12Cr ODS steel samples were prepared by mechanical alloying of the metal powders with 20-30 nm Y2O3 particles followed by isostatic pressing, hot rolling and final heat treatment. Evolutions of oxide particles such as YTaO4 and YCrO3 after each fabrication step were investigated by using TEM with EDS. Crystallographic correlation between oxide particles and the matrix was investigated in a HIPped sample, and interactions between dislocations and oxide particles were observed in hot rolled or heat treated sample. Size distributions of oxide particles were measured by carbon replica samples and it was found that coarsening of oxide particles from 9 to 12 nm occurred during hot rolling process. Additional isothermal annealing at 1250 ˚C revealed that phase transformation of oxide particles from monoclinic YTaO4 to face centered cubic Y3TaO7 was observed.

During a survey of the prevalent subtypes of extended-spectrum β-lactamases in a university hospital in Korea, a nosocomial outbreak of Escherichia coli producing CTX-M-15 and OXA-30 β-lactamases was detected. The outbreak comprised various infections, including bloodstream infections and colonization, and persisted for several months in various areas of the hospital.

System in package (SiP) is a superb candidate to enhance the area efficiency and performance of electronic packaging. Here, recent work on stacked chip type 3D SiP with vertically interconnected through hole vias are reported. The process includes; formation of 50um-diameter via holes, conformal deposition of SiO2 dielectric layer, deposition of Ta and Cu barrier layers, via filling by Cu electroplating, Cu/Sn bump formation for multi-chip stacking, and finally chip-to-PCB bonding using Sn-3.0Ag-0.5Cu solder and ENIG pad. A prototype 3D SiP stacked up to 10 layers was successfully fabricated.

A high frequency electrical model of the through hole via was proposed and the model parameters were extracted from measured S-parameters. The proposed model was verified by TDR/TDT (time domain reflectometry/time domain transmission) and eye-diagram measurement. Contact resistances of Cu via and bump joint were presented.

Dielectric properties and leakage current characteristics of the Al2O3 thin films, deposited by reactive sputtering at room temperature, have been investigated with variations of the O2 content in the sputtering gas and the film thickness. The Al2O3 films of 10-300 nm thickness were amorphous without depending on the O2 contents of 25-75% in the sputtering gas. Maximum dielectric constant was obtained for the Al2O3 film deposited with the sputtering gas of 50% O2 content. With reduction of the film thickness from 300 nm to 10 nm, dielectric constant decreased from 9.04 to 3.71 and tangent loss increased from 0.0035 to 0.0594, respectively. When the O2 content in the sputtering gas was higher than 50%, the Al2O3 films exhibited no shift of the flatband voltage in C-V curves. The leakage current density increased with increasing the film thickness, and the Al2O3 films thinner than 100 nm exhibited the leakage current densities lower than 10−6 A/cm up to 650 kV/cm.

Pt/Sr0.85Bi2.4Ta2O9/Al2O3/Si structures were prepared for MFIS-FET applications. After depositing Al2O3 film of 10-50 nm thickness by reactive sputtering on Si(100) substrate as a buffer layer, Sr0.85Bi2.4Ta2O9 (SBT) thin film of 400 nm thickness was prepared onto it by metalorganic decomposition process. With annealing at 800°C for 1 hour in oxygen ambient, the 400 nm-thick SBT film exhibited 2Pr of 10.2 μC/cm2 and Ec of 37.5 kV/cm at ±5V. C-V characteristics of the Pt/SBT/Al2O3/Si structures exhibited hysteresis loops due to the ferroelectric switching behavior of the SBT film. When the Al2O3 buffer layer was thicker than 10 nm, the memory window and maximum capacitance of the Pt/SBT/Al2O3/Si structure increased with decreasing the thickness of the Al2O3buffer layer, and the Pt/SBT(400 nm)/Al2O3(10 nm)/Si structure exhibited a memory window of 2.2 V at ±5 V.

Pt/Sr0.85Bi2.4Ta2O9/TiO2/Si structures were prepared with variation of the Sr0.85Bi2.4Ta2O9 (SBT) film thickness for MFIS-FET applications. After depositing TiO2 film of 10 nm thickness by reactive sputtering on Si(100) substrate as a buffer layer, SBT thin film of 210-400 nm thickness was prepared onto it by metal organic decomposition process. Regardless of the SBT film thickness, the Pt/SBT/TiO2/Si structures exhibited clockwise directional hysteresis, indicating well-defined ferroelectric switching behavior of the SBT films. While the memory window of the Pt/SBT/TiO2/Si MFIS structures increased with increasing the SBT film thickness, the maximum capacitance of the Pt/SBT/TiO2/Si MFIS structures decreased with increasing the SBT film thickness. The Pt/SBT(400 nm)/TiO2(10 nm)/Si structure exhibited a memory window of 1.3 V at ±5 V.

The mechanical properties of the 1-9 vol % Cu and Cu6Sn5-dispersed 63Sn-37Pb solder alloys were characterized with tensile test. Also, the Cu and Cu6Sn5-dispersed 63Sn-37Pb solder bumps of 760 μm size were fabricated on the Au(5 μm)/Ni(5 μm)/Cu(27 μm) BGA substrates by screen printing process, and their shear strength were characterized with variations of the dwell time at the reflow peak temperature(220°C) and aging time at 150°C. The yield strength and ultimate tensile strength of the 63Sn-37Pb solder alloy increased with dispersion of 1-9 vol % Cu and Cu6Sn5. In general, however, the Cu and Cu6Sn5-dispersed solder bumps exhibited lower shear strengths than those of the 63Sn-37Pb solder bumps The failure surface of the solder bumps after ball shear test could be divided into two regions of slow crack propagation and critical crack propagation, and the shear strength of solder bumps was inversely proportional to the slow crack propagation length.

