POI (Piezoelectric on Insulator) employs a high-resistivity silicon substrate, a buried oxide layer as the intermediate layer, and a thin, uniform single-crystal LN/LT (Lithium Niobate/Lithium Tantalate) thin-film layer as the top layer. In the RF field, POI has emerged as a critical material for 5G/6G filters and resonators due to its high-frequency and low-loss characteristics. By leveraging heterogeneous integration technology, POI achieves ultra-thin single-crystal layers with a high electromechanical coupling coefficient, excellent temperature stability, and high-Q resonators, making it widely applicable in high-performance filters.