Design and Fabrication of a High-Frequency Lithium Niobate (LN) Resonator for 5G Applications

Abstract

Laterally excited bulk acoustic wave resonators (XBARs) have gained increasing interest in the past few years for their large bandwidth at high-frequencies utilized in 5G applications. This thesis aims to develop a fabrication process using direct laser writing lithography with the maskless aligner to enable faster and cost-effective research and development at USN’s cleanroom. It starts with a brief introduction to XBARs and a literature review of the latest research developments, followed by the simulation model and fabrication process details in the methods chapter.

The results demonstrate a successful fabrication of electrodes at 300nm resolution, with a front-to-back alignment accuracy of 0.5um. Although the performance of the fabricated resonator was affected by an issue related to the LN membrane release process, the reason behind the issue was identified, and the required improvements were suggested for future work. Overall, the thesis provides a strong foundation for fabricating XBARs using the maskless aligner, supporting future research and development at USN’s cleanroom.