Magnetron Sputtering Preparation Of Silicon-lithium Niobate <sub> 3 </ Sub> Waveguide Thin-film Materials Research,

As an important ferroelectric material for fabrication of SAW and integrated optical devices, LiNbO₃ exhibits excellent electro-optical, piezoelectric and nonlinear optical properties. Generally speaking, LiNbO₃ wave-guided structures are demanded in the optical devices. However there are several problems in the traditional wave-guided films so that there are increasing interests on the fabrication hetero-structure LiNbO₃ films. Compared with bulk materials, hetero-structure LiNbO₃ films possess a series of advantages, like available step index profiles in the multilayer structures. UP to now, there have been various techniques which were used to prepare the hetero-structure LiNbO₃ films. Among them, RF-sputtering method shows some advantages over the others. As the base in the microelectronic technology, Si is an interesting host for preparing LiNbO₃ films, because it provides an ideal and cheap substrate for large area processing of device which can be integrated in the current semiconductor technology, and this will make it possible to develop integrated electro-optics technology. Therefore, this work on Si-based LiNbO₃ films is of great interests and potentials.Buffer layer is an important aspect in film growing. In this dissertation, the buffer layer is Si₃N₄/SiO₂ and the structure of wave-guided is LiNbO₃/Si₃N₄/SiO₂/Si. The function of the buffer layer and the method of depositing buffer layer are introduced. LiNbO₃ thin films are deposited on Si₃N₄/SiO₂/Si substrates and the relationship between the quality of LiNbO₃ thin films and the growing parameters of LiNbO₃ thin films are analyzed. The optimized conditions of growing LiNbO₃ thin films on Si₃N₄/SiO₂/Si substrates are concluded: sputtering power 30W, O₂/Ar rate 6:4, substrate temperature 550℃, gas pressure 3Pa, rapid thermal annealing (T=700℃,t=60s).The films are analyzed by the result of experiment which show that the films deposited in the optimized condition are highly C-axis oriented columnar multi-crystal have smooth surface and clear cross-sectional morphology. Due to their excellent crystalline quality, the films would be very potential in the application of optical wave-guided and SAW and useful for photo-acoustic-electric integration.