EOS is a technology demonstrator, designed to explore the capabilities of hybrid event detection technology, leveraging both Cherenkov and scintillation light simultaneously. With a fiducial mass of four tons, EOS is designed to operate in a high-precision regime, with sufficient size to utilize time-of-flight information for full event reconstruction, flexibility to demonstrate a range of cutting edge technologies, and simplicity of design to facilitate potential future deployment at alternative sites. Results from EOS can inform the design of future neutrino detectors for both fundamental physics and nonproliferation applications.

Polarity-switching photopatternable guidelines can be directly used to both orient and direct the self-assembly of block copolymers. We report the orientation and alignment of poly(styrene-block-4-trimethylsilylstyrene) (PS-b-PTMSS) with a domain periodicity, L0, of 44 nm on thin photopatternable grafting surface treatments (pGSTs) and cross-linkable surface treatments (pXSTs), containing acid-labile 4-tert-butoxystyrene monomer units. The surface treatment was exposed using electron beam lithography to create well-defined linear arrays of neutral and preferential regions. Directed self-assembly (DSA) of PS-b-PTMSS with much lower defectivity was observed on pXST than on pGST guidelines. The study of the effect of film thickness on photoacid diffusion by Fourier transform infrared spectroscopy and near-edge X-ray absorption fine structure spectroscopy suggested slower diffusion in thinner films, potentially enabling production of guidelines with sharper interfaces between the unexposed and exposed lines, and thus, the DSA of PS-b-PTMSS on thinner pXST guidelines resulted in better alignment control.

ADVERTISEMENT RETURN TO ISSUEEditorialNEXTGrowing Contributions of Nano in 2020C. Jeffrey BrinkerC. Jeffrey BrinkerMore by C. Jeffrey Brinkerhttp://orcid.org/0000-0002-7145-9324, Jillian M. BuriakJillian M. BuriakMore by Jillian M. Buriakhttp://orcid.org/0000-0002-9567-4328, Warren C. W. ChanWarren C. W. ChanMore by Warren C. W. Chanhttp://orcid.org/0000-0001-5435-4785, Manish ChhowallaManish ChhowallaMore by Manish Chhowallahttp://orcid.org/0000-0002-8183-4044, Sharon C. GlotzerSharon C. GlotzerMore by Sharon C. Glotzerhttp://orcid.org/0000-0002-7197-0085, Yury GogotsiYury GogotsiMore by Yury Gogotsihttp://orcid.org/0000-0001-9423-4032, Paula T. HammondPaula T. HammondMore by Paula T. Hammondhttp://orcid.org/0000-0002-9835-192X, Mark C. HersamMark C. HersamMore by Mark C. Hersamhttp://orcid.org/0000-0003-4120-1426, Ali JaveyAli JaveyMore by Ali Javeyhttp://orcid.org/0000-0001-7214-7931, Cherie R. KaganCherie R. KaganMore by Cherie R. Kaganhttp://orcid.org/0000-0001-6540-2009, Kazunori KataokaKazunori KataokaMore by Kazunori Kataokahttp://orcid.org/0000-0002-8591-413X, Ali KhademhosseiniAli KhademhosseiniMore by Ali Khademhosseinihttp://orcid.org/0000-0002-2692-1524, Il-Doo KimIl-Doo KimMore by Il-Doo Kimhttp://orcid.org/0000-0002-9970-2218, Nicholas A. KotovNicholas A. KotovMore by Nicholas A. Kotovhttp://orcid.org/0000-0002-6864-5804, Shuit-Tong LeeShuit-Tong LeeMore by Shuit-Tong Leehttp://orcid.org/0000-0003-1238-9802, Young Hee LeeYoung Hee LeeMore by Young Hee Leehttp://orcid.org/0000-0001-7403-8157, Yan LiYan LiMore by Yan Lihttp://orcid.org/0000-0002-3828-8340, Luis M. Liz-MarzánLuis M. Liz-MarzánMore by Luis M. Liz-Marzánhttp://orcid.org/0000-0002-6647-1353, Jill E. MillstoneJill E. MillstoneMore by Jill E. Millstonehttp://orcid.org/0000-0002-9499-5744, Paul MulvaneyPaul MulvaneyMore by Paul Mulvaneyhttp://orcid.org/0000-0002-8007-3247, Andre E. NelAndre E. NelMore by Andre E. Nelhttp://orcid.org/0000-0002-5232-4686, Peter NordlanderPeter NordlanderMore by Peter Nordlanderhttp://orcid.org/0000-0002-1633-2937, Wolfgang J. ParakWolfgang J. ParakMore by Wolfgang J. Parakhttp://orcid.org/0000-0003-1672-6650, Reginald M. PennerReginald M. PennerMore by Reginald M. Pennerhttp://orcid.org/0000-0003-2831-3028, Andrey L. RogachAndrey L. RogachMore by Andrey L. Rogachhttp://orcid.org/0000-0002-8263-8141, Raymond E. SchaakRaymond E. SchaakMore by Raymond E. Schaakhttp://orcid.org/0000-0002-7468-8181, A. K. SoodA. K. SoodMore by A. K. Soodhttp://orcid.org/0000-0002-4157-361X, Molly M. StevensMolly M. StevensMore by Molly M. Stevenshttp://orcid.org/0000-0002-7335-266X, Andrew T. S. WeeAndrew T. S. WeeMore by Andrew T. S. Weehttp://orcid.org/0000-0002-5828-4312, Tanja WeilTanja WeilMore by Tanja Weilhttp://orcid.org/0000-0002-5906-7205, C. Grant WilsonC. Grant WilsonMore by C. Grant Wilsonhttp://orcid.org/0000-0002-2072-3981, and Paul S. WeissPaul S. WeissMore by Paul S. Weisshttp://orcid.org/0000-0001-5527-6248Cite this: ACS Nano 2020, 14, 12, 16163–16164Publication Date (Web):December 22, 2020Publication History Published online22 December 2020Published inissue 22 December 2020https://pubs.acs.org/doi/10.1021/acsnano.0c10429https://doi.org/10.1021/acsnano.0c10429editorialACS PublicationsCopyright © Published 2020 by American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views4624Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (4 MB) Get e-AlertscloseSUBJECTS:Nanoscale,Nanoscience,Nanotechnology,Vaccination,Viruses Get e-Alerts

