Morphology and Bond Strength of Copper Wafer Bonding

Abstract

Abstract: The morphology and bond strength of copper-bonded wafer pairs prepared under different bonding/annealing temperatures and durations are presented. The interfacial morphology was examined by transmission electron microscopy (TEM) while the bond strength was examined from a diesaw test. Physical mechanisms explaining the different roles of post-bonding anneals at temperatures above and below 300°C are discussed. A map summarizing these results provides a useful reference on process conditions suitable for actual microelectronics fabrication and three-dimensional integrated circuits based on Cu wafer bonding. 1 Copper wafer bonding is a promising option for future three-dimensional integrated circuits (3-D IC) application. 1-2 Consequently; investigation of its mechanical and electrical properties, as well as the bonding mechanism has become an important subject of research. The qualitative bond strength, interfacial bonding morphologies, possible bonding mechanisms and the parameters required for an excellent Cu wafer bonding have been reported. 3-5 These discussions focused on one particular bonding condition which