Enhanced dielectric properties of Ca2+ doped Li-Al-Si photoetchable glass

The Li-Al-Si photoetchable glass (PEG) easily forms a complex three-dimensional (3D) structure, which is promising as an interposer in 3D integrated microsystems. However, its dielectric loss is rather large (~10−2@ 1 GHz), which inhibits the corresponding application in radio frequency (RF) microsystems. In this paper, the enhancement of dielectric properties caused by of Ca doping on the microstructure of the Li-Al-Si photoetchable glass system was investigated. The structure and performance were analyzed through X-ray diffraction (XRD), Mid-infrared spectroscopy analysis (MIR), Raman spectroscopy and impedance analysis. The results demonstrated that a significant modification in the dielectric properties were obtained with dielectric loss of 3 × 10−3. The reason was attributed to the decreased number of the non-oxygen bridge, which makes the structure more stable. Using hydrofluoric (HF) etching, through glass vias with a diameter of 117 µm were obtained.