During the course of studying silicon-containing diblock copolymers, it was discovered that poly(3,5-di(trimethylsilyl)styrene)-block-poly(3,4-methylenedioxystyrene) (PDTMSS-b-PMDOS) showed very unusual thermal properties. The material can be recovered as a free-flowing powder despite heating above 250 degrees C. To better understand this behavior, homopolymers of the 3,5-disubstituted styrenes, poly(3,5-di(trimethylsilyl)styrene) (PDTMSS) and poly(3,5-di-tert-butylstyrene) (PDtBS), were prepared. These polymers are soluble in common organic solvents and formed clear, glassy thin films upon spin coating. These homopolymers were studied by differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS), dynamic mechanical analysis (DMA), and temperature-programmed ellipsometry. These experiments document the lack of a conventional glass transition in these materials below their decomposition temperature. A series of statistical copolymers of PDTMSS and PDtBS with styrene was synthesized and studied by DSC in an attempt to establish the T-g of the homopolymers by model-based extrapolation.

During the course of studying silicon-containing diblock copolymers, it was discovered that poly(3,5-di(trimethylsilyl)styrene)-block-poly(3,4-methylenedioxystyrene) (PDTMSS-b-PMDOS) showed very unusual thermal properties. The material can be recovered as a free-flowing powder despite heating above 250 degrees C. To better understand this behavior, homopolymers of the 3,5-disubstituted styrenes, poly(3,5-di(trimethylsilyl)styrene) (PDTMSS) and poly(3,5-di-tert-butylstyrene) (PDtBS), were prepared. These polymers are soluble in common organic solvents and formed clear, glassy thin films upon spin coating. These homopolymers were studied by differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS), dynamic mechanical analysis (DMA), and temperature-programmed ellipsometry. These experiments document the lack of a conventional glass transition in these materials below their decomposition temperature. A series of statistical copolymers of PDTMSS and PDtBS with styrene was synthesized and studied by DSC in an attempt to establish the T-g of the homopolymers by model-based extrapolation.

