Papers

ICMCTF2008 Session FP: Symposium F Poster Session

Thursday, May 1, 2008 5:00 PM in Room Town & Country

Thursday Afternoon

Time Period ThP Sessions | Topic F Sessions | Time Periods | Topics | ICMCTF2008 Schedule

FP-1 Characterization of Interface Between the Hf-Based High-K Thin Film and Si Using Spatially Resolved Electron Energy Loss Spectroscopy X.F. Wang, Q. Li (The Chinese University of Hong Kong, China) Being a critical factor in affecting the final electrical performance of the CMOS device, the interfacial structure (both microstructure and electronic structure) of HfO₂-based thin on Si are of intense focus. Using scanning transmission electron microscope (STEM)-electron energy loss spectroscopy (EELS), we investigate the interface between the HfO₂ thin film and the Si. Although the interface of the as-synthesized sample is found to be atomically sharp between the oxide and the Si, an interfacial oxide layer is identified with high defect density of states. In addition, sample annealing in the oxygen environment introduce a rather thick SiO_x layer in-between the high-K film and the Si substrate. We find that introducing Al to the HfO₂ film not only passivates the interfacial defect density of states for the as-deposited sample, but also prevents the formation of the interfacial SiO_x layer upon oxygen annealing, which mechanism is disclosed by an ab-intio calculation the Al block the diffusion of O through the high-K film to reach the interface, and thus effectively prevent the reaction between the O and the Si and the formation of SiO_x in the interfacial region. This work is supported by a grant of the Research Grant Council of HKSAR, under project No. 402105.
FP-3 Structural and Electrical Properties of Strained Ba_{0.5√sub 0.5}(Ti,Mn)O₃ Thin Films Buffered With La_0.68Ba_0.32MnO₃ Conductive Layers Y.-C. Liang (Chienkuo Technology University, Taiwan); Y.-C. Liang (University of Southern California) The microstructure and electrical properties of 3mol% Mn-doped Ba_{0.5√sub 0.5}TiO₃(BST) thin films deposited on La_0.68Ba_0.32MnO₃(LBMO)-coated LaNiO₃/Pt/Ti/SiO₂/Si substrates by rf magnetron sputtering were studied. The deposited Mn-doped BST films exhibit (001)-textured orientation due to the same perovskite-type structure of the buffer-layers. The 60nm-thick Mn-doped BST films on the 100nm-thick LBMO buffer-layers show the elongation of c-axis lattice constant. The Mn-doped BST film that was deposited on the LaNiO₃ without LBMO buffer-layer exhibits a bulk-like lattice constant. The misfit between the BST and LaNiO₃ is around 1.55% and that between the BST and LBMO is 0.7%. The 60nm-thick BST films are partially constrained by the LBMO buffer-layers due to the smaller lattice mismatch between the BST and LBMO buffer-layer. A suitable degree of lattice distortion of the BST films is required to obtain a larger dielectric constant. A non-linear characteristic of dielectric constant vs. the applied voltage reveals that partially strained BST films on the LBMO buffer-layers have ferroelectric properties, which fact is consistent with the crystalline structure of the strained BST films, as revealed by X-ray diffraction. The LBMO buffer-layer deposited at a higher growth temperature processes a larger grain size structure, which results in a rougher surface structure of the deposited BST film. BST film with larger grain size has relatively short conduction paths in the film resulting in an increase of leakage current.
FP-4 Adhesion and Interfacial Characteristics of Metal/PI Composite Film Modified by O₂ Ion Beam W.J. Lee (Korea Institute of Science and Technology); Y.B. Kim (Korea Institute of Science and Technology, KIST, Korea) Polyimide(PI)/Metal film has been widely used in the field of electronic packaging for applications such as a flexible printed circuit and a cable assemble. One of the technical concerns for the PI/Metal system is the improvement of the interfacial adhesion. In this study, PI film surface was modified by O₂ ion beam and subsequently NiCr/Cu metal film was deposited on PI film by DC sputtering. The adhesion and interface characteristics between PI film and metal film were investigated. The surface modification of PI film by O₂ ion beam enabled a significant decrease of contact angles of water from 68° to 4.4° at an ion dose of 1x10¹⁸ ions/cm², which results in an increase of surface energy by a factor of two. The XPS(X-ray Photoelectron Spectroscopy) spectrum obtained from the modified PI film showed that the functional groups of C-O and C=O bonding on PI surface were increased by the interaction between scissored unstable chains and reactive ions. A peel strength between PI and NiCr/Cu metal film increased with an increase of ion dose and the highest peel strength of 0.70 kgf/cm could be achieved from the specimen with PI film modified at an ion dose of 1x10¹⁸ ions/cm². In order to find out the reason that leads to the improvement of adhesion between metal and PI film, the interface between PI film and NiCr layer was analyzed by XPS depth profile. According to the XPS depth profile from NiCr metal layer into modified PI film, the O1s peak was broadened with an increase of depth from NiCr layer at near-interface region, which indicates that the new chemical bonding state was formed. In addition to C-O and C=O bonding in O1s peak, the newly formed chemical bonding at the interface between NiCr metal film and PI film was identified as metal-oxide compound such as NiO, Cr₂ O₃, and Cr-O by XPS curve fitting. Consequently, the improvement of adhesion is primarily attributed to the strong chemical bonding caused by chemical interaction between NiCr and newly formed functional group by O₂ ion beam.
