Vapor-phase, metal-containing organic compounds can diffuse into polymers and modify the material composition and structure. In this work, using a sequential vapor infiltration process based on atomic layer deposition chemistry, we combine in situ Fourier transform infrared transmission and quartz crystal microbalance experiments with ab initio quantum chemical modeling analysis to evaluate and identify likely reaction mechanisms when poly(methyl methacrylate) (PMMA) thin films are exposed to trimethylaluminum (TMA) vapor. We find that TMA readily diffuses into the PMMA, where it physisorbs to ester carbonyl units (C]O) to form a metastable C]O/Al(CH 3 ) 3 adduct structure that desorbs at moderate temperatures (<100 C). The Lewis-acidic TMA withdraws charge from the C]O, shifting its stretching frequency from 1732 cm À1 in untreated PMMA to 1670 cm À1 after TMA exposure. At higher temperatures IR results show a new feature near 1568 cm À1 that is stable, even upon exposure to water vapor, indicating covalent bond formation. Based on known TMA-polymer reaction mechanisms and ab initio model results, we propose that at T > 100 C, TMA reacts with PMMA to form covalent resonant C]O/Al-O-C bonding units, and does not form -O-C-O-Al(CH 3 ) as previously hypothesized. This mechanistic insight will help elucidate other polymer/Lewis-acid vapor reactions and could enable new applications for sequential vapor infiltration processes.

The sequential vapor infiltration (SVI) method, based on atomic layer deposition chemistry, allows the creation of a polymer–inorganic hybrid material through the diffusion of metal–organic vapor reagents into a polymer substrate. This study investigates the reactivity of the ester, amide, and carboxylic acid functional groups of poly­(methyl methacrylate) (PMMA), poly­(vinylpyrrolidone) (PVP), and poly­(acrylic acid) (PAA), respectively, in the presence of trimethylaluminum (TMA) vapor. This work explores the possible reaction mechanisms of these functional groups through in situ Fourier transform infrared spectroscopy and ab initio quantum chemical analysis. At temperatures of ≤100 °C, TMA physisorbs to the carbonyl groups of PMMA. As the temperature is increased, TMA forms a covalent bond with PMMA. TMA physisorbs to PVP and then partially desorbs in the presence of water for all studied temperatures of ≤150 °C. PAA readily reacts with TMA to form a covalent bond with the carbonyl group at 60 °C. This increased reactivity is attributed to the acidic proton in the carboxylic acid moiety based on TMA’s reactivity with hydroxyl-terminated surfaces and ab initio calculations. At temperatures of ≥100 °C, TMA catalyzes anhydride formation in PAA. These insights will help with the prediction of chemical interactions in SVI processes for the development of organic–inorganic hybrid materials.

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The Extreme Ultraviolet(EUV)-induced radiation exposure chemistry in organotinoxo systems, represented by the archetypal [(R Sn) 12 O 14 (OH) 6 ](A) 2 cage, has been investigated with density functional theory. Upholding existing experimental evidence of Sn-C cleavage dominant chemistry, computations have revealed either electron attachment or ionization can single-handedly trigger tin-carbon bond cleavage, partially explaining the current EUV sensitivity advantage of metal oxide systems. We have revealed that tin atoms at dierent parts of the molecule react dierently to ionization and 1 electron attachment, and have identied such selectivity as a result of local coordination chemistry instead of the macro geometry of the molecule. An ionizationdeprotonation pathway has also been identied to explain observed evolution of anion conjugate acid upon exposure and anion mass dependence in resist sensitivity.

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