An investigation of bonding mechanism for Au-Al solid-phase diffusion flip chip bonding

Au bump and Al wire can be bonded by using the solid-phase diffusion between Au and Al. This Au-Al solid diffusion flip chip bonding technique was first used in connecting liquid display devices to the driving IC circuit, and is becoming attractive as a method for interconnect between other types of semiconductor chips and substrates. The samples are evaluated and analyzed at different bonding temperatures, and the relationship between reliability and bonding interface is investigated. The results indicate that the reliability is dependent on the bonding temperature during storage of the samples at high temperature. Since the bonding occurs when the solid diffusion reaction is almost in balanced condition in the case of high-temperature bonding, the bonding is reliable. When the bonding is formed before the solid diffusion reaction reaches balanced condition in the case of low-temperature bonding, if storing the sample at high temperature, the bonding deteriorates since the diffusion reaction persists at high temperature. (C) 1998 Scripta Technica.