Formation Kinetics and Thin Film Stress of Tin Containing Intermetallic Compounds

Thin film reactions and its influence on mechanical stress have been investigated in Cr/Cu/Sn and Cr/Ni/Sn multilayer structures. Thin film stresses of different intermetallic compounds in each material system were evaluated using substrate bending technique. Stress state in the thin film structures was round directly related to formation kinetics and thermal properties of intermetallics. In Cu-Sn system, a large internal stress increase in tension was generally observed after being heat treated at high temperatures. In Ni-Sn systems, formation of intermetallics is a relatively slow reaction at elevated temperatures as compared to that of Cu-Sn samples. Contrary to that of Cu-Sn system, formation of Ni-Sn intermetallics causes a decrease in stress in the thin film structure. The correlation of thin film stress state and the structure evolution at the interface is studied and discussed in details.