Au系共晶合金を用いた薄膜溶融接合について

概要

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As for diamond heat sinks, the properties of Au eutectic alloys used for bonding a semiconductor chip to a diamond are investigated, and then, film-soldering method is studied in which a semiconductor chip is soldered to a metallized diamond substrate evenly under small load with low melting alloyed film. As soldering materials, Au-Sb, Au-Sn and Au-In alloys are selected and their properties, viz. thermal conductivity, electric resistance, hardness and tensile strength, are investigated. In all alloys, their eutectic alloys have similar properties, and in Au-Sb alloy, which has no alloy phase in hypo-eutectic region, it can improve its properties when its composition becomes Au-rich from the eutectic composition. In soldering experiments, Au-Sb alloy is mainly used and GaAs chips and Pyrex glass, as model specimens, are soldered in an atmosphere of H2 gas. The effects of temperature, time, load, film thickness, film structure, and film composition on the soldering strength are investigated, resulting that the conditions for assuring the appropriate soldering are defined. From the XMA analysis of alloyed films composition, together with above results, it is found that the rate of soldering reaction is controlled by the interdiffusion of Sb into Au solid phase. In comparison with above results, similar investigation is carried out using Au-Sn alloy.