Pt/SBT/TiO2/Si structure was proposed for metal/ferroelectric/insulator/semiconductor field effect transistor (MFIS-FET) applications. SrBi2.4 Ta2O9 (SBT) thin films of 400 nm thickness were prepared using liquid source misted chemical deposition (LSMCD) on Si(100) substrates with TiO2 buffer layers deposited by DC reactive sputtering with the thickness ranging from 5 nm to 200 nm and electrical properties of MFIS structures were investigated. Memory window and maximum capacitance of the Pt/SBT/TiO2 /Si structure increased with decreasing the thickness of TiO2 buffer layer. The Pt/SBT(400 nm)/TiO2(10 nm)/Si structure exhibited C-V hysteresis loop with the memory window of 1.6 V at ±5 V, and could be applicable for MFISFET applications.

Adhesion strength of polyimide/Cr interfaces was measured using T-peel test on polyimide/Cr/Cu structures fabricated on BPDA-PDA polyimide, and correlation between adhesion strength and peeling angle has been investigated. Adhesion strength of BPDA-PDA/Cr interface decreased with increasing the thickness of Cr/Cu metal films to a critical value, and then increased with further increasing metal film thickness. When the thickness of Cr/Cu metal films was below a critical value, plastic bending of metal films mainly occurred during T-peel test. With metal films thicker than a critical thickness, however, plastic bending of polyimide film has been observed. A critical thickness of metal film, where transition from metal bending to polyimide bending occured, became thinner with decreasing the yield strength of metal film and increasing thickness of polyimide substrate. Without depending on the plastic bending of metal film or polyimide substrate, adhesion strength increased with increasing the peeling angle during T-peel test.

The effect of the post plasma treatment on the dielectric properties and reliability of fluorine doped silicon oxide (SiOF) films was studied. Also, the thermal stability of a Cu/WN interconnect system with SiOF intermetal dielectrics was examined by RTA. The surface roughness of SiOF films increased with the increasing plasma treatment power due to ion bombardment effect during the plasma treatment. As the plasma treatment power increased, the dielectric constant increased from 3.16 to 3.43, while the change in the relative dielectric constant of the plasma treated films by the boiling treatment was decreased in magnitude. Furthermore, the chemical properties of the plasma treated SiOF films near the top layer tend to resemble those of thermal oxides by the plasma treatment of sufficient power because of the reduction in the Si-F bonding in the films. In the case of Cu/WN/SiOF/Si multilayer structure, surface oxidation and densification due to the plasma treatment seemed to play an important role in protecting the interdiffusion between SiOF and metal interconnects.

Thermoelectric properties of polycrystalline (Bi1−xSbx)2Te3 (0.75 ≤ x ≤ 0.85), fabricated by mechanical alloying and hot pressing methods, have been investigated. Formation of (Bi0.25Sb0.75)2Te3 alloy powder was completed by mechanical alloying for 5 hours at ball- to-material ratio of 5: 1, and processing time for (Bi1−xSbx)2Te3 formation increased with Sb2Te3 content x. When (Bi0.25Sb0.75)2Te3 was hot pressed at temperatures ranging from 300°C to 550°C for 30 minutes, figure-of-merit increased with hot pressing temperature and maximum value of 2.8 × 10−3/K could be obtained by hot pressing at 550°C. When hot pressed at 550°C, (Bi0.2Sb0.8)2Te3 exhibited figure-of-merit of 2.92 × 10−3/K, which could be improved to 2.97 × 10−3/K with addition of 1 wt% Sb as acceptor dopant.

Thermoelectric properties of polycrystalline Bi2(Te1−xSex)3 (0.05 ≤ x ≤ 0.25), fabricated by mechanical alloying and hot pressing, have been investigated. Formation of n-type Bi2(Te0.9 Se0.1)3 alloy powders was completed by mechanical alloying for 3 hours at ball-to-material ratio of 5: 1, and processing time for Bi2(Te1−xSex)3 formation increased with Bi2Se3 content x. Figure-of-merit of Bi2(Te0.9Se0.1) was markedly increased by hot pressing at temperatures above 450°C, and maximum value of 1.9 × 10−3/K was obtained by hot pressing at 550°C. With addition of 0.015 wt% Bi as acceptor dopant, figure-of-merit of Bi2 (Te0.9Se0.1)3, hot pressed at 550°C, could be improved to 2.1 × 10−3/K. When Bi2(Te1−xSex)3 was hot pressed at 550°C, figure-of-merit increased from 1.14 × 103/K to 1.92 × 10−3/K with increasing Bi2Se3 content x from 0.05 to 0.15, and then decreased to 1.30 × 103/K for x = 0.25 composition.

Effects of mechanical properties of Cu/Cr metal films on the peel strength of Cr/PI interfaces have been studied. Cr and Cu thin films were successively sputter-deposited on in-situ RF plasma-treated polyimides, and 20 μm-thick Cu was electroplated. With increasing the yield strength of Cu/Cr films from 156 MPa to 325 MPa, peel strength of Cr/PMDA-ODA and Cr/BPDA-PDA were lowered from 75 g/mam to 57 g/mm and from 69 g/mm to 20 g/mm, respectively. With identical Cu/Cr metal films, lower peel strength was obtained on Cr/BPDA-PDA interfaces, compared to the values of Cr/PMDA-ODA. Peel strength was also decreased more pronouncedly on Cr/BPDA-PDA with increasing the yield strength of Cu/Cr metal films. With T/H (80°C/94% R.H.) exposure, however, peel strength was lowered much more pronouncedly on Cr/PMDA-ODA than on Cr/BPDA-PDA, especially for specimens with Cu/Cr metal films of lower yield strength.