The recent development of wafer-level, low-cost packaging platform based on silicon interposer and direct wafer bonding has paved a new way toward high-performance millimeter-wave to terahertz 2.5/3D heterogeneous integration, enabling high-speed wireless communication and chip-to-chip interconnects. Using this emerging technology, several passive components are designed. One 150 GHz distributed mushroom antenna is proposed using interposers to form multiple resonances unit-cell, achieving 7.16 dBi gain with 76% radiation efficiency. A 300 GHz differential patch antenna is designed, delivering 5.6 dBi gain with 88% radiation efficiency. A 60 GHz directional coupler based on interleaving topology is proposed and simulated, showing a 3.3 dB coupling factor with more than 30 GHz bandwidth. These preliminary results reveal a promising solution by using the wafer-to-wafer packaging platform to build high-performance passive building blocks.