Molecular bixbyite-like In-oxo clusters with tunable functionalization sites for lithography patterning applications.

Indium oxides have been widely applied in many technological areas, but their utilization in lithography has not been developed. Herein, we illustrated a family of unprecedented In-oxo clusters with a general formula [In(μ-O)(μ-OH)(OCHCHNHCHCHO)(OR)X]X (where X = Cl or Br; R = CH, CHNO or CHF), which not only present the largest size record in the family of indium-oxo clusters (InOCs), but also feature the first molecular model of bixbyite-type InO. Moreover, through the labile coordination sites of the robust diethanolamine-stabilized In-oxo core, these InOCs can be accurately functionalized with different halides and alcohol or phenol derivatives, producing tunable solubility. Based on the high solution stability as confirmed by ESI-MS analysis, homogeneous films can be fabricated using these In-oxo clusters by the spin-coating method, which can be further used for electron beam lithography (EBL) patterning studies. Accordingly, the above structural regulations have significantly influenced their corresponding film quality and patterning performance, with bromide or -nitrophenol functionalized In-oxo clusters displaying better performance of sub-50 nm lines. Thus, the here developed bixbyite-type In-oxo cluster starts the research on indium-based patterning materials and provides a new platform for future lithography radiation mechanism studies.