Preparation of Sn and Cu–Sn Alloy Films Using Organometallic Compounds by a Wet Chemical Method

Abstract

To obtain Sn and Cu–Sn alloy films, Sn and Cu–Sn precursors, respectively, were first prepared by a wet chemical method using metal organics as the starting materials. The change in the chemical form during a heat treatment and the effect of atmosphere on the formation of the films were investigated. A dense metallic Sn film was successfully obtained from the Sn precursor solution, which was prepared by mixing Sn oxalate, tetraethylene glycol, and 1,2-diaminocyclohexane with a molar ratio of 1 : 3 : 3, and by pyrolysis at 500°C in a nitrogen stream containing 3 vol% hydrogen. During the formation of the Sn precursor, the viscosity of the solution was found to increase with the formation of an oxamide, which was in turn created by the reaction between Sn oxalate and 1,2-diaminocyclohexane in a polymerization process. Tetraethylene glycol did not participate in the reaction because it functions as a dispersant. A Cu–Sn alloy film was also successfully obtained by the pyrolysis of the Cu–Sn precursor prepared by the mixture of Cu and Sn precursors at 500°C in a nitrogen stream containing 3 vol% hydrogen. The composition of the Cu–Sn alloy film can be controlled by changing the mixing ratio of the Cu and Sn precursors.