Micromachining of large area amorphous carbon membranes prepared by filtered cathodic vacuum arc technique

Currently, there is a strong drive to make micro-electro-mechanical system (MEMS) devices from higher performance materials such as diamond-like carbon or amorphous carbon (a-C) films, due to their excellent tribological properties, low-stiction (hydrophobic) surfaces, chemical inertness and high elastic modulus, compared to that of Si. The hydrogen free a-C films prepared, by Nanyang Technological University's (NTUs) patented filtered cathodic vacuum arc (FCVA) technique, at 100 eV exhibits high fraction of tetrahedral (sp ³ bonded) carbon atoms. These films exhibit relatively high hardness, stiffness and wear resistance in addition to low friction and stiction behaviour. However, the primary problem lies in the large intrinsic compressive stress induced during the deposition process. By making use of high substrate pulse bias, we have successfully produced low stress, thick a-C films. The films were then characterised using different equipments to evaluate the stress, microstructure and morphological roughness. Large area a-C membranes, of 2 mm × 2 mm in size, have also been fabricated using the low stress, thick film deposited by the above method.