Low-Temperature Chemical Vapor Deposition of Sn-Based Metal−Organic Nanofilms for Photoresponsive Resist Applications

Abstract

Photoresponsive materials that enable light-induced modulation of surface chemical properties have attracted increasing attention for patterning applications, particularly in vapor-deposited resist materials. In this study, Sn-based metal−organic films were deposited via low-temperature chemical vapor deposition at 50 °C using tert-butyltris(dimethylamino)stannane and H2O, and their potential as photoresponsive vapor-deposited resist films was investigated. Upon deep ultraviolet (DUV, 254 nm) irradiation, the films undergo photochemically induced structural transformation, including ligand decomposition, a shift of Sn species toward a more highly oxidized Sn−O bonding environment, and the formation of hydroxyl (−OH) groups. These changes convert the initially hydrophobic, ligand-rich surface into a hydrophilic, oxide-like network, resulting in an increase in surface polarity. Consequently, the exposed regions exhibit enhanced solubility in a tetramethylammonium hydroxide (TMAH) developer. This light-induced modulation of surface chemistry enables positive-tone patterning, where the exposed regions are selectively removed, yielding a residual thickness contrast of approximately 55.2 nm between the unexposed and exposed regions, with ∼98.4% of the exposed film removed. These results demonstrate photoinduced chemical transformation and dissolution contrast in Sn-based metal−organic films.