In this study, a series of perpendicular lamellae-forming poly(polyhedral oligomeric silsesquioxane methacrylate-block-2,2,2-trifluoroethyl methacrylate)s (PMAPOSS-b-PTFEMAs) was developed based on the bottom-up concept of creating a simple yet effective material by tailoring the chemical properties and molecular composition of the material. The use of silicon (Si)-containing hybrid high-χ block copolymers (BCPs) provides easy access to sub-10 nm feature sizes. However, as the surface free energies (SFEs) of Si-containing polymers are typically vastly lower than organic polymers, this tends to result in the selective segregation of the inorganic block onto the air interface and increased difficulty in controlling the BCP orientation in thin films. Therefore, by balancing the SFEs between the organic and inorganic blocks through the use of poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) on the organic block, a polymer with an SFE similar to Si-containing polymers, orientation control of the BCP domains in thin films becomes much simpler. Herein, perpendicularly oriented BCP thin films with a χ value of 0.45 were fabricated using simple spin-coating and thermal annealing processes under ambient conditions. The thin films displayed a minimum domain size of L = 11 nm, as observed via atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, directed self-assembly (DSA) of the BCP on a topographically prepatterned substrate using the grapho-epitaxy method was used to successfully obtain perpendicularly oriented lamellae with a half pitch size of ca. 8 nm.

Polystyrene- block-poly(methyl methacrylate) (PS- b-PMMA) is one of the prototypical block copolymers in directed self-assembly (DSA) research and development, with standardized protocols in place for processing on industrially relevant 300 mm wafers. Scaling of DSA patterns to pitches below 20 nm using PS- b-PMMA, however, is hindered by the relatively low Flory-Huggins interaction parameter, χ. Here, we investigate the approach of adding small amounts of ionic liquids (ILs) into PS- b-PMMA, which selectively segregates into the PMMA domain and effectively increases the χ parameter and thus the pattern resolution. The amount of IL additive is small enough to result in limited changes in PS- b-PMMA's surface and interfacial properties, thus maintaining industry-friendly processing by thermal annealing with a free surface. Three different ILs are studied comparatively regarding their compositional process window, capability of increasing χ, and thermal stability. By adding ∼3.1 vol % of the champion IL into a low-molecular-weight PS- b-PMMA ( M = 10.3k- b-9.5k), we demonstrated DSA on chemically patterned substrates of lamellar structures with feature sizes <8.5 nm. Compatibility of the PS- b-PMMMA/IL blends with the standardized processes that have been previously developed suggests that such blend materials could provide a drop-in solution for sub-10 nm lithography with the processing advantages of PS- b-PMMA.

Nanofabrication based on block copolymer self-assembly is one of the most promising methods for producing nanopatterns with a sub-10 nm feature size. Although polystyrene-block-poly­(methyl methacrylate) (PS-b-PMMA) has been widely studied as a suitable template for nanofabrication, the insufficient incompatibility between the PS and PMMA blocks makes it difficult to achieve a microphase separation with the domain spacing of less than ca. 20 nm. We now present a simple and efficient method for the postpolymerization modification of PS-b-PMMA for effectively increasing the incompatibility between the two blocks, so that microphase separation can be achieved even at a low degree of polymerization. The ester–amide exchange reactions of PS-b-PMMA with primary and secondary amines were performed to introduce a small number of methacrylamides into the PMMA block to increase its hydrophilicity. The results of small-angle X-ray scattering measurements performed on bulk samples showed that the modified PS-b-PMMA self-assembled to form a lamellar phase even at the extremely low molecular weight of 8.5 kg mol–1 due to the increased incompatibility between the blocks. The smallest domain spacing of the modified PS-b-PMMA observed in this study was 11.1 nm. That is to say, the smallest feature size was 5.6 nm. The modified PS-b-PMMA thin film showed well-aligned line patterns via the graphoepitaxy directed self-assembly process, demonstrating that these materials obtained from PS-b-PMMA have the potential to be used for sub-10 nm nanofabrication applications.

The Japanese version of the DN4 was found to be a helpful tool for discriminating between neuropathic and non-neuropathic pain.

The challenges of patterning next generation integrated circuits have driven the semiconductor industry to look outside of traditional lithographic methods in order to continue cost effective size scaling. The directed self-assembly (DSA) of block copolymers (BCPs) is a nanofabrication technique used to reduce the periodicity of patterns prepared with traditional optical methods. BCPs with large interaction parameters (χ eff ), provide access to smaller pitches and reduced interface widths. Larger χ eff is also expected to be correlated with reduced line edge roughness (LER), a critical performance parameter in integrated circuits. One approach to increasing χ eff is blending the BCP with a phase selective additive, such as an Ionic liquid (IL). The IL does not impact the etching rates of either phase, and this enables a direct interrogation of whether the change in interface width driven by higher χ eff translates into lower LER. The effect of the IL on the layer thickness and interface width of a BCP are examined, along with the corresponding changes in LER in a DSA patterned sample. The results demonstrate that increased χ eff through additive blending will not necessarily translate to a lower LER, clarifying an important design criterion for future material systems.