Journal of the Korean Society for Precision Engineering

Laser Ablation Patterning of Metal Thin Films for On-demand of Shadow Mask Patterning in Vacuum Deposition: Beomsun Do, Seunghun Lee, Hyunho Lee, Hoon Jeong, Joel Ndikumana, Kunsik An; J. Korean Soc. Precis. Eng. 2025;42(10):775-782.
Published online October 1, 2025; DOI: https://doi.org/10.7736/JKSPE.D.25.00001

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This study explores the use of laser ablation technology for creating on-demand shadow masks, which are essential in the fabrication of thin film transistor (TFT) devices. Traditional methods for producing shadow masks often encounter significant challenges, such as high costs, lengthy production times, and difficulties in achieving fine, high-resolution patterns. To address these issues, this study introduces a method for manufacturing shadow masks using fiber laser-based laser ablation. Key laser parameters, including frequency and power, were optimized throughout the research. Systematic experimentation revealed that a frequency of 20 kHz and a power output of 14 W enabled the precise and uniform creation of patterns with a 50 μm channel spacing. When these custom shadow masks were employed in the TFT fabrication process, the resulting devices exhibited stable and reliable electrical performance. The findings suggest that laser ablation-based on-demand shadow mask technology offers a cost-effective and flexible solution for producing large-area, high-resolution TFTs. Additionally, this approach significantly reduces the prototyping cycle, making it ideal for rapid development and iterative testing in research and development environments.

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Pinhole Detection in Thin Film Solid Oxide Electrolytes Using Selective Adsorption of Ag Nanoparticles via a Spark Discharge Generator: Doyoon Kim, Ikwhang Chang, Jong Dae Baek; J. Korean Soc. Precis. Eng. 2025;42(6):441-446.
Published online June 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.024

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Pinhole-free ionic conductors are critical to achieve optimal performance in thin film-solid oxide fuel cells (TF-SOFCs). However, nanoscale defects, especially pinholes, can induce current leakage and contribute to cell failure by creating electrical short circuits. This study introduced a novel methodology for detecting pinholes in yttria-stabilized zirconia (YSZ) thin-film solid oxide electrolytes. The approach utilized selective adsorption of silver (Ag) nanoparticles generated via a spark discharge generator (SDG). Analytical techniques, including focused ion beam (FIB), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), were employed to investigate interactions between Ag nanoparticles and nanoscale defects. Results showed that nanoparticle-based diagnostic methods were efficacious for defect characterization, offering a solution for enhancing the quality of thin-film electrolytes.

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Enhanced Insertion Loss and Frequency Selectivity in SAW Devices through Tailored Ag-Ti Thin Films: Jae Cheol Park; J. Korean Soc. Precis. Eng. 2024;41(12):991-996.
Published online December 1, 2024; DOI: https://doi.org/10.7736/JKSPE.024.103

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A compositional library of Ag-Ti thin films was fabricated using combinatorial RF magnetron sputtering. The films exhibited a gradual compositional gradient across the substrate, ranging from Ag-rich to Ti-rich compositions. SEM analysis revealed a uniform thickness of approximately 150 nm for all films. The relationship between composition and properties was investigated, demonstrating that increasing Ag content led to decreased resistivity and increased density. These results can be attributed to the high electrical conductivity and density of Ag. To optimize SAW device performance, a balance between resistivity and density must be achieved. While Ag-rich films offer higher electrical conductivity, they may experience reduced inverse piezoelectric effects due to increased density. Conversely, Ag-poor films may have improved inverse piezoelectric effects but reduced electrical conductivity.

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Characterization of a Copper Thin Film Using the Surface Acoustic Wave Measurement Technique: Taehyung Kim, Yun Young Kim; J. Korean Soc. Precis. Eng. 2024;41(3):183-189.
Published online March 1, 2024; DOI: https://doi.org/10.7736/JKSPE.023.125

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The elastic property of a copper (Cu) thin film was investigated using the surface acoustic wave (SAW) measurement technique. The Cu film was deposited on a quartz substrate using a direct current magnetron sputter and its surface morphology was inspected using atomic force microscopy. Time-domain waveforms of the SAW on the film were acquired at different propagation distances to estimate the Young’s modulus of Cu such that the experimentally-obtained dispersion curve can be compared to the analytical result calculated using the Transfer Matrix method for curve-fitting. Results showed that the film’s elastic property value decreased by 18.5% compared to that of the bulk state, and the scale effect was not significant in the thickness range of 150-300 nm, showing good agreement with those by the nanoindentation technique. The property, however, increased by 15.5% with the grain coarsening.

