• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.1-6
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• 2022

In this research, a ring-shaped silicon carbide (SiC) single crystal manufactured using the PVT (Physical Vapor Transport) method was proposed to be applied to a SiC focus ring in semiconductor etching equipment. A cylindrical graphite structure was placed inside the graphite crucible to grow a ring-shaped SiC single crystal by the PVT method. SiC single crystal ring without crack was successfully obtained in case of using SiC single crystal wafer as a seed. A plasma etching process was performed to compare plasma resistance between the CVD-SiC focus ring and the PVT-SiC focus ring. The etch rate of ring materials in PVT-single crystal SiC focus ring was definitely lower than that of CVD-SiC focus ring, indicating better plasma resistance of PVT-SiC focus ring.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.18-25
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• 2024

Objectives: The primary aim of this study is to create an Occupational Safety and Health (OSH) guide for high-risk maintenance tasks, specifically one designed for maintenance work (MW) in the electronics industry. Methods: The methodology involved a literature review, field investigations, and discussions. An initial draft of the OSH guide was created and then refined through consultations with experts possessing extensive experience in MW for electronic processes. Results: Specific MW tasks within electronics processing facilities identified as high-risk by the research were selected. A comprehensive OSH guide for these tasks was developed consisting of approximately 11 to 12 components and encompassing about 20-25 pages. Implementing safety and health measures before, during, and after MW is crucial for the protection of maintenance personnel. The guide is enriched with real-case scenarios of industrial accidents and occupational diseases to enhance maintenance workers' comprehension of the OSH principles. For a clearer understanding of and adherence to the safety protocols, the guide incorporates visual aids, including cartoons and photographs. Conclusions: This OSH guide is designed to ensure the protection of workers involved in maintenance activities in the electronics industry. It aligns with global standards set by the International Organization for Standardization (ISO) and Semiconductor Equipment and Material International (SEMI) to ensure a high level of safety and compliance.

• Analytical Science and Technology
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• v.19 no.6
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• pp.535-543
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• 2006

Being used widely in semiconductor and display manufacturing, $NF_3$ is internationally considered as one of the regulated compounds in emission. Numerous companies have been continuously trying to reduce the emissions of $NF_3$ to comply with the global environmental regulation. This work is made to report the destruction and removal efficiency (DRE) of electrically heated scrubbers and the use rate in process chambers installed in three main LCD manufacturing companies in Korea. As the measurement techniques for $NF_3$ emission, mass flow controlled helium gas was continuously supplied into the equipment by which scrubber efficiency is being measured. The partial pressures of $NF_3$ and helium were accurately measured for each sample using a mass spectrometer, as it is emitted from inlet and outlet of the scrubber system. The results show that the DRE value for electrically heated scrubbers installed before 2004 is less than 52 %, while that for the new scrubbers modified based on measurement by scrubber manufacturer has been sigificentely improved upto more than 95 %. In additon, we have confirmed the efficiency depends on such variables as the inlet gas flow rate, water content, heater temperature, and preventative management period. The use rates of $NF_3$ in process chambers were also affected by the process type. The use rate of radio frequency source chambers, built in the $1^{st}$ and $2^{nd}$ generation process lines, was determined to be less than 75 %. In addition, that of remote plasma source chambers for the $3^{rd}$ generation was measured to be aboove 95 %. Therefore, the combined application of improved scrubber and the RPSC process chamber to the semiconductor and display process can reduce $NF_3$ emmision by 99.95 %. It is optimistic that the mission for the reduction of greenhouse gas emission can be realized in these LCD manufacturing companies in Korea.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.49-63
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• 2018