FP-5 The Characterization of Cuprous Oxide Films Prepared by Post-Annealing of Cupric Oxide Under Atmospheric Nitrogen Pressure Plasma Torch H.-Y. Chen, L.-T. Kuo (National Kaohsiung University of Applied Sciences, Taiwan); S. Han (National Taichung Institute of Technology, R.O.C.); C.-H. Tsai (National Kaohsiung University of Applied Sciences, Taiwan) The cuprous oxide films were prepared by post-annealing of cupric oxide via atmospheric pressure microwave plasma torch. The metallic copper films were deposited on glass substrate by magnetron sputtering. After that, the films were annealed in air at 500°C for 12 h, which would result in the formation of cupric oxide. The annealed films were then treated by nitrogen plasma at 800 W for 10 or 20 mins. The films color obvious changed from black to reddish brown above 10 mins. The X-ray diffraction patterns show that annealed films were cupric oxide and the signals vanished after plasma treatment. The cuprous oxide diffraction peaks appeared above 10 mins. The resistivity of annealed films was about 20 MΩ, which the value reduced significantly to 2.4 MΩ after plasma treatment. The optical band gap of cupric oxide films was 1.8 eV, but shifts toward 2.2 eV after plasma treatment. The microstructure and plasma constitutes correlate to the resultant properties of films are also further investigated.
FP-6 The Evaluation of Created Circumferential Gap Defect Around Dental Implants According to Implant Surface, Defect Width and Defect Morphology S.U. Im, J.Y. Hong, G.J. Chae, U.W. Jung, C.S.K Kim, Y.K. Lee, K.S. Cho, C.K. Kim, S.H. Choi (Yonsei University College of Dentistry, Korea) The aim of this study was to evaluate the factors affecting healing of created circumferential gap defect around implants in dogs. Materials and Methods : In four mongrel dogs, all mandibular premolars were extracted and after 8 weeks of healing period submerged type implants were placed. According to the implant surfaces groups were divided into two, which are group A with turned surface and group B with rough surface. In each dog, the defect of the mandibular left side was performed surgically with a customized tapered step drill and in the right with a customized paralleled drill. Groups were also divided according to the width of the coronal gaps: 1.0 mm, 1.5 mm, or 2.0 mm. The dogs were sacrificed following 8 week healing period and the specimens were analyzed histologically and histomorphometrically. Results : During the postoperative period healing was uneventful and implants were well-maintained. As the size of the coronal gap increased, the amount of bone-to-implant contact decreased. The bone healing was greater in rough surface implants compared to turned surface implants. With the defect morphologies, tapered shape showed good bone filling and direct bone to implant contact even in smooth surface implants. Conclusion : It can be concluded that the healing of circumferential defect around the implant is influenced by the implant surface, defect width and the morphology of the defect. When using rough surface implants, circumferential gap defects within 2 mm do not need any kind of regenerative procedures and the healing appeared to be faster in the tapered defect morphology than the paralleled one.
FP-7 The Histometric Analysis of Osseointegration in Hydroxyapatite Surface Dental Implants by Ion Beam-Assisted Deposition M.K. Kim, J.Y. Choi, G.J. Chae, U.W. Jung, I.S. Lee, K.S. Cho, C.K. Kim, S.H. Choi (Yonsei University College of Dentistry, Korea) This study compared the effects of coating implants with hydroxyapatite (HA) using an ion beam-assisted deposition (IBAD) method those prepared with machined, anodized and sandblasted and large-grit acid etched (SLA) surfaces in minipigs, and verified the excellency of coating method with HA using IBAD. Material and Methods: Four male Minipigs,18 to 24 months old and weighing approximately 35 to 40 kg, were chosen. All premolars and the first molars of the maxilla were carefully extracted on each side. The implants were placed on the right side after a healing period of eight weeks. The implant stability was assessed by resonance frequency analysis (RFA) at the time of placement. Forty implants were divided into five groups; machined, anodized, anodized plus IBAD, SLA and SLA plus IBAD surface implants. Four weeks after implantation on the right side, the same surface implants were placed on the left side. After four weeks of healing, the minipigs were sacrificed and the implants were analyzed by RFA and histologically and histometrically analyzed. Results: RFA showed a mean implant stability quotient (ISQ) of 75.625 ± 5.021, 76.125 ± 3.739 ISQ and 77.941 ± 2.947 at placement, after four weeks healing and after eight weeks, respectively. Statistical analysis showed no significant differences in the values among the 5 groups. There was no significant difference for the time intervals. Histological analysis of the implants demonstrated newly formed, compact, mature cortical bone with a nearby marrow spaces. HA coating did not separate from the HA coated implant surfaces using IBAD. In particular, the SLA implants coated with HA using IBAD showed better contact osteogenesis, with a coverage of the implant surface with a bone layer as a base for intensive bone formation and remodeling. No inflammatory infiltrates were present around the implants. Statistical and histometric analysis showed no significant differences in the bone to implant contact and bone density among the 5 tested surfaces. Conclusion: We can conclude that rough surface implants coated with HA by IBAD demonstrated better biocompatibility, and clinical, histological, and histometric analysis showed no differences when compared with the other established implant surfaces in normal bone.
