Integrated fabrication and ferroelectric domain adjustment of lithium niobate single crystal films based on silicon substrate

Abstract

In the post Moore era, as the size miniaturization approaches limit of the devices, silicon-based sensors cannot meet the requirements of micro/nano sensing with small size and high precision. The piezoelectric sensor based on lithium niobate (LN) single crystal thin film has excellent electromechanical property, photoelectric property, piezoelectric property, which can realize high precision sensing at small size. In our work, 4-inch silicon-based LN single crystal thin film was prepared based on low-temperature bonding technology and chemical mechanical polishing (CMP) method. The oxygen plasma treatment was adopted for increasing the surface hydrophilia to enhance the bonding strength. Grinding parameters under different film thickness were determined by experiments. The parameters of the film was characterized by scanning electron microscope (SEM) with a thickness of 6.294 μm and by atomic force microscope (AFM) obtained the surface roughness is 585 pm. The x-ray diffraction (XRD) test showed that the CMP process could release the compressive stress caused by the bonding, thus obtaining high quality LN single crystal films. The prepared films are polarized and the domain walls can be clearly observed by piezoresponse force microscopy (PFM). It provides a more comprehensive way to prepare ferroelectric domain devices.

Keywords

• Lithium niobate
• Low temperature heterogeneous integration
• Chemical mechanical polishing
• Polarization