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To investigate the reproducibility and I–V non-linearity characteristics in resistive-switching random-access memory (RRAM), we studied the switching characteristics through Pt/TiO2 interface control using a non-stoichiometric TiO2−x/TiN interface formation in a resistive switching Pt/TiO2/TiN stack. Using the TiO2−x/TiN interface instead of the TiO2/TiN interface induced nearly forming-free switching, decreased the reset current, suppressed the gradual reset process, and resulted in faster switching by electric pulse. These results indicate that the Pt/TiO2 interface experienced reduced oxygen-vacancy-mediated switching. The discrepancy between the reduced oxygen-vacancy-mediated switching and the initially large number of oxygen vacancies can be resolved via the oxygen vacancy distribution dependent field effect. To clarify this process, we performed reaction-diffusion-drift model simulations. The drift velocity, which was calculated using the vacancy distribution, described the dynamic movement, and the simulation results supported the experimentally observed faster switching response. The field effect, which provided successive feedback between the drift velocity and vacancy distribution, can potentially be exploited to generate vacancy-designed devices.

In this study, the enhancement of the silicon etch rate with the heavy doping of phosphorus and arsenic was studied during cyclic selective epitaxial growth process using batch-type equipment. The reaction between molecular chlorine and heavily doped silicon was stimulated during the initial stage of cyclic SEG process at low temperature lower than 700° to induce voids at the interface. Heavy doping of n-type dopants into active regions also brought about the decrease in the growth rate of SEG process. It was possible to attain a stable process window by the elaborate control of total amount ratio of SiH4/Cl2. The window provided the robust interface between SEG silicon and active regions as well as the selectivity to an oxide layer. Vertical diodes which were realized within the window revealed eligible on- and off-current characteristics for cell switches applicable to next generation cross-point memories.

Protective effect of ethanol extract from Hericium erinaceus cultivated with Artemisia capillaries (HEAC) on gastric mucosal damage induced by 0.15M HCl in ethanol in rats was evaluated. HEAC showed higher potent protective effect on gastritis with effective dose 50 (ED50) value of 22.6mg/kg compared those of selbex and stillen at 46.5 and 44.2 mg/kg, respectively, the presently used medicines for treating gastritis. ichloromethane fraction showed a dose-dependent protective effect on gastritis with ED50 value of 18.1 mg/kg. The biologically active component of dichloromethane fraction derived from HEAC ethanolic extract was characterized by spectroscopic analysis as scoparone with protective rate of 93% and ED50 value of 4.2 mg/kg on gastritis. Taken together, administration of HEAC and scoparone provided protective effect on the gastric lesion induced by ethanol-HCl and may therefore be a promising drug for treatment of gastritis and gastric ulcer.

cis -(3R,5R)-Atorvastatin Ca (1) used for hyperlipidemia have four stereomers. However, It is very difficult to prepare stereoselective stereomers. In this paper, the reduction of 3,5-diketo atorvastatin ester (3) was performed using Me 4 NHB(OAc) 3 in acetic acid as a reductant and showed excellent stereoselectivity in the double reduction of 3,5-diketo atorvastatin ester (3). As a result, reduction of compound 3 by Me 4 NHB(OAc) 3 was purely obtained with cis -(3R,5R)-atorvastatin ester (4) of 1.5% and trans -(3R,5S)-atorvastatin ester (5) of 98.5%. Also, cis-(3R,5R)-atorvastatin Ca (1) and trans-(3R,5S)-atorvastatin Ca (7) were used to determine efficacy in the treatment of liver damage and hyperlipidemia induced by a high-fat diet in rats and to study the performance of the January 2010 experient was conducted. As a result, total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-c), low-density lipoprotein-cholesterol (LDL-c), and triglyceride (TG) levels of compound 1 and 7 groups were 93.0±0.5, 43.5±0.8, 40.4±1.4, 45.6±0.9 mg/㎗ and 110.0±0.7, 33.3±0.6, 65.8±1.9, 54.8±1.2 mg/㎗, respectively. Atherogenic index (AI) and cardiac risk factor (CRF) in compound 1 and 7 were 1.14±0.05, 2.14±0.05 and 2.31±0.06, 3.31±0.06, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were 51.9±4.6, 16.0±2.1 IU/l and 75.8±4.4, 35.1±9.7 IU/l. Taken together, while compound 1 treat against high-fat diet-induced hyperlipidemia by attenuating hepatic lipid depots and reducing oxidative stress, compound 7 group had a low curative effect on hyperlipidemia induced by a high-fat diet in rats. These findings suggest that new method about synthesis of stereoselective stereomers and indicate that it may consider using in a clinical trial.

