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MEMS용 NiTi 형상기억합금박막의 열기계적 물성에 관한 연구
김희연(Hee Yeoun Kim),홍순형(Soon Hyung Hong) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.8
NiTi shape memory alloy have many MEMS applications such as microgripper, micro valve and micropump which need higher displacement. Mechanical properties of NiTi thin film are strongly dependent on concentration change and evolved residual stress during deposition process. In this paper, thermomechanical properties of RF sputtered NiTi thin film have been investigated. 3 types of NiTi thin film, Ni-rich, equiatomic and Ti-rich, was fabricated on p-Si(100) substrate at room temperature and crystallized for 1hr at 500℃. M↔A transformation temperatures with Ti concentration increased. Ti-rich NiTi thin film had martensite structure at room temperature and this type could be applied for microactuator application. In the annealed condition, residual stress showed highest value at Ni-rich composition and concentration dependence of residual stress were contrary from the concentration dependence of transformation stress. This is due to the shift of M↔A to positive direction as Ti contents increased. According to the results of laser curvature measurements, the residual stress of about 400㎫ were relieved by the A->M transformation and this residual stress were well matched to the calculated values from the misfit strain between thin film and substrate during cooling. The microtensile behavior of NiTi thin film showed the plateau at about 200㎫ and this meant the thin film could show higher recovery force rather than bulk NiTi materials residual stress successfully relieved by shape memory effect. Strain-temperaure hysterisis by TMA showed that Ti-rich NiTi thin film could be applied as a microactuator for MEMS at room temperature.
자전고온반응에 의한 금속간화합물/금속 적층복합재료의 제조공정변수가 미세조직에 미치는 영향
김희연 ( Hee Yeoun Kim ),정동석 ( Dong Seok Chung ),홍순형 ( Soon Hyung Hong ) 한국복합재료학회 2003 Composites research Vol.16 No.3
본 논문에서는 Ni과 A1 금속박판 사이의 자전고온반응을 이용한 금속간화합물/금속 적충복합재료의 제조 시 제조공정 조건이 최종 미세조직에 미치는 영향을 연구하였다. 열분석을 통하여 Ni과 A1 사이의 반응은 먼저 NiA1₃가 핵생성-성장기구에 의해 생성된 후 다시 Ni₂A1₃로 확산변태됨을 확인하였다. 자전고온반응을 열역학적으로 해석하여 금속박판의 두께비(NiA1) 및 반응 전 열처리와 반응 후 미세조직에서 잔류한 A1의 부피분율과의 관계를 정립하였다. 후열처리 공정에 의해 Ni/Ni₃A1/NiA1의 적충구조와 각 두께비에서82%(1:1), 59.5%(2:1), 40%(4:1)의 부피분율을 가지는 금속간화합물/금속 적충재료를 얻을 수 있었다. In this paper, intermetallic/metal laminated composites have been successfully produced that utilizes SHS reactions between Ni and Al elemental metal foils. The reaction between Ni and Al started from the nucleation and growth of NiAl₃and was followed by the diffusional growth of Ni₂A1₃between Ni and NiAl₃. The SHS reaction was thermodynamically analyzed through the final volume fraction of the non-reacted Al related with the initial thickness ratio of Ni:Al and prior heat treatment. Thermally aging these laminates resulted in formation of a functionally gradient series of intermetallic phases. Microstructure showed that the intermetallic volume percent was 82, 59.5, 40% in the 1:1, 2:1, 4:1 thickness ratio specimen. Main phases of the intermetallic were NiAl and Ni₃AI having higher strength at room and high temperatures.
지속성 외래 복막투석 환자에서 발생한 만성 결절성 통풍 치료
윤정희 ( Jeong Hee Yun ),김희연 ( Hee Yeoun Kim ),김동한 ( Dong Han Kim ),오준석 ( Joon Seok Oh ),김성민 ( Seong Min Kim ),신용훈 ( Young Hun Sin ),김중경 ( Joong Kyung Kim ) 대한내과학회 2015 대한내과학회지 Vol.89 No.2
Hyperuricemic patients with gouty arthritis or tophi, a serum uric acid concentration of 8.0 mg/dL or higher, and complications should be treated with urate-lowering drugs. Conventionally, allopurinol is used to treat hyperuricemia and gout, but it is necessary to adjust the dosage according to the degree of renal impairment. Uncommonly, allopurinol may have severe or fatal side effects. The non-purine xanthine oxidase inhibitor febuxostat undergoes hepatic metabolism and may require less dose adjustment in association with renal function. It is considered to be an alternative treatment for hyperuricemic patients with chronic kidney disease. Our experience suggests that low-dose febuxostat is a promising alternative to allopurinol for the treatment of gouty arthritis or tophi in peritoneal dialysis patients. (Korean J Med 2015,89:229-232)
비정질 실리콘을 이용한 미세 피치 적외선 이미지 센서 제조 및 특성
김경민 ( Kyoung Min Kim ),김병일 ( Byeong Il Kim ),김희연 ( Hee Yeoun Kim ),장원수 ( Won Soo Jang ),김태현 ( Tae Hyun Kim ),강태영 ( Tai Young Kang ) 한국센서학회 2010 센서학회지 Vol.19 No.2
The microbolometer array sensor with fine pitch pixel array has been implemented to the released amorphous silicon layer supported by two contact pads. For the design of focal plane mirror with geometrical flatness, the simple beam test structures were fabricated and characterized. As the beam length decreased, the effect of beam width on the bending was minimized, Mirror deformation of focal plane in a real pixel showed downward curvature by residual stress of a-Si and Ti layer. The mirror tilting was caused by the mis-align effect of contact pad and confirmed by FEA simulation results. The properties of bolometer have been measured as such that the NETD 145 mK, the TCR -2%/K, and thermal time constant 1.99 ms.
