Zirconium nitride/silver nanocomposite structures for biomedical applications

Abstract

Silver zirconium nitride films deposited by unbalanced magnetron sputtering were studied by means of x-ray diffraction, transmission electron microscopy, x-ray photoelectron spectroscopy, spectroscopic ellipsometry, and nanoindentation. Coatings were deposited on silicon substrates at room temperatures with bias voltages in the −45 to −160 V range. The concentration of zirconium and silver was regulated by controlling the power to the sputtering guns. The nitrogen concentration was selected so that the nitrogen flow rate corresponded to the production of stoichiometric zirconium nitride. The films consisted of nanocrystals of zirconium nitride embedded in a silver matrix. The grain size was deduced from the width of the XRD peaks using the Scherrer formula and was found to decrease with the addition of silver. The chemical and phase composition was determined from XPS measurements. The optical constants were measured using spectroscopic ellipsometry. A correlation between film structure/composition and optical constants was established. The mechanical properties of the coatings were evaluated using nanohardness testing and were found to depend on composition and deposition parameters. Optimum mechanical properties were achieved for a silver content of 6% and a substrate bias of −160 V.

Characterization of Sputtered Ta and TaN Films by Spectroscopic Ellipsometry

“…Fig. 3 depicts the complex refractive index of the samples showing considerable differences predominantly in the imaginary part k. The results are similar to values reported by Aouadi and Debessai [7], while the advantage of a broad-band measurement is clearly visible. Figure 3.…”

“…Figure 3. Optical properties of TaN films and Ta 2 N/Ta 4 N samples compared with literature data [7].…”

Synthesis and in situ characterization of low-resistivity TaNx films by remote plasma atomic layer deposition

“…For example, for conductive materials information on the electric film properties such as resistivity and electron mean free path can be extracted during the deposition process. 21 This kind of information has recently also been extracted by SE for sputtered TaN x films, as reported by Aouadi and Debessai 22 and Mistrik et al 23 The plasma-assisted ALD process also yields the possibility to use plasma-related diagnostics during the plasma exposure step. In our previous work on plasmaassisted ALD of Al 2 O 3 from a metal-organic precursor and O 2 plasma, we showed that optical emission spectroscopy can yield information on the ALD reaction mechanisms and the timing of the plasma step.…”

“…For TaN x , the two Lorentz oscillators account for interband absorptions around 2.2 and 6.4 eV. 22,23 The imaginary ͑ 2 ͒ part of the dielectric function for a typical TaN x film with a low resistivity is shown in Fig. 2͑a͒ and the contributions of the Drude and Lorentz oscillators are indicated.…”

“…The Lorentz oscillators account for the interband absorption by bound electrons. Following the literature on PVD TaN films, 22,23 we used a combination of one Drude and two Lorentz oscillators to describe the dielectric function of the conductive TaN x deposited by ALD:…”