Abrupt changes in sidewall profile were induced in pulsed plasma etch process for high aspect ratio isolation trench structuring. Impacts of operational parameters when applying pulsed RF bias power were investigated. Silicon sidewall chipping problems were removed mainly by increasing bias power level and pulse frequency. The chemical sensitivity of O2 has shown decreased in extremely narrow trench spaces of high pattern density

Fungicidal activity against phytopathogenic fungi of diarylthiazole compound of N-[4-(4-fluoro) phenyl-2-(N-methyl)piperidin-4-yl-thiazol-5-yl]pyrimidin-2-yl-N-(3-hydroxy-methyl)phenylamine (I) have been determined to be a superior and compound I was used as the leading compounds in this study. Furthermore, the synthesis of this compound was conducted by reacting them with four functional groups, N-cyclopropyl, N-cyclopentyl, N-cyclohexyl, and N-isopropylamine instead of the phenylamine. Also, 2-aminothiazole, 2-(N-ethoxycarbonyl)piperidin-4-yl, and 2-piperidin-4-ylthiazole were introduced as the leads instead of the 2-aminothiazole group of compound I. From this scheme, VIII-1∼VIII-4 and XII-1∼XIV-4 compounds were newly synthesized and their structures were confirmed by 1H-NMR-spectrum. The fungicidal activities of all the synthesized compounds against Phytophthora capsici were examined using the whole plant method. While the EC50 value of the commercial fungicide dimethomorph and I was 4.26 mM and that of N-[4-(4-fluoro phenyl-2-(N-methyl)piperidin-4-yl-thiazol-5-yl]pyrimidin-2-yl-cyclopropylamine (XIV-2) on P. capsici was 0.84 mM. Among the XII-1∼XIV-4 chemicals, XIV-2 showed the most potential antifungal activity in vivo. Therefore, XIV-2 can be considered as a viable candidate for the control of phytopathogenic diseases characterized by P. capsici infection, and further studies will be conducted on the mode of action XIV-2.

We studied the misalignment between active and gate layer in terms of silicon dislocation caused by high temperature anneal process in SOG based STI gap-fill process. The SOG process is one of good candidates to overcome gap-fill limitation due to its excellent gap-fill characteristics. However, the SOG process needs high temperature anneal process to convert from Si-H, N-H to Si-O bond, which leads to the misalignment due to large stress change. We suggest that silicon defect is generated from ion bombardment at trench etch process and accelerated from hysteresis at anneal process. The O2 cure process is known as one of feasible methods to cure silicon damage through recrystallization. Based on this model, the misalignment was significantly improved as removing the defect through O2 cure process following trench etch process.

Twenty five compounds isopropylmethylphenyl benzenesulfonate derivatives of thymol (1), 4-isopropyl-3-methylphenol (2), 5-isopropyl-3-methylphenol (3), 4-isopropylphenol (4), and 2-isopropylphenol (5) derivatives were synthesized. These compounds were analyzed for their structural confirmation with IR, GC/MS, and -NMR. Synthetic compounds were tested against phytopathogenic fungi activities such as Pyrcularia grisea, Rhizoctonia solani, Phytophthora infestans, Colletotrichum orbiculare, and Sphaerotheca fusca. 2-Isopropyl-5-methylphenyl o-toluenesulfonate (1a), 2-isopropylphenyl 2,4,5-trichloro-benzenesulfonate (5b) and 2-isopropylphenyl 2-methyl-5-nitrobenzenesulfonate (5e) showed a potent in vivo antifungal activity against Pyrcularia grisea, Phytophthora infestans and Sphaerotheca fusca.