FP-8 Residual Stresses in Thermally Cycled Cr-CrN Coatings on Si(100) and on Steel K.J. Martinschitz, C. Kirchlechner (Austrian Academy of Sciences, Austria); R. Daniel, C. Mitterer, J. Keckes (University of Leoben, Austria) Hard coatings based on CrN are used to protect working tools from abrasion and corrosion. Residual stress in the coatings influences decisively mechanical and thermal performance of those tools. The stresses can be engineered by selecting specific deposition conditions like bias voltage, substrate temperature, substrate treatment or by selecting specific coating architecture. The stresses are additionally influenced by thermal loading which results in the annealing of intrinsic stresses. In order to understand the relationship between the mechanical performance and the residual stresses in hard coatings, it is necessary to perform a complex temperature-dependent characterization of stresses and correlate the results with the mechanical characteristics. In this contribution CrN/Cr coatings are deposited on monocrystalline Si(100) and polycrystalline austenitic substrates by physical vapour deposition at the temperature of 350 degrees. The structures are characterized using X-ray diffraction and wafer curvature technique in the temperature range of 25-550 degrees. The thermal cycling reveals the magnitude of intrinsic and extrinsic stresses which depend on the substrate material and the annealing temperature. Both types of stresses are larger in coatings on austenitic substrates what indicates a different coating growth mechanism. The annealing results in the remove of point defects, in a decrease of intrinsic stresses in both types of coatings and in the decrease of roughness in Cr caused probably by surface diffusion. The temperature dependencies stresses in individual sublayers of CrN/Cr coatings indicate that the presence of CrN layer influences the stress relaxation in Cr interface layer. The data are correlated with an independent mechanical characterization of the coatings. This work was supported by Austrian NANO Initiative within the project "StressDesign - Development of Fundamentals for Residual Stress Design in Coated Surfaces”.
FP-9 Characterization of Intermetallics Formed in Fe/Ti Nanometer-Scale Multilayers During Thermal Annealing Z.L. Wu, B.S. Cao, T.X. Peng, M.K. Lei (Dalian University of Technology, China) Kinetic process of intermetallics formation in the Fe/Ti nanometer-scale multilayers on Si(100) substrate deposited by direct current magnetron sputtering is addressed during thermal annealing at annealing temperature of 523-873 K for annealing time of 1 h, which is constructed with the thickness of alternating Fe and Ti sublayers of 16.2 nm and the sublayer thickness ratio of 1:1. Formation of α-Fe(Ti) solid solution and intermetallics FeTi and Fe2Ti is subsequently detected with increase of annealing temperature using small angle and wide angle x-ray diffraction (SA/WAXRD), and cross-sectional transmission electron microscopy (XTEM). An initial interdiffusion at lower temperature leads to formation of the α-Fe(Ti) solid solution in the interface between α-Fe and α-Ti sublayers. Intermetallic FeTi forms by nucleation at the triple joins of α-Fe(Ti)/α-Ti interface and α-Ti grain boundary following lateral growth to coalesce into a layer, which possesses an orientational relationship of FeTi(110)//α-Ti(10-10) and FeTi[001]//α-Ti[0001] to adjacent α-Ti grains. Intermetallic Fe₂Ti produces between FeTi formed and excess Fe at higher temperature, resulting in the coexistence of intermetallics FeTi and Fe₂Ti. It is found that the low energy interfaces as well as the dominant diffusion path constraint the nucleation and growth of intermetallic from the metallic sublayers during interfacial reactions in the nanometer-scale metallic multilayers.
