Methods of forming bonded semiconductor structures include providing a first semiconductor structure including a device structure, bonding a second semiconductor structure to the first semiconductor structure below about 400° C., forming a through wafer interconnect through the second semiconductor structure and into the first semiconductor structure, and bonding a third semiconductor structure to the second semiconductor structure on a side thereof opposite the first semiconductor structure. In additional embodiments, a first semiconductor structure is provided. Ions are implanted into a second semiconductor structure. The second semiconductor structure is bonded to the first semiconductor structure. The second semiconductor structure is fractured along an ion implant plane, a through wafer interconnect is formed at least partially through the first and second semiconductor structures, and a third semiconductor structure is bonded to the second semiconductor structure on a side thereof opposite the first semiconductor structure. Bonded semiconductor structures are formed using such methods.