AIP Digital Archive
CNx films were deposited on Si(100) substrates at a substrate temperature of 600 °C using dc magnetron sputtering of a high-purity graphite target in pure nitrogen. The film characteristics were primarily controlled by the pressure, p, (0.05–5 Pa), the discharge current on the magnetron target, Im, (0.5–3 A), and the rf induced negative substrate bias voltage, Ub, (−300 to −1200 V). The films, typically 1–2 μm thick, were found to be amorphous, and they possessed the N/C atomic concentration ratio up to 0.35, the hardness up to 40 GPa, the elastic recovery up to 85%, and good adhesion and promising tribological properties. The energy and flux of ions bombarding the target and the growing films were evaluated on the basis of the discharge characteristics measured for both the dc magnetron discharge and the rf discharge in the deposition zone. Optical emission spectroscopy was used to study the behavior of significant atomic and molecular species, such as N, N2, N+, N2+, CN, C, and C2, near the substrate and in the plasma bulk. The measurements indicated that both dc and rf discharges are mutually coupled. We confirmed that CN radicals and N atoms are the principal precursors for reactive magnetron sputtering of the CNx films. Good correlation between the N/CN concentration ratio in the deposition zone and the N/C atomic ratio in the films was found over a wide range of the investigated process parameters. We have shown that the CNx films have a high hardness only when the energy and flux of the nitrogen ions are sufficiently high for effective incorporation of nitrogen in the layers; such conditions require the pressures lower than 0.5 Pa and the Ub values between −500 and −700 V. It has been proved that the frequently used deposition parameters such as Im, Ub, p, and Ts, do not generally suffice to satisfactorily characterize the film growth process. © 1999 American Institute of Physics.
Type of Medium: