Interaction in liquid medium has been focused for analyzing pattern development, pattern plating, wet etching and cleaning. Adsorption forces due to surface energy of a micro tip and various inorganic substrates can be measured in liquid environment. Hamaker constant between two surfaces is determined based on Lifshitz theory. In liquid condition, Hamaker constant in this system is proportional to adhesion force between the tip and substrates. Experimental value of Hamaker constant indicates good agreement with that of theoretical one.
Diesel particulate filter (DPF) is widely used to trap fine soot particles emitted from diesel engines. It can collect particles as small as submicron but it is necessary to oxidize accumulated particles by heating the filter. Temperatures of 600 degree C or higher is required to oxidize the soot but it is difficult to maintain stable reaction because this is exoergic reaction. The filter is sometimes damaged due to thermal runaway of the reaction. To address this trade-off problem, we have studied low temperature regeneration of DPF using sliding discharge, which can be generated on the surface of DPF and produces oxidative species at room temperature. Diesel soot collected by DPF was used. Simulated air consisting of N2 and O2 and not including CO2 or CO was used and CO and CO2 concentration was monitored by real time FTIR to estimate the soot oxidation. All the experiment was carried out at temperatures between 100 and 190 degree C to simulate exhaust temperature under low load. Experimental results show that soot was oxidized by generating sliding discharge on the DPF. No thermal damage of the DPF was found. Energy efficiency, denoted by the amount of oxidized soot per electric energy dissipated in the sliding discharge, increased with increasing the temperature as well as oxygen concentration in the test gas. Small amount of Ag2O supported by the DPF significantly increase the energy efficiency of soot oxidation. On the contrary, excessive amount of Ag2O resulted in energy efficiency lower than that of DPF without Ag2O probably because the sliding discharge was not generated favorably due to high conductivity resulted from metal Ag. These results suggest that sliding discharge can induce soot oxidation and that Ag2O possibly catalyzes soot oxidation.
Holograms are recorded in near-stoichiometric LiNbO3 doped with 8 ppm of Mn by use of two-color holographic recording method, where an IR laser of 778 nm is used for writing and an UV laser of 350 nm is used for gating. Dependences of two-color sensitivity and M/# on gating and writing intensities are presented. Significant improvements of sensitivity, M/# and dark decay are obtained compared with reduced near-stoichiometric LiNbO3. To our knowledge, the measured two-color sensitivity of 0.21 cm/J with a gating intensity of 1.5 W/cm2 is the highest among the values reported so far, which is attributed to large light-induced absorption of small polarons. 50 plane-wave holograms are recorded by the conventional angle-multiplexing method.
Regarding to inner bump formation using solder paste for FC-BGA and FC-CSP, the voids and abnormal bump shape generation are undesirable problems to achieve high quality assembly. The solder pastes which contain small solder particle and flux are applied to wafer bumping and substrate bumping method. However, as the bump pitch becomes tighter, the influence of those problems gets more serious especially for yield issue. In this study, we tried to solve the following issues 1)voids generation using 99.3mass%Sn-0.7mass% Cu solder paste and other alloys, 2)the dint bumps generation on the top of bumps using 95mass%Pb-5mass%Sn paste and 3)the needle and plate like intermetallic compound generation on the top and side of bumps using 96.5mass%Sn-3mass%Ag-0.5mass%Cu paste and 95.5mass%Sn-4mass%Ag-0.5mass%Cu paste. In terms of 1), it was available to understand when and where voids were generated by in-situ soft x-ray observation, and we could construct our original consideration why voids were generated during bumping process. In terms of 2) and 3), it was found that some kind of impurities affected on the dint, needle and plate like IMC generation. Furthermore, we tried to understand from the influence of reflow profile. By understanding these defects, we believe we can bring benefits to operating solder paste for printing method.
We investigated the oxidation state of Fe in stoichiometric LiNbO 3 (SLN) in comparison with congruent LiNbO 3 (CLN) from the viewpoint of digital holographic data storage. The dual oxidation states (Fe 2+ and Fe 3+ ) were controlled by changing Fe-doping levels and thermal annealing conditions after growth. We found that the photorefractive (PR) sensitivity of SLN under extraordinary polarization is more than 50% higher than that of CLN, which is more than 10 times higher than that of CLN under the generally used ordinary polarization. This high performance in PR sensitivity can be explained by the increased Pockels constant and photoconductivity. We could demonstrate high performance digital recording with fast writing speed and low bit-error rate using stoichiometric LiNbO 3 under extraordinary polarization. We also observed that SLN showed a smaller erasure time constant than that of CLN because of increased photoconductivity. Consequently, the “M/# value” was almost the same as that of CLN. The M/# value is the metric for multiplexing and is proportional to the product of PR sensitivity and erasure time constant.
Deformation and stress distribution of ultra thin resist pattern are estimated by finite element method (FEM) from the measurement values of van der Waals (vdW) force and mechanical properties of resist material. In this simulation, strain and stress distribution in the simple model of the resist pattern are obtained. These results show that the thin resist pattern has high sensitivity to weak vdW force. And, the stress concentrates at an interface between the resist pattern and the substrate. The stress concentration point in the resist pattern would be destructed due to the weak force. In the experiment, the vdW attractive force is measured with an atomic force microscope (AFM) system. The maximum value of the attractive force is about 180nN. The error of the force measurement is prevented to be lower because the no torsion of the cantilever can be observed when the tip is approaching to the thin film resist surface. It is possible to discuss the realization of a soft micro chamber wall made of a soft material such as the cell.
Nano-scale deformation of resist film surface is analyzed by using atomic force microscope (AFM) in a humidity controlled chamber. It is clarified that the condensation size of polymer aggregates of resist material are slightly changed due to humidity change. As one major factor, Laplace force acting among polymer aggregate due to surface adsorbed water is discussed. The deformation model of condensed polymer aggregates is proposed.
We show that stoichiometric LiNbO3 crystal containing nonstoichiometric defects much less than congruent LiNbO3 exhibit some advantageous properties for the holographic data storage (HDS) applications. This was confirmed by the two-beam coupling experiment and digital hologram test. In order to interpret the high performance of stoichiometric LN, we compared some related parameters such as linear electro-optic constants, photoconductivity and photovoltaic constants between stoichiometric and congruent LN crystals. In all measurements, the stoichiometric crystals grown by the novel double crucible CZ method were found to be more excellent as HDS medium. This superiority was obvious at the geometry using the extraordinary polarization.
Summary form only given. Recent development of digital holographic data storage shows its potential advantages such as high storage capacity, fast transfer rate, and short access time compared with currently available technologies. Iron doped congruent LiNbO/sub 3/ single crystals have been well studied as material for volume holographic memory applications because of their good mass productivity and excellent photorefractive properties. In this work, we have quantified the optical quality of various LiNbO/sub 3/ crystals via the diffraction efficiency, bit error rate (BER), and light scattering noise in a holographic digital storage system. Optical quality Fe-doped stoichiometric LiNbO/sub 3/:Fe crystals were grown from melt.
