• Korean Journal of Materials Research
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• v.31 no.11
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• pp.649-656
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• 2021

K_0.5Bi_0.5TiO₃ (KBT) thin films were prepared by sol-gel processing for future use in piezoelectric generators. It is believed that the annealing temperature of films plays an important role in the output performance of piezoelectric generators. KBT films prepared on Ni substrates were annealed at 500 ~ 700 ℃. Tetragonal KBT films were formed after annealing process. As the annealing temperature increased, the grain size of KBT films increased. KBT thin films show piezoelectric constant (d₃₃) from 23 to 41 pC/N. The increase of grain size in KBT films brought about output voltage and current in the KBT generators. Also, the increase in the displacement of specimens during bending test resulted in increases in output voltage and current. Although KBT generators showed lower output power than those of generators prepared using NBT films, as reported previously, the KBT films prepared by sol-gel method show applicability as piezoelectric thin films for lead-free nano-generators, along with NBT films.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.31-37
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• 2009

Cu-Cu thermo-compression bonding process was successfully developed as functions of the $N_2+H_2$ forming gas annealing conditions before and after bonding step in order to find the low temperature bonding conditions of 3-D integrated technology where the quantitative interfacial adhesion energy was measured by 4-point bending test. While the pre-annealing with $N_2+H_2$ gas below $200^{\circ}C$ is not effective to improve the interfacial adhesion energy at bonding temperature of $300^{\circ}C$, the interfacial adhesion energy increased over 3 times due to post-annealing over $250^{\circ}C$ after bonding at $300^{\circ}C$, which is ascribed to the effective removal of native surface oxide after post-annealing treatment.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.861-869
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• 2018

To determine the origin of the inhomogeneous microstructure and texture observed in drawn and annealed high purity copper wires, two kinds of drawing process conditions and their influence was investigated. The regular condition, based on a symmetric die, and a condition designed intentionally to produce an inhomogeneous shear deformation using an asymmetric die were employed. The difference in intensity of <111>-<100> distributed texture between the two wires confirmed that the wire drawn under the asymmetric die condition experienced a higher amount of shear deformation. The extensive shear strain in the wire drawn under the asymmetric die condition gave rise to inhomogeneous primary and secondary recrystallization behavior. After annealing at $200^{\circ}C$, grains with <100> texture, which were larger than the surrounding recrystallized grains, were extensively present on one half circle of the wire drawn under the asymmetric die condition, while larger grains with <100> were sparsely observed around the middle region of the wire drawn under the regular condition. Interestingly, the area where the larger grains with <100> texture existed was identical to the area where the high shear strain occurred during drawing in both wires. During annealing at $400^{\circ}C$, grains with <112> texture started to grow abnormally at the center of both wires as a result of secondary recrystallization. After annealing at $900^{\circ}C$ grains with <112> due to secondary recrystallization occupied the entire region of the wire drawn under the regular condition. On the other hand, in the wire drawn under the asymmetric die condition and then annealed at $900^{\circ}C$, the <100> oriented grains as a result of the normal grain growth of the larger <100> grains which were observed after annealing at $200^{\circ}C$, coexisted with the abnormally grown <112> grains. These results indicate that dynamic recrystallization induced by the shear strain during drawing plays an important role in the inhomogeneity of the microstructure and texture of wires after annealing.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.61-66
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• 2010

Cu-Cu thermo-compression bonding process was successfully developed as functions of the deposited Cu thickness and $Ar+H_2$ forming gas annealing conditions before and after bonding step in order to find the low temperature bonding conditions of 3-D integrated technology where the interfacial toughness was measured by 4-point bending test. Pre-annealing with $Ar+H_2$ gas at $300^{\circ}C$ is effective to achieve enough interfacial adhesion energy irrespective of Cu film thickness. Successful Cu-Cu bonding process achieved in this study results in delamination at $Ta/SiO_2$ interface rather than Cu/Cu interface.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.352-356
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• 2011

In this paper, we prepared new type of hydrophilic block copolymers that exhibit the long-ranged lateral ordering in thin film. It was previously demonstrated that poly(ethyleneoxide-b-styrene) and poly(ethyleneoxide-b-metharylate-b-styrene) block copolymer thin films have a high degree of lateral ordering after solvent annealing process. In these cases, the relative humidity plays an important role in long-ranged lateral ordering. However, the origin of the humidity effect on the orders of these hydrophilic block copolymers is not fully understood. To investigate the effect of the humidity further, we prepared other hydrophilic poly(N,N-dimethylacrylamide-b-styrene)(PDMA-b-PS) block copolymers via RAFT polymerization. As with PEO-containing block copolymers, PDMA-b-PS block copolymers exhibit the long-ranged lateral ordering after solvent annealing process.

