Optimisation of nanooxide mask fabricated by atomic force microscopy nanolithography: A response surface methodology application

The mutual and individual effects of ambient humidity, applied voltage and tip speed on nanooxide masks fabricated by atomic force microscopy were investigated in a statistical system. A response surface methodology and central composite design were used to determine the optimum conditions for nanooxidation. The effects of simultaneous changes in the three independent variables on the thickness of the nanooxide mask were investigated; each variable was found to significantly contribute to the oxide thickness. The experimental results obtained were fitted to a quadratic equation model by multiple regression analysis of all of the response variables studied. The optimum nanooxidation conditions were found to be an ambient humidity of 63.81%, an applied voltage of 7.5%V, and a tip speed of 0.20%%m/s. Application of these conditions resulted in an experimental oxide thickness of 3.14%nm, which is in very close agreement with that predicted by the model. Nanogap electrodes fabricated by the proposed method were very smooth and had straight edges, indicating that the technique has a great potential for the fabrication of nanoelectronic devices.