The Photopolymer Science and Technology Award No.131100, the Outstanding Achievement Award 2013, was presented to Murrae J. Bowden (Stevens Institute of Technology) for his outstanding achievements in photopolymer science and technology, involving “Development of New Advanced Resist Materials for Microelectronics”.

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The Photopolymer Science and Technology Award No.132100, the Best Paper Award 2013, was presented to Shingo Ueno[a,b], Aiko Ono[a,b], Ryo Kobayashi[a,b], Yoko Tanaka[a,b], Shusuke Sato[a,b], Manish Biyani[a,b], Naoto Nemoto[b,c], and Takanori Ichiki[a,b] ([a]The University of Tokyo, [b]JST-CREST, [c]Saitama University), for their outstanding contribution published in the Journal of Photopolymer Science and Technology, 25, (2012) 67-72, entitled “Photoassisted recovery of DNA molecules for on-chip directed evolution”.

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The Photopolymer Science and Technology Award No. 132200, the Best Paper Award 2013, was presented to Atsushi Asano, Yuta Maeyoshi, Katsuyoshi Takano, Masaaki Omichi, Masaki Sugimoto, Masahito Yoshikawa, Satoshi Tsukuda, Shun-ichiro Tanaka, Akinori Saeki, and Shu Seki, from Osaka University, Japan Atomic Energy Agency, and Tohoku University for their outstanding contribution published in Journal of Photopolymer Science and Technology 25(5), 685-688 (2012), entitled “Fabrication of Nanowires Based on Polystyrene Derivatives by Single Particle Nano-Fabrication Technique”.

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We use self-consistent field theory (SCFT) to study the self-assembly of diblock copolymers confined in cylindrical and non-cylindrical prepatterns. This situation arises in contact holes -the hole shrink problem- where the goal is to produce a contact hole with reduced dimensions relative to a guiding prepattern. In this study, we focus on systems with a critical dimensions (CD) ranging from ~50nm to ~100nm leading to the formation of a single PMMA domain in the middle of the holes. We found that different morphologies arise from the self-assembly process and are strongly governed by the prepattern dimensions, wetting conditions, shape of prepatten as well as the polymer molecular weight. We also considered blends of diblock copolymers and homopolymers and determined optimal blending configurations that not only favor the formation of the desired cylindrical morphology but also extend the processing window relative to the pure diblock case in cylindrical confinements.

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In this study, we conducted electrical via chain yield tests for the purpose of verifying the total process performance of directed self-assembly (DSA) contact hole shrink process. DSA was utilized on the via level connecting between two metal levels. From the analysis of single via resistance data, the best process condition was determined and the via chain yield was obtained. The best yield was 74% at the via chain size of 2.3k and one chip passed the test at the via chain size of 358k. In order to find the root cause of the via chain yield degradation, the failure location was identified by absorbed electron current images and STEM images were taken. It was found that the via did not contact the lower metal level at the failure location. However, we concluded that it was not necessarily caused by DSA process because such failure mode was also observed for the via chains without DSA. Although the via chain size tested at the pre-production stage is much larger by orders of magnitude than the via chain size tested in this study, we believe that significant progress has been made in this study toward semiconductor device manufacturing using DSA contact hole shrink process.

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The Directed Self-Assembly (DSA) method is becoming a key complementary technology for enabling lithographic pattern feature shrinkage. Recent DSA technology has developed remarkable improvements in many aspects of materials and process. Polystyrene- b-polymethylmethacrylate (PS-b-PMMA) block copolymer (BCP) is a typical material used in DSA, but more advanced materials are required for achieving patterning less than 10 nm in size. High-χ block copolymers are being researched as next generation PS-b-PMMA material successors. Polymers with high-χ produce smaller pattern sizes than PS-b-PMMA. However, doing DSA with these high-χ materials requires a special method to separate one phase of BCP such as phase separation in solvent. We have done further research to improve high-χ materials to enable better DSA technology. Here we report 8.4 nm half-pitch line patterns were formed with our high-χ block co-polymer, annealing under air. DSA is a candidate for next generation lithography. However, DSA materials are not used alone. DSA materials are always used with guide pattern to “direct” self assembly materials. Currently ArF resist is well studied as guide pattern. ArF resist is extended to use further generation, but the required resolution level is already severe for 193nm patterning. Employment of blend DSA could improve the ArF pattern profile.

