We developed a multiscale model that integrates density functional theory (DFT), molecular dynamics (MD), and the finite difference method (FDM) to reflect the heterogeneous spatial distribution of the material ingredients on sub-10 nm photoresist (PR) pattern fabrication using extreme ultraviolet lithography (EUVL). It allowed the exploration of phototriggered chemical reactions at the molecular level, including photoacid generator (PAG) dissociation, acid diffusion-coupled deprotection, and solubility switching of individual polymer chains. To quantify the progress of the deprotection, a protection ratio of each pendant group was tracked to distinguish the dissoluble PR chains from the developer as the process time elapsed. Deprotection was shown to preferentially occur in the pendant group adjacent to the acid molecule (<0.74 nm), which determined the chemical gradient and solubility switching trend of the PR chains. Based on the full description of the phototriggered chemical reaction, the morphology of the PR line pattern was predicted after wiping out the dissoluble chains. We particularly examined the PAG loading effect (5.68−30.12 wt %) on the line edge roughness (LER) of the PR pattern and predicted the LER inversion phenomenon at the critical threshold PAG concentration, which qualitatively agreed with the experimental observations. Such a LER trend due to PAG loading was explained by the reciprocal interaction between the homogeneous packing of the acid from the dissoluble PR chains and the acid clustering behavior. The variation of the homogeneity of the deprotection in each pendant group was verified as a function of PAG concentration, which rationalized the existence of the reciprocal interaction.

Impact of acid–base neutralization in EUV lithography was investigated using our newly developed multi-scale framework (DFT-MD-FDM).

Two-dimensional molybdenum disulfide (MoS2) is one of the most promising candidates for next-generation semiconductors. Among the advantages offered by MoS2, a tunable bandgap that depends on the thickness is essential for the on-demand manufacturing of nanoelectronics. For this reason, elaborate layer control of MoS2 has been a long-standing research objective. However, prior efforts had several critical issues including surface roughness, poor uniformity/scalability, and impurities. Through this study, we aimed to achieve both ultrahigh precision and purity in large-scale (4 in.) layer control of MoS2 by two consecutive plasma processes: plasma-enhanced chemical vapor deposition (PECVD) and reactive ion etching (RIE). The 4 in. wafer-scale MoS2 was synthesized by PECVD, and the as-grown bulk layers were etched using RIE with a computationally screened gas mixture in the cyclic step. For every RIE cycle, the 4 in. MoS2 wafer was evenly etched to a thickness of 0.3–0.4 nm while there was no damage to the atomic structure and chemical impurities. For the computational screening of candidate gases, first-principles calculations explored the energetics of surface reaction and offered physical insights into the associated electronic interaction. The combination of computational screening and experimentation accelerates optimal process design and provides an in-depth understanding of the plasma–surface interactions.

A photoresist (PR) that can be fabricated in sub-10 nm patterns with the introduction of extreme ultraviolet lithography (EUVL) is a key requirement for transistor downsizing. To produce such ultrafine patterns, assigning small molecular components on the edge surface is a fundamental approach; however, lightweight constituents (PR chain) trigger severe polymer loss in unexposed regions (dark loss) during the dissolution process, thus destroying the uniformity of the pattern. Using computational modeling, we designed a new hybrid-type PR that can eliminate the dark loss of the low-M n polymer (≤5 kg/mol) by integrating the positive-tone resist (deprotection) with the negative one (cross-linking). Through the selective cross-linking reaction on protection side groups, chemical linkages are generated exclusively for the unexposed chains and adequately endure the aqueous treatment. Moreover, the accurately controlled cross-link density enables suppression of resist swelling. Such improvements result in the smoothing of the line edge roughness (LER) for the hybrid pattern at the sub-10 nm scale. To set up the design rule of the proposed system, physical correlation among the chain size–dark loss–LER was thoroughly investigated, and the PR chain of 54-mers (10 kg/mol) was shown to exhibit the best LER quality with the mild condition of dark loss (≤11 mol %) and the moderate chain dimension (R g ∼ 2 nm). The sequential multiscale simulation used in this computational approach allows a full description of the photochemistry in the EUVL process at the molecular level, which involves phototriggered acid activation/diffusion, deprotection, PR dissolution, and cross-linking reaction, and also provides reliable LER prediction, consistent with experimental observations.