MEMS fabrication based on nickel-nanocomposite: film deposition and characterization

Abstract

Electrosynthesized metal-nanocomposites represent a unique class of microelectromechanical systems (MEMS) structural material due to their compatibility with MEMS and CMOS fabrication technologies via a one-step, selective on-chip deposition process at low temperatures (similar to 50-90 degrees C). In this paper, particle-reinforced, electrosynthesized nickel-nanocomposites of various compositions have been successfully demonstrated as potential structural materials for MEMS. We have achieved 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 micro- and nanoparticles of either cordierite (diameter approximate to 100 nm-5 mu m) or diamond (diameter similar to 4 nm). The as-deposited nickel-cordierite films exhibit better thermal compatibility with silicon, compared to nickel. The measured coefficients of thermal expansion (CTE) of EN-cordierite and EN are 17.34 ppm K-1 and 26.69 ppm K-1, respectively. Stress-temperature measurement of EN-cordierite composite also confirms that residual stress decreases with the incorporation of cordierite. Finally, by adding various concentrations of nanodiamond particles into an EL matrix, It is found that higher diamond concentration renders these films more compressively stressed.