SPUTTERED WSIX FOR MICROMECHANICAL STRUCTURES

Tungsten silicide (WSix) thin films have been investigated for use as integrated circuit interconnect and self-aligned MESFET (metal-semicon ductor field-effect transistor) gates because of their low resistivity and thermal and chemical stability. These same characteristics make t hem interesting materials for prospective use in micromechanical struc tures. However, little information on residual stresses, elastic modul i, or other micromechanical properties has been available for refracto ry metal silicide thin films. This paper presents the morphology and s tress characteristics of cosputtered WSix thin films, including crysta l structure variations and orientation-dependent stresses, as a functi on of the deposition pressure. The compositions of WSix thin films wer e analyzed by Rutherford backscattering spectrometry (RES). The biaxia l elastic modulus and thermal coefficient of expansion were found for the sputtered films. Stress-measurement methods and annealing are disc ussed. Released diaphragms of different sizes and shapes. having contr olled residual stress, have been fabricated.