Amorphous carbon films are deposited employing high power impulse magnetron sputtering (HiPIMS) at pulsing frequencies of 250 Hz and 1 kHz. Films are also deposited by direct current magnetron sputtering (dcMS), for reference. In both HiPIMS and dcMS cases, unipolar pulsed negative bias voltages up to 150 V are applied to the substrate to tune the energy of the positively charged ions that bombard the growing film. Plasma analysis reveals that HiPIMS leads to generation of a larger number of ions with larger average energies, as compared 2 to dcMS. At the same time, the plasma composition is not affected, with Ar + ions being the dominant ionized species at all deposition conditions. Analysis of the film properties shows that HiPIMS allows for growth of amorphous carbon films with sp 3 bond fraction up to 45% and density up to 2.2 gcm -3 . The corresponding values achieved by dcMS are 30% and 2.05 gcm -3 , respectively. The larger fraction of sp 3 bonds and mass density found in films grown by HiPIMS are explained in light of the more intense ion irradiation provided by the HiPIMS discharge as compared to the dcMS one.
Hafnium oxynitride films are deposited from a Hf target employing direct current magnetron sputtering in an Ar-O 2 -N 2 atmosphere. It is shown that the presence of N 2 allows for the stabilization of the transition zone between the metallic and the compound sputtering mode enabling deposition of films at well defined conditions of target coverage by varying the O 2 partial pressure. Plasma analysis reveals that this experimental strategy facilitates control over the flux of the O − ions which are generated on the oxidized target surface and accelerated by the negative target potential toward the growing film. An arrangement that enables film growth without O − ion bombardment is also implemented. Moreover, stabilization of the transition sputtering zone and control of the O − ion flux without N 2 addition is achieved employing high power pulsed magnetron sputtering. Structural characterization of the deposited films unambiguously proves that the phase formation of hafnium oxide and hafnium oxynitride films with the crystal structure of HfO 2 is independent from the O − bombardment conditions. Experimental and theoretical data indicate that the presence of vacancies and/or the substitution of O by N atoms in the nonmetal sublattice favor the formation of the cubic and/or the tetragonal HfO 2 crystal structure at the expense of the monoclinic HfO 2 one.
The broad energy distributions of the condensing particles typically encountered in ion assisted vapor deposition techniques are often a drawback when attempting to understand the effect of the energetic bombardment on the film properties. In the current study, a monoenergetic Al+ beam generated by a filtered cathodic arc discharge is employed for the deposition of alumina (Al2O3) films at well defined Al+ ion energies between 4 eV and 200 eV at a substrate temperature of 720 °C. Structural analysis shows that Al+ energies of 40 eV or larger favor the formation of the thermodynamically stable α‐Al2O3 phase at the expense of other metastable Al2O3 polymorphs. The well defined ion energies are used as input for Monte‐Carlo based simulations of the ion–surface interactions. The results of these simulations reveal that the increase of the Al+ ion energy leads to an increase in the fraction of ions subplanted into the growing film. These findings underline the previously not considered role of subsurface processes on the phase formation of ionized physical vapor deposited Al2O3 films. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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