Nickel nano-composite film for MEMS applications

Abstract

We have successfully demonstrated low-temperature, stress-free, wafer-level fabrication of nano-composite MEMS via both an electroless nickel (EN) and an electrolytic nickel (EL) deposition process, with the addition of uniformly dispersed nanoparticles of either cordierite (diameter /spl ap/100 nm/spl sim/5 /spl mu/m) or diamond (diameter /spl sim/4 nm). The as-deposited nickel-cordierite films exhibit better thermal compatibility with Si, compared to nickel. The measured coefficient of thermal expansion (CTE) of EN-cordierite and EN is 17.34 ppm/K and 26.69 ppm/K, respectively. Stress-temperature measurement of EN-cordierite composite also confirms that residual stress decreases with the incorporations of cordierite. Finally, by adding various concentrations of nanodiamond particles into an EL matrix, it is found that higher diamond concentrations render the film to be more compressively stressed.