• Transactions on Electrical and Electronic Materials
• /
• v.9 no.4
• /
• pp.137-142
• /
• 2008

The parasitic resistance is studied to silicon/metal contact junction for improving device performance and to lower contact/serial resistance silicide in natural sequence. In this paper constructs the stepwise Ni silicide process for parasitic resistance reduction for silicon/metal contact junction. We have investigated multi-step Ni silicide on SiGe substrate with stepwise annealing method as an alternative to compose more thermally reliable Ni silicide layer. Stepwise annealing for silicide formation is exposed to heating environment with $5^{\circ}C/sec$ for 10 seconds and a dwelling for both 10 and 30 seconds, and ramping-up and the dwelling was repeated until the final annealing temperature of $700\;^{\circ}C$ is achieved. Finally a direct comparison for single step and stepwise annealing process is obtained for 20 nm nickel silicide through stepwise annealing is $5.64\;{\Omega}/square$ at $600\;^{\circ}C$, and it is 42 % lower than that of as nickel sputtered. The proposed stepwise annealing for Ni silicidation can provide the least amount of NiSi at the interface of nickel silicide and silicon, and it provides lower resistance, higher thermal-stability, and superior morphology than other thermal treatment.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.292-292
• /
• 2014

Wide band gap semiconductors, such as III-nitrides (GaN, AlN, InN, and their alloys), SiC, and diamond are expected to play an important role in the next-generation electronic devices. Specifically, GaN-based high electron mobility transistors (HEMTs) have been targeted for high power, high frequency, and high temperature operation electronic devices for mobile communication systems, radars, and power electronics because of their high critical breakdown fields, high saturation velocities, and high thermal conductivities. For the stable operation, high power, high frequency and high breakdown voltage and high current density, the fabrication methods have to be optimized with considerable attention. In this study, low ohmic contact resistance and smooth surface morphology to AlGaN/GaN on 2 inch c-plane sapphire substrate has been obtained with stepwise annealing at three different temperatures. The metallization was performed under deposition of a composite metal layer of Ti/Al/Ni/Au with thickness. After multi-layer metal stacking, rapid thermal annealing (RTA) process was applied with stepwise annealing temperature program profile. As results, we obtained a minimum specific contact resistance of $1.6{\times}10^{-7}{\Omega}cm2$.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.8
• /
• pp.1341-1345
• /
• 2007

The surface chemistry of D2O dosed Zircaloy-4 (Zry-4) surface followed by Ar-ion bombardment and annealing was studied by means of X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS). In the XPS study, Ar-ion bombardment caused decrease of the oxygen on the surface region of Zry-4 and therefore led to change the oxidation states of the zirconium from oxide to metallic form. In addition, oxidation states of zirconium were changed to lower oxidation states of zirconium due to depopulation of oxygen on the surface region by annealing. Up to about 787 K, the bulk oxygen diffused out to the subsurface region and after this temperature, the oxygen on the surface of Zry-4 was depopulated. UPS study showed that the valence band spectrum of the D2O exposed Zry-4 exhibited a dominant peak at around 13 eV and no clear Fermi edge was detected. After stepwise Ar+ sputtering processes, the decrease of the oxygen on the surface of Zry-4 led to suppress the dominant peak around 13 eV, the peak around 9 eV and develop a new peak of the metallic Zr 4d state (20.5-21.0 eV) at the Fermi level.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.6
• /
• pp.1349-1352
• /
• 2009

We report the results of the surface chemistry of deuterized ethanol exposed Zircaloy-4 (Zry-4) surfaces with various amount of $C_2D_5$OD exposures at 190 K. This system was examined with Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) techniques. In TPD study, $D_2$ was evolved at two different desorption temperature regions accompanying with broad desorption background. The lower temperature feature at around 520 K showed first-order desorption kinetics. The high temperature desorption peak at around 650 K shifted to lower desorption temperature as the exposure of $C_2D_5$OD increased. The Zr(MNV) Auger peak shifted about 2.5 eV from 147 eV to lower electron energy followed by 300 L of $C_2D_5$OD dosing. This implies metallic zirconium was oxidized by deuterized ethanol adsorption. After stepwise annealing of the oxidized Zry-4 sample up to 843 K, the shifted Zr(MNV) peak was gradually shifted back to metallic zirconium peak position. After the sample was heated to 843 K, the oxygen content near the Zry-4 surface was recovered to clean surface level. The concentration of carbon, however, was not recovered by annealing the sample.

• Polymer(Korea)
• /
• v.25 no.1
• /
• pp.56-62
• /
• 2001

When polyethylene terephthalate(PET) film specimen were stepwise elongated under tension with various speeds of about 0.5~500 mm/min, the necking area, consisted of transparent and opaque bands, was formed during plastic deformation. Stress oscillation was apparently obtained in the stress-strain curve of above specimen. However, stress oscillation was not obtained in the stress-strain curve of annealing specimen. Microstructure was examined dynamically using an optical microscopy and thermal analysis was carried out in a differential scanning calorimeter at a heating rate of 10${\circ}$/min. Also, orientation and crystallization were examined using monochromatic-pinhole technique and elastic modulus was measured by a dynamic mechanical analyzer in the temperature range of -150~70 ${\circ}$ with the frequency of 1 Hz. Transparent PET products were fabricated by use of the PET pellets annealed at 83${\circ}$ for 30 min in an electric furnace.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.571-574
• /
• 2005

We demonstrated a high speed liquid crystal (LC) display mode based on a nonchiral smectic C LC in an antiparallel planar geometry. In this antiparallel planar nonchiral smectic C (APNSC) LC mode, analog gray scales and wide viewing properties are achieved using a stepwise thermal annealing process (STAP). Because of an initially stable LC alignment in large area through the STAP, the APNSC LC mode exhibits the characteristics of fast response and high contrast ratio. This new APNSC mode is suitable for processing the dynamic image at a video rate in the next-generation LCDs.

• Bulletin of the Korean Chemical Society
• /
• v.9 no.5
• /
• pp.289-291
• /
• 1988

The ratio of trivalent to divalent copper has been determined by the redox titration for two superconducting phases of $YBa_2Cu^{3+}_{2x}Cu^{2+}_{3-2x}O_{6.5+x}$ with the onset temp. of 60K (x = 0.23 ${\pm}$ 0.01) and 90K (x = 0.35 ${\pm}$ 0.02), and for the insulating one (x ${\cong}$ 0) which was kept in an ambient atmosphere for 72 hrs. It is found that $T_c$, and the ratio of $Cu^{3+}/Cu^{2+}$ depend strongly on the annealing temperature and time. A typical orthorhombic phase can easily be obtained by a slow cooling or stepwise cooling at $PO_2$ = 1 atm, and shows a high Tc (ca. 90K) superconductivity.

• Korean Journal of Materials Research
• /
• v.3 no.6
• /
• pp.624-631
• /
• 1993

The composites in the system aluminium titanate-mullite were synthesized by stepwise alkoxide hydrolysis of tetraethylorthosilicate, Si(OCLH5), and titaniumtetraethoxide, $Ti(OC_{2}H_{5})_4$ in $Al_{2}O_{3}$ ethanolic colloidal solution. All particles produced by sol-gel-process were amorphous, monodispesed and had a narrow particle size distribution. Sintered bodies at $1600 ^{\circ}C$ for 2h were subjected to prolonged durability tests-on the one hand annealing at the critical decomposition temperature of $1100 ^{\circ}C$ for lOOh and on the other cyclic thermal shock between 750 and $1400 ^{\circ}C$ for 100h. The best thermal durability was achieved by a composition containing 70 and 80 vol% aluminium titanate, which showed little change in microstructure and thermal expansion cycles during the tests. The microstructural degradation of samples studied using scanning electron microscopy, X-ray diffraction, and dilatometry, was presented here. The study was conducted in order to predict the service life of aluminium titanate-mullite ceramics formed by this processing route.

• Journal of Korean Vacuum Science & Technology
• /
• v.2 no.2
• /
• pp.63-77
• /
• 1998

The oxidation of NiAl(110) was investigated in the temperature regime between 300K and 1300 K using LEED (low energy electron diffraction), TPD (temperature programmed desorption) and HREELS (high resolution electron energy loss spectroscopy). The adsorption of N2O and O2 up to reconstructions. Stepwise annealing of the oxygen-saturated sample from 600 K to 1300K in UHV (ultra-high vacuum,) results in firstly the onset of randomly oriented then finally fairly well-ordered. 5 ${\AA}$ Al2O3 film with quasi-hexagonal periodicity. Ordered thicker oxide films of 18-30 ${\AA}$ seem to be grown on this interfacial oxide layer by direct oxidation of sample at elevated temperature between 1150 and 1300 K because of the LEED pattern consisting of new broad hexagonal spots and the previous 5 ${\AA}$ spots. Although the periodicity of surface oxygen arrays shows no significant change from an hexagonal close-packing, the O-O distance changes from ∼3.0 ${\AA}$ film to ∼2.9 ${\AA}$ for thicker oxides. with the appearance of Auger parameter, for the 5${\AA}$ film can be described better as an interfacial oxide layer. The observation of three symmetric phonon peaks can be also a supporting evidence for this phase assignment since thicker oxide films on the Same Ni2Al3(110) show somewhat different phonon structure much closer to that of the ${\gamma}$-Al2O3. The adsorption/desorption of methanol further proves the preparation of less-defective and/or oxygen-terminated Al2O3 films showing ordered phase transitions with the change of oxide thickness between 5 ${\AA}$ to 30 ${\AA}$.