• Journal of the Korean Ceramic Society
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• v.26 no.3
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• pp.390-394
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• 1989

The stored elastic strain energy due to the thermal expansion mismatch between the thermally oxidized crystalline layer (cristobalite) and CVD Si3N4($\alpha$-Si3N4) on cooling form high oxidation temperature (1000-140$0^{\circ}C$) to room temperature, releases through the crazing of film and lifting at the SiO2/Si3N4 interface. The ratial equation (1/n) which corresponds to the ratio of the relaxation of the stored elastic stain energy due to crazing of film to the total energy, is derived under the assumption of the square crazed pattern, as follow. 1/n={8${\gamma}$(1-v)2}/(ΔL2dE) The ratial equation suggests the reason for the lifting at the SiO2/Si3N4 interface which was observed in this research.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.260-265
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• 1999

$SiC/Si_3N_4$ composites were prepared by mixing ${\alpha}-Si_3N_4$ powder to $\alpha$-SiC powder in the range of 10 to 30 vol% with 10 vol% interval. 6 wt% of $Al_2O_3$ and $Y_2O_3$ were also added respectively as sintering aids. Then, pressureless sintering was performed at 1,78$0^{\circ}C$ for 2 hours in $N_2$ gas. In the case of adding 20 vol% of ${\alpha}-Si_3N_4$ powder, the relative desity to theoretical value and the flexutal strength were 92 % and 3,560 MPa, respectively. The smallest relative worn amount thereof was $2.68{\times}10^{-3}\;mm^2$ for 20 vol% ${\alpha}-Si_3N_4$. The composite containing 30 vol % of ${\alpha}-Si_3N_4$ powder showed the highest fracture toughness $(K_{1c})$ of $4.9\;MN/m^{3/2}$, although the reduction of the wear resistance due to the effect of the pores was observed.

• Tribology and Lubricants
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• v.4 no.2
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• pp.44-51
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• 1988

Titanium carbide(TiC), Titanium nitride(TiN), and Titanium carbonnitride(Ti(C,N)) films were deposited on $Si_3N_4$-TiC composite cutting tools by chemical vapor deposition(CVD) using $TiCl_4-CH_4-H_2$, $TiCl_4-N_2-H_2$, and $TiCl_4-CH_4-N_2-H_2$ gas mixtures, respectively. The experimental results indicate that TiC coatings compared with TiN coatings on $Si_3N_4$ -TiC ceramic have an improved microstructural property, good thermal shock resistance, and good interfacial bonding. However TiN coatings compared with TiC coatings have a low friction coefficient with steel and good chemical stability. It is found by cutting test that coated insert compared with $Si_3N_4$-TiC ceramic have a superior flank and crater wear resistance. And multilayer coating compared with monolayer coating shows a improved wear resistance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.128-129
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• 2008

The annealing effects of $SiO_2/Si_3N_4$ stacked tunneling dielectrics were investigated. I-V characteristics of band gap engineered tunneling gate stacks consisted of $Si_3N_4/SiO_2/Si_3N_4$(NON), $SiO_2/Si_3N_4/SiO_2$(ONO) dielectrics were evaluated and compared with $SiO_2$ single layer using the MOS(Metal-Oxide-Semiconductor) capacitor structure. The leakage currents of engineered tunneling barriers (ONO, NON stacks) are lower than that of the conventional $SiO_2$ single layer at low electrical field. Meanwhile, the engineered tunneling barriers have larger tunneling current at high electrical field and improved electrical characteristics by annealing processes than $SiO_2$ layer.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.41.1-41
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• 2000

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.189-190
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• 2008

The electrical characteristics of band-gap engineered tunneling barriers consisting of thin $SiO_2$ and $Si_3N_4$ dielectric layers were investigated. The band structure of stacked tunneling barriers was studied and the effectiveness of these tunneling barriers was compared with that of the conventional tunneling barrier. The band-gap engineered tunneling barriers show the lower operation voltage, faster speed and longer retention time than the conventional $SiO_2$ tunnel barrier. The thickness of each $SiO_2$ and $Si_3N_4$ layer was optimized to improve the performance of non-volatile memory.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.1
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• pp.17-21
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• 2009

The electrical characteristics of band-gap engineered tunneling barriers consisting of thin $SiO_2$ and $Si_3N_4$ dielectric layers were investigated for nonvolatile memory device applications. The band structure of band-gap engineered tunneling barriers was studied and the effectiveness of these tunneling barriers was compared with the conventional tunneling $SiO_2$ barrier. The band-gap engineered tunneling barriers composed of thin $SiO_2$ and $Si_3N_4$ layers showed a lower operation voltage, faster speed and longer retention time than the conventional $SiO_2$ tunnel barrier. The thickness of each $SiO_2$ and $Si_3N_4$ layer was optimized to improve the performance of non-volatile memory.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.410-418
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• 1992

Si3N4, AlN and Y2O3 powder mixtures of the Y0.1(Si, Al)12(N, O)16 composition were hot-pressed at 1900℃ for 0 to 60 min under 30 MPa in order to fabricate the partially-stabilized α-Sialon ceramics (X=0.1). Room and high temperature flexural strengths of the specimens were compared with those of Si3N4-5 wt%Y2O3, Si3N4-5 wt%Y2O3-2 wt%Al2O3, and β-Sialon (Z=0.5) ceramics. The flexural strength of the α-Sialon ceramics which was hot-pressed for 15 min showed the highest value of 820 MPa at 1400℃ that is relatively higher temperature. It is guessed that a little amount of glassy phase existed in grain boundary because Y2O3 and AlN components were incoperated in Si3N4 grains, or transient liquid phase sintering, and microstructure with the smaller grain size and the interlocked grains of α'-and β-Si3N4 was obtained by the hot-pressing at high temperature of 1900℃ for the short time (15 min).

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.890-897
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• 1998

The direct wafer bonding between n-InP(001) wafer and the ${Si}_3N_4$(200 nm) film grown on the InP wafer by PECVD method was investigated. The surface states of InP wafer and ${Si}_3N_4$/InP which strongly depend upon the direct wafer bonding strength between them when they are brought into contact, were characterized by the contact angle measurement technique and atomic force microscopy. When InP wafer was etched by $50{\%}$ HF, contact angle was $5^{\circ}$ and RMS roughness was $1.54{\AA}$. When ${Si}_3N_4$ was etched by ammonia solution, RMS roughness was $3.11{\AA}$. The considerable amount of initial bonding strength between InP wafer and ${Si}_3N_4$/InP was observed when the two wafer was contacted after the etching process by $50{\%}$ HF and ammonia solution respectively. The bonded specimen was heat treated in $H^2$ or $N^2$, ambient at the temperature of $580^{\circ}C$-$680^{\circ}C$ for lhr. The bonding state was confirmed by SAT(Scannig Acoustic Tomography). The bonding strength was measured by shear force measurement of ${Si}_3N_4$/InP to InP wafer increased up to the same level of PECVD interface. The direct wafer bonding interface and ${Si}_3N_4$/InP PECVD interface were chracterized by TEM and AES.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.380-384
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• 1988

This investigation includes nitridation phenomena of silicon powder compacts in air. Nitridation reaction condition has been provided with using silicon nitride bed and active carbon additive. Reaction products are Oxynitride, $\alpha$-Si3N4, and $\beta$-Si3N4, Oxynitride(Si2N2O) phase in formed at outer surface layer ofsilicon powder compacts. $\alpha$-Si3N4, and $\beta$-Si3N4 are formed at inner region of powder compacts. Microstructural observation indicates that nitridation mechanism in this work is the same as conventional nitridation mechanism nitrogen gas.