Effect of contact potential barrier of organic resists on atomic force microscope anodization lithography

The local oxidation on Si substrate has been studied by atomic force microscope lithography. Heights of protruded patterns were changed during the lithographic process with thin films of 2-amino-6-methoxybenzothiazole-azo (MBT-A) and 2-amino-6-methoxybenzothiazol-azo-Ni ([MBT-A]2Ni2+) on Si substrates. The current-value in a tip-sample junction was investigated by using scanning tunneling spectroscopy with a contact mode atomic force microscope (AFM), and it was confirmed that a change of current-values depends on applied voltages. The difference of potential barrier between [MBT-A]2Ni2+ and MBT-A was also confirmed by using UV-vis spectrophotometry and ultraviolet photoelectron spectroscopy. The tunneling current value of a [MBT-A]2Ni2+ film was larger than that of MBT-A film and the difference from threshold voltages was also observed.