The fungicidal activities against phytopathogenic fungi of two aminothiazole compounds of N-[4-(4-fluoro)phenyl-2-aminothiazol-5-yl]pyrimidin-2-yl-N-subst. phenylamine (V-1, V-2) have been determined and these two compounds were used as the leading compounds in this study as V-1 for N-[4-(4-fluoro)phenyl-2-aminothiazol-5-yl]pyrimidin-2-yl-N-(3-hydroxymethyl)phenylamine and V-2 for N- [4-(4-fluoro)phenyl-2-aminothiazol-5-yl] pyrimidin-2-yl-N-3-(l-hydroxyethyl)phenylamine. Further syntheses of these two compounds, V-l and V-2, were conducted by reacting them with three functional groups, 2-(N-ethoxycarbonyl)piperidin-4-yl, 2-piperidin-4-yl, and 2-(N-methyl)-piperidin-4-yl-thiazole. From this scheme, 21 compounds were newly synthesized and their structures were confirmed by 1H-NMR-spectrum. The fungicidal activities of all the synthesized compounds against Phytophthora capsici were examined using the whole plant method. While the EC50 value of the commercial fungicide dimethomorph was 4.26 mM, that of IX-3g on P. capsici was 1.03 mM. Among the 21 chemicals, IX-3g showed the most potential antifungal activity in vivo. Therefore, IX-3g may be considered as a potential candidate for the control of phytopathogenic diseases characterized by P. capsici infection, and further studies will be conducted on the mode of action IX-3g.

Coenzyme $Q_{10}$ 과 그 유도체 coenzyme $Q_n$ 6종을 합성하고, 이들 유도체에 대하여 상피세포(LLC-PK1 cell)를 이용한 항산화 효과와 NIH/3T3 세포를 이용한 세포독성 실험을 실시하였다. 그 결과, 합성한 coenzyme $Q_n$ 유도체들이 coenzyme $Q_{10}$ 에 비해 우수한 항산화 효과를 나타내었으며, 그 중 coenzyme $Q_3$ -C가 모든 농도에서 $107.7{\sim}135.9%$ 로 가장 우수한 효과를 나타내었다. 또한, 모든 coenzyme $Q_n$ 유도체들이 Coenzyme $Q_{10}$ 과 유사한 세포독성을 나타내었다. Coenzyme $Q_n$ 의 n수에 따른 항산화 효과 및 세포독성 실험에서 isoprene unit의 수가 적은 유도체들에서 우수한 효과를 나타내었다. 【Coenzyme $Q_{10}$ and six derivatives of coenzyme $Q_n$ were synthesized and tested for their antioxidative effects occurred in proximal tubular epithelial cell (LLC-PK1 cell) and cytotoxicities using in NIH/3T3 cell. As the result, synthetic coenzyme $Q_n$ derivatives showed a potent antioxidative effect compared to coenzyme $Q_{10}$ . Among these synthetic compounds, coenzyme $Q_3$ -C at ranged 0.04 to 0.4 mmol showed the $107.7{\sim}135.9%$ of cell viability in LLC-PK1 cell. In the test of NIH/3T3, all synthesized coenzyme $Q_n$ derivatives showed the similar effect compared with coenzyme $Q_{10}$ . A correlation between isoprene unit number of coenzyme $Q_n$ derivatives and its biological effects, we suggest reduction of isoprene unit number of $Q_n$ derivatives may be related to the increase of antioxidants effects and the reduction of cytotoxicities.】

Department of Polymer Science and Engineering, Kumoh National Institute of Technology, Gumi 730-701, Korea(Received April 6, 2007)주제어: 보조효소 Qn, 이소피렌, p-하이드로퀴논Keywords: Coenzyme Qn, Isoprene, p-HydroquinoneCoenzyme Qn 유도체의 구조는 극성을 나타내는benzoquinone 머리 부분과 소수성인 polyprenyl 꼬리부분으로 이루어져 있다. Polyprenyl기에 포함된isoprene 단위에 의해 Coenzyme Qn으로 표시되며,여기서 n은 isoprene 단위의 수를 나타낸다. CoenzymeQn 유도체들 중에서 생체 내 가장 많이 존재하는 화합물은 n=10 이고 탄소수가 50개인 Coenzyme Q

