• Korean Journal of Materials Research
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• v.4 no.6
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• pp.662-668
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• 1994

The physical and electrical characteristics of sub-l0nm thick capacitor dielectrics formed by wet oxidation of silicon nitride(oxide/nitride composite) and by removing the top oxide of oxidized silicon nitride(0xynitride) are described. For the capacitors with an oxide/nitride composite layer, the capacitance decreases sharply, but the breakdown field increases with an increase in the wet oxidation time at $900^{\circ}C$. For the capacitors with oxynitride layers, the values of both the capacitance and the breakdown field increase with increasing wet oxidation time. The reduction of effective thickness and the improved quality of oxynitride film are responsible for the improved capacitance and increased breakdown fields, respectively. In addition, intrinsic TDDB characteristics and early breakdown failure rate of oxynitride film are improved with increasing oxidation time. Consequently, the oxynitride film is suitable for dynamic memories as a thin dielectric film.

• Korean Journal of Materials Research
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• v.28 no.2
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• pp.118-123
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• 2018

5 nm-thick $SiO_2$ layers formed by plasma-enhanced chemical vapor deposition (PECVD) are densified to improve the electrical and interface properties by using nitric acid oxidation of Si (NAOS) method at a low temperature of $121^{\circ}C$. The physical and electrical properties are clearly investigated according to NAOS times and post-metallization annealing (PMA) at $250^{\circ}C$ for 10 min in 5 vol% hydrogen atmosphere. The leakage current density is significantly decreased about three orders of magnitude from $3.110{\times}10^{-5}A/cm^2$ after NAOS 5 hours with PMA treatment, although the $SiO_2$ layers are not changed. These dramatically decreases of leakage current density are resulted from improvement of the interface properties. Concentration of suboxide species ($Si^{1+}$, $Si^{2+}$ and $Si^{3+}$) in $SiO_x$ transition layers as well as the interface state density ($D_{it}$) in $SiO_2/Si$ interface region are critically decreased about 1/3 and one order of magnitude, respectively. The decrease in leakage current density is attributed to improvement of interface properties though chemical method of NAOS with PMA treatment which can perform the oxidation and remove the OH species and dangling bond.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.298-302
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• 2004

Thick films of $LaNiO_{3}$ having perovskite structure impregnated with indium and bismuth oxides have been used as sensing material for acetonitrile ($CH_{3}CN$) gas. The sensor response for $CH_{3}CN$ is quite good with an excellent recovery for partial pressure from 3 ppm to 20 ppm between 200 and $250^{\circ}C$. $LaNiO_{3}$ alone has exhibited low response, but after impregnation of $In_{2}O_{3}$ and $Bi_{2}O_{3}$ have given increased sensitivity even with 3 ppm partial pressure of $CH_{3}CN$ at $200^{\circ}C$. It is assumed that $CH_{3}CN$ is undergoing oxidation reaction on surface of the film.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.8-15
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• 2012

Silicon-based thin film was prepared at room temperature by an electrochemical deposition method and a feasibility study was conducted for its use as an anode material in a rechargeable lithium battery. The growth of the electrodeposits was mainly concentrated on the surface defects of the Cu substrate while that growth was trivial on the defect-free surface region. Intentional formation of random defects on the substrate by chemical etching led to uniform formation of deposits throughout the surface. The morphology of the electrodeposits reflected first the roughened surface of the substrate, but it became flattened as the deposition time increased, due primarily to the concentration of reduction current on the convex region of the deposits. The electrodeposits proved to be amorphous and to contain chlorine and carbon, together with silicon, indicating that the electrolyte is captured in the deposits during the fabrication process. The silicon in the deposits readily reacted with lithium, but thick deposits resulted in significant reaction overvoltage. The charge efficiency of oxidation (lithiation) to reduction (delithiation) was higher in the relatively thick deposit. This abnormal behavior needs to clarified in view of the thickness dependence of the internal residual stress and the relaxation tendency of the reaction-induced stress due to the porous structure of the deposits and the deposit components other than silicon.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.295-302
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• 2008

$TiO_2,\;ZrO_2$, and $SiO_2$ were added in the concentration of 1 - 3 wt.% to improve long-term stability for the $SnO2$ thick film gas sensor. Short-term sensor resistances up to 90 h were measured to investigate the stabilization time of initial resistance in air. Long-term resistance drifts in air and in gas to 5000 ppm methane for the sensors annealed at $750^{\circ}C$ for 1 h and continuously heated at an operating temperature of $400^{\circ}C$ were also measured up to 90 days at an interval of 1 day. The long-term drifts in methane sensitivity for the three metal oxide-doped $SnO2$ sensors are closely related to methane sensitivity level, catalytic activity, and long-term drift in sensor resistance in air. Those stabilities are mainly discussed in terms of oxidation state and catalytic activity.

