Fabrication of on-chip single-crystal lithium niobate waveguide microstructures based on mask-chemical mechanical polishing technology

Single-crystal thin-film lithium niobate (TFLN) photonic devices have become a highly popular research area in recent years. The mask-chemical mechanical polishing (CMP) etching technique for TFLN photonic devices has garnered significant attention due to its potential for the efficient and large-scale fabrication of integrated photonic device microstructures. This paper focuses on the physical processes involved in etching TFLN waveguide microstructures using mask-CMP technology. Innovatively, the pressure distribution function of a superelastic polishing pad is combined with the Preston equation to establish a finite element theoretical model. Based on this model, systematic theoretical calculations and analyses were conducted on factors affecting etching efficiency and waveguide structure, such as load magnitude, contact pressure, and mask dimensions. The simulation results were compared with experimental data. This research provides a theoretical reference for advancing the large-scale, high-efficiency fabrication of TFLN photonic chips using mask-CMP etching technology.