• Polymer(Korea)
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• v.34 no.3
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• pp.220-225
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• 2010

The optical properties and dimensional stability of polyethersulfone(PES) retardation film have been studied as function of chain orientation and the temperature applied to PES retardation film. It was confirmed that the appropriate retardation values of $R_e$ and $R_{th}$ for the retardation film application were able to obtain by the chain orientation and these values could be controlled by the chain relaxation through the thermal annealing process. It was found that unstable $R_e$ and $R_{th}$ values were shown by the repeated cooling and heating applied to the retardation films but this could be stabilized by means of the annealing process after stretching of PES film. The dimensional shrinkage due to the chain orientation was found as temperature increase and the intrinsic thermal expansion of PES appeared after shrinking. The shrinkage of PES films affected by the chain orientation and thermal annealing dramatically but the effect on the coefficient of thermal expansion was found to be negligible.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.326-336
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• 1997

From the concept that the ion implantation-induced defect is one of the major factors in determining source/drain junction characteristics, high quality ultra-shallow $p^+$-n junctions were formed through the control of ion implantation-induced defects in silicon substrate. In conventional process of the junction formation. $p^+$ source/drain junctions have been formed by $^{49}BF_2^+$ ion implantation followed by the deposition of TEOS(Tetra-Ethyl-Ortho-Silicate) and BPSG(Boro-Phospho-Silicate-Glass) films and subsequent furnace annealing for BPSG reflow. Instead of the conventional process, we proposed a series of new processes for shallow junction formation, which includes the additional low temperature RTA prior to furnace annealing, $^{49}BF_2^+/^{11}B^+$ mixed ion implantation, and the screen oxide removal after ion implantation and subsequent deposition of MTO (Medium Temperature CVD oxide) as an interlayer dielectric. These processes were suggested to enhance the removal of ion implantation-induced defects, resulting in forming high quality shallow junctions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1186-1191
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• 2010

Colored cubic zirconia specimen made by skull melt process were annealed in vacuum at the temperature of $1200^{\circ}C{\sim}1400^{\circ}C$ for 10~60 minutes to enhance the color. All the seven specimen become darker and eventually be black as annealing temperature and time increase. The black samples turned into original colors when we elevated the temperature with oxy-acetylene torch for around 10 minutes in the air. Finally, we could tune the colors of cubic zirconia either anneal in vacuum or the black samples in the air to obtain the proposed colors. Our proposed new process may be appropriate to fabricate the precious synthetic colored cubic zirconia to simulate the natural colored gem quality diamonds.

• Korean Journal of Materials Research
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• v.27 no.11
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• pp.597-602
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• 2017

In this study, an Al-0.7wt%Fe-0.2wt%Mg-0.2wt%Cu-0.02wt%B alloy was designed to fabricate an aluminum alloy for electrical wire having both high strength and high conductivity. The designed Al alloy was processed by casting, extrusion and drawing processes. Especially, the drawing process was done by severe deformation of a rod with an initial diameter of 12 mm into a wire of 2 mm diameter; process was equivalent to an effective strain of 3.58, and the total reduction in area was 97 %. The drawn Al alloy wire was then annealed at various temperatures of 200 to $400^{\circ}C$ for 30 minutes. The mechanical properties, microstructural changes and electrical properties of the annealed specimens were investigated. As the annealing temperature increased, the tensile strength decreased and the elongation increased. Recovery or/and recrystallization occurred as annealing temperature increased, and complete recrystallization occurred at annealing temperatures over $300^{\circ}C$. Electric conductivity increased with increasing temperature up to $250^{\circ}C$, but no significant change was observed above $300^{\circ}C$. It is concluded that, from the viewpoint of the mechanical and electrical properties, the specimen annealed at $350^{\circ}C$ is the most suitable for the wire drawn Al alloy electrical wire.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.696-698
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• 2011

We present a new method for the fabrication of film bulk acoustic wave resonator (FBAR) devices that exploits the thin piezoelectric ZnO films particularly sputter-deposited in a mixture of N2O and Ar gases as the reactive and sputtering gases, respectively. Some thermal annealing treatments were performed on the as-deposited ZnO films and also their effects on the resonance characteristics of the FBAR devices were investigated. It was found that with an optimized process, the resonance characteristics of the fabricated FBAR devices could be further improved.