Hard quasiamorphous carbon -- A prospective construction material for micro-electro-mechanical systems

摘要

A new form of sp{sup 3}/sp{sup 2} carbon has been fabricated which exhibits a large number of valuable properties. This material combines low density ({le} 1.65 g/cm{sup 3}), low stress ({le} 0.05 GPa), low thermal expansion(1.6 x 10{sup {minus}6} K{sup {minus}1}) with high hardness ({approximately} 30 GPa), modulus ({approximately} 200 GPa), cracking threshold ({ge} 3 N), fracture toughness ({ge} 10 MPa-m{sup 1/2}), long-term thermal stability ({ge} 450 C in air and {ge} 600 C without oxygen), extremely high thermal shock resistance, excellent interface and adhesion to silicon, metals, and ceramics and an absolute resistance to the silicon etching acids. Mot of its properties are actually constant up to 700 K. The material combines a basically amorphous structure with one-axis anisotropy and a graphite-like layered arrangement with a length scale of the modulation about 14 {angstrom}. The authors refer to this quasi-amorphous material as QUASAM. This paper describes QUASAM synthesis conditions, growth front planarity and material characterization with high-resolution x-ray diffraction, positron annihilation spectroscopy, atomic force microscopy and micro-Raman spectroscopy. In addition the mechanical and thermal examination of QUASAM and QUASAM/Si will be presented in terms of micro-electro-mechanical systems (MEMS) and the technology prospective requirements of MEMS.