Growth process and surface acoustic wave characteristics of LiNbO3/diamond/silicon multilayered structures

Lithium niobate (LiNbO3) films have been grown at 490degreesC on diamond-coated silicon substrates by radio-frequency magnetron sputtering. A multi-step process was developed to produce thick layers on diamond with a good structure and a smooth morphology. To assess the structural quality of our films, we performed X-ray diffraction, transmission electron microscopy and atomic force microscopy of the films. The structure is conserved whatever the film thickness. A delay line structure of wavelength of 28 mum was realized and transducers were deposited on top of LiNbO3. The objective was to verify the high velocity in such a multi-layered structure. The first results indicated a SAW velocity estimated of 8200 m/s and, a coupling factor was k(2) around 1%. The film growth, the technology and the electrical measurements are described in this paper.