Synthesis and Properties of Al-Based Amorphous and Microcrystalline Thin Films

Abstract

ABSTRACTAmorphous metal alloys are ideally suited for interconnects in micro-electromechanical sys- tems (MEMS) because of their resistance against stress- and electromigration, and their stability in chemically aggressive environments, which should both lead to a substantial improvement of lifetime and reliability of robust sensors. While amorphous refractory metal alloys and amor- phous silicides are excellent interconnect materials for devices operating at elevated tempera- tures, these systems lack the cost-effective and easy interconnect processing of the prevalent polycrystalline aluminum alloy metallizations. Amorphous aluminum alloys are applicable to devices operating at up to 200°C, and their stressmigration resistance and chemical stability is far superior to conventional polycrystalline aluminum alloys. These new metallizations are very promising for processing interconnects, in particular because of their high strength and ductility, though having low density, and their relatively low electrical resistivity compared to other amor- phous metal alloys. Therefore these metallizations are especially suited for surface acoustic wave (SAW) sensors, where the interconnects are exposed to considerable mechanical strains. In this work amorphous Aluminum Yttrium alloy thin film metallizations deposited on appropriate sub- strates at room temperature (R.T.) by ultra-high vacuum (UHV) electron beam evaporation will be presented, and their mechanical and electronic properties together with their temperature sta- bility will be investigated.