Silicon-containing block copolymers are considered promising materials for high resolution pattern generation through directed self-assembly. The nonpolar organo-silicon moieties result in a high Flory-Huggins interaction parameter (χ) when paired with a polar block, allowing features well below 20 nm full pitch to be generated. In addition, the incorporation of silicon provides excellent dry etch selectivity under a variety of reactive ion etching conditions. However, similar to all block copolymer systems under development, achieving sufficiently low defect density remains a critical hurdle for implementation of directed self-assembly into high volume manufacturing. This work reports our progress towards this end, using a chemo-epitaxy flow to direct the assembly of poly(4-trimethylsilylstyrene-block-4- methoxystyrene), resulting in sub-20 nm full pitch line/space patterns. This process employs 193 nm immersion lithography to define the guide structure and is run on 300 mm wafers in a fab-like environment. Our efforts in understanding the possible root cause(s) of the dominant defect modes and reducing the total defect density of the flow will be described. This study includes research on the influence of various process parameters as well as the chemical compositions of the different materials involved, and their interactions with specific defect modes.

Preparation of an unzipping polyester is reported. The monomer was prepared from benzoic acid in a four-step sequence. Step growth polymerization of the monomer provides the target polymer. Efficient depolymerization upon irradiation at 254 nm was confirmed with a quantum yield of >0.8. The photolysis mechanism was investigated, and the results of radical trapping experiments are consistent with an initial Norrish type I like homolysis followed by a radical mediated depropagation reaction driven by aromatization.

This study is based on a latent ruthenium catalyst that includes a Schiff base moiety. This catalyst was formulated with a photoacid generator and a ring-opening metathesis polymerization (ROMP) active monomer such as cyclooctadiene or dicyclopentadiene. Exposure of this mixture to ultraviolet light generates acid that protonates the Schiff base and thereby renders the latent catalyst active leading to ROMP of the monomer. A resist system based on new photoinitiated ROMP chemistry has been developed. This sort of formulation has been used to produce high-resolution replicas of a transparent mold by imprint lithography.

Directed self-assembly (DSA) of high-χ block copolymer thin films is a promising approach for nanofabrication of features with length scale below 10 nm. Recent work has highlighted that kinetics are of crucial importance in determining whether a block copolymer film can self-assemble into a defect-free ordered state. In this work, different strategies for improving the rate of defect annihilation in the DSA of a silicon-containing, high-χ block copolymer film were explored. Chemo-epitaxial DSA of poly(4-methoxystyrene-block-4-trimethylsilylstyrene) with 5× density multiplication was implemented on 300 mm wafers by using production level nanofabrication tools, and the influence of different processes and material parameters on dislocation defect density was studied. It was observed that only at sufficiently low χN can the block copolymer assemble into well-aligned patterns within a practical time frame. In addition, there is a clear correlation between the rate of the lamellar grain coarsening in unguided self-assembly and the rate of dislocation annihilation in DSA. For a fixed chemical pattern, the density of kinetically trapped dislocation defects can be predicted by measuring the correlation length of the unguided self-assembly under the same process conditions. This learning enables more efficient screening of block copolymers and annealing conditions by rapid analysis of block copolymer films that were allowed to self-assemble into unguided (commonly termed fingerprint) patterns.

Directed self-assembly (DSA) of block copolymers (BCPs) is one approach to the pattern density multiplication required to achieve high-volume manufacturing of the next-generation memory and storage devices. One important application for DSA is in manufacturing of nanoimprint templates for the next-generation bit patterned media. A hybrid chemo-/grapho-epitaxy DSA process has been developed that produced 5 nm line-and-space DSA patterns on a chromium hard mask surface. The guide lines for this process were produced by imprint lithography. The process requires a polar guide stripe, which is the trim-etched imprint resist, and a near neutral substrate, which is the etched chromium. This requires selective grafting of near neutral polymer brushes to the etched chromium and not to the etched imprint guidelines. This selectivity is one critical requirement for the process [1]. Orientation and alignment of line-and-space patterns that traverse through the entire BCP film were successfully employed to pattern the chromium hard mask. We have investigated the reactivity of etched chromium surfaces with various polymer brush chemistries and found that the choice of the end-functional groups, monomer structures, and grafting temperature all play significant roles in selective functionalization. The etched chromium surface was found to be more reactive with various polymer brushes than etched silicon under mild brush grafting conditions. Hence, lower grafting temperatures could be exploited for achieving selectivity of polymer brush to the etched chromium while not reacting with the etched imprint guidelines. Thus, several polymer brushes that form a thin layer of brush on etched chromium were found to modify the surface energy of the etched chromium without significant interaction with the etched imprint resist. Successful pattern transfer of 5 nm line-and-space patterns was achieved. 1. Lane, A. P., et al. ACS Nano (2017), 11 (8), 7656–7665.

