• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.67-72
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• 1989

Room Temperature Plasma Nitridation of silicon was investigated as a new LOCOS (local oxidation of silicon) process in order to reduce the bird's beak length. In $N_2$ plasma formed by 100kHz, 400W AC power, a thin silicon nitride film (<100${\AA}$) was uniformly grown on a silicon substrate. SEM studies showed that the nitride layer formed by this method can effectively protect the silicon from oxidation and reduce the bird's beak length to $0.2{mu}m$ when 4000${\AA}$ field oxide is grown. This is a considerable improvement comparing with 0.7${mu}m,$ the bird's beak, for the conventional LOCOS process using a thick LPCVD nitride. No appreciable crystalline defect could be found around the bird's beak with SEM cross-section afrer Secco etch. Leakage current tests were carried out on the $N^+/P^-$ well and $P^+/N^-$ well diodes formed by this new LOCOS process. The electrical tests indicate that this new process has electrical properties similar or superior to those of the conventional LOCOS process.

• Korean Journal of Materials Research
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• v.22 no.10
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• pp.539-544
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• 2012

We have grown AlN nanorods and AlN films using plasma-assisted molecular beam epitaxy by changing the Al source flux. Plasma-assisted molecular beam epitaxy of AlN was performed on c-plane $Al_2O_3$ substrates with different levels of aluminum (Al) flux but with the same nitrogen flux. Growth behavior of AlN was strongly affected by Al flux, as determined by in-situ reflection high energy electron diffraction. Prior to the growth, nitridation of the $Al_2O_3$ substrate was performed and a two-dimensionally grown AlN layer was formed by the nitridation process, in which the epitaxial relationship was determined to be [11-20]AlN//[10-10]$Al_2O_3$, and [10-10]AlN//[11-20]$Al_2O_3$. In the growth of AlN films after nitridation, vertically aligned nanorod-structured AlN was grown with a growth rate of $1.6{\mu}m/h$, in which the growth direction was <0001>, for low Al flux. However, with high Al flux, Al droplets with diameters of about $8{\mu}m$ were found, which implies an Al-rich growth environment. With moderate Al flux conditions, epitaxial AlN films were grown. Growth was maintained in two-dimensional or three-dimensional growth mode depending on the Al flux during the growth; however, final growth occurred in three-dimensional growth mode. A lowest root mean square roughness of 0.6 nm (for $2{\mu}m{\times}2{\mu}m$ area) was obtained, which indicates a very flat surface.

• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.45-50
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• 2015

In the present work, to increase the chemical stability of the lithium-ion-conducting ceramic electrolyte ($Li_{1+x+y}Al_xTi_{2-x}Si_yP_{3-y}O_{12}$, LATP) in the strong alkaline solution, the surface of LATP was modified by the nitridation process. The surface and structural properties of nitride LATP solid electrolyte were characterized by X-ray diffraction, X-ray photoelectron spectrometer and scanning electron microscopy and ac-impedance spectroscopy, which were correlated to the chemical stability and electrochemical performance of LATP. The nitrided LATP immersed in the alkaline solution for 30 days exhibits the enhanced chemical stability than the pristine LATP. Moreover, a rechargeable hybrid Li-air battery constructed with the nitrided LATP solid electrolyte shows considerably reduced discharge-charge voltage gaps (enhanced the round-trip efficiency) in comparison to the cell constructed with pristine LATP, which indicate that the surface nitridation process can be the efficient way to improve the chemical stability of solid electrolyte in alkaline media.

• Korean Journal of Materials Research
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• v.15 no.5
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• pp.348-352
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• 2005

Gallium oxyhydroxide (GaOOH) powders were heat-treated in a flowing ammonia gas to form GaN, and the reaction kinetics of the oxide to nitride was quantitatively determined by X-ray diffraction analysis. GaOOH turned into intermediate mixed phases of $\alpha-\;and\;\beta-Ga_2O_3$, and then single phase of GaN. The reaction time for full conversion $(t_c)$ decreased as the temperature increased. There were two-types of rapid reaction processes with the reaction temperature in the initial stage of nitridation at below $t_c$, and a relatively slow processes followed over $t_c$ does not depends on temperatures. The nitridation process was found to be limited by the rate of an interfacial reaction with the reaction order n value of 1 at $800^{\circ}C$ and by the diffusion-limited reaction with the n of 2 at above $1000^{\circ}C$, respectively, at below $t_c$. The activation energy for the reaction was calculated to be 1.84 eV in the temperature of below $830^{\circ}C$, and decreased to 0.38 eV above $830^{\circ}C$. From the comparative analysis of data, it strongly suggest the rate-controlling step changed from chemical reaction to mass transport above $830^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.267-275
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• 1988