• The Korean Journal of Ceramics
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• v.2 no.2
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• pp.95-101
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• 1996

Variations of the leakage current behaviors and interface potential barrier $({\Phi}_B)$ of rf-sputter deposited (Ba, Sr)$TiO_3$ (BST) thin films with thicknesses ranging from 20 nm to 150nm are investigated as a function of the thickness and bias voltages. The top and bottom electrodes are dc-sputter-deposited Pt films. ${\Phi}_B$ critically depends on the BST film deposition temperature, postannealing atmosphere and time after the annealing. The postannealing under $N_2$ atmosphere results in a high interface potential barrier height and low leakage current. Maintaining the BST capacitor in air for a long time reduces the ${\Phi}_B$ from about 2.4 eV to 1.6 eV due to the oxidation. ${\Phi}_B$ is not so dependent on the film thickness in this experimental range. The leakage conduction mechanism is very dependent on the BST film thickness; the 20 nm thick film shows tunneling current, 30 and 40 nm thick films show Shottky emission current.

• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.67-78
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• 1996

Gas sensing element, $\gamma-Fe_2O_3$was synthesized by dehydration, reduction, and oxidation of $$${\gamma}$-FeOOH, which was synthesized with $FeSO_4\;{\cdot}\;7H_2O$ and NaOH. They were produced as a bulk-type, a thick film-type. Then, their responses and mechanisms of response to the gas of liquefied-petroleum were studied. The qualities of gas sensing elements are decided by the structure and the relative surface area. In the process of $\alpha-FeOOH $synthesis, the effects of reaction conditions as the equivalent ratio, on the structure and the relative surface area of gas sensing element were observed. The changes of the structure were measured with XRD, SEM, TG-DTA and BET. The resistance changes of the synthesized gas sensor in the air were measured. The response ratio were also measured for the changes of working temperature and gas concentration. As a result of analysis with XRD, it was confirmed that the the best conditions for the synthesis of $\alpha -FeOOH$ were equivalent ratio 0.65. The thick film-type element of $\gamma-Fe_2O_3$responded more quickly than the bulk-type did. The structure and the relative surface area of the $\alpha-FeOOH $were confirmed as the important factors deciding gas response charcteristics.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.425-427
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• 1996

New fabrication technique was developed to make three dimensional silicon microstructure with five fold vertical steps through entire wafer thickness. Each step is pre-defined on multiply stacked thermal oxide and silicon nitride (O/N) layers by photolithographies. Multi-stepped silicon microstructure is formed by anisotropic etch in aqueous KOH solution with the patterned nitride film as masking layer. Fabricated microstructure consists of four $16{\mu}m$ thick flexural spring beams, $290{\mu}m$ thick proof mass, mesas for overrange stop with $10{\mu}m$ height from the surface of the proof mass, and the other mesas and V grooves used for assembling this structure to the packaging frame of pendulous servo accelerometer. Using the numerical finite element method (FEM) simulator: ABAQUS, mechanical characteristics of the fabricated microstructure by the developed technique was compared with those of the same structure processed by one step silicon bulk etch followed by oxidation and patterning the etched region.

• Journal of the Korean institute of surface engineering
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• v.34 no.1
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• pp.33-38
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• 2001

10cm-diameter Si(100)∥$1.3\mu\textrm{m}$-X$1.3_2$X$1.3\mu\textrm{m}$-$SiO_2$∥Si(100) afers were prepared using a fast linear annealing (FLA) equipment. 1.3$\mu\textrm{m}$-thick $SiO_2$ films were grown by dry oxidation process. After cleaning and premating the wafers in a class 100 clean room, they were heat treated using with the FLA and conventional electric furnace. Bonded area and bond strength of wafer pairs were measured using a infrared (IR) camera and razor blade crack opening method, respectively. It was confinmed that the bonded area by FLA was around 99% and the bond strength value reached 2172mJ/$\m^2$, which is equivalent to theoritical bond strength. Our result implies that thick $SiO_2$ SOI may be prepared more easily by using $SiO_2$$SiO_2$ bonding interfaces then those of Si/$SiO_2$'s.

• Journal of the Korean institute of surface engineering
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• v.54 no.2
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• pp.62-70
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• 2021

Al2024 aluminum alloy specimens were exposed to atmospheric conditions for maximum 24 months and analyzed by electron microscopes to characterize their corrosion behavior and oxide film characteristics. As the exposure time increased from 12 months to 24 months, the number of pitting sites per 1 mm² increased from ~100 to ~200. The uniform oxidation (or non-pitting) region of the 12-month exposure specimen showed 30~120 nm thick oxide layer, whereas the 24-month exposure specimen showed 170~200 nm thick oxide with the local oxygen penetration region up to 1 ㎛ deep. There was no local corrosion area observed in the 12-month exposure specimen except pitting. However, in the 24-month exposure specimen, local oxygen penetration region was observed beneath the uniform oxide layer and near the pitting cavity. Al2024 showed two times thicker uniform oxide layer but much shallower local oxygen penetration region than Al1050, which appears to be related to low Si concentration. Further research is needed on the effects of Mg segregation near the tip of the oxygen penetration region.