FP-10 High-Temperature X-ray Elastic Constants Determined by the Combination of sin²psi and Substrate Curvature Methods K.J. Martinschitz, C. Kirchlechner (Austrian Academy of Sciences, Austria); J. Keckes (University of Leoben, Austria) The determination of residual stresses in anisotropic thin films using diffraction techniques requires usually an application of stress factors F_ij or X-ray elastic constants linking the measured elastic strain with the unknown residual stress. In this contribution, a new technique is presented which combines the characterization of the elastic strain in the film and the curvature of the underlying mono-crystalline substrate as a function of temperature. The curvature is determined by the measurement of rocking curves of the substrate symmetrical reflections at different sample positions. The curvature data are used to calculate the macroscopic in-plane stress applied on the film. Combining the experimental strain and stress data, experimental X-ray elastic constants can be calculated for the thin film possessing specific texture, anisotropy, grain size distribution, grain interaction and dislocation density. Using the approach it is possible to calibrate diffraction characterization of stresses especially in anisotropic materials. The approach is demonstrated on a variety of thin films like TiN, CrN, Cu, Al. This work was supported by Austrian NANO Initiative within the project "StressDesign - Development of Fundamentals for Residual Stress Design in Coated Surfaces".
FP-11 Reliability Behavior of a-Si:H TFTs Under Drain DC/AC Operation Y.H. Tai, S.C. Huang, M.H. Tsai (National Chiao Tung University, Taiwan) With the evolution of advanced applications, a-Si:H TFTs no longer play the roles as switch elements alone but driving devices as well. Unlike switch elements, TFTs in driving circuits are subjected to high frequency signals in both gate and drain terminals. In this study, the device degradation of a-Si:H TFTs under drain DC stress in both on (with gate biased) and off region (with gate grounded) has been investigated. Besides, the degradation under drain AC stress with different peak levels, frequencies and duty ratios is also been contributed. The degradation decreases as drain voltage level increases for on region drain DC stress which corresponds with the result as previous study. For off region drain DC stress, we have observed the result of reverse order which shows the similar behavior as negative gate DC stress except for the asymmetry between source and drain electrode. The state creation and insulator charge trapping are still the dominant mechanisms of drain stress. In addition, the degradation of drain AC stress in both on and off region is found to have the same trend as drain DC stress. But for off region drain AC stress, it is found that the degradation be dependent of the drain signal frequency but shows no frequency dependence for on region drain AC stress. The RC time effect may be introduced to explain the frequency dependent phenomena. Furthermore, the degradation is associated with the duty ratio due to the accumulation of stress time. These findings would be helpful in the understanding of the device degradation mechanisms and provide a guideline to design for reliability of a-Si:H TFT circuits.
FP-12 Application of the Copper as the Recombination Centers on TFT-LCD to Suppress the Photo Leakage Current H.W. Li, Y.H. Tai (National Chiao Tung University, Taiwan); T.-C. Chang (National Sun Yat Sen University, Taiwan); C.C. Ling (National Tsing Hua University, Taiwan) To improve the characteristics of switches has become a tendency in active matrix liquid-crystal display (AMLCD) technology. Particularly, the large photo-induce leakage current is an issue that needs to be imminently solved. In this paper, the amorphous silicon thin film transistors (a-Si:H TFTs) with low photo-induced leakage current will be proposed and studied. An alternative method has been proposed to suppress the photo leakage current of a-Si TFT operated at off-state. The deep level trap center copper is introduced into silicon film to act as recombination centers. After dipping conventional back-channel-etched (BCE) TFTs into CuSO₄ solution, copper would diffuse into the back channel. Experimental results had shown the photo leakage current of devices was lower than that of a-Si TFT without the introduction of copper. Although the mobility was decreased slightly, the degradation of mobility was still tolerable. The mechanism was mainly based on the photo-field effect that more recombination centers induce less reduction of band bending under illumination.
FP-13 Study on Electrical Properties of ZrZnO Thin Film Transistor With Dual Stacks of Gate Dielectrics P.-T. Liu, Y.T. Chou, H.W. Li, Y.C. Kuo (National Chiao Tung University, Taiwan); T.-C. Chang (National Sun Yat Sen University, Taiwan); L.F. Teng (National Chiao Tung University, Taiwan); F.J Luo (AU Optronics, Taiwan); B.C. Huang, J.S. Chiuan, CCY Yu (Industrial Technology Research Institute, Taiwan) ZrZnO-based thin film transistors (TFTs) have attracted attentions in recent years because of their transparency and insensitivity to visible light, gaining large aperture ratio of display pixels. Among several kinds of ZrZnO-layer deposition technologies, the sol-gel process is paid much attention due to its simplicity, cost effectiveness and potential for large area deposition. Previous documents have reported the excess carriers in ZrZnO film dominate the conduction operation of the ZrZnO TFT device, and make the electrical output characteristic "Hard saturation". It thereby requires a high negative voltage to deplete the channel layer for achieving the off-state of TFT device. In this work, the ZrZnO TFT with dual stacks of gate dielectric layers consisting of SiN_x and a buffer layer of Al₂O₃ or HfO_x film was developed to improve the interface between ZrZnO and gate SiN_x insulator layer. The improvement can effectively suppress the hard saturation leakage. Furthermore, with the buffer layer, the voltage to deplete channel and subthreshold swing of ZrZnO TFT could be reduced obviously, compared to the counterpart without the buffer layer. Therefore, these experimental results clearly indicate the proposed sol-gel ZrZnO TFT has great potential for the application to the advanced AMLCD technology.