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Directed self-assembly (DSA) of block copolymers (BCPs) is a promising technology for advanced patterning at future technology nodes, but significant hurdles remain for commercial implementation. The most widely studied material for DSA is poly(styrene-block-methyl methacrylate) (PS-PMMA), but the relatively weak segregation strength of PS-PMMA results in some limitations. This paper reports on these limitations for PS-PMMA and highlights a path to success through use of more strongly segregated “high-?” block copolymers. In general, stronger segregation is predicted to lower defectivity at equilibrium, but unfortunately, kinetics of self assembly also becomes much slower as segregation strength increases. Recognizing diffusion is much faster for cylinder morphologies than lamellar ones, we have investigated new cylinder-forming BCPs that enable defect elimination with thermal annealing processes. In addition, a formulation strategy is presented that further improves the kinetics of the assembly process, enabling tremendous improvements in defectivity over simple BCP systems. Excitingly, successful chemoepitaxy DSA with a high-? lamellar BCP is also demonstrated using a thermal annealing process and no top coat. These technologies hold promise to enable DSA with thermal annealing processing across pitches from 40 - 16 nm.

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An ultra narrow line structure was prepared in the lamellar morphology of polyhedral oligomeric silsesquioxane (POSS)-containing triblock terpolymer in the bulk via the self-assembly. The triblock terpolymers, which comprised polystyrene, POSS-containing poly(methacrylate) (PMAPOSS) and poly(methyl methacrylate), were synthesized by anionic polymerization. The self-assembled structures were studied by using a transmission electron microscopy (TEM) and a small-angle X-ray scattering (SAXS). It was found that a narrow PMAPOSS domain was layered in triple-domain lamellar, which caused by the effect of strongly segregation with the middle PMAPOSS block. The total d-spacing was 32 nm, and the smallest width of PMAPOSS domain layer was ca. 4 nm.

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A spin-on-glass (SOG) film, which can serve as a perpendicular orientation control layer for direct self-assembly (DSA) using a block copolymer (BCP) was developed. A lamellar pattern and a cylindrical pattern made of polystyrene polymethylmethacrylate diblock copolymer (PS-b-PMMA) were oriented perpendicularly on the SOG film. The SOG film also can be applied to the upper layer of tri-resist process. It was also found that contact angles of water could not be used as indices of surface energies quantitatively in the case of the SOG films.

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The directed self-assembly (DSA) of polymer blends in various types of guiding patterns was investigated. The change in CD and aspect ratio before and after the DSA process as a function of the pitch and aspect ratio of the guiding patterns are reported. The behavior of polymer blend DSA was found to depend on guiding pattern design rather than a simple conformal, spacer-like shrinking. The results achieved from this study provided useful information for guiding pattern design for this specific polymer blend system.

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Conventional imprint (dry-imprint) requires a low polymer viscosity by means of thermal annealing to enhance sufficient flow. Nevertheless, NIL patterning of semiconducting polymers like P3HT and PCPDTBT demands for no or low heating to avoid degradation. Therefore, we tried different layer preparation (no soft bake and low temperature soft bake) and low imprint temperatures in order to maintain the patterning fidelity but to reduce degradation of the imprint polymer. Different patterns were investigated: relatively large sizes (50/100 μm pads) and relatively small sizes (5 μm grating). We achieved similar cavity filling with wet-NIL (no soft bake) imprinted at 110 °C and dry-NIL imprinted at 200 °C for the small pattern size. In addition, we found that the PCPCDTBT has higher viscosity than Reg-P3HT. Admittedly, the large pattern size suffered from non-uniformity and limited reproducibility due to the higher η of the semi-crystalline polymer Reg-P3HT (compared with amorphous polymer Ran-P3HT).

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We propose an organic photodiode for radiation detection with nanoimprinted structure in p-n junction to increase the X-ray induced current. It is found that the nanoimprited structure made from lower molecular weight P3HT, less than 90 K g/mol, is dissolved by the solvent of PCBM, that is, dichloromethane (DCM), on the other hand, the structure made from high molecular weight, 300 K g/mol, is not dissolved. The effect of expanding the p-n junction using nanoimprint lithography is observed in the case of visible light and X-ray induced scintillation light irradiation.

