Photo-Induced Fragmentation of a Tin-Oxo Cage Compound

Tin-oxo cage materials are of interest for use as photoresists for EUV (Extreme­ Ultraviolet) lithography (13.5 run, 92 eV), owing to their large absorption cross section for EUV light. In this work we exposed an n-butyl tin-oxo cage dication in the gas phase to photons in the energy range 4-14 eV to explore its fundamental photoreactivity. At all energies above the onset of electronic absorption at 5 eV (250 run) cleavage of tin-carbon bonds was observed. With photon energies >12 eV (<103 run) photoionization can occur, leading to 3+ ions. Besides the higher charge promotion, butyl chain loss without electron ejection (leading to 2+ fragments) still occurs.

Keywords: Tin-oxo cage, Photoresist, Mass spectrometry, Photochemistry