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Resistant Characteristics of AAO-Based Thin Film Solid Oxide Fuel Cells Using Ni-GDC Anode by GLAD Method: Jaewon Yoo, Myung Seok Lee, Yang Jae Kim, Suk Won Cha; J. Korean Soc. Precis. Eng. 2023;40(4):335-340.
Published online April 1, 2023; DOI: https://doi.org/10.7736/JKSPE.022.135

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In this study, we fabricated thin film solid oxide fuel cells on nanoporous anodic aluminum oxide (AAO) substrate for low-temperature operation using the all-through sputtering method. To deposit up to a three-micrometer thick anode with both porosity and electrical conductivity, we used the glancing angle deposition and co-sputtering methods. For the anode materials, we used nickel gadolinium-doped-ceria (Ni-GDC) mixed ionic and electronic conductor (MIEC), which improved hydrogen oxidation reaction reactivity at the anode side. TF-SOFCs were successfully operated at 500℃, and 223.6 mW/cm² was their highest measured maximum power density. We conducted structural and electrochemical analyses to figure out cells’ unique resistant characteristics; ohmic resistance through the anode thin film and polarization resistance of reaction area near the narrowed anode pores. We found how the anode thin film thickness affects the current collecting performance and the anode reactivity, and their effects were qualitatively and quantitatively compared.

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Development of Thin Film Solid Oxide Fuel Cell for Direct Use of Hydrocarbon Fuels: Gu Young Cho, Yoon Ho Lee; J. Korean Soc. Precis. Eng. 2022;39(10):773-777.
Published online October 1, 2022; DOI: https://doi.org/10.7736/JKSPE.022.039

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Energy devices in modern society require high efficiency, carbon neutrality, and the capability of distributed power generation. A fuel cell is an energy conversion device, that satisfies all of these requirements. However, most fuel cells use hydrogen as a fuel, and more than half of hydrogen is currently produced through hydrocarbon reforming, resulting in significant energy loss. Additionally, the storage and supply of hydrogen require costly systems, and a large amount of energy is consumed during compression or liquidation processes. This paper develops a solid oxide fuel cell, that uses hydrocarbon directly as fuel to resolve this problem. A small amount of Ru is mixed with the Ni-based electrode, for the effective internal reforming of hydrocarbons. For rapid deposition of YSZ electrolytes, we developed a reactive sputtering process, using a DC power source. The developed thin-film solid oxide fuel cell, showed a performance of 76 mW/cm² at 500℃ using methane as fuel.

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Preparation of SrCo_0.8Nb_0.1Ta_0.1O_3-δ as a Cathode for Solid Oxide Fuel Cells by Pulsed Laser Deposition: Sangbong Ryu, Wonjong Yu, Arunkumar Pandiyan, Sanghoon Lee, Wonyeop Jeong, In won Choi, Myung Seok Lee, Suk Won Cha; J. Korean Soc. Precis. Eng. 2020;37(1):83-87.
Published online January 1, 2020; DOI: https://doi.org/10.7736/JKSPE.019.051

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Recently, new perovskite cathode material, SrCo_0.8Nb_0.1Ta0.1O_3-δ (SCNT) was reported, showing high oxygen reduction reaction (ORR) activity. This study demonstrates thin film deposition of SCNT by pulsed laser deposition technique applied to anodic aluminum oxide (AAO) based thin-film solid oxide fuel cells (TF-SOFCs) to assess the possibility of SCNT application to TF-SOFCs. The SCNT powder and the target were prepared by the solid state reactive sintering method (SSRS). This target was then mounted to the pulsed laser depositing machine and deposited on the Si wafer, and the nano-porous substrate, AAO. The physical structure and the chemical phase were investigated by the field emission scanning electron microscope, focused ion beam scanning electron microscope, and X-ray diffraction. On the top of the AAO, thin Pt film and yttria stabilized zirconia (YSZ) were first deposited by sputtering and the SCNT was deposited on the top of it afterward. The open circuit voltage of AAO cell was tested at 500°C, and successful polarization activity of SCNT was observed.

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Experimental Analysis of Performance Variation on Thin Film Solid Oxide Fuel Cell with Different Cathode Area Sizes: Jong Dae Baek, Ikwhang Chang; J. Korean Soc. Precis. Eng. 2019;36(12):1183-1187.
Published online December 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.12.1183

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To study the geometrical scale dependency of thin film solid oxide fuel cells (SOFCs), we fabricated three thin films SOFCs with the same cross-sectional structure but with different electrode areas of 1, 4 and 9 ㎟. Since the activation and ohmic losses of SOFCs depend on their active region, we examined the variations of the power density of the cells with a Pt (anode)/sputtered YSZ/Pt (cathode) structure. We found that a cathode electrode with a low aspect ratio may suffer from high ohmic and activation losses because of the geometrical scale dependency.

