Research On The Design, Preparation And Properties Of Surface Multilayer Metallization On AlN Ceramic

Aluminum nitride (AIN) is the most attractive substrate material because of several excellent characteristics such as high thermal conductivity, a thermal expansion coefficient close to that of Si and Al2O3, and a low dielectric constant. AIN ceramic surface metallization quality is one of the key factors for applications. In this paper, AIN ceramic surface metallization system has been designed. Metallized thin films on AIN substrate were prepared by e-beam evaporation and ion beam sputtering. Preparation technology, adhesive strength, internal stresses and electrical properties were studied.According to the performance of AIN ceramic surface metallization process the design principles of the films were confirmed. Combined with practical factors, metallization system was composed of Ti/Ni and TiW/Ni layer. Double metallized films were prepared by e-beam evaporation and ion beam sputtering. Deposition rate of e-beam evaporation was higher than that of ion beam sputtering. Preferred orientation of Ti thin film prepared by e-beam evaporation was (002) plane, while that prepared by ion beam sputtering was (100) plane. Preferred orientation of Ni thin film was related to the bonding layer. If the bonding layer is Ti thin film, preferred orientation of Ni thin film was (111) plane. If the bonding layer is TiW or W thin film,it changes to (220) and (111).Preparation technology, adhesive strength, residual stresses and electrical properties of metallized thin films on AIN substrate were researched. The adhesion strength of metallized Ti/Ni thin films prepared by e-beam evaporation was greatly improved by ion beam sputter-cleaning. The sample showed a high adhesion strength over 3kg·mm-2. After annealing at 400-550℃, the adhesion strength of metallized Ti/Ni thin films did not significantly increase. The adhesion strength of thin films prepared by ion beam sputtering was lower than that of thin films prepared by e-beam evaporation. By analyzing the residual stress, it found that optimum process parameters of ion beam sputter-cleaning was 600V and 70mA. The sheer resistance of metallized Ti/Ni thin films prepared by e-beam evaporation decreased during annealing below 450℃on account of grain growth. The sheer resistance increased during annealing above 450℃owing to the damage of the thin film system. The electrical properties of metallized Ti/Ni thin films on AIN substrate maintained...