Integration Technology for Wafer-Level LiNbO<sub>3</sub> Single-Crystal Thin Film on Silicon by Polyimide Adhesive Bonding and Chemical Mechanical Polishing
Wenping Geng,
Xiangyu Yang,
Gang Xue,
Wenhao Xu,
Kaixi Bi,
Linyu Mei,
Le Zhang,
Xiaojuan Hou,
Xiujian Chou
Affiliations
Wenping Geng
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Xiangyu Yang
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Gang Xue
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Wenhao Xu
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Kaixi Bi
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Linyu Mei
School of Mechanical Engineering, North University of China, Taiyuan 030051, China
Le Zhang
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Xiaojuan Hou
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
Xiujian Chou
Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
An integration technology for wafer-level LiNbO3 single-crystal thin film on Si has been achieved. The optimized spin-coating speed of PI (polyimide) adhesive is 3500 rad/min. According to Fourier infrared analysis of the chemical state of the film baked under different conditions, a high-quality PI film that can be used for wafer-level bonding is obtained. A high bonding strength of 11.38 MPa is obtained by a tensile machine. The bonding interface is uniform, completed and non-porous. After the PI adhesive bonding process, the LiNbO3 single-crystal was lapped by chemical mechanical polishing. The thickness of the 100 mm diameter LiNbO3 can be decreased from 500 to 10 μm without generating serious cracks. A defect-free and tight bonding interface was confirmed by scanning electron microscopy. X-ray diffraction results show that the prepared LiNbO3 single-crystal thin film has a highly crystalline quality. Heterogeneous integration of LiNbO3 single-crystal thin film on Si is of great significance to the fabrication of MEMS devices for in-situ measurement of space-sensing signals.
