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Authors: Sung Hwa Choi, Young Bae Kim, Yu Hang Wang, Duck Kyun Choi
Abstract: In field aided lateral crystallization process which is one of the low temperature crystallization processes for the amorphous silicon films, the effect of the alternating field (AC voltage) instead of the static field (DC voltage) was investigated. Following the deposition of 2 nm thick Cu catalyst outside of the 5 mm bar patterns in the PECVD amorphous silicon film, the specimen was heated at 500°C in N₂ambient for 5 hours with applying 5 V/cm AC-field along with 30 V/cm DC-field. As compared to the case of 35 V/cm DC-field only, the specimen from both the 30 V/cm DC and 5 V/cm AC resulted in 1.5 times faster crystallization velocity, regardless of the experimental frequency ranges of 100 Hz ~ 50 MHz. Presumably, the enhancement of the crystallization velocity under the combined field is associated with the increase in the flux of the crucial diffusion species, Cu atoms, which govern the overall crystallization velocity due to the agitation effect by the AC-field.
Authors: Dong Young Sung, In Soo Kim, Min Gu Lee, Bee Lyong Yang, Jun Mo Yang, Jung Kyu Ko
Abstract: The uniform and dense structure of thin films is influenced by the texture of films. It was good to have uniform and dense structure and bad to have an open columnar structure in TiN thin films. Therefore, the property of diffusion barrier of the TiN films in semiconductor also is related to the texture and microstructure of TiN coated layers. In this study, the relationships between the textures and microstructures and the properties of TiN films on semiconductor were investigated under different processing methods (PVD and MOCVD). The property of diffusion barrier of RF sputtered (PVD) TiN is better than that of metal organic chemical vapor deposited (MOCVD) TiN thin films. Also the property of diffusion barrier of PVD (111) textured TiN is better than that of PVD (100) textured TiN thin films on oxidized Si wafer.
Authors: Jung Suk Lee, J.P. Jung, Woong Ho Bang, Kyu Hwan Oh
Abstract: TLP method was applied to the lead free soldering process; Sn-3.5Ag core solder (Tm of 221°C) / Sn-Bi coating layer (Tm of 139°C at eutectic) was reflowed on UBM pad. Sn-Bi was formed by electroplating method at current range of 2~6A/dm2, which had varied the coating layer composition from 96wt% to 28wt% Bi. Specimens were reflowed on copper pad at temperature range of 200 and 220°C, and then interface reaction was examined. It was claimed that high Bi adding in the plated layer improved the wetting performance on Cu. Even at the reflow temperature of 200°C, SEM observation revealed well-defined interface junctions between solder and copper pad, i.e. nucleation and growth of CuxSn intermetallic compound. After heating for 5min at 220°C, Bi was resolved into Sn-3.5Ag core solder and completely homogenized, which is favorable from the viewpoint of long term fatigue reliability.
Authors: Shang Shu Kim, Su Dong Park, Byung Geol Kim, Hee Woong Lee, Goo Yong Sin, Dong Il Lee, Byung Uk Min
Abstract: Fatigue properties of INVAR/AW wires have been investigated under the heat exposure in order to ensure stable operation and to estimate life span of their power line. In the case of heat exposure for 1000hr, fatigue life and limit increased. For further heat exposure, fatigue limit decreased due to the decrease in yield strength. The variation fatigue of strand wire was strongly dependent on its amplitude. Also, cracks in wires of 7 strands were caused by stress concentration at the outer surface and fretting between each wire during vibration.
Authors: Sowjun Matsumura, Ju Sheng Ma
Authors: Se Hoon Park, Young Ho Kim
Abstract: The shear force of Sn-3.5Ag and Sn-3.8Ag-0.7Cu solder bumps formed by the stencil printing method was measured and the effects of intermetallic formation on the shear force of solder bumps were investigated. The Sn-Ag(-Cu) solder paste was printed on the Au/Ni/Ti under bump metallurgy (UBM) and then reflowed repeatedly. The shear force of the solder bumps was measured as a function of the reflow times. The intermetallic formation in the Sn-Ag(-Cu) solder/UBM was characterized using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffractormeter. Ni3Sn4 phase was formed in the Sn-3.5Ag solder/UBM interface and (Cu,Ni)6Sn5 phase formed at the Sn-3.8Sg-0.7Cu solder/UBM interface. The shear force of solder bumps was sensitive to the depletion of Ni layer and the intermetallic thickness at the solder/Ni interface. The shear forces of Sn-3.5Ag solder bumps decreased rapidly after the fifth reflow due to the depletion of Ni layer in the UBM. The shear forces of Sn-3.8Ag-0.7Cu solder bumps decreased after the tenth reflow due to extensive growth of intermetallic layer in the solder/Ni interface.
Authors: Won-Hyo Kim, Joon Shik Park, Kyu Shik Shin, Kwang Bum Park, Woo Kyeong Seong, Chan Woo Moon
Abstract: The eight types of micro-grippers with silicon were simulated by ANSYS and fabricated by MEMS(Micro Electro Mechanical System) process. Each type of micro-grippers had a small difference in design shape such as beam width, gap between beams. In order to modify design shape, these micro-grippers were estimated and simulated in point of structure, actuation characteristics by changing design factors. Micro-grippers were composed of five parts which were piezoelectric actuation part, fixing part, rotation arms, the block and gripping jaws. The shape of gripping jaws was designed as the teeth of a saw to reduce adhesion force by decreasing the contact area. The 10.2 µm movement by piezoelectric actuator at 120 V generated the 142.8 µm gripping range of a micro-gripper in real measurement. In the case of simulation result, the gripping range of 162 µm was generated at the same condition. This gripping range was enough to handle small objects like micro-parts
Authors: Hyuck Jung, Duck-Jin Lee, Hyun-Tae Chun, Nam-Je Koh, Young Rae Cho, Dong-Gu Lee
Abstract: In this study, a 10"-sized panel with novel tetrode structure was tried to prevent broadening of electrons emitted from CNTs. The structure of the novel tetrode is composed of CNT emitters on a cathode electrode, a gate electrode, an extracting electrode coated on the top of a hopping electron spacer (HES), and an anode. HES contains funnel-shaped holes whose inner surfaces are coated with MgO. Electrons extracted through the gate are collected inside the funnel-shaped holes and hop along the hole surface to the top extracting electrode. The effects of HES on emission characteristics of field emission display (FED) were investigated. An active ozone treatment for the complete removal of residues of organic binders in the emitter devices was applied to the FED panel as a post-treatment
Authors: C.C. Yang, Qing Jiang
Abstract: The pressure-dependent melting temperature of bulk Si, bulk Ge and nanocrystalline (nc) Si are predicted by the Clapeyron equation where the pressure-dependent volume difference is modeled by introducing the effect of surface stress induced pressure. The predictions are found to be consistent with the present experimental and other theoretical results.
Authors: W. Lei, Y.H. Chen, Y.L. Wang, X.L. Ye, P. Jin, Bo Xu, Yi Ping Zeng, Z.G. Wang
Abstract: InAs quantum wires (QWRs) have been fabricated on the InP(001), which has been evidenced by TEM and polarized photoluminescence measurements (PPL). The monlayer-splitting peaks (MSPs) in the PL spectrum of InAs QWRs can be clearly observed at low temperature measurements. Supposing a peak-shift of MSP identical to that of bulk material, we obtain the thermal activation energies of up to 5 MSPs. The smaller thermal activation energies for the MSPs of higher energy lead to the fast red-shift of PL peak as a whole.

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