Papers by Author: Takuro Tamura

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Authors: Takuro Tamura, Yasunari Tanaka, Takashi Akahane, You Yin, Sumio Hosaka
Abstract: In this study, we investigated the possibility of forming the fine Si dot arrays by means of electron beam (EB) lithography and dry etching technique for the future’s devices with nano-scale structures. We examined the properties of Ar ion milling for the fabrication of nanometer sized Si dot arrays on a Si substrate. We have succeeded in forming 40 nm pitched Si dot arrays with a diameter of <20 nm using dot array patterns of the calixarene resist as a mask. We also obtained the Ar ion milling property that there exists the horizontal milling rate as well as the vertical milling rate. We formed Si dot arrays with a dot diameter of about 10 nm using this property. It was clarified that Ar ion milling and EB lithography with calixarene resist has the potential to form Si nano dot arrays for the nano devices.
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, 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.
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