Wafer level fabrication of 3D glass-embedded components using glass reflow process

As glass has the superiorities of insulation, chemically stability, low coefficient of thermal expansion (CTE), and transparency for internal reliability monitoring, it is proposed as an alternative interposer material to organic and silicon. Increasing demand for miniaturization and integration of devices calls for new packaging method like packaging-embedded packaging. Considering the upper two design points, this paper presents the first demonstration of glassembedded RF components fabricated by glass reflow process and seedless electroplating process. Comparing to planar packaging, thickness of the components here is only limited by the substrate thickness, which can be used as an extra design parameter to increase the flexibility of design. Glass-embedded components including conductive through-holes, capacitors and inductors with a thickness of 50-200um were successfully fabricated here. The HFSS simulation results show that a minor thickness increase contributes to a large increase in Q and a relatively small decrease in L when the thickness is small, the thickness increase cannot effectively increase Q but leads to Q roll-off when the thickness is too large (>20um for glass-embedded Cu meander inductor and >100um for glass-embedded Cu square spiral inductor). Nevertheless, large Q and L can still be acquired by using glass-embedded Cu inductor.