Sputter deposition of nanocrystalline b-SiC films and molecular dynamics simulations of the sputter process

C. Ziebert¹, J. Ye¹, S. Ulrich¹, A. Prskalo², S. Schmauder²

¹ Institute for Materials Research I, Forschungszentrum Karlsruhe, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

² Institute for Materials Testing, Materials Science and Strength of Materials (IMWF), University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany

Thin nanocrystalline films of silicon carbide (SiC) have been deposited on Si and hard metal substrates by rf magnetron sputtering in Ar atmosphere. In parallel molecular dynamics simulations of the sputtering of b-SiC by Ar atoms were performed using IMD and Materials Explorer software with a combination of the Tersoff and the Ziegler-Biersack-Littmark (ZBL) potential in order to get more insight into the sputter process, the film deposition, the growth and the phase formation. In the experiments the bias voltage (0 to -40 V) has been varied at constant substrate temperature of 900 °C to investigate the influence on the composition, the constitution and the mechanical properties of crystalline b-SiC films. At second the substrate temperature has been varied between 900 °C and 600 °C to find the minimum substrate temperature that is needed to get nanocrystalline b-SiC under the applied sputter conditions (ceramic SiC target, 300 W rf power, target-substrate distance: 18 cm: Ar 50 sccm, 0.26 Pa gas pressure). The films have been characterized by EPMA, XRD, FTIR and AFM. Hardness and residual stress have been investigated by nanoindentation and wafer bending.

In the MD simulations the sputter yield was determined as a function of the energy of the incident Ar atoms (in the interesting range for PVD deposition, i.e. 20-2000 eV) and the temperature of the b-SiC target. Furthermore, the trajectories of the Ar atoms, the damage caused by collision cascades inside the crystal and the ranges of Ar ions and sputtered Si and C atoms were investigated. The time evolution of the damaged crystal was studied at different temperatures. Moreover, preliminary results for the sputter deposition of SiC films at different substrate temperatures using MD simulations will be presented.