Papers by Author: Yong Jin Kim

Abstract: In this paper, novel Ni Germanosilicide technology using the 1%-nitrogen doped Ni and pure Ni stack structure has been proposed for nano-scale CMOS technology. The Ni Germanosilicide is formed on the Si0.8Ge0.2 layer which is known as an optimal composition for strained silicon application. Proposed structure showed much better thermal stability than pure Ni case. Silicide characteristics such as the sheet resistance, the interface uniformity of silicide/SiGe, surface roughness, and depth profile of the Ni, Si, and Ge showed little degradation even with the high temperature post-silicidation annealing at 600
for 30 min. Therefore, the proposed method is highly promising for nano-scale CMOS technology.

Abstract: In this paper, the electrical properties of NiSi have been characterized using multi capping layer structure for nano CMOS application. We have investigated the formation and thermal stability of Ni silicide using Ni, Ti and TiN capping layers (Ti/Ni/TiN) as a function of Rapid Thermal Processing (RTP) temperature. It was shown that the NiSi with multi capping layer has lower sheet resistances than that with single capping (TiN) layer. NiSi with multi capping layer also showed much better thermal stability. It was verified that the formation Ni-Ti-Si ternary like layer at the top region of thhe NiSi results in improvement of thermal stability.

Abstract: We have synthesized multi-wall carbon nanotube (MWCNT)-reinforced Al matrix composites. The Al/MWCNT composite powders were prepared by ball milling using pristine Al or ball-milled Al powders as starting materials. The composite powders were consolidated by a conventional cold-compaction, followed by sintering. Uniform dispersion of individual MWCNTs within the matrix was in particular a critical factor for obtaining high density and high quality Al/MWCNT composites. Compared to pristine Al powders as starting materials, the Al powders previously attrition-ball-milled with carbon-based PCA (process control agent) in an ammonia atmosphere resulted in a better distribution of carbon nanotubes within the Al matrix and a higher density after sintering.

Abstract: This study examines the ball-milling of CVD-processed multi-wall carbon nanotubes for cutting and opening their tips. Results show that dry milling causes nanotubes to rapidly collapse, hence transforming into graphite structure, while wet milling with some organic compounds effectively shortened and opened the nanotubes. Carbon-based milling agents are known to alter surface structure of carbon nanotubes, minimizing an excess algglomeration and consequently improving dispersion of nanotubes. The open tip structure was unstable and quite susceptible to re-close during milling and thermal treatments to minimize their surface energy.

Abstract: Ni59Zr20Ti16Si2Sn3 bulk metallic glass (BMG) powders were produced by a gas atomization process, and ductile Cu powders were coated on the Ni-based BMG powders using a spray drying process in order to increase the ductility. Characteristics of the as-prepared powders with the atomization and spray drying process conditions were investigated. The atomization was conducted at 1450oC under the vacuum of 10-2 torr and the powders were mixed with water-soluble Cu nitrate. The mixture was sprayed at the temperature of 130oC to prepared initial powder. After reduction treatment, sub-micron size Cu powders were successfully coated on the surface of the atomized Ni BMG powders.

Abstract: We investigated the effect of SiO
cap layer on the thermal stability of nickel and nickel-cobalt silicide by measuring its sheet resistance. The stability of nickel silicide was deteriorated as a function of annealing temperature, while that of nickel-cobalt silicide was not. In case of both silicides, the SiO
cap layer improved the stability. Tensile stress from the difference of thermal expansion coefficients between SiO2 and nickel silicide may suppress the agglomeration of nickel silicide.

Abstract: The hypereutectic prealloyed Al-Si powders were prepared by gas atomization process. The microstructure and compacting ability of the atomized Al-Si powders were investigated. With increasing the gas pressure of the atomization, the average powder size and oxygen content were decreased. The size of primary eutectic Si particles in the as-atomized powders was about 8~10. As-atomized powders were hot-pressed into a cylindrical shape. Relative density of the hot-pressed samples was achieved about 96~99 % of theoretical density. Some properties of the samples were evaluated in this paper.

Abstract: Ag and SnO2 nanopowders were synthesized by reverse-micelle method. The reverse micelles were prepared to form tiny aqueous droplets dispersed in oil-based solvents. Two reverse micelles containing metallic salts and reductive agents were rigorously mixed to form nanoparticles inside aqueous droplets by a reductive reaction. The spherical powders of 20~50 nm were formed during the process. The resulting Ag and SnO2 nanopowders were examined as the anode electrode for lithium-ion cells. The reversible discharge capacity of the Ag and SnO2 nanopowders after 25 cycles were 315 and 380 mAh/g, respectively.