FP-14 In - Situ Mechanical Characterization of the Tin/NbN, NbN/CrN and TiN/CrN Multilayer Coatings K.A. Rzepiejewska-Malyska, M. Parlinska-Wojtan (Swiss Federal Institute for Materials Testing and Research (Empa), Switzerland); Z. Rymuza (Warsaw University of Technology, Poland); J. Michler (Swiss Federal Institute for Materials Testing and Research (EMPA), Switzerland) Ultrathin multilayer coatings TiN/NbN, NbN/CrN and CrN/TiN as well as single layer reference coatings of TiN, NbN and CrN were deposited on silicon <100> by dc magnetron sputtering. Chemical composition of the coatings was verified by glow discharge optical emission spectroscopy. Mechanical properties were assessed by nanoindentation in-situ inside a high resolution Scanning Electron Microscope, which allows for observation of pile-up, sinking-in and crack propagation during the indentation loading cycle. FIB cross sections on the indents and Transmission Electron Microscopy (TEM) analysis were performed to analyze the subsurface deformation mechanisms. TEM revealed that all films were nanocystalline. The reference coatings of pure materials exhibited different mechanical behavior. NbN had a tendency to pile-up. TiN coatings showed sink-in and crack propagation for similar applied loads. The CrN coating had a tendency to pile-up and exhibited shear band formation around the indent as well as longer cracks compared to the other materials. For multilayers sink-in behavior was never observed for any combination and the extend of cracking was much more limited. TEM revealed different deformation mechanisms in single layer coatings. In TiN grain boundary sliding and in CrN compression of nanopores was evidenced. TiN and CrN sublayers were found to deform in a similar way within the multilayer. The difference in deformation mechanisms observed will be discussed and linked to the observed pile-up and sink-in behavior.
FP-15 Physical and Electrical Characteristics of Ba(Zr_0.1Ti_0.9)O₃ Ferroelectric Thin Films Deposited on ITO Substrate Under the Different Temperature K.-H. Chen (Tung-Fang Institute of Technology, Taiwan); C.-F. Yang (National University of Kaohsiung); D.-W. Chou (Air Force Institute of Technology, Taiwan) Recently, electronic devices and systems on panel (SOP) technology had been widely discussed and researched. The high temperature fabrication process for electronic devices is sometimes essential and indispensable technology, such as the conventional annealing, rapid temperature annealing and etc. The glass substrate would be deformed and fused under high temperature process. As a result, the detailed structures and properties of these processes and technologies for glass substrate, especially in ferroelectric thin film applications, have not been reported. In this study, ferroelectric thin films of Ba(Ti_0.9Zr_0.1)O₃ would be deposited on ITO glass substrates by RF sputtering technology under the different depositing parameters. The dielectric and electrical characteristics of the resulted films were investigated. The thickness and maximum grain size of BZT thin films deposited at the glass substrate temperature of 550°C were 220 nm and 50 nm, respectively, from the FESEM morphologies. In addition, the deposition rate of BZT thin films, calculated from the films thickness of BZT thin films, was found to be about 3.65 nm/min. The dielectric constant of BZT thin films was about 90 and the leakage current density of BZT thin films under the electrical field of 0.5 MV/cm was 5?10-6A/cm², respectively. From the P-E curves obtained, the coercive field and remanent polarization of BZT films were found to be 250 kV/cm and 4 ?C/cm², respectively, as the frequency of 500 kHz was applied. Finally, the variations of coercive filed and remanent polarization of BZT thin films under ITO substrate temperature changing form 400°C to 550°C were also discussed in detail.
FP-16 Microstructure and Corrosion Properties of Nano-Composite Cr-Al-Si-N Coating by Reactive DC Unbalanced Magnetron Sputtering C.-L. Chang, C.-J. Shen (MIngdao University, Taiwan); J.-W. Lee (Tung Nan University, Taiwan); D.-Y. Wang (Mingdao University, Taiwan) Nano-composite Cr-Al-Si-N films have been deposited on Si wafer and WC-Co substrates using CrSi (80:20 at.%) and AlSi (80:20 at.%) alloy target by a dual reactive DC unbalanced magnetron sputtering system. The Cr-Al-Si-N coatings were designed with CrSi/CrSiN as an interlayer and enhancing adhesion strength between substrate and top coating. The Cr-Al-Si-N coatings were deposited under the constant flow of nitrogen with various bias voltages. The influences of bias voltage on the synthesis, microstructure, mechanical, and corrosion properties of the Cr-Al-Si-N films were investigated. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction techniques were employed to analyses the microstructure, grain size and residual stress. Adhesion strength was identified using a scratch test and Rockwell-C indentation methods. Nano-indentation and tribometer testes were used to measure the microhardness, mechanical and tribological properties of Cr-Al-Si-N thin films. The results showed that both the hardness and residual stress of the films decreased from 48 to 32 GPa and -8.5 to -5.8 GPa, respectively, with decreased the bias voltages. The corrosion resistance of coatings tested in 1 N H₂SO₄ solution was confirmed that Cr-Al-Si-N coatings was better than both CrN and AlN coating since the effect of Si add in CrN or AlN, and more dense nano-crystalline structure formed.
