Process and characterization of photo-definable organic–inorganic dielectric for wafer level packaging

The introduction of an organic–inorganic dielectric material into the redistribution layers in fan-out wafer level packaging technology has been investigated to improve mechanical stress, thermal stability, and electrical breakdown compared to organic dielectric materials. A photo-definable organic–inorganic dielectric material called polysilsesquioxane (PSSQ) has been studied in this work. The photo-definable PSSQ dielectric allows a simultaneous UV patterning and curing process. A PSSQ sample was prepared by spin-coating on a 6-in. Si wafer, pre-baking at 100 °C for 5 min, UV exposure, and then PGMA developing. The cured PSSQ films have a dielectric constant from 2.0 to 2.38 and dielectric loss from 0.0001 to 0.005. In addition, the 2 μm line patterns were obtained after 10 min of UV exposure. It has been demonstrated that PSSQ dielectric materials can provide excellent process capability of simultaneous UV patterning and curing process.