Anisotropy of the thermal expansion of the Ni(Si1-xGe x) phases investigated by high-temperature x-ray diffraction

Abstract

Thin films of Ni(Si1-xGex) are of interest for their applications in metal-oxide semiconductor transistors as contacts and interconnections. In this work, the lattice parameters and the coefficients of linear thermal expansion (γa, γb, and γc) of the orthorhombic Ni(Si1-xGex) alloys, with 0≤x ≤1, were determined from high-temperature x-ray diffraction data (298-1073 K). A negative thermal expansion along the b axis of Ni(Si1-xGex) is observed for all x values of the Ge concentration: the magnitude of the thermal expansion coefficient decreases with increasing Ge concentration. The anisotropy of the thermal expansion is potentially important for the integration of Ni(Si1-xGex) in microelectronic devices. © 2007 American Institute of Physics.