Methods of manufacturing multi-band surface acoustic wave filters

A method of manufacturing a surface acoustic wave filter, the method comprising:

• providing a substrate;
• disposing a first piezoelectric layer and a second piezoelectric layer on a first main surface of the substrate and a second main surface of the substrate opposing the first main surface, respectively;
• forming a plurality of first surface acoustic wave resonators and a plurality of second surface acoustic wave resonators on a top surface of the first piezoelectric layer and a bottom surface of the second piezoelectric layer, respectively;
• forming a first wiring layer and a second wiring layer on the top surface of the first piezoelectric layer and the bottom surface of the second piezoelectric layer, respectively, the first wiring layer connecting the plurality of first surface acoustic wave resonators to each other and the second wiring layer connecting the plurality of second surface acoustic wave resonators to each other;
• forming a plurality of through electrodes extending through the substrate, the first piezoelectric layer, and the second piezoelectric layer, the plurality of through electrodes include a through electrode connected to the first wiring layer and/or the second wiring layer;
• and
• forming respective cavities over the plurality of first surface acoustic wave resonators, the first wiring layer, and the plurality of through electrodes on the top surface of the first piezoelectric layer and over the plurality of second surface acoustic wave resonators, the second wiring layer, and the plurality of through electrodes on the bottom surface of the second piezoelectric layer, a circuit including the plurality of first surface acoustic wave resonators and the first wiring layer on the top surface of the first piezoelectric layer forming at least one first radio frequency filter, a circuit including the plurality of second surface acoustic wave resonators and the second wiring layer on the bottom surface of the second piezoelectric layer forming at least one second radio frequency filter, the at least one first radio frequency filter and the at least one second radio frequency filter belonging to different frequency bands.