: Click to Email
As a result of covalent bonding, the four elements boron, carbon, nitrogen and silicon can form superhard materials. Considering the well-known diamond-like and cubic boron nitride films, which are limited by their temperature resistance and adhesion, respectively, further research in the as before mentioned system is required. Thus, BCN and SiBCN thin films are very promising candidates which are therefore investigated. A capacitive rf discharge in an asymmetrical but confined geometry is chosen for the deposition experiments to sustain well defined plasma conditions. The bias voltage depending on delivered power and pressure is taken as control parameter. Due to the use of single-source precursors - pyridine borane (PB) and triazaborabicyclodecane (TBBD) for BCN, tris(dimethylamino)silylamino-bis(dimethylamino)borane (TDADB) for SiBCN - relative low substrate temperatures (300°C) can be applied yielding amorphous films. Ar or N@sub 2@ in an excess of 50:1 serves as carrier gas. Both with BCN and SiBCN film deposition, several regimes of different chemical composition become apparent increasing the bias voltage. An influence of the used precursor is merely observed at low biases. At moderate bias voltages films comparable to thermal CVD processes are obtained. Further increasing the bias yields hard coatings up to 13.5 GPa and 30.8 GPa measured by microindentation for BCN and SiBCN, respectively. It is found that the hardness scales mainly with the carbon content of both films, analogously. Annealing the films for 5 h in argon or air exhibits a thermal and oxidation resistance of the SiBCN films exceeding 1200°C. On the other hand, BCN films start to decompose at about 1000°C in argon and 800°C in air. Moreover, the SiBCN films show lower internal stresses (1-2 GPa) compared to BCN, which is attributed to a stabilization effect of sp@super 3@ hybridized carbon by silicon incorporation.