신경회로망을 이용한 ITO 박막 성장 공정의 모형화

민철홍,박성진,윤능구,김태선,Min, Chul-Hong,Park, Sung-Jin,Yoon, Neung-Goo,Kim, Tae-Seon 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.9

Compare to conventional Indium Tin Oxide (ITO) film deposition methods, cesium assisted sputtering method has been shown superior electrical, mechanical, and optical film properties. However, it is not easy to use cesium assisted sputtering method since ITO film properties are very sensitive to Cesium assisted equipment condition but their mechanism is not yet clearly defined physically or mathematically. Therefore, to optimize deposited ITO film characteristics, development of accurate and reliable process model is essential. For this, in this work, we developed ITO film deposition process model using neural networks and design of experiment (DOE). Developed model prediction results are compared with conventional statistical regression model and developed neural process model has been shown superior prediction results on modeling of ITO film thickness, sheet resistance, and transmittance characteristics.

고밀도 프로빙 테스트를 위한 수직형 프로브카드의 제작 및 특성분석

민철홍,김태선,Min, Chul-Hong,Kim, Tae-Seon 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.9

As an increase of chip complexity and level of chip integration, chip input/output (I/O) pad pitches are also drastically reduced. With arrival of high complexity SoC (System on Chip) and SiP (System in Package) products, conventional horizontal type probe card showed its limitation on probing density for wafer level test. To enhance probing density, we proposed new vertical type probe card that has the $70{\mu}m$ probe needle with tungsten wire in $80{\mu}m$ micro-drilled hole in ceramic board. To minimize alignment error, micro-drilling conditions are optimized and epoxy-hardening conditions are also optimized to minimize planarity changes. To apply wafer level test for target devices (T5365 256M SDRAM), designed probe card was characterized by probe needle tension for test, contact resistance measurement, leakage current measurement and the planarity test. Compare to conventional probe card with minimum pitch of $50{\sim}125{\mu}m\;and\;2\;{\Omega}$ of average contact resistance, designed probe card showed only $22{\mu}$ of minimum pitch and $1.5{\Omega}$ of average contact resistance. And also, with the nature of vertical probing style, it showed comparably small contact scratch and it can be applied to bumping type chip test.

편재형 컴퓨팅을 위한 미세구조 에너지 하베스팅 시스템의 구조 설계

민철홍,김태선,Min, Chul-Hong,Kim, Tae-Seon 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.11

In this paper, we designed micro-structured electromagnetic transducers for energy harvesting and verified the performance of proposed transducers using finite element analysis software, COMSOL Multiphysics. To achieve higher energy transduce efficiency, around the magnetic core material, three-dimensional micro-coil structures with high number of turns are fabricated using semiconductor fabrication process technologies. To find relations between device size and energy transduce efficiency, generated electrical power values of seven different sizes of transducers ($3{\times}3\;mm^2$, $6{\times}6\;mm^2$, $9{\times}9\;mm^2$, $12{\times}12\;mm^2$, $15{\times}15\;mm^2$, $18{\times}18\;mm^2$, and $21{\times}21\;mm^2$) are analyzed on various magnetic flux density environment ranging from 0.84 T to 1.54 T and it showed that size of $15{\times}15\;mm^2$ device can generate $991.5\;{\mu}W$ at the 8 Hz of environmental kinetic energy. Compare to other electromagnetic energy harvesters, proposed system showed competitive performance in terms of power generation, operation bandwidth and size. Since proposed system can generate electric power at very low frequency of kinetic energy from typical life environment including walking and body movement, it is expected that proposed system can be effectively applied to various pervasive computing applications including power source of embodied medical equipment, power source of RFID sensors and etc. as an secondary power sources.

증속기어 모듈을 이용한 발판형 에너지 하베스터의 설계 및 제작

민철홍,김태선,Min, Chul Hong,Kim, Tae Seon 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.12

In this paper, we designed and fabricated electromagnetic induction based scaffold type energy harvester. For energy harvesting, mechanical energy of vertical motion is transferred to rotational energy using rack gear and multiplying gear was used to maximize energy transfer. To optimize design parameters, physical structure of energy harvester was modeled using finite element method. The effect of multiplying gear ratio and frequency levels of applied mechanical energy on energy generation efficiency are analyzed by computer simulation and experimental test. Experimental results showed that maximum 25.36 W of electric power can be achieved at the frequency of 2 Hz and 1:77 of gear ratio with only 5 mm of vertical changes on scaffold structure.