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Improvement of Interface Diffusion in Cu thin films using SiN/CoWB Passivation Layer: Jung Woong Kim, Sean Jhin Yoon, Hyun Chan Kim, Youngmin Yun, Jaehwan Kim; J. Korean Soc. Precis. Eng. 2018;35(12):1163-1168.
Published online December 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.12.1163

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Silicon nitride/cobalt tungsten boride (SiN/CoWB) passivation layer improves mass transport rate at copper thin film layers of semiconductor wafers after chemical mechanical polishing process. This study evaluates mass transport at the interface between copper and passivation layers by stress relaxation method, followed by deduction of interface diffusivity via a kinetic model. For comparison, SiN/CoWB, SiN, silicon carbon nitride (SiCN) and silicon carbide (SiC) passivation layers are introduced. A thin layer of SiN/CoWB demonstrates an outstanding performance as diffusion retarding material, especially at high temperature. The order of stress relaxation in terms of passivation layers is SiN/CoWB < SiN < SiCN < SiC, implying the order of mass transport at the interface. Using the kinetic model, the diffusivities and activation energies regarding passivation layers are calculated and reveal a good agreement with experimental results.

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High-k Thin Films by Atomic Layer Deposition for Energy and Information Storage: Jihwan An; J. Korean Soc. Precis. Eng. 2018;35(12):1131-1136.
Published online December 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.12.1131

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High-k dielectric thin films are widely applied in energy conversion/storage and information storage devices such as Dynamic Random access Memory (DRAM), Multilayer Ceramic Capacitor (MLCC), thermoelectric devices, etc. Among them, perovskite thin films, for instance, strontium titanate (STO) and barium titanate (BTO) are known to have extremely superior dielectric properties. Atomic layer deposition (ALD), can deposit thin films through atomic layering producing uniform and conformal high-k thin films with precise thickness control. While relatively low crystallinity of film quality due to low deposition temperatures of ALD can develop practical issues, they can be overcome by employing additional processes such as thermal annealing, plasma treatment, and seed layering. ALD, STO and BTO thin films treated with these additional processes demonstrate more improved crystallinity and electrical properties. In this paper, the processes to enhance properties of ALD high-k thin films, BTO and STO films are reviewed. Perspectives into high quality ALD high-k thin films as well as current efforts to further improve the film quality are discussed.

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Thin Film Process for Thin Film Solid Oxide Fuel Cells - A Review: Gu Young Cho, Yoon Ho Lee, Suk Won Cha; J. Korean Soc. Precis. Eng. 2018;35(12):1119-1129.
Published online December 1, 2018; DOI: https://doi.org/10.7736/KSPE.2018.35.12.1119

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Thin film solid oxide fuel cells (TF-SOFCs) are considered to be a promising next generation energy conversion device. TFSOFCs have many advantages such as rapid turn-on and off, fuel flexibility, material flexibility, high power density and availability of compact system. Electrodes and electrolytes of TF-SOFCs are fabricated by thin film processes. In order to fabricate high performance TF-SOFCs, proper thin film processes have to be used due to the unique requirements of each part of the TF-SOFCs. This paper reviews the thin film deposition process for fabrication of TF-SOFCs and the advantages and disadvantages of physical and chemical vapor deposition processes. In addition, materials prepared through thin film processes and the performance results of TF-SOFCs are reviewed.

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Manipulating the grain boundary properties of BaCeO3-based ceramic materials through sintering additives introduction
Gennady Vdovin, Anna Rudenko, Boris Antonov, Vacheslav Malkov, Anatoly Demin, Dmitry Medvedev
Chimica Techno Acta.2019; 6(2): 38. CrossRef

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The Properties of ZrO₂ Film Deposition by ALD at Low Temperature: Byung Chan Yang, Jeong Woo Shin, Hyuk-Dong Kwon, Jihwan An; J. Korean Soc. Precis. Eng. 2017;34(10):735-738.
Published online October 1, 2017; DOI: https://doi.org/10.7736/KSPE.2017.34.10.735

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ZrO₂ film is widely used for high-k applications and also has good mechanical properties. This paper covers the study of the properties of ZrO₂ film deposited by atomic layer deposition (ALD) using TEMA Zr and water in the temperature range of 110 to 250^oC for potential application in flexible-device fabrication. At a low deposition temperature, ALD ZrO₂ films showed a uniform growth rate of ~1 Å per cycle, good uniformity, partial crystallinity, and smooth surface. ZrO₂ can also be deposited on the trench structure with a high aspect ratio (~1:50), but conformality needs to be improved for practical applications.

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