Purpose : The purpose of this study is investigating the changes of treatment plan and comparing skin dose with or without the skin flash. To investigate optimal applications of the skin flash, the changes of skin dose of each plans by various thicknesses of skin flash were measured and analyzed also. Methods and Material : Anthropomorphic phantom was scanned by CT for this study. The 2 fields hybrid IMRT and the 6 fields static IMRT were generated from the Eclipse (ver. 13.7.16, Varian, USA) RTP system. Additional plans were generated from each IMRT plans by changing skin flash thickness to 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm and 2.5 cm. MU and maximum doses were measured also. The treatment equipment was 6MV of VitalBeam (Varian Medical System, USA). Measuring device was a metal oxide semiconductor field-effect transistor(MOSFET). Measuring points of skin doses are upper (1), middle (2) and lower (3) positions from center of the left breast of the phantom. Other points of skin doses, artificially moved to medial and lateral sides by 0.5 cm, were also measured. Results : The reference value of 2F-hIMRT was 206.7 cGy at 1, 186.7 cGy at 2, and 222 cGy at 3, and reference values of 6F-sIMRT were measured at 192 cGy at 1, 213 cGy at 2, and 215 cGy at 3. In comparison with these reference values, the first measurement point in 2F-hIMRT was 261.3 cGy with a skin flash 2.0 cm and 2.5 cm, and the highest dose difference was 26.1 %diff. and 5.6 %diff, respectively. The third measurement point was 245.3 cGy and 10.5 %diff at the skin flash 2.5 cm. In the 6F-sIMRT, the highest dose difference was observed at 216.3 cGy and 12.7 %diff. when applying the skin flash 2.0 cm for the first measurement point and the dose difference was the largest at the application point of 2.0 cm, not the skin flash 2.5 cm for each measurement point. In cases of medial 0.5 cm shift points of 2F-hIMRT and 6F-sIMRT without skin flash, the measured value was -75.2 %diff. and -70.1 %diff. at 2F, At -14.8, -12.5, and -21.0 %diff. at the 1st, 2nd and 3rd measurement points, respectively. Generally, both treatment plans showed an increase in total MU, maximum dose and %diff as skin flash thickness increased, except for some results. The difference of skin dose using 0.5 cm thickness of skin flash was lowest lesser than 20 % in every conditions. Conclusion : Minimizing the thickness of skin flash by 0.5 cm is considered most ideal because it makes it possible to keep down MUs and lowering maximum doses. In addition, It was found that MUs, maximum doses and differences of skin doses did not increase infinitely as skin flash thickness increase by. If the error margin caused by PTV or other factors is lesser than 1.0 cm, It is considered that there will be many advantages in with the skin flash technique comparing without it.

• Journal of Internet Computing and Services
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• v.25 no.1
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• pp.99-107
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• 2024

Along with economic growth and industrial development, there is an increasing demand for various electronic components and device production of semiconductor, SMT component, and electrical battery products. However, these products may contain foreign substances coming from manufacturing process such as iron, aluminum, plastic and so on, which could lead to serious problems or malfunctioning of the product, and fire on the electric vehicle. To solve these problems, it is necessary to determine whether there are foreign materials inside the product, and may tests have been done by means of non-destructive testing methodology such as ultrasound ot X-ray. Nevertheless, there are technical challenges and limitation in acquiring X-ray images and determining the presence of foreign materials. In particular Small-sized or low-density foreign materials may not be visible even when X-ray equipment is used, and noise can also make it difficult to detect foreign objects. Moreover, in order to meet the manufacturing speed requirement, the x-ray acquisition time should be reduced, which can result in the very low signal- to-noise ratio(SNR) lowering the foreign material detection accuracy. Therefore, in this paper, we propose a five-step approach to overcome the limitations of low resolution, which make it challenging to detect foreign substances. Firstly, global contrast of X-ray images are increased through histogram stretching methodology. Second, to strengthen the high frequency signal and local contrast, we applied local contrast enhancement technique. Third, to improve the edge clearness, Unsharp masking is applied to enhance edges, making objects more visible. Forth, the super-resolution method of the Residual Dense Block (RDB) is used for noise reduction and image enhancement. Last, the Yolov5 algorithm is employed to train and detect foreign objects after learning. Using the proposed method in this study, experimental results show an improvement of more than 10% in performance metrics such as precision compared to low-density images.