GaN Micromechanical Resonators with Meshed Metal Bottom Electrode.

Area of Science:

• Materials Science
• Electrical Engineering
• Acoustics

Background:

• Gallium Nitride (GaN) is a promising material for high-frequency electronic devices.
• Bulk Acoustic Wave (BAW) resonators offer high performance but face fabrication challenges.

Purpose of the Study:

• To develop a novel architecture for high-performance GaN BAW resonators.
• To leverage GaN's piezoelectric properties for enhanced acoustic device functionality.

Main Methods:

• Growth of thick GaN on a patterned metal electrode grid integrated with a Si (111) substrate.
• Regrowth of GaN to form a thick device layer, enabling vertical piezoelectric actuation.
• Frontside release using xenon difluoride (XeF₂) etch, eliminating backside processing.

Main Results:

• Achieved vertical piezoelectric actuation utilizing GaN's highest piezoelectric coefficient (d33).
• Demonstrated a higher coupling coefficient due to the bottom electrode, beneficial for acoustic filters.
• Enabled simplified fabrication by eliminating backside lithography and etching.

Conclusions:

• The novel architecture provides a pathway to high-performance GaN BAW resonators.
• The fabrication method simplifies processing and enhances device performance.
• This approach is suitable for advanced acoustic filters and resonant applications.