Effect of B-doping, UV exposure and thermal annealing on dielectric properties and crystallization behavior of Li-Al-Si photoetchable glasses

Abstract

Relatively high dielectric loss often limits the widespread utilization of photoetchable glasses (PEG) in three-dimensional system packaging. Herein, we present the influence of B-doping on network structures and dielectric properties of a Li-Al-Si-based PEG. The addition of B is found to markedly reduce the dielectric losses over the VHF-UHF bands making these PEGs more suitable for applications. Moreover, the effect of UV exposure on structural transformations is studied by X-ray diffraction and Raman spectroscopy. At a B2O3 additive content of 2 wt.-%, the average dielectric loss and dielectric constant are found to be 0.005 and 4.57, respectively, before UV exposure. However, these values decrease to 0.0015 and 3.65, respectively, after UV exposure and thermal annealing. The annealing temperature of PEG can be adjusted based on crystallization temperature since the stability of the boron trihedra are higher than that of the silicon-oxygen tetrahedra. Overall, it is determined that the use of B2O3 as an additive is effective in altering the dielectric properties of photosensitive glass making the PEGs more suitable for low loss three-dimensional system packaging for use over VHF and UHF bands.