Influence of Substrate Temperature on Structural Properties and Deposition Rate of AlN Thin Film Deposited by Reactive Magnetron Sputtering

摘要

Aluminum nitride (AlN) thin films with c-axis preferred orientation have been prepared by reactive direct-current (DC) magnetron sputtering. The degree of preferred crystal orientation, the cross-sectional structure, and the surface morphology of AlN thin films grown on Si (100) substrates at various substrate temperatures from 60 deg C to 520 deg C have been investigated by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. Results show that the substrate temperature has a significant effect on the structural properties, such as the degree of c-axis preferred orientation, the full-width at half-maximum (FWHM) of the rocking curve, the surface morphology, and the cross-sectional structure as well as the deposition rate of the AlN thin films. The optimal substrate temperature is 430 deg C, with corresponding root-mean-square surface roughness (R_(rms)) of 1.97 nm, FWHM of AlN (002) diffraction of 2.259 deg, and deposition rate of 20.86 nm/min. The mechanisms behind these phenomena are discussed. Finally, film bulk acoustic resonators based on AlN films were fabricated; the corresponding typical electromechanical coupling coefficient (k_(t)~(2)) is 5.1percent with series and parallel frequencies of 2.37 GHz and 2.42 GHz, respectively.