ICMCTF2011 Session F2-2: High Power Impulse Magnetron Sputtering

In this paper we present results on flexible polymeric substrate (PET) pre-treatment using a method comprising a magnetically enhanced plasma powered by either a) medium frequency (50-250 kHz) or b) low frequency (50-300 Hz) high power (HIPIMS) sources. Plasma pre-treatment processes are carried out in Ar – O₂ atmosphere. The effects of different pre-treatments on the surface properties are investigated by XPS, ToF-SIMS and AFM and compared.

Hafnium dioxide (HfO₂) films are widely used as dielectric layers in microelectronic devices. Among the various polymorphs of HfO₂ the high temperature cubic (c) and tetragonal (t) phases are of importance since they exhibit significantly larger dielectric constant (k) as compared to the low temperature monoclinic (m) HfO₂ configuration. In the present study we grow films at room temperature by sputtering a metallic hafnium target in a reactive Ar-O₂-N₂ atmosphere employing high power impulse magnetron sputtering (HiPIMS). The deposition process exhibits a stable transition zone between the metallic and the compound sputtering mode which enables to tune the composition of the target surface (target coverage) by varying the partial pressures of the sputtering gases. The well defined target coverage conditions, in turn, facilitate control over the non-metal sublattice configuration of the growing hafnium oxynitride (Hf-O-N) films in terms of N and O incorporation. Structural characterization tools are employed to define deposition conditions that lead to the growth of films with the HfO₂ crystal structure. Experimental data and first principle calculations suggest that N incorporation and O vacancies favor the formation of the c- and the t-HfO₂ crystal structure at the expense of the m-HfO₂ one [1]. Optical analysis employing spectroscopic ellipsometry in the near-infrared to ultra-violet spectral range indicates that Hf-O-N films with the crystal structure of c- and t-HfO₂ exhibit larger dielectric constants as compared to films with the m-HfO₂ structure.

[1] K. Sarakinos et al., J. Appl. Phys. 108 (2010) 014904

V-Al-C thin films were deposited onto Al₂O₃ (11-20) substrates by HPPMS and DC magnetron sputtering using a hot-sintered multi-component target with 2:1:1 MAX phase-like composition. The film composition was found to be a strong function of the deposition pressure and target-to-substrate distance. The formation of crystalline phases with the close-to-MAX-phase-like composition was investigated as a function of the substrate temperature, from room temperature up to 500°C, and duty cycle, from 1.7 % to 20 %, respectively. Al-containing hexagonal vanadium carbide was formed during both DC and HPPMS at 500°C, where the lattice parameter of the hexagonal solid solution was dependent on the duty cycle employed during HPPMS. The change in c lattice parameter comparing DC sputtering with HPPMS at a duty cycle of 5 % is with 2.6 % rather extensive and appears to be primarily affected by the ion bombardment by film forming species. Plasma composition analysis data supports this notion. The here presented data are of relevance for understanding the mechanisms that govern the growth of MAX phase thin films at low substrate temperatures.

In this paper we present preliminary results of industrial size (150 mm target O.D.) rotatable magnetron sputtering of aluminium target in continuous and pulse (HIPIMS) modes using standard commercially available magnetic arrays, such as a normal strength array (e.g. as used for DC and AC processing) and an ‘RF’ array (i.e. as commonly used for RF rotatable magnetron sputtering). A comparison is made in terms of magnetic field distribution, process characteristics and deposition rates. It is shown that deposition rates using HIPIMS and one of the commercially available magnetic arrays can be as high as those obtained when operating in DC mode.