Papers by Author: Miftakhul Huda

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Authors: Miftakhul Huda, Zulfakri bin Mohamad, Takuya Komori, You Yin, Sumio Hosaka
Abstract: The progress of information technology has increased the demand of the capacity of storage media. Bit patterned media (BPM) has been known as a promising method to achieve the magnetic-data-storage capability of more than 1 Tb/in.2. In this work, we demonstrated fabrication of magnetic nanodot array of CoPt with a pitch of 33 nm using a pattern-transfer method of block copolymer (BCP) self-assembly. Carbon hard mask (CHM) was adopted as a mask to pattern-transfer self-assembled nanodot array formed from poly (styrene)-b-poly (dimethyl siloxane) (PS-PDMS) with a molecular weight of 30,000-7,500 mol/g. According to our experiment results, CHM showed its high selectivity against CoPt in Ar ion milling. Therefore, this result boosted the potential of BCP self-assembly technique to fabricate magnetic nanodot array for the next generation of hard disk drive (HDD) due to the ease of large-area fabrication, and low cost.
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: 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.
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