RESUMEN
Predicting photolithography performance in silico for a given materials combination is essential for developing better patterning processes. However, it is still an extremely daunting task because of the entangled chemistry with multiple reactions among many material components. Herein, we investigated the EUV-induced photochemical reaction mechanism of a model photoacid generator (PAG), triphenylsulfonium cation, using atomiC-Scale materials modeling to elucidate that the acid generation yield strongly depends on two main factors: the lowest unoccupied molecular orbital (LUMO) of PAG cation associated with the electron-trap efficiency 'before C-S bond dissociation' and the overall oxidation energy change of rearranged PAG associated with the proton-generation efficiency 'after C-S bond dissociation'. Furthermore, by considering stepwise reactions accordingly, we developed a two-parameter-based prediction model predicting the exposure dose of the resist, which outperformed the traditional LUMO-based prediction model. Our model suggests that one should not focus only on the LUMO energies but also on the energy change during the rearrangement process of the activated triphenylsulfonium (TPS) species. We also believe that the model is well suited for computational materials screening and/or inverse design of novel PAG materials with high lithographic performances.
RESUMEN
First-principles total energy calculations are performed to investigate the energetics and electronic structures of graphene adsorbed on both an oxygen-terminated SiO2 (0001) surface and a fully hydroxylated SiO2 (0001) surface. We find that there are several stable adsorption sites for graphene on both O-terminated and hydroxylated SiO2 surfaces. The binding energy in the most stable geometry is found to be 15 meV per C atom, indicating a weak interaction between graphene and SiO2 (0001) surfaces. We also find that the graphene adsorbed on SiO2 is a semiconductor irrespective of the adsorption arrangement due to the variation of on-site energy induced by the SiO2 substrate.
RESUMEN
A Mexican woman, aged 71 years, with life-long exposure to soot from a wood cook stove in a closed environment, who was treated for tuberculosis 4-years prior, presented with prominent mediastinal lymphadenopathy with anthracosis. Mediastinal lymphadenopathy is a common presentation of diverse granulomatous, malignant and infectious conditions like tuberculosis. Anthracotic pigment is found in different conditions such as tuberculosis or domestically acquired particulate lung disease. Accurate assessment of chronology and causative factors presents a challenge. Recognizing that pneumoconiosis can mimic or coexist with other granulomatous, infectious and malignant conditions presenting as mediastinal lymphadenopathy is important. Misdiagnosis may result in under- or over-treatment of potentially curable conditions such as tuberculosis, under-treatment of a lethal condition such as melanoma, or exposure of patients to inappropriate administration of costly therapy with potential untoward effects.