Fine powders of amorphous $Al_2O_3,\;SiO_2,\;Al_2O_3-SiO_2$ system were prepared by hydrolysis of solutions containing alkoxides, aluminium tri-isopropoxide and silicon tetra-ethoxide. High purity ultrafine ${\beta}-sialon$ powders were prepared by the carbothermal reduction-nitridation of amorphous $Al_2O_3-SiO_2$ powders mixed with carbon black as a reducing agent. In the hydrolysis step the effect of the factors such as pH, reaction temperature and amount of water on the conversion rate of alkoxides to oxides was investigated. In the carbothermal reduction-nitridation the reaction path was assumed by the analysis of intermediates formed in the process of ${\beta}-sialon$ synthesis and the reaction kinetics of ${\beta}-sialon$ formation was considered.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.11
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• pp.1227-1232
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• 2014

This paper relates 10% shrink from $0.13{\mu}m$ design for core devices as well as input and output (I/O) devices different from previous poly length shrink size only. We analyzed body effect with different channel length and doping profile simulation. After fixing the gate oxide module process, LDD implant conditions were optimized such as decoupled plasma nitridation of gate oxide, TEOS oxide $100{\AA}$ before LDD implant and 22o tilt-angle(45o twist-angle) LDD implant respectively to match the spice DC parameters of pre-shrink and finally matched them within 5%.

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

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$\mu\textrm{m}$ 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 ton 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 Ceramic Society
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• v.36 no.2
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• pp.193-202
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• 1999

Al powder, AlN powder, SiC whisker and sintering aids were wet-mixed, and then the specimens prepared with mixed powder were reacted by nitridation at 600∼1400$^{\circ}C$ for 5 hrs. It was cleat that the higher nitridation and the more SiC whisker content were, the better bending strength was. The specimen of Al50/AlN50 reacted at 1400$^{\circ}C$ for 5hrs had the nitridation percent of 97%, the shrinkage under 2%, and the relative density of 78%. And the maximum bending strength of reaction-bonded specimen was 250 MPa. The specimens completely nitrided were post-sintered at 1700, 1800 and 1900$^{\circ}C$ for 2hrs. The post-sintered body had the shrinkage under 6% and the relative density of 86%. Because of the formation of solid solution between AlN and SiC whisker over 1800$^{\circ}C$, the promotion of mechanical properties according to SiC whisker addition was not observed. The post-sintered body had the maximum bending strength of 195 MPa.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1614-1618
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• 2007

We have demonstrated the experimental results to obtain the immunity of FN (Fowler Nordheim) stress for S-RCAT (Spherical-Recess Cell Array Transistor) which has been employed to meet the requirements of data retention time and propagation delay time for sub-100-nm mobile DRAM (Dynamic Random Access Memory). Despite of the same S-RCAT structure, the immunity of FN stress of S-RCAT depends on the process condition of gate oxidation. The S-RCAT using DPN (decoupled plasma nitridation) process showed the different degradation of device properties after FN stress. This paper gives the mechanism of FN-stress degradation of S-RCAT and introduces the improved process to suppress the FN-stress degradation of mobile DRAM.

• Journal of the Korean Ceramic Society
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• v.28 no.5
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• pp.390-398
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• 1991

$\beta$-Sialon powder was prepared from Wando pyrophyllite by the carbothermic reduction and nitridation at 135$0^{\circ}C$ for 10 h nitrogen atmosphere. Amorphous silica prepared from Si(OC2H5)4 was added to Wando pyrophyllite powder in order to control the final Z value. Two different methods were applied for synthesis of $\beta$-sialon powders. In Process A, the amorphous silica prepared from Si(OC2H5)4 was admixed to Wando pyrophyllite powder. Process B was started from the mixture of Wando Y2O3 was added to the synthesized $\beta$-Sialon powders as a sintering aid, and the mixed powders were hot pressed at 175$0^{\circ}C$ for 120 min in nitrogen atmosphere under 30 MPa. Their mechanical properties were compared. The maximum values of M.O.R., hardness and KIC were 667 MPa, 16 GPa and 6.3 MN/m3/2, respectively, and they are the values obtained form $\beta$-Sialon ceramics prepared by process A of Z=0.5.