Physical and Electrical Characterization of 3D Embedded Capacitor: A High-Density MIM Capacitor Embedded in TSV

This paper demonstrates the feasibility of 3D embedded capacitor for on-chip applications in 3D/2.5D ICs. Compared with stand-alone trench capacitor, its capacitance density is 2.5 times higher. 3D embedded capacitor can be implemented by embedding MIM capacitor into TSV trench to minimize occupied area. In this study, structure integrity of test vehicles was firstly examined with SEM, under which MIM layers can be observed on TSV sidewalls. Then, electrical characterization was conducted. J-E results show that leakage current density is 1.6×10-10A/cm2 under applied field of 2.4MV/cm for a test vehicle containing 3D embedded capacitors with diameter of 30µm. Subsequently, an annealing process was applied to improve the dielectric quality. This additional step results in a 4× reduction in the leakage current density to 4.0×10-11A/cm2 at 2.4MV/cm. Meanwhile, dielectric strength of 3D embedded capacitor remains unchanged at 8MV/cm for 32nm Al2O3 insulation layer, before and after annealing process.