• Proceedings of the Korean Magnestics Society Conference
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• 2016.11a
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• pp.38-38
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• 2016

• Korean Journal of Materials Research
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• v.14 no.3
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• pp.191-195
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• 2004

Tunnel junctions with AI-N barriers fabricated by microwave-excited plasma were studied. When the Al thickness, nitridation time, and annealing temperature were 1 nm (0.8 nm), 50 s (35 s), and $280^{\circ}C$ ($300^{\circ}C$), TMR ratio and resistance-area product (RA) were 49% (34%) and $3 ${\times}$ 10^4$ $\Omega$$\mu\m^2$ ($1.5 ${\times}$ 10^4$ $\Omega$$\mu\m^2$), respectively. In order to clarify the annealing temperature dependence of TMR ratio, the local transport properties were measured for Ta 5 nm/Cu 20 nm/Ta 5 nm$29_{76}$ $Fe_{24}$ 2 nm/Cu 5 nm/M $n_{75}$$Ir_{25}$ 10 nm/ $Co_{71}$ $Co_{29}$ 4nm/Al-N junction with Al thickness of 0.8 nm and nitridation time of 35s at various temperatures. The increase of TMR ratio after annealing at $300^{\circ}C$, where the TMR ratio of the corresponding MTJ had the maximum value of 34%, can be well explained by the enhancement of the average barrier height ($\Phi_{ave}$) and the reduction of its fluctuation. After further annealing at $340^{\circ}C$, the leakage current was observed and the TMR ratio decreaseded

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.363-368
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• 2012

Nitriding and post-sintering behavior of powder mixture compacts were investigated. As mixture compacts are different from simple Si compacts, the fabrication of a sintered body with a mixture composition has engineering implications. In this research, in specimens without a pore former, the extent of nitridation increased with $Si_3N_4$ content, while the highest extent of nitridation was measured in $Si_3N_4$-free composition when a pore former was added. Large pores made from the thermal decomposition of the pore former collapsed, and they were filled with a reaction product, reaction-bonded silicon nitride (RBSN) in the $Si_3N_4$-free specimen. On the other hand, pores from the decomposed pore former were retained in the $Si_3N_4$-added specimen. Introduction of small $Si_3N_4$ particles ($d_{50}=0.3{\mu}m$) into a powder compact consisting of large silicon particles ($d_{50}=7{\mu}m$) promoted close packing in the green body compact, and resulted in a stable strut structure after decomposition of the pore former. The local packing density of the strut structure depends on silicon to $Si_3N_4$ size ratio and affected both nitriding reaction kinetics and microstructure in the post-sintered body.

• Journal of the Korean Ceramic Society
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• v.29 no.7
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• pp.511-516
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• 1992

In this study, SiC powder and Si powder were used as the raw materials. Mixture was prepared with addition of Al2O3 and Fe2O3 at 0.1~0.5wt% respectively. After this step, the mixture was pressed and nitrided for 30 hrs at 140$0^{\circ}C$ under NH3-N2 atmosphere. Mechanical properties of sintered specimens were investigated from measurement of porosity, bulk density and three point bending test. nitration reaction extent was observed at the change of mass before and after reaction, and the microstructure and the change of $\alpha$-Si3N4 and $\beta$-Si3N4 were observed by XRD and SEM. In the current work, the results are as follows 1. When Fe2O3 added, the nitridation increased with the content of Fe2O3, and the bending strength was increased from 0.1 wt% to 0.3 wt%, and decreased to 0.5 wt%. 2. When Al2O3 added, the nitridation and the bending strength increased little by little with the content of Al2O3 3. The bending strength of the specimen added with Fe2O3 were higher than that with Al2O3. Because the specimens contained Fe2O3 had much more the whisker type crystal of Si3N4 contributing to strength than contained Al2O3.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.272-277
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• 2002

Aluminum nitride (AlN) powders and whiskers were synthesized by a modified carbothermal reduction and nitridation where a ($NH_4)[Al(ethylenediaminetetraacetate)]{\cdot}2H_2O$ complex is used as precursor. The AlN powders were obtained by calcining the complex without mixing any carbon source under a flow of nitrogen in the temperature range 1200∼1500$^{\circ}$C and then burning out the residual carbon. The nitridation process was investigated by $^{27}Al$ magic-angle spinning (MAS) unclear magnetic resonance, infrared spectroscopy and X-ray diffraction. The complex is pyrolyzed, converted to ${\rho}$- and ${\gamma}$- alumina and then nitridated to AlN without ${\gamma}-{\alpha}$ alumina transition. The morphology of ${\gamma}$-alumina, when it was converted to AlN, was retained, strongly indicating that ${\gamma}$-alumina is converted to AlN through solid-state $AlO_xN_y$, not through gaseous intermediates such as aluminum and aluminaum suboxides. AlN whiskers were obtained, when a (0001) sapphire was used as a catalyst.

• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1414-1420
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• 1996

Using Si powder with average particle size of 8${\mu}{\textrm}{m}$ Si compacts were formed by pressureless powder packing method. The compacts were reaction bonded at 1350, 140$0^{\circ}C$ for 3~35 hrs under N2/H2 atmosphere and its microstructures were examined. Reaction bonded silicon nitrides showed nitridation of 90% and relative density of 88% After the impregnation of 5wt% MgO as sintering additive using aqueous solution of Mg nitrate the Si compacts were reaction bonded at 140$0^{\circ}C$ for 15hrs. The reaction bonded bodies were gas pressure sintered at 180$0^{\circ}C$ 190$0^{\circ}C$ 200$0^{\circ}C$ for 150, 300min. They showed relative density of 95% bending strength of 600MPa and fracture toughness of 6 MPa.m1/2.

• Journal of the Korean Ceramic Society
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• v.50 no.3
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• pp.218-225
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• 2013

The densification behavior and strength of sintered reaction bonded silicon nitrides (SRBSN) that contain $Lu_2O_3-SiO_2$ additives were improved by the addition of fine Si powder. Dense specimens (relative density: 99.5%) were obtained by gas-pressure sintering (GPS) at $1850^{\circ}C$ through the addition of fine Si. In contrast, the densification of conventional specimens did not complete at $1950^{\circ}C$. The fine Si decreased the onset temperature of shrinkage and increased the shrinkage rate because the additive helped the compaction of green bodies and induced the formation of fine $Si_3N_4$ particles after nitridation and sintering at and above $1600^{\circ}C$. The amount of residual $SiO_2$ within the specimens was not strongly affected by adding fine Si powder because most of the $SiO_2$ layer that had formed on the fine Si particles decomposed during nitridation. The maximum strength and fracture toughness of the specimens were 991 MPa and $8.0MPa{\cdot}m^{1/2}$, respectively.

• Transactions on Electrical and Electronic Materials
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• v.9 no.1
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• pp.6-11
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• 2008

In this study, we investigated effects of hydrogen annealing (HA) and plasma nitridation (PN) applied in order to improve $Si/SiO_2$ interface characteristics of TiN metal gate. In result, HA and PN showed a positive effect decreasing number of interface state $(N_{it})$ respectively. After FN stress for verifying reliability, however, we identified rapid increase of $N_{it}$ for TiN gate with HA, which is attributed to hydrogen related to a change of $Si/SiO_2$ interface characteristic. In contrast to HA, PN showed an improved Nit and gate oxide leakage characteristic due to several possible effects, such as blocking of Chlorine (Cl) diffusion and prevention of thermal reaction between TiN and $SiO_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.17-20
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• 2001

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectrics were fabricated, and nitrogen distribution and bonding species which contribute to memory characteristics were analyzed. Also, memory characteristics of devices depending on the anneal temperatures were investigated. The devices were fabricated by retrograde twin well CMOS processes with $0.35{\mu}m$ Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectric were fabricated, and nitrogen distribution and bonding species which contributing memory characteristics were analyzed. Also, memory characteristics of devices according to anneal temperatures were investigated. The devices were fabricated by $0.35{\mu}m$ retrograde twin well CMOS processes. The processes could be simple by in-situ process of nitridation anneal and reoxidation. The nitrogen distribution and bonding state of gate dielectric were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary Ion Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). Nitrogen concentrations are proportional to nitridation anneal temperatures and the more time was required to form the same reoxidized layer thickness. ToF-SIMS results show that SiON species are detected at the initial oxide interface and $Si_{2}NO$ species near the new $Si-SiO_{2}$ interface that formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. These could be said that nitrogen concentration near initial interface is limited to a certain quantity, so excess nitrogen are redistributed near the $Si-SiO_{2}$ interface and contributed to electron trap generation.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.85-99
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• 1998

A ultrahigh vacuum chemical vapor deposition(UHVCVD)/metalorganic chemical vapor deposition(MOMBE) system equipped with a radio frequency(RF)-plasma cell was employed to grow GaN layer on the sapphire at a low temperature. The x-ray photoelectron spectroscopy analysis of nitrogen composition on the nitridated sapphite surface indicated that a nitridation process is mostly affected by the RF power at low temperature. Atomic force microscope images of nitridated surface the protrusion density on the nitridated sapphire is dependent on the nitridation temperature. The crystallinity of GaN grown at $450^{\circ}C$ was found to be much improved when the sapphire was nitridated at low temperature prior to the GaN layer growth. Moreover, a strong photoluminescence spectrum of GaN grown by UHVCVD/MOMBE with a rf-nitrogen plasma was observed for the first time at room temperature.