NANOSCALE PATTERNING OF AN ORGANOSILANE MONOLAYER ON THE BASIS OF TIP-INDUCED ELECTROCHEMISTRY IN ATOMIC-FORCE MICROSCOPY

An organosilane trimethylsilyl (TMS) monolayer prepared on silicon (Si ) substrate by chemical vapor deposition was successfully applied as a self-developing resist for atomic force microscope (AFM) lithography. The thickness of the monolayer was less than 1 nm. This resist was lo cally degraded due to electrochemical reactions induced in the junctio n between a conductive AFM probe and a SI-TMS sample. The generated pa ttern on the sample was then transferred to the Si substrate by chemic al etching using the degraded region as an etching window. Degradation of the monolayer proceeded with both positive and negative sample bia ses. However, the absolute values of the voltage at which the probe-sc anned region began to show etching were +3.0 for V-s>0 and -5.0 V for V-s<0, in a 60% relative humidity air atmosphere. Faster patterning wa s achieved through increased current flow by applying a higher bias vo ltage. A 500 mu m/s line drawing at V-s=+20.0 V with 2-3 nA was obtain ed. The number of injected electrons was estimated to be hundreds of t imes larger than the number of TMS groups in the scanned area. We ther efore concluded that only a small part of the current flowing through the probe-sample junction is actually responsible for the degradation. (C) 1996 American Vacuum Society.