• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.477-478
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• 2019

We have investigated the experiments in which fabrication and characterization of single-electron transistors were conducted due to easy fabrication and high functionality. In the Fe-MgF2 granular film, in which Fe grains are distributed between insulators instead of the conventional quantum dots, it can be easily fabricated by EB deposition alone, and various output values can be expected by applying two or more gate voltages. The tunneling thickness of the film for single-electron operation was investigated and it was confirmed that the tunneling occurred at 2.1 nm.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.4
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• pp.33-39
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• 2009

A microlens array (MLA) was developed based on the wet-etched quartz substrate and coating of UV adhesive on the substrate for maskless lithography application. The developed MLA has the focal length of ${\sim}45\;{\mu}m$ and the spot size of ${\sim}1\;{\mu}m$. The spot size of the focused beam passing through the MLA was detected by CCD camera, and its intensity was monitored by beam profiler. Uniform spots with nearly identical intensities were observed on the focal plane when a beam passes through the fabricated MLA. The focal length was varied depending on thickness of the coated UV adhesive. The thicker the thickness of the UV adhesive was, the shorter the focal length of the MLA was. With a general mask aligner, UV beam focusing was tested onto photoresist (PR). The beams were well focused onto PR when UV passes through the MLA. Depending on the variable distances from the MLA, beam sizes onto PR were controlled. Even at high temperature for a long time, the performances of the MLA were not changed.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.134-139
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• 2008

A spirally arrayed nano-pattern is designed as a model pattern for the next generation optical storage media. The pattern consists off types of embossed rectangular dot, which are 50nm, 100nm, 150nm and 200nm in length and 50nm in width. The height of the dot is designed to be 50nm. The pitch of the spiral track of the pattern is 100nm. A ER(Electron resist) master for this pattern is fabricated by e-beam lithography process. The ER is first spin-coated to be 50nm thick on a Si wafer and then the model pattern is written on the coated ER layer by e-beam. After developing this pattern written wafer in the solution, a ER pattern master is fabricated. The most conventional e-beam machine can write patterns in orthogonal way, so we made our own pattern generator which can write the pattern in circular or spiral way. This program generates the patterns to be compatible with the e-beam machine from Raith(Raith 150). To fabricate 50nm pattern master precisely, a series of experiments were done including the design compensation for the pattern size, optimization of the dose, acceleration voltage, aperture size and developing. Through these experiments, we conclude that the higher accelerating voltages and smaller aperture size are better for mastering the nano pattern which is in order of 50nm. With the optimized e-beam lithography process, a spiral arrayed 50nm pattern master adopting PMMA resist was fabricated to have dimensional accuracy over 95% compared to the designed. Using this pattern master, a metal pattern stamp will be fabricated by Ni electro plating for injection molding of the patterned plastic substrate.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.339-344
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• 2011

The Ohmic contact of Ti/Au metals on n-type ZnO thin film deposited on c-plane sapphire substrates by pulsed laser deposition was investigated by TLM (transfer length method) patterns. The Ti/Au metal films with thickness of 35 nm and 90 nm were deposited by electron-beam evaporator and thermal evaporator, respectively. By using the photo-lithography method, the $100{\times}100{\mu}m^2$ TLM patterns with $6{\sim}61{\mu}m$ gaps were formed. To improve the electrical properties as well as to decrease an interface states and stress between metal and semiconductor, the post-annelaing process was done in oxygen ambient by rapid thermal annealing system at temperature of $100{\sim}500^{\circ}C$ for 1 min. In this study, it appeared that the minimum specific contact resistivity shows about $1.1{\times}10^{-4}{\Omega}{\cdot}cm^2$ in $300^{\circ}C$ annealed sample, which may be originated from formation of oxygen vacancies of ZnO during an oxidation of Ti metal at the interface of Ohmic contacts.