Papers by Keyword: Nanodot

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Authors: Sumio Hosaka, Takashi Akahane, Miftakhul Huda Huda, Takuya Komori, Hui Zhang, You Yin
Abstract: A possibility to fabricate nanodot arrays with a dot size of <10 nm="" and="" a="" dot="" pitch="" of="" 12="" along="" guide="" lines="" has="" been="" studied="" for="" ultrahigh-density="" patterned="" media="" in="" magnetic="" recording="" this="" was="" by="" using="" self-assembling="" block="" copolymers="" polystyrene-poly="" dimethyl="" siloxane="" ps-pdms="" electron="" beam="" eb="" drawing="" with="" hydrogen="" silsesquioxane="" hsq="" negative="" resist="" their="" fusion="" method="" it="" demonstrated="" that="" the="" could="" possibly="" achieve="" 6-nm-sized="" nanodot="" arrays="" 10="" 4="" x="" sup="">2 using self-assembling with PS-PDMS of molecular weight 7000-1500 and EB-drawing for narrow guide lines. These results prove that the fusion method is required for achieving extremely small dot arrays as 5 Tbit/in2 magnetic storage devices.Keywords: Nanodot, self-assembly, electron-beam drawing, graphoepitaxy, patterned media, magnetic recording.
Authors: Ting Wang, Li Guo
Abstract: Cobalt oxyhydroxide nanocrystals were synthesized in an aqueous solution in the cavity of the apoferritin from horse spleen (HsAFr), and two-dimensional CoOOH-ferritin nanodots were prepared by simple touch method on modified silicon surface. In the synthesis, CoOOH nanocrystals are encapsulated and growth is restricted to the internal dimension of the protein cavity. The obtained nanodots were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), absorption and photoluminescence (PL) measurements. From the results, it was concluded that CoOOH nanocrystals were successfully synthesized in the core of ferritin and the monolayer of CoOOH-ferritin could be obtained on the surface of modified silicon surface. In addition, CoOOH quantum dots(QDs) in ferritin core provided the PL emission peak. Accordingly, the CoOOH-ferritin arrays can be employed as a potential useful biosensor material for PL technique.
Authors: Miftakhul Huda, Takuro Tamura, You Yin, Sumio Hosaka
Abstract: In this work, we studied the fabrication of 12-nm-size nanodot pattern by self-assembly technique using high-etching-selectivity poly (styrene)-poly (dimethyl-siloxane) (PS-PDMS) block copolymers. The necessary etching duration for removing the very thin top PDMS layer is unexpectedly longer when the used molecular weight of PS-PDMS is 13.5-4.0 kg/mol (17.5 kg/mol total molecular weight) than that of 30.0-7.5 kg/mol (37.5 kg/mol total molecular weight). From this experimental result, it was clear that PS-PDMS with lower molecular weight forms thicker PDMS layer on the air/polymer interface of PS-PDMS film after microphase separation process. The 22-nm pitch of nanodot pattern by self-assembly holds the promise for the low-cost and high-throughput fabrication of 1.3 Tbit/inch2 storage device. Nanodot size of 12 nm also further enhances the quantum-dot effect in quantum-dot solar cell.
Authors: Takashi Akahane, Miftakhul Huda, You Yin, Sumio Hosaka
Abstract: In this paper, we report two kinds of guide patterns precisely created by electron beam drawing. These guide patterns are expected to precisely control the arrangement of nanodots self-assembled from block copolymer (BCP) in order to obtain long-range-order nanofabrication. The first guide pattern is comprised only of a post lattice. The second guide pattern adds guide lines to the post lattice. The added guide lines are expected to better control the location and orientation of the BCP nanodots. We succeeded in fabricating these two kinds of guide patterns for 22-nm- and 33-nm-pitch BCP nanodots.
Authors: Takashi Akahane, Miftakhul Huda, Takuro Tamura, You Yin, Sumio Hosaka
Abstract: We have studied functionalization of guide pattern with brush treatment. Especially, the effect of brush treatment on ordering of nanodots formed on the guide pattern was investigated. We used polydimethylsiloxane (PDMS) as brush modification to form self-assembled nanodots on the guide pattern using polystyrene (PS) - PDMS as block copolymer. The brush treatment using toluene solvent made guide patterns of the electron beam (EB) drawn resist behave like PDMS guide patterns and good ordering of the nanodots has been achieved. It was demonstrated that the brush treatment enabled the PDMS nanodots to be regularly located in the desired positions defined by the EB drawn guide patterns.
