Sung-Lak Choi

P‐166: Microstructural Characterization of the Interface between IZO and Mo/Al/Mo Metal Line Used in TFT‐LCDs

Mo layer is used as a protective layer of Al metal line causing problems such as hillock and oxidation in TFT-LCDs. When the insulating SiNx and passivation layer is etched to form a contact hole in Mo/Al/Mo trilayered metal line, the upper Mo layer is also removed due to the lack of selectivity of the dry etching process. As a result, IZO layer appear to contact to Al directly, possibly resulting in the formation of Al2O3 increasing the contact resistivity. However, detailed investigation by TEM revealed that there are two amorphous layers, inner and outer layers, preventing the direct contact of IZO to Al layer. The inner layer was enriched with Mo, while the outer layer was enriched with Al and oxygen. Oxygen concentration was considerably reduced in front of the inner layer, indicating the Mo-rich inner layer as a barrier layer against oxygen diffusion. On the other hand, Al concentration was still higher and decreasing continuously across the inner layer, exhibiting fast Al diffusion through the inner layer. It was shown that Al-Mo alloy is able to form an amorphous phase at the interface during deposition because of large difference in melting point between Al and Mo. Based on the observed details, the interfacial amorphous layers are considered to produce thermodynamically stable phase, oxide and intermetallic compound, upon further annealing.

Smart material actuators for micro optical zoom lens driving systems

Micro-optical system designs for slim mobile device are presented. Evaluations on advantages and the drawbacks in terms of mechanical actuation performance of smart materials such as conducting polymer, co-polymer, and dielectric elastomers are provided for the efficient optical system driving actuation. In addition the present work makes an attempt to optimize fabrication process for each possible smart material candidate.

Photo-Induced Structural Change of and Interaction Between Organic Materials in Liquid Crystal Display Panel

Structural changes of and the interactions between organic materials in liquid crystal display panel after UV exposure were systematically investigated using FT-IR, XPS, AFM, and LC-ESI-MS. When the photo-curing of the sealant was imperfect during the assembly of LCD panel, both the components in the sealant such as UV-initiator contaminated the LCs and the stray UV light oxidized the benzene rings and other chemical bonds in the polymer backbone of the alignment layer. This resulting contamination of LCs and degradation of the alignment layer could disturb the pretilt angle of the VA-mode LCs and cause the display defects on the LCD panel. In this regard, careful control of the photo-curing of the sealant will be required for precise alignment of the LCD panel and better performance of the display.

28.2: The Molecular Orientation of Polyimide Alignment Layer used in TFT‐LCDs with NEXAFS Study

Aromatic polyimide thin films are used as the alignment film in thin film transistor-liquid crystal displays (TFT-LCDs). The films play an important role in the initial alignment of the liquid crystal materials in LCD panels. Therefore, any structural or morphological deformation may lead to defect in the physical interactions thus malfunction of the display eventually. for example, an LCD is known to bear image sticking problem when it is assembled following 3 days or longer stagnancy in the process after main curing of the layer. In this paper, the molecular orientation of polyimide surfaces with respect to the stagnancy is investigated by means of surface sensitive Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. NEXAFS measurements clearly reveal preferred in-plane and out-of-plane orientation of phenyl and C=O groups at the surface of the polyimide thin film in regard to the stagnancy after main curing. with longer stagnancy phenyl and C=O groups preferred in-plane orientation. The preferred in-plane orientation within the film can accelerate the image sticking problem in LCDs operating in PVA mode. Based on the result, vertical alignment of polyimide pendant group is found helpful for the better alignment of LC molecules in LCDs operating in the patterned vertical alignment (PVA) mode.

Effects of Magnetic Field Annealing on a Micro-fluxgate Sensor

A silicon based micro-fluxgate sensor with a cobalt based amorphous soft magnetic core for electronic compass is presented in this paper, and effects of magnetic field annealing were tested under 3 different field directions (length, width, and rotation) for improving the sensors performance.

P-10: Mechanism of Lowering Contact Resistance between Transparent Conducting Oxide Layer and Mo/Al/Mo Layer in TFT-LCDs

It was found that the mechanism of lowering contact resistance between TCO and Mo/Al/Mo layer is the side ring contact between TCO and top Mo of Mo/Al/Mo. This is contrary to the previous results that used MoxAly interfacial layer to explain the low contact resistance of TCO and Mo/Al/Mo layer.