FP-17 The Interfacial Hysteretic Stress Study for Copper and Low-K Process Application Beyond the Nano-Scale Interconnect Y.-L. Wang, K.-W. Chen (Taiwan Semiconductor Manufacturing Company Ltd., Taiwan) While the IC device shrunk to nano-scale, the interconnect was also droved to shrink the feature scale to nanometer scope for the reduction of RC delay. In general, the copper metallization and low-K dielectric film deposition were widely applied to the interconnect and combined with the damascene process scheme. The integration issue between copper metallization and low-K dielectric film would be faced and challenged with the stress-induced void and migration problem under the feature size shrinking. This study was focus on the hysteretic stress behavior investigation between copper and dielectric film deposition stacking. Besides, from the hysteretic stress studies, we found the high hysteretic phenomena between the copper and low-K dielectric induced the void in the vias structure; however, the lower hysteretic stress curve observed with low stress-induced void formation in the vias. The hysteretic curve would be controlled with the copper barrier film type, grain size of electroplating copper film, the low-K film type, and so on. In addition, the optimization of the sandwich copper plating metallization would be reduced for the behavior of the hysteretic stress, then reduce the stress residue in the film after the thermal torture cycle. The novel solution and mechanism would be developed with the rapid stress relaxation under larger grain size distributions. It was benefit to the device speed and reliability improvement of the semiconductor manufacturing productions.
FP-18 Characteristics of Colossal Magnetoresistance Thin Films Deposited at Low Substrate Temperature by RF Magnetron Sputtering S.G. Choi, T.J. Ha, A.Sivasankar Reddy (Yonsei University, Korea); B.G. Yu (Electronics and Telecommunication Research Institute, Korea); H.-H. Park (Yonsei University, Korea) Colossal magnetoresistance (CMR) thin films (L_1-xA_xMnO₃ where L and A are trivalent rare-earth ions and divalent alkaline earth ions respectively) are received attention because it has a high temperature coefficient of resistance (TCR) property which was discovered in the metal to semiconductor phase transition temperature region. Most of the epitaxial and polycrystalline CMR thin films were deposited on the single crystal substrates, for example LaAlO₃, SrTiO₃ and MgO. Also for the crystallization, they have been known to be needed high substrate temperature and high post annealing temperature about 700°C. But for using CMR films to the sensing part of IR sensing bolometer through CMOS process, film formation should be performed under 500°C, so a lower deposition and annealing temperatures of CMR thin films is desired. In this study, we prepared CMR thin films on Si and SiO₂ substrates by RF magnetron sputtering. Also CMR thin films were deposited in low substrate temperature of 350 °C. Crystal structure and grain size of films were measured X-ray diffractometor and secondary electron microscopy. Their electrical properties were measured by sheet resistance and TCR value. With these results, it could be confirmed that good polycrystalline CMR thin film of low sheet resistance and high TCR value are possibly obtained with low deposition temperature. These results show that the CMR thin film deposited under 500°C can be promising candidate material for IR-sensing microbolometer applications.
FP-19 Schottky Barrier Characterization of Lead Phthalocyanine/Aluminium Interfaces T. Sadat-Shafai (Staffordshire University, United Kingdom) Thin film sandwich structure consisting of several cells is fabricated by successive thermal sublimation of aluminium, lead phthalocyanine and aluminium under high vacuum conditions (10-4 Pa). The dark current density-voltage (J-V) characteristics indicate rectifying junctions exists at PbPc/Al interface. Devices exposed to oxygen were found to exhibit an enhanced Schottky type behaviour. Measurements on the dependence of capacitance and conductance on frequency and temperature is also investigated. This is quantitatively interpreted using an equivalent circuit model. Structural properties of Lead phthalocyanine film were studied using X-ray diffraction techniques.