This project, “Pitch Division Photolithography at I-line,” seeks to accomplish pitch multiplication by using a traditional 248 nm photoresist polymer in conjunction with a photo-acid generator (PAG) and a photo-base generator (PBG). This formulation can achieve a two-fold improvement in resolution without the need for new equipment or significant changes in processing conditions. The photoresist matrix used in this work is poly[4-[(tert-butoxycarbonyl)oxy] styrene] (PTBOC), which is employed in combination with a PAG in 248 nm resists. When exposed to light, the PAG decomposes to form acid which, upon post-exposure baking, deprotects multiple pendant groups on the PTBOC to produce hydroxyl groups, thereby changing its solubility. This polymer exhibits another key feature: the dissolution rate with respect to dose has a threshold-like response, meaning that below a threshold dose, the polymer will not appreciably dissolve in a developer containing tetramethyl ammonium hydroxide (TMAH), but above this dose, the dissolution rate increases several orders of magnitude. This behavior becomes vital at feature sizes that approach theoretical resolution limits where the aerial image near the photoresist becomes more sinusoidal. Because the dissolution rate is controlled by the acid content within the polymer matrix, it is possible to cross this dissolution threshold twice with increasing dose if the acid is somehow quenched at higher doses. A PBG is an easy way to achieve this goal. If a PBG is chosen such that it is decomposes more slowly than the PAG and is incorporated with a stochiometric excess, then this dissolution threshold may be crossed twice. The addition of a PBG generates three different regimes with respect to dose: At low doses, neither the PAG nor PBG will have appreciably decomposed and the resist remains insoluble in aqueous base. At medium doses, enough acid will be generated by the PAG to cross the threshold, with too little PBG decomposition to effectively quench said acid. At high doses, both the PAG and PBG have mostly decomposed and the net acid concentration will be below the dissolution threshold. If the relative rates of the PAG and PBG can be tuned such that these two dissolution thresholds properly match the sinusoid intensity profile, the resolution of patterns can be improved by a factor of two. Dr. Xinyu Gu previously demonstrated the feasibility of such a system for 193 nm tools [1]. In this work, we report several combinations of PAGs and PBGs that meet the above criteria and show promise for exhibiting pitch-division. In some cases, a photosensitizer was needed to enable the decomposition of the PAG. These combinations were tested by exposing a film to a given dose and then developing in an aqueous solution of TMAH. It was found that the relative dissolution rates closely match the ideals as described above. These combinations are ready for testing with an exposure tool to verify and optimize their function as a pitch division photoresist. Reference: [1] Gu, X. et al. “Photobase generator enabled pitch division: a progress report,” Proc. SPIE 7972, 79720F (2011).

We report the first measurement of the neutron cross section on argon in the energy range of 100-800 MeV. The measurement was obtained with a 4.3-h exposure of the Mini-CAPTAIN detector to the WNR/LANSCE beam at LANL. The total cross section is measured from the attenuation coefficient of the neutron flux as it traverses the liquid argon volume. A set of 2631 candidate interactions is divided in bins of the neutron kinetic energy calculated from time-of-flight measurements. These interactions are reconstructed with custom-made algorithms specifically designed for the data in a time projection chamber the size of the Mini-CAPTAIN detector. The energy averaged cross section is 0.91±0.10(stat)±0.09(syst)  b. A comparison of the measured cross section is made to the GEANT4 and FLUKA event generator packages, where the energy averaged cross sections in this range are 0.60 and 0.68 b, respectively.