Developing Ni–Al and Ru–Al intermetallic films for use in microelectromechanical systems

Ordered intermetallic films have a favorable combination of properties such as high strength, metallic electrical conductivity, good oxidation and corrosion resistance, and a high melting temperature and thermal stability that make them suitable for microelectromechanical systems (MEMS). One potential drawback to intermetallics is a lack of ductility at room temperature; however, the B2 compounds NiAl and RuAl show some ductility at room temperature, which has been shown to increase as the grain size decreases. Additionally, the fracture toughness of both materials is higher than those of Si and SiGe. It is also possible to deposit these materials at temperatures that make them compatible with complementary metal oxide semiconductor processing. The authors have shown that by controlling the Ar pressure during cosputtering, NiAl and RuAl thin films can be deposited near room temperature with stresses ranging from compressive to tensile, possibly eliminating the need for annealing. This article examines Ni–...