Ultrathin resist films have been prepared by both Langmuir-Blodgett (LB) and self-assembly (SA) techniques. The LB films include both monomer films (stearic alcohol) and polymer films (polymethyl-methacrylate). Nanometer scale patterning of these thin films have been performed on different substrates (GaAs, Au, and Pt) by using the scanning tunneling microscope (STM) as the exposing tool. Both carbon deposit buildup and chain breakdown underneath the STM tip are observed. The STM-generated patterns are transferred into metal films and semiconductor substrates by chemical etching. Using an atomic force microscope for imaging, lines with 25 nm width have been observed.