Details of the chemistry enabling the patterning of organotin photoresists to single-digit-nm resolution continue to engage study. In this report, we examine the contributions of atmospheric gases to the differential dissolution rates of an n-butyltin oxide hydroxide photoresist. Cryo scanning tunneling electron microscopy (cryo-STEM) produces a micrograph of the latent image of an irradiated resist film, readily distinguishing exposed and unexposed regions. Temperature-programmed desorption mass spectrometry (TPD-MS) and cryo electron energy loss spectroscopy (cryo-EELS) show that irradiated films are depleted in carbon through desorption of butane and butene. Upon aging in air, irradiated films absorb H2O, as previously established. TPD-MS also reveals a previously unrecognized absorption of CO2, which correlates to a heightened dissolution contrast. This absorption may play an active role in determining intrinsic patterning performance and its variability based on changes in atmospheric-gas composition.
Keywords: electron-beam lithography; extreme ultraviolet lithography; inorganic resist; organotin clusters.