마이크로 스프링 구조를 갖는 121 pins/mm² 고밀도 프로브 카드 제작기술

민철홍,김태선,Min, Chul-Hong,Kim, Tae-Seon 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.9

Recently, novel MEMS probe cards can support reliable wafer level chip test with high density probing capacity. However, manufacturing cost and process complexity are crucial weak points for low cost mass production. To overcome these limitations, we have developed micro spring structured MEMS probe card. For fabrication of micro spring module, a wire bonder and electrolytic polished gold wires are used. In this case, stringent tension force control is essential to guarantee the low level contact resistance of micro spring for reliable probing performance. For this, relation between tension force of fabricated probe card and contact resistance is characterized. Compare to conventional probe cards, developed MEMS probe card requires fewer fabrication steps and it can be manufactured with lower cost than other MEMS probe cards. Also, due to the small contact scratch patterns, we expect that it can be applied to bumping types chip test which require higher probing density.

임프린트 공정을 이용한 연성동박적층필름(FCCL)의 마이크로 패턴 제작

민철홍,김태선,Min, Chul Hong,Kim, Tae Seon 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.12

In this paper, we designed and fabricated low cost imprinting process for micro patterning on FCCL (flexible copper clad laminate). Compared to conventional imprinting process, developed fabrication method processing imprint and UV photolithography step simultaneously and it does not require resin etch process and it can also reduce the fabrication cost and processing time. Based on proposed method, patterns with $10{\mu}m$ linewidth are fabricated on $180mm{\times}180mm$ FCCL. Compared to conventional methods using LDI (laser direct imaging) equipment that showed minimum line with $10{\sim}20{\mu}m$, proposed method shows comparable pattern resolution with very competitive price and shorter processing time. In terms of mass production, it can be applied to fabrication of large-area low cost applications including FPCB.

MEMS기반 에너지 하베스터 제작을 위한 실리콘 KOH 식각 모형화

민철홍,강경우,김태선,Min, Chul-Hong,Gang, Gyeong-Woo,Kim, Tae-Seon 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.3

Due to the high etch rate and low fabrication cost, the wet etching of silicon using KOH etchant is widely used in MEMS fabrication area. However, anisotropic etch characteristic obstruct intuitional mask design and compensation structures are required for mask design level. Therefore, the accurate modeling for various types of silicon surface is essential for fabrication of three-dimensional MEMS structure. In this paper, we modeled KOH etch profile for MEMS based energy harvester using fuzzy logic. Modeling results are compared with experimental results and it is applied to design of compensation structure for MEMS based energy harvester. Through Fuzzy inference approaches, developed model showed good agreement with the experimental results with limited etch rate information.

PCB 일체형 에너지 하베스터의 설계 및 제작

민철홍,김태선,Min, Chul Hong,Kim, Tae Seon 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.11

Recently, energy harvesting technologies are considered as the great alternatives to reduce the dependency on secondary batteries. In this paper, we proposed PCB type energy harvester which can be directly integrated with other electronic components on same board. To form the three dimensional coil structure, two PCBs with patterned metal lines are solder bonded. For magnetic induction, inside of coil structure was filled with magnetic substance and rotary motioned external magnets are applied to near the harvester. The effects of metal wire width on PCB, thickness of magnetic substance, and frequency of rotary motion on energy harvesting performance are analyzed by computer simulation and experiments. Experimental results showed 29.89 ${\mu}W$ of power generation performance at the frequency of 5.2 Hz and it is shown that designed harvester can be effectively applied on vibration environment with very limited frequency.

심전도 기반 생체인식 알고리즘의 개발

민철홍(Chul Hong Min),김태선(Tae Seon Kim) 대한전기학회 2010 정보 및 제어 심포지엄 논문집 Vol.2010 No.4

In this paper, new biometric method using electrocardiogram (ECG) signal is proposed. In contrast to conventional lead Ⅱ type ECG based biometrics, to enhance the consistency of biometric data, lead Ⅲ type signals are selected. For characterization, twenty-two different features are defined and feed-forward error back-propagation neural networks (BPNN) are applied for classification. To consider five kinds of accuracy evaluation methods, unknown two extra peoples are tested together with twelve biometrics candidates. Experimental results showed 100% of accuracy for identification of pre-defined candidates and 97.77% of overall identification accuracy.

마이크로 스프링 구조를 갖는 고밀도 MEMS 프로브 카드의 제작

민철홍(Chul Hong Min),김태선(Tae Seon Kim) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7

MEMS type probe card can support reliable wafer level test with a high density probing performance. However, manufacturing cost and process complexity problems are crucial obstacles for mass production To overcome these limitations, we propose the micro-spring based low-cost and high-density MEMS probe card. For fabrication of micro-spring module, electrolytic polished gold wire bonders are used. Proposed MEMS probe card is simple the fabrication process but also is cheap the fabrication cost.