Study On Optimized Fabrication Of Glass Interposer For 3D Integration

System-level 3D integration has become the main trend of MEMS packaging,which meets the urgent demand for electronic products with high density integration and multifunction.Meanwhile,many MEMS devices require hermetic packaging.Glass interposer can effectively realize 3D integration;Moreover,as glass has the abvantages of superior electrical insulation performance,closely matched CTE to silicon die and excellent airtightness,it is regarded as a potential material for MEMS hermetic packaging.However,the mold formation of embedded microstructures into glass and its metallization are the challenges for glass interposer.On the basis of previous study of group,an optimized method was proposed to fabricate glass interposer simply.For this method,glass reflow process is used to form embedded microstructures into glass and the highly-doped silicon with good electrical conductivity properties as the TGV filling material is applied to solve its metallization problem.Glass interposer with embedded component is implemented and characterized,revealing its great potential for wafer level MEMS hermetic packaging.A systematic thermo-mechanical reliability simulation of TGV is taken by COMSOL to verify higher reliability of highly-doped silicon as TGV filling material for glass interposer compared with Cu.First of all,the optimized process to fabricate glass interposer with embedded component is described in detail.Especially for glass reflow process in small size mold,the experimental reveals the influence of the reflow temperature,reflow time and mold structure on the glass filling ratio,and it has actual significance to operation.Second,the fabricated wafer level glass interposer with embedded component is characterized.The results show that the glass interposer has good wafer morphology,the glass reflow process has the capacity to form high aspect-ratio structure,the highly-doped silicon has good electrical conductivity,and the combined interface between silicon and glass is tight.Finally,a systematic thermo-mechanical reliability simulation of TGV is taken by COMSOL.The results reveal that the optimization of TGV structure parameters reduce the maximum thermo mechanical stress by 7.86%of copper TGV and 7.35%of highly-doped silicon TGV,respectively.However,the maximum thermo-mechanical stress is decreased by 96%by using highly-doped silicon to replace Cu as TGV filling material for material optimization.