Journal of Vacuum Science & Technology A, Vol.22, No.4, 1397-1405, 2004
Nanoscale fatigue and fracture toughness measurements of multilayered thin film structures for digital micromirror devices
The digital micromirror device (DMD), which lies at the heart of Digital Light Processing(TM) projection display technology by Texas Instruments, Dallas, Texas, comprises a surface-micromachined array of mirrors on a base CMOS substrate. The nanomechanical properties of the thin-film structures used are important to the performance of the DMD. In this article, the nanoscale fatigue and fracture toughness of the single and multilayered thin film structures which are of interest in DMDs, i.e., TiN/Si, SiO2/Si, Al alloy/Si, TiN/Al alloy/Si, and SiO2/TiN/Al alloy/Si, were measured using nanoindentation techniques. The multilayered thin film structures with hard films on soft interlayer exhibit shorter fatigue life and higher ductility than the corresponding top hard films. The hardness plays an important role in determining the indentation fatigue life. Longer fatigue life is associated with higher hardness. The fracture toughness of TiN/Si and SiO2 /Si was measured using the strain energy release method. (C) 2004 American Vacuum Society.