To accommodate the exceedingly demanding power integrity (PI) requirements for the advanced artificial intelligence (AI) and high performance computing (HPC) components, high-K (HK) based deep trench capacitors (DTC) have been integrated the first time in the silicon interposer with through silicon via (TSV) and fine-pitch interconnects for chip-on-wafer-on-substrate (CoWoS) integration. A specific capacitance density (C s ) of up to 340 nF/mm 2 is achieved over a large capacitor array, providing a total capacitance (C t ) of up to 68 μF per interposer die. The HK dielectric has intrinsic time-dependent dielectric breakdown (TDDB) lifetime of > 1,000 years at an operation voltage (V cc ) of 1.35V, and a normalized leakage current (I LK ) density < 1 fA/μm 2 under 1.35V at 105° C. No discernable process-induced damage or performance degradation (capacitance, I LK & V bd tailing) were observed. The high capacitance, low leakage, large area and reliability-proven Si-interposer integrated DTC, or iCap, provides superior PI performance and therefore greatly enhances the merit of using CoWoS for the next-generation heterogeneous wafer level system integration (WLSI).