Wettability and interfacial reactions for AlN/CuTi and AlN/SnTi systems

Wetting experiments for AlN/CuTi and AlN/SnTi systems were performed through the sessile drop technique in vacuum. Both Cu and Sn do not wet AlN and the final contact angles of the systems are 138° at 1200 °C and 113° at 1000 °C, respectively. In the AlN/CuTi system, the contact angles at the same temperature decrease rapidly when Ti content increases. The final contact angle of the AlN/Cu19.0Ti (the number 19.0 denotes the atomic percentage of Ti) system after holding at 1200 °C for 420 s is 8°. In the AlN/SnTi system, the contact angles decrease rapidly at the beginning of the wetting experiment and stabilized final contact angles are observed. When the Ti content increases from 5 at.% to 15 at.%, the final contact angle decreases from 62° to 60° only. Ti improves the wettability of the AlN/Cu system and the AlN/Sn system through different ways: for the former, by reaction to form a new interface of TiN/CuTi; and for the latter, by diffusion and accumulation of Ti in the interfacial area to form a Ti-rich diffusion layer.