Pesticidal activities of 4-[5-(2-cyclopropylaminopyrimidin-4-yl)-4-(4-chloro-2-fluoro-phenyl)thiazol-2-yl]-1-methylpiperidine, designated as Comp I, have been determined against a mosquito larva,Culex pipiens pallens, and a phytopathogenic fungus,Phytophthora capsici. Comp I was used as the leading compound in this study. The compounds were synthesized by reacting them with two functional groups, 3-thiophenyl and 2-thiophenyl groups, instead of 4-chloro-2-fluorophenyl group in Comp I. Other functional groups such as 2-aminothiazole, 2-(1-methylpiperazin-4-yl)thiazole, and 2-(piperazin-4-yl)thiazole were also introduced instead of 2-methylpiperidin-4-yl-thiazole of Comp I. Compounds designated as XIII-6~XV-7 were newly synthesized and their structures were confirmed by1H- and13C-NMR spectroscopy. Mosquito larvicidal activities of all the synthesized compounds againstC. pipiens pallenswere examined and Comp I among them showed the strongest larvicidal activity as 0.513 mM of LC50value. The fungicidal activities of all the synthesized compounds againstP. capsiciwere examined using the whole plant method. Among the XIII-6~XV-7 chemicals, 5-(2-cyclopropylaminopyrimidin-4-yl)-4-(thiophen-2-yl)thiazol-2-amine (VIII-6) showed the most potent antifungal activityin vivo. While the EC50value of the commercial fungicide dimethomorph was 4.26 μM, EC50of VIII-6 was 0.94 μM. Therefore, thiazole derivatives can be considered as viable candidates for the control of mosquito larvae and plant diseases.

The effect of interfacial reactions at the poly Si1−xGex/HfO2 interface on the electrical properties of metal–oxide–semiconductor (MOS) capacitors with a poly Si1−xGex (x=0,0.6)/HfO2 gate stack was investigated relative to the deposition conditions for the poly Si1−xGex films, the Ge content of the poly Si1−xGex films, and the annealing temperatures, by the electrical measurements and x-ray photoelectron spectroscopy. With an increase in hydrogen induced from doping or from deposition gas used during the deposition of poly Si1−xGex (x=0,0.6) films, the accumulation capacitance of the MOS capacitors with a poly Si1−xGex/HfO2 gate stack became anomalous and the leakage current increased significantly, due to the formation of hydroxyl(OH–) ions or the partial reduction of HfO2 at the grain boundary. With an increase in Ge content of the poly Si1−xGex films, silicate formation became dominant at the poly Si1−xGex/HfO2 interface, resulting in a significant decrease in leakage current.

Hafnium oxide (HfO 2 ) thin films were deposited by two different sputtering methods. In one case, hafnium (Hf) metal layer was pre-deposited before reactive sputtering process (method A), with the object of suppressing growth of the interfacial layer. Another one is conventional reactive sputtering, using DC magnetron in Ar+O 2 ambient (method B). Films made by method A showed thinner interlayer as well as good leakage current behavior, demonstrating that Hf pre-deposited layer can protect from incorporation of the oxidizing species. With high-temperature annealing, interfacial layer increases considerably, showing composition changes from silicate to SiO 2 (method A). In contrast, films by method B displayed little change in interlayer thickness since there exists previously thick SiO x bottom layer formed by O 2 stabilizing before reactive sputtering. Equivalent oxide thickness (EOT) of as-deposited and annealed HfO 2 films by method A is calculated to be ∼20 and ∼30 A, respectively, with allowable level of leakage current density.

In this letter, a cost-effective vertical diode scheme for next-generation memory devices, including phase-change memories (PCMs), is realized. After the contact formation for diodes with only one mask layer, an amorphous silicon (a-Si) film was deposited within the contacts using SiH4 ramp-up ambient in a conventional batch-type furnace in order to minimize the growth of native oxide. A deposition/etch-back/deposition scheme enabled us to achieve robust vertical diodes without any seams or interfacial oxide layer within the vertical diode pillars. Subsequent annealing at 600 °C provided solid-phase epitaxial alignment of the a-Si layer. An ideality factor revealed that the new scheme provided noticeable crystallinity of the silicon diodes. Moreover, the electrical characteristics of the diodes verified that the scheme was suitable for full operation of PCM devices.

Hafnium oxide thin films were deposited on p-type (1 0 0) silicon wafers by reactive dc magnetron sputtering. Prior to the deposition of HfO2 films, a thin Hf film was deposited. Sputtered HfO2 thin films deposited at room temperature remain amorphous at T ° C and orthorhombic phases were observed above 650 °C. The monoclinic phase which is a stable HfO2 polymorphic form appeared after annealing above 800 °C. Capacitance equivalent thickness values decreased and leakage characteristics are improved by the Hf interlayer and O2 settlement process. The decrease of accumulation capacitance values upon annealing is due to the growth of an interfacial layer upon post-annealing. The flat band voltage (VFB) shifts negatively due to positive charge generated during post-annealing.

We first present chemical-vapor-deposited GeBiTe (CVD GBT) in a confined cell for high-performance phase-change random access memory (PRAM). Due to the