| PhD Seminar

Name of the Speaker: Ms. Nivedita Rai (EE21D040)
Guide: Dr. Deleep R Nair
Venue: ESB-244 (Seminar Hall)
Date/Time: 1st May 2025 (Thursday), 9:30 AM
Title: A method to improve the Quality factor of the piezoelectric MEMS resonator

Abstract :

Component miniaturization and integrability with CMOS IC are technological necessities that have increased the popularity of oscillators based on micro-electromechanical system (MEMS) resonators over quartz crystals. A composite of piezoelectric film in between the top and bottom metal electrodes stacked on top of a high energy density material Silicon (Si), popularly known as the thin film piezoelectric on silicon (TPoS) resonator offers high-quality factor and low motional resistance. However, the various dissipation mechanisms, such as anchor loss and additional loss, lower the quality factor of TPoS resonators. The additional loss occurs due to the undercut in the buried oxide layer (BOX) during the resonator structure release. With increase in an undercut area, the resonator Q-factor reduces, and insertion loss increases.

In this presentation, the influence of the additional loss on the quality factor (Q factor), as well as on the other performance parameters of the device, is analyzed. Based on our study, it is found that the quality factor of the resonator is much higher without undercuts. Hence, to overcome these undercut issues, a design modification in the current fabrication process flow of the TPoS resonator is done. The final aim is to make an oscillator by bonding the modified resonator structure with a CMOS amplifier.