Sequential infiltration synthesis (SIS) has been recently demonstrated to increase the etch resistance of optical, e-beam, and block copolymer lithography resists for sub-50 nm pattern transfer. Although SIS can dramatically enhance pattern transfer relevant to device applications, the complex processes involved in SIS are still not clearly understood. Fundamental knowledge of the underlying chemistry of SIS is necessary to ensure a high degree of perfection in large-scale lithography. To this end, we performed in situ Fourier transform infrared (FTIR) spectroscopic measurements during the SIS of Al2O3 using trimethylaluminum (TMA) and H2O into poly(methyl methacrylate) (PMMA). The FTIR results show that TMA forms an unstable complex with the PMMA, rather than a permanent, covalent bond as previously reported.  As a consequence, the TMA can desorb slowly with time, and the detailed history of the TMA exposure becomes critical to the outcome.  This better understanding of the SIS reaction dynamics should improve reliability in SIS lithography as well as other SIS applications.

New insight into the interaction mechanism of sequential infiltration synthesis from infrared spectroscopy

248th National Meeting (2014)

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