Digest Journal of Nanomaterials and Biostructures Vol. 5, No 4, October-December 2010, p. 1041-1054 HIGHLY TEXTURED (001) AlN NANOSTRUCTURED THIN FILMS SYNTHESIZED BY REACTIVE MAGNETRON SPUTTERING FOR SAW AND FBAR APPLICATIONS G. E. STAN * , I. PASUK, A. C. GALCA, A. DINESCU a National Institute of Materials Physics, P.O. Box MG-7, Bucharest-Magurele, 077125, Romania a IMT-Bucharest, 32B, Erou Iancu Nicolae street, Bucharest 077190, Romania Highly oriented (001) AlN (wurtzite type) thin films have been successfully deposited on silicon, platinized silicon and glass substrates by reactive radio-frequency magnetron sputtering at low temperature (150°C). X-ray diffraction, spectroscopic ellipsometry and scanning electron microscopy techniques have been employed to asses the structural characteristics of the AlN films. We have investigated both the influence of AlN film’s thickness and of the substrate nature on crystallinity. The thicker films present a better c axis alignment, a minimum orientation dispersion of 3.5 being reached for 1 μm AlN on silicon. The micro-and macrostrain of the AlN lattice relaxes as the film thickness increases. The film deposited onto platinum has the maximum value of tensile strain along c axis. The film on glass exhibited the poorest texturing and the highest defect concentration. From an optical point of view the film deposited on Pt is the denser one and that deposited on glass is the most rarefied. One can conclude that when using a low deposition temperature and a base pressure of ~10 -4 Pa the increase of film thickness leads to improved AlN structure on Si or Pt supports. (Received November 12, 2010; accepted November 22, 2010) Keywords: AlN films, magnetron reactive sputtering, texture, microstrain, optical properties 1. Introduction In the last years, the development of wide band gap (WBG) semiconductor processing technologies has opened the perspective of manufacturing surface acoustic wave (SAW) and film bulk acoustic resonator (FBAR) devices for application in the GHz frequency range. The 4G mobile communication systems are expected to work within the 3–6 GHz range [1,2]. Among the WBG materials, the aluminium nitride (AlN), a III–V compound semiconductor, is of great technological interest due to its exceptional properties such as wide energy band gap (6.2 eV), high breakdown voltage, high electrical resistivity (~1015 ohm·cm), high hardness (11–15 GPa), high piezoelectric coupling factor, good chemical and thermal stability, high thermal conductivity, and high surface acoustic velocity (up to 6000 m/s) [3–5]. Among the nitrides AlN has the largest piezoelectric coefficients and the higher corrosion resistance [4]. Highly c-axis oriented AlN thin films are attractive for many acoustic and optic applications: micro-electromechanical (MEMS) and nano-electromechanical (NEMS) devices, high-power and high-temperature electronic devices and optoelectronic devices at the ultraviolet region [4,6]. The MEMS and NEMS resonators are regarded as promising technologies for many hi-tech applications (electrometry, chemical and biological sensing, and scanning probe techniques) [6]. In order to develop better acoustic devices, a wide range of deposition methods have been employed with the aim of growing highly oriented AlN thin films, including chemical vapour * Corresponding author: george_stan@infim.ro