MASS AND ENERGY-RESOLVED DETECTION OF IONS AND NEUTRAL SPUTTERED SPECIES INCIDENT AT THE SUBSTRATE DURING REACTIVE MAGNETRON SPUTTERING OF TI IN MIXED AR+N2 MIXTURES

The fluxes of ions and neutral sputtered particles incident at the gro wth surface during the deposition of TiN by reactive magnetron sputter ing from a Ti target in mixed Ar+N2 discharges were determined using a combination of in situ double-modulation mass spectrometry, Langmuir probe, discharge, deposition rate, and film composition measurements. The N2 fraction f(N2) in the discharge was varied from 0 to 1 with the total pressure maintained at 3 mTorr (0.4 Pa). Target nitridation, ob served directly through the detection of sputter-ejected TiN molecules , was found to occur over the narrow f(N2) range between congruent-to 0.035 and 0.06. With f(N2) <0.1, more than 94% of the ion flux inciden t at the substrate is Ar+ while for pure N2 discharges, N2+ accounts f or more than 95% of the incident ions. Both the incident Ar+ and N2+ i on fluxes are highly monoenergetic with energies corresponding to eV(s ), where V(s) is the applied negative substrate bias with respect to t he plasma potential. However, the energy distributions of incident Ti and N+ ions are extended due to the high-energy tails in their sputte r-ejection energy distributions. The primary sputter-ejected particles are Ti and N atoms. TiN, TiN+, and Ti+ do not contribute significantl y to film growth kinetics.