Cu-Cu 접합 공정으로 제조된 실리콘 웨이퍼의 계면 접합 평가
김광섭(Kwang-Seop Kim),이희정(Hee-Jung Lee),김희연(Hee-Yeoun Kim),김재현(Jae-Hyun Kim),현승민(Seungmin Hyun),이학주(Hak-Joo Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Four-point bending tests were performed to investigate the interfacial adhesion of Si wafer pairs fabricated by direct Cu-to-Cu bonding process for the application of advanced electronic packaging. A Ti glue layer of 50㎚ thick and a Cu film of 1.5 ㎛ thick were sequentially deposited on a 500 ㎛ thick Si wafer with a thermal grown SiO₂ layer by a sputtering system. A pair of Cu-coated Si wafers was bonded under the pressure of 15 kN at 350 ℃ for 1 hour, followed by post annealing at 350 ℃ for 1 hour. The bonded wafers were diced by 30 mm x 3 mm for the test. Each specimen had a 400 ㎛ depth notch along the center line. A optical inspection module was installed in the testing apparatus to observe crack initiation at the notch and crack propagation through the weak interface. The tests were performed under fixed displacement rate, and the corresponding load was measured. The measured interfacial adhesion energy of the Cu-to-Cu bonding system was 9.75 J/㎡, and delaminated interfaces after the test were analyzed.
열가압 접합 공정으로 제조된 Cu-Cu 접합의 계면 접합 특성 평가
김광섭(Kwang-Seop Kim),이희정(Hee-Jung Lee),김희연(Hee-Yeoun Kim),김재현(Jae-Hyun Kim),현승민(Seungmin Hyun),이학주(Hak-Joo Lee) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.7
3 차원 패키징을 위해 열가압 공정으로 제조된 Cu-Cu 접합 계면의 접합 특성을 평가하기 위해 4 점 굽힘 실험을 수행하였다. Cu 가 코팅된 Si 웨이퍼 2 장을 350 ℃ 에서 1 시간 동안 15kN 의 하중으로 접합시킨후, 동일한 온도에서 1 시간동안 어닐닝을 수행하였다. 접합된 웨이퍼를 30 ㎜ × 3 ㎜ 크기로 잘라 시험편을 준비하였다. 시험편의 중심에 깊이 400 ㎛ 의 노치를 가공하였다. 시험기에 광학계를 부착하여 노치에서의 크랙 발생과 계면에서의 크랙 진전을 관찰하였다. 일정한 테스트 속도로 실험을 수행하여, 이에 상응하는 하중을 측정하였다. Cu-Cu 접합 계면 에너지는 10.36 J/㎡ 으로 측정되었으며, 파괴된 계면을 분석하였다.표면 분석 결과, SiO₂ 와 Ti 의 계면에서 파괴가 일어났음을 확인하였다. Four-point bending tests were performed to investigate the interfacial adhesion of Cu-Cu bonding fabricated by thermo-compression process for three dimensional packaging. A pair of Cu-coated Si wafers was bonded under a pressure of 15 kN at 350 ℃ for 1 h, followed by post annealing at 350 ℃ for 1 h. The bonded wafers were diced into 30 ㎜ × 3 ㎜ pieces for the test. Each specimen had a 400-㎛-deep notch along the center. An optical inspection module was installed in the testing apparatus to observe crack initiation at the notch and crack propagation over the weak interface. The tests were performed under a fixed loading speed, and the corresponding load was measured. The measured interfacial adhesion energy of the Cu-to-Cu bonding was 9.75 J/㎡, and the delaminated interfaces were analyzed after the test. The surface analysis shows that the delamination occurred in the interface between SiO₂ and Ti.
3중 접합 공정에 의한 MEMS 공진기의 웨이퍼레벨 진공 패키징
양충모 ( Chung Mo Yang ),김희연 ( Hee Yeoun Kim ),박종철 ( Jong Cheol Park ),나예은 ( Ye Eun Na ),김태현 ( Tae Hyun Kim ),노길선 ( Kil Son Noh ),심갑섭 ( Gap Seop Sim ),김기훈 ( Ki Hoon Kim ) 한국센서학회 2020 센서학회지 Vol.29 No.5
The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10<sup>-6</sup> mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.
저항성 홀배열이 적용된 볼로미터의 적외선 흡수 특성 변화
김태현 ( Tae Hyun Kim ),오재섭 ( Jaesub Oh ),박종철 ( Jongcheol Park ),김희연 ( Hee Yeoun Kim ),이종권 ( Jong-kwon Lee ) 한국센서학회 2018 센서학회지 Vol.27 No.5
In order to develop a highly sensitive infrared sensor, it is necessary to develop techniques for decreasing the rate of heat absorption and the transition of the absorption wavelength to a longer wavelength, both of which can be induced by decreasing the pixel size of the bolometer. Therefore, in this study, 1 μm hole-arrays with a subwavelength smaller than the incident infrared wavelength were formed on the amorphous silicon-based microbolometer pixels in the absorber, which consisted of a TiN absorption layer, an a-Si resistance layer and a SiNx membrane support layer. We demonstrated that it is possible to reduce the thermal time constant by 16% relative to the hole-patternless bolometer, and that it is possible to shift the absorption peak to a shorter wavelength as well as increase absorption in the 4-8 μm band to compensate for the infrared long-wavelength transition. These results demonstrate the potential for a new approach to improve the performance of high-resolution microbolometers.