Methods for bonding semiconductor wafers requiring the transfer of electrical and optical signals between the bonded wafers and across the bonding interface by interfusing optical interconnects on one wafer with optical interconnects on a second wafer, interfusing electrical interconnects on one wafer with electrical interconnects on the second wafer, and interfusing a dielectric intermediary bonding layer on one wafer with the dielectric intermediary bonding layer on the second wafer to bond the wafers together with electrical interconnections and optical interconnections between the wafers. The methods are also applicable to the bonding of semiconductor wafers to provide a high density of electrical interconnects between wafers.