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The effectiveness of condensable gas, used as ambience, in UV nanoimprint lithography has been demonstrated. Bubble defect problem, which is inherent in UV nanoimprint under non vacuum ambience, can be solved by PFP condensable gas. UV nanoimprint lithography using PFP was validated for 45 nm pattern fabrication under thin residual layer conditions, which are required for UV nanoimprint used as UV nanoimprint lithography. PFP reduces the viscosity and demolding force of UV curable resins. These properties are helpful in increasing the throughput and reliability of UV nanoimprint. PFP occasionally produces large shrinkages, and degrades pattern quality depending on UV curable resin. These drawbacks can be mitigated by selecting UV curable monomers with a low PFP absorption with a solubility parameter away from 20( J/cm³)^1/2. UV nanoimprint using PFP is so striking that we now think use of PFP be an integral part of UV nanoimprint.

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We propose a mixture molecular resist system consisting of high and low molecular weight resins to achieve fine and high aspect ratio pattern fabrication by nanoimprint lithography. Poly-methyl methacrylate (PMMA) with molecular weights of 50,000 g/mol and that of 350,000 g/mol are mixed. Using the mixture polymer, thermal nanoimprint is examined. The resist system is good for easy deformation into narrow patterns by low-molecular-weight components and reinforces stiffness at the pattern’s root portion against mold releasing defects by high molecular weight components. We confirm a fine pattern transfer using the proposed resist.

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The shrinkage of polymethylmethacrylate and polystyrene patterns fabricated by the thermal nanoimprint process by the conventional UV/O3 treatment is examined. The reduction rate at the pattern top is larger than those at the side wall and bottom. This shows that the pattern height decreases rapidly. The line width control by the UV/O₃ treatment should be carried out carefully. The stretched layer is often observed at the cutting surface of the resist pattern. The formation of the stretched layer can be effectively suppressed by the short UV/O₃ treatment.

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As a new manufacturing technique based on replication of surface topographies, nanoimprint lithography makes specific demands on materials used as resists for pattern transfer, as molds during replication or as functional materials for permanent application. Thus, highly specialized polymer solutions play a key role for the innovations in nanoimprint-related production technology where a high-throughput and low-cost nanolithography step is performed. In this contribution, recent material innovations at micro resist technology GmbH are reviewed with focus on OrmoStamp^(R)as versatile working stamp material with superior mold properties and its unique applicability to various nanoimprint processes. It is shown by the example of multidimensional nanofluidic devices how tailor-made materials facilitate mass production of innovative applications using nanoimprint lithography.

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Nanoimprint technology (NIT) has been developed as a method of microfabrication technology. Roll-to-roll process has been applied to NIT, because high throughput and cost reduction are essential to achieve practical mass-production. In this study, we developed a film mold made of self-developed UV-curable resin and applied the film mold to the UV roll-to-roll nanoimprinting process. The film mold exhibited several superior properties, excellent mold releasability, high transmittance in the UV-Vis range and appropriate mechanical properties. Obtained transcribed products had high transcription accuracy without remarkable defects even after 1500 m imprinting. Pattern sizes of transcribed products were almost constant at line speeds ranging from 1 to 5 m/min. Moreover, various nano and micro patterned transcribed products were obtained as well. These results indicate the developed film mold is adequate for practical mass-production by applying to UV roll-to-roll nanoimprinting process.

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In recent years, the size of patterns used in nanoimprint lithography (NIL) continues to shrink rapidly. Since nanoimprinting is a form of contact printing, increasing the separation force might damage the master and imprinting tool, as well as degrading the pattern quality. The mold-release characteristics of the master and resin remain a key concern. Although Optool DSXTM (DAIKIN Ind. Ltd.) is the de facto standard for mold release agents, its durability with regard to UV-NIL is suspect. Our solution is a class of material that offers enhanced mold-release characteristics. The new fluorinated copolymers based on α-chloroacrylate and low molecular weight perfluorocompounds, are intended to be resist additives. This paper reports the synthesis method of low molecular weight perfluorocompounds, specific properties such as changed surface tension after added to resist, release force and the use of other fluorinated compounds for resin surface treatment.

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To investigate template releasing process in nanoimprint lithography, template releasing energy from resist polymer is evaluated under various conditions using test rig. The template releasing energy is proportional to the surface energy of the template, however it does not depend on rigidness of the system and template lifting speed.

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