FP-20 The Effects of Hydroxyapatite Nano-Coating Implants on Healing of Surgically Created Circumferential Gap in Dogs G.J. Chae, J.Y. Choi (Yonsei University College of Dentistry, Korea); S.M. Jung (Dentium Co., Korea); I.S. Lee, K.S. Cho, C.K. Kim, S.H. Choi, H.-C. Lim (Yonsei University College of Dentistry, Korea) Laboratory animal studies and experiences with human implants suggested that Hydroxyapatite (HA) coated dental implants could induce a chemical bond with bone and achieve biological fixation. The aim of this study is to compare the healing response of various HA nano-coating surface dental implants placed in the surgically created circumferential gap. In Four mongrel dogs, all mandibular premolars and the first molar were extracted. After an 8-week healing period, six submerged type implants were placed and the circumferential cylinderical 2mm coronal defects around the implants were made surgically with a customized step drill. In two groups, bone graft was performed additionally. Groups were divided into six categories- SLA surface, SLA with bone graft, SLA surface with 150nm HA and heat treatment, SLA surface with 300nm HA and heat treatment, SLA surface with 150nm HA without heat treatment, and SLA surface with 150nm HA, heat treatment and bone graft. The dogs were sacrificed following a 12 -week healing period. Specimens were analyzed histologically and histomorphometrically. During the healing period, healing was uneventful and implants were well maintained. The bone-to-implant contact (BIC) for SLA surface with 150nm HA, heat treatment and bone graft showed the highest value and the SLA surface with HA and heat treatment was also higher than the other groups. Bone density showed similar results as the BIC. Within the scope of this study, HA nano-coated implants may improve the bone response and the HA coating may be suitable in implant design with complex surface geometries. [This work was partially supported by a grant (code #: 05K1501-01620) from Center for Nanostructured Materials Technology under 21st Century Frontier R&D Program of the Ministry of Science and Technology, Korea.].
FP-21 Nanometer Scale Mechanical Property Evaluation of Various Cured Lubricant and DLC Film Coated Magnetic Disks by Forced Modulation Atomic Force Microscopy W. Kurosaka, S. Miyake (Nippon Institute of Technology, Japan) It was proposal that the surface functions of the lubricant- diamond-like-carbon (DLC) protective layer were evaluated by mapping and analyzing atomic force microscopy (AFM) images of wear marks obtained in wear tests on the basis of forced modulation atomic force microscopy (FM-AFM) and friction force microscopy (FFM). The nanometer-scale tribology properties of heat-treated and ultraviolet (UV)-irradiated magnetic disk are investigated by a lateral and vertical vibration wear tests using AFM with a force modulation. The distributions of the frictional force and electrical current of the surface of the magnetic disks indicate the dynamic behavior of the lubricant oil as compared the wear area with the no-wear area. The damage of lateral vibration wear test is the larger than those of vertical vibration wear test and without vibration wear test. From the current distribution, the worn area has bright images corresponded to damaged and less lubricant areas. The wear-resistance of UV-irradiated disk is improved due to solidification of lubricant.
FP-22 Application of Fluorine Doped Oxide (SiOF) Spacers for Improving Reliability in Low Temperature Polycrystalline Thin Film Transistors L.-W. Feng (National Chiao Tung University, Taiwan); T.-C. Chang (National Sun Yat Sen University, Taiwan); P.-T. Liu, C.-H. Tu (National Chiao Tung University, Taiwan); Y.-C. Wu (National Tsing-Hua University, Taiwan); C.-Y. Yang, C.-Y. Chang (National Chiao Tung University, Taiwan) The novel process of self-aligned fluorine doped oxide (SiOF) spacers on low temperature poly-Si (LTPS) Light Doped Drain(LDD) TFTs is proposed. A fluorine doped oxide spacers were provided to generate the higher dissociation Si-F bonds adjusted to the interface of the drain which is the largest lateral electric field region for light doped drain structure. The stronger Si-F bonds can reduce the bonds broken by impact ionization. It is found that the output characteristics of SiOF spacers TFTs show the superior immunity to kink effect. The degradations in Vth shifting, drain current and trans-conductance of SiOF spacers after DC stress are improved.
FP-24 Deposition of Fe-Nb Powder Mixtures with Plasma Transferred Arc A.S.C.M d´Oliveira, J. Manica, E.H. Takano (Federal University of Paraná, Brazil) Iron-niobium alloy system presents several challenges to researchers, in particular within the range 40-75%wtNb, due to the low toughness intermetallic phases expected. In the present work, Fe-Nb powder mixtures with 60%wtNb and 40%wtNb, respectively, were processed. Mixtures were dried and homogenized before deposition on AISI 1020 carbon steel and on AISI 304 stainless steel plates. Plasma Transferred Arc processing was done to produce welded coatings. Deposits were processed with current intensities within the range 150 A - 200 A. Chemical composition analyses were investigated by X-ray photoelectron spectroscopy and by X-ray diffraction. Microstructure was evaluated by Scanning Electron Microscopy. Vickers microhardness completed the evaluation. Coatings soundness depended on the current intensity used during processing. Deposits processed with current intensities up to 170 A exhibited lack of soundness as revealed by non-uniform thickness and the presence of porosities and holes. As current intensity increased, above 180 A, soundness improved and smooth 1.5 mm thickness coatings were obtained. Excess penetration was observed after processing with higher current intensities, which account for similar hardness measurements on coatings processed with both powder mixtures. Substrate chemical composition affected coating microstructures and hardness with deposits processed on AISI 304 stainless steel exhibiting higher hardness.
