Real-Time Investigation of Solid and Liquid State Reactions In Au-Sn/Cu System

Abstract

A real-time x-ray analysis technique has been developed and employed for in-situ investigation of solid and liquid state reactions in Au-Sn/Cu system as a function of temperature. Typically, 1 pm eutectic Au-Sn films were deposited on 1.5 pm Cu layers on Si wafers. Phase changes in Au-Sn films on Cu from ambient to above the eutectic temperature have been investigated. Cu diffusion into Au-Sn film above 250 °C resulted in a ternary Au-Sn-Cu compound and raised the melting temperature of the structure to about 325 *C. This affects joining characteristics of the Au-Sn metallization.