Preparation And Research On The Piezoelectric Properties Of Multilayer Films Of "c-BN/Diamond"

With satellite communications, network communications, and wireless communicationtechnology development to high-frequency (4.8GHz and above), High-frequency SAWdevices must have a loud-speed, high electromechanical coupling factor, low velocitydispersion and other characteristics of a low voice."Diamond/piezoelectric film" multilayerstructure of high-frequency SAW devices has been in hot study, but the conventionalpiezoelectric materials as ZnO, LiNbO3and AlN films have defects of whispered speeddispersiond.C-BN have nearly the sound wave propagation speed (8000-10000) witn diamond, itconstitutes a multi-layer structure film with diamond, can effectively reduce the speed ofsound dispersion, enhance the performance of the devices. so the subject, the "c-BN/diamond"multi-layer structure SAW device substrate were preparation and analysis.In the present paper, BN films were deposited on n-Si(100) substrate by changing theprocess parameters by RF magnetron sputtering. The structure of BN films was investigatedby fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) spectra. Thesurface morphology of BN film was characterized by atomic force microscopy (AFM). Theresults show that: when the RF power is300w, negative substrate bias is-200V, the substratetemperature is500℃, working pressure in the0.8pa, nitrogen and argon flow ratio is4:20,high levels of c-BN films deposited. Then, based on the preparation process, BN filmsdeposited on the Ti/Al/Si substrate by changing the ratio of nitrogen and argon, thepiezoelectric properties of BN films argon and nitrogen than the BN piezoelectric propertieswere studied. Finally, in the optimization process based on the diamond deposited on thesubstrate c-BN films, and the results show that: the particles of c-BN films are more uniform,relatively smooth surface, dense structure and adhesion on the surface of the diamond film,forming the substrate of "c-BN/Diamond" multi-layer film structure for high-frequency SAWdevices.