FP-25 Nano-Sized Amorphous Tungsten Oxide Films for Gas Sensing Applications C.-Y. Su (National Taipei University of Technology, Taiwan); L.-Y. Chen, C.-Y. Tsay (Feng Chia University, Taiwan); J.-L. Huang (National Cheng-Kung University, Taiwan); C.-K. Lin (Feng Chia University, Taiwan) In the present study, nano-sized amorphous tungsten oxide powders were synthesized by a gas condensation process. Pure tungsten raw materials were firstly oxidized at 1000°C in furnace and then put into gas condensation high vacuum chamber to produce nanocrystalline tungsten oxide powders. The as-prepared powders were then characterized by X-ray diffraction (XRD), in-situ XRD, differential scanning calorimetry (DSC) - thermogravimetry analysis (TGA), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS). In addition, gas sensing properties of tungsten oxide films prepared by as-received nanocrystalline powders were investigated. XRD ad TEM results showed that the as-prepared tungsten oxide powders were amorphous and nano-sized. Revealed by in situ XRD and thermal analysis results, the as-prepared nano-sized amorphous powders transformed into WO₃ phase after heat treating at 400°C. The gas sensors prepared by amorphous powders exhibited a better gas sensing properties than those prepared by crystalline ones. Gas sensor prepared by amorphous powders exhibited a high sensitivity of 53.62 when tested under 1 ppm NO₂ at 100°C. The sensitivity decreased to ~37.0 after 10 repetitive gas adsorption-desorption cycles. Meanwhile, the nano-sized amorphous gas sensors also exhibited good gas sensing selectivity against reductive CO gas, where opposite resistance response was noticed.
FP-26 Effects of Post-Annealing Temperature on Electrical Behavior of CCTO Thin Films for Resistance Random Access Memory Application Y.-S. Shen, C.-C. Ho (National Chiao-Tung University, Taiwan); L.-C. Chang (Huafan University, Taiwan); B.-S. Chiou (National Chiao-Tung University, Taiwan) In this study, a novel material CaCu₃Ti₄O₁₂(CCTO), for resistance random access memory application, was prepared by sol-gel method and then annealed at various temperatures from 600 to 900°C for 30 min. The crystallinity and microstructure of CCTO thin films become better as increasing post-annealing temperature, analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Due to the better crystallinity of CCTO thin films under post-anneal temperature at 800 °C and above, the endurance cycle of CCTO thin films is over 1000 times with a small degradation of the resistance ratio between high resistance state and low resistance state and is larger than those of CCTO thin film annealed below 800°C. The relation between resistance switching behaviors and corresponding crystallinity are investigated here.
FP-27 Effects of Al Content and Physical Properties on the Electromagnetic Interference Shielding of Sn-xAl Coating Thin Layers F.-S. Hung, F.-Y. Hung, C.-M. Chiang, T.-S. Lui (National Cheng Kung University, Taiwan) This study coats complex colloid mixed with Sn-xAl powders and polyethylene on glass to examine the shield effect on electromagnetic interference (EMI). In addition, the sputtering specimens and powder coating specimens were compared. The results show that adding Al to the Sn-xAl powders can increase the electromagnetic interference (EMI) shield at lower frequencies. Notably, the number of cavities in the coating layer increased with the coating thickness, with the result that the EMI shield could not improve with an increase in the coating thickness at higher frequencies. However, the EMI shield of sputtering films had a tendency to increase as the thin thickness increased. The Sn-40Al undergoes a dispersing effect which forms a fine overlapping structure, thereby improving the low frequency EMI shielding. In addition, the Sn-20Al powders possessed the properties of a small particle size, closed structure and higher electric conductivity which improved the high frequency EMI shielding. For the sputtering films, the annealed treatment not only had higher electric conductivity, but also increased the high frequency EMI shielding.
FP-28 Evaluation of Actual Crack Size and Morphology of Eco-Friendly Trivalent Chromium Layers by Using Small Angle Neutron Scattering Y. Choi (Sunmoon University, Korea) Defects are inevitably formed during electro-deposition process because of hydrogen evolution and metallic reduction. In this study, small angle neutron scanning (SANS) is applied to non-destruvtively evaluate defect size and distribution of electro-deposited chromium layers on AISI 1002 steel prepared by various electroplating conditions like electro-wave form, current voltage, and solution chemistry. Pulse plating with low voltage and current density produces smaller defects in the chromium. The number of nano-size defects less than about 40 nm in size increases with plating voltage at constant current density. Large defect sizes of trivalent chromium layer are 4.9 micro-meter for direct current plating, 3.3-7.9 micro-meter for the pulse plating, which was decreased with decreasing plating current density and voltage. Large defects evaluated by SANS results from the inter-connection of nano-size small defects.

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