Silicon-lithium Niobate <sub> 3 </ Sub> Multilayer Structure Of The Piezoelectric Thin Film Preparation And Characterization

Surface acoustic wave device (SAW) has been used widely in many fields of our society due to it's characteristics of miniaturization, plane structure and easy to design. With the popularity of SAW products on a large scale, the frequency at the low band had been used up already. This situation is restricting the development of SAW devices badly. So, it becomes the unique choice to get higher center frequency of SAW except miniaturization and low insertion loss. As a kind of piezoelectric material with excellent properties discovered earlier, LiNbO₃ has been paying much attention to all the time. Additionally, diamond has the highest velocity of all kinds of material. This means a perfect prospect of SAW.In this article, we have studied the preparation of polycrystalline diamond films for SAW and LiNbO₃ piezoelectric films with highly C-axis orientation. We also put forward a novel multilayer film structure, LiNbO₃\SiO₂\diamond\Si structure, on the base of summing up the current situation of the preparation of LiNbO₃ and the analysis of theories to increase the centre frequency of SAW device. Using the pulsed laser deposition (PLD) technology, we studied some key parameters of the multilayer film and got the conclusions as follow:1. Using PLD technology, we prepared fully C-axis oriented LiNbO₃ film on SiO₂/Si substrate (made by heat oxidation method) without the application of induced electrical field. A systematic study of processing parameters on the quality of LiNbO₃ thin films has been carried out, and thus we obtained the best process parameters the growth of LiNbO₃ thin films: substrate temperature is 650℃, oxygen pressure is 50 Pa, laser frequency is 3Hz, substrate-to-target distance is 4cm.2. Using PLD technology, we prepared fully C-axis oriented LiNbO₃ film on SiO₂/Si substrate (made by PLD method) without the application of induced electrical field. A systematic study of processing parameters on the quality of LiNbO₃ thin films has been carried out, and thus we obtained the best process parameters the growth of LiNbO₃ thin films: substrate temperature is 700℃, oxygen pressure is 50 Pa, laser frequency is 3 Hz, substrate-to-target distance is 4cm. 3. Through changing the temperatures of the substrate, we prepared LiNbO₃ films with (012),(104) and (006) orientations respectively.4. Preliminary study has been carried out on the growth situation of LiNbO₃ films on diamond polycrystalline film with SiO₂ buffer layer deposited by PLD.