Glass-based air-cavity with parylene C/spin-on- glass suspended film process for low loss microstrip antenna

This paper proposes a novel antenna process strategy with Parylene C/spin-on-glass (SOG) film on air-cavity glass substrate for low dielectric loss. This innovative process utilizes wafer-level transfer technology to fabricate an air-cavity structure on a glass substrate. A comprehensive comparative analysis of the demonstrated air-cavity antenna was performed, taking into account parameters such as thickness, cavity area, and other relevant factors. A 3D optical profilometer characterizes the surface flatness of the prepared device, maximum fluctuation is less than 5 μm. Scratch test characterizes the film-substrate adhesion strength, about 0.2N. The SOG bonding strength at different material interfaces was tested. The proposed air-cavity antenna achieves an exceptionally compact size of just 1 × 1 × 0.01 λ₀³. The measured results show that the antenna has a center frequency of 12.18 GHz, bandwidth of 1.8%, and peak gain of 8.43 dBi. The proposed antenna can maintain miniaturization while considering good performance.