Authors: Takashi Akahane, Takuya Komori, Jing Liu, Miftakhul Huda, Zulfakri bin Mohamad, You Yin, Sumio Hosaka
Abstract: In this work, improvement of the observation contrast was investigated by using a carbon film as the hard mask for pattern transfer of block copolymer (BCP) nanodots. The PS-PDMS (Poly (styrene-b-dimethyl siloxane)) block copolymer was adopted here. The observation contrast was greatly improved after transferring block copolymer (BCP) nanodots pattern to the underlying Si substrate through the carbon hard mask compared that before nanodot pattern transfer. Pattern transfer was also demonstrated to be very effective using carbon hard mask.
Authors: Takuya Komori, Miftakhul Huda, Takashi Akahane, Muneyasu Masuda, Jing Liu, Zulfakri bin Mohamad, You Yin, Sumio Hosaka
Abstract: We investigated the possibility of ordering of 12 nm pitced self-assembled nanodots from block copolymer (BCP) improved by the guide pattern with low line edge roughness (LER) for patterned media. We found that LER of the line pattern (σ-value) was reduced by using high-resolution salty development for HSQ resist line pattern fabrication compared with conventional tetramethyl ammonium hydroxide (TMAH) developer. By adopting this development technique to guide pattern fabrication, we demonstrated 10 rows of ordered self-assembled BCP nanodot arrays with a size of 6 nm and a pitch of 12 nm (5 Tbit/in.2) between the guide patterns.
Authors: Miftakhul Huda, Jing Liu, Zulfakri bin Mohamad, You Yin, Sumio Hosaka
Abstract: The self-assembly of block copolymer (BCP) has demonstrated as promising alternative technology to overcome the limitation of conventional lithography owing to its ability in forming nanostructure with size 3-100 nm. In this study, we investigated a technique to transfer self-assembled nanodots of Poly(styrene-b-dimethyl siloxane) (PS-PDMS) BCP to Si. The pattern transfer of PS-PDMS nanodots with the pitch of 33 nm and the diameter of 23 nm using CF4 etching with Carbon Hard Mask (CHM) as Mask is demonstrated. Si nanopillar with height of 51 nm was fabricated. This result improves the potential use of PS-PDMS BCP self-assembly technique for fabrication nano-electronic devices, such as quantum dot solar cell and ultrahigh density of magnetic recording.
Authors: Miftakhul Huda, You Yin, Sumio Hosaka
Abstract: In this study, we investigate self-assembled large-area nanodot fabrication on a silicon substrate using poly(styrene)-poly(dimethyl-siloxane) (PS-PDMS) for the application to quantum dot solar cell. By optimizing the PS-PDMS concentration by 2% and the volume of PS-PDMS solutions by 20 μL/cm2 dropped to silicon substrate, nanodots with a pitch size of 33 nm and a diameter of 23 nm are achieved with the molecular weight of 30,000-7,500. It is found that the dropped volume of PS-PDMS solution correlated to the thickness of spin-coated PS-PDMS layer has a great effect on the size and the pattern morphology.
Authors: Yasuo Takahashi, Ming Yu Jo, Takuya Kaizawa, Yuki Kato, Masashi Arita, Akira Fujiwara, Yukinori Ono, Hiroshi Inokawa, Jung Bum Choi
Abstract: Small single-electron devices (SEDs) consisting of many Si nanodots are fabricated on a silicon-on-insulator (SOI) wafer by means of pattern-dependent oxidation (PADOX) method. We investigated SEDs from two kinds of viewpoint. One is how to fabricate the nanodots, especially coupled nanodots, which are important to achieve quantum computers and single-electron transfer devices. The other is demonstration of new applications that tolerate the size fluctuation. In order to achieve multi-coupled nanodots, we developed an easy method by applying PADOX to a specially designed Si nanowire which has small constrictions at the ends of the wire. We confirmed the double-dot formation and position of the Si nanodots in the wire by analyzing the measured electrical characteristics. To achieve high functionality together with low-power consumption and tolerance to size fluctuation, we developed nanodot array device which has many input gates and outputs terminals. The fabricated three-input and two-output nanodot device actually provide high functionality such as a half adder and a full adder.
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