The present technology is directed to manufacturing collars for under-bump metal (UBM) structures for die-to-die and/or package-to-package interconnects and associated systems. A semiconductor die includes a semiconductor material having solid-state components and an interconnect extending at least partially through the semiconductor material. An under-bump metal (UBM) structure is formed over the semiconductor material and is electrically coupled to corresponding interconnects. A collar surrounds at least a portion of the side surface of the UBM structure, and a solder material is disposed over the top surface of the UBM structure.