Heterogeneous 3D integration technology has increasingly attracted much attention as it is indispensable for Internet of Things (IoT). Low-power consumption, small form factor, and multifunctionality are required for embedded devices in IoT. Heterogeneous 3D integration can provide these embedded devices with low-power consumption, small form factor, and multifunctionality. We have developed new heterogeneous 3D integration and system integration technologies using self-assembly to achieve multichip-to-wafer stacking with high throughput and high precision. Furthermore, we are challenging to develop new technologies such as DSA through-silicon vias (TSVs) and Cu nanopillar (CNP) hybrid bonding for future 3D LSIs with high-density TSVs and microjoints.