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

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Abstract
The fluxes of ions and neutral sputtered particles incident at the growthsurface during the deposition of TiN by reactive magnetron sputtering 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, observed directly through the detection of sputter‐ejected TiN molecules, was found to occur over the narrow f N2 range between ≂0.035 and 0.06. With f N2 <0.1, more than 94% of the ion flux incident at the substrate is Ar+ while for pure N2 discharges, N+ 2 accounts for more than 95% of the incident ions. Both the incident Ar+ and N+ 2 ion fluxes are highly monoenergetic with energies corresponding to eV s , where V s is the applied negative substrate bias with respect to the plasma potential. However, the energy distributions of incident Ti+ and N+ ions are extended due to the high‐energy tails in their sputter‐ejection energy distributions. The primary sputter‐ejected particles are Ti and N atoms. TiN, TiN+, and Ti+ do not contribute significantly to film growth kinetics.

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