We have used the scanning tunneling microscope (STM) to investigate self-assembled monolayer films formed from three organosilane precursors. We have studied these films in order to understand better the interaction between them and the microscope and their utility as resist materials for STM-based lithography. These films were chemisorbed onto hydrogen-passivated silicon substrates. One was studied immediately after film growth; another sample of that film, as well as the other two, were studied four weeks later. We compared topography, morphology, and site-specific current-voltage spectroscopy of the films with each other before and after patterning the films. Patterning consisted of operating the STM at tip biases expected to induce a modification of the film that inhibits an electroless metallization process we have described previously. Two films did not exhibit observable changes after operation at conditions expected to induce exposure. We attribute this to high resist sensitivity and a low voltage threshold for exposure, and thus inadvertant exposure. The film that was studied when fresh and after aging in air exhibited changes attributable to oxidation of the substrate. We conclude that the STM is interacting directly with the films and is sensitive to their chemical composition. The effects of exposure on the individual molecular precursors are slight. The molecules remain present on the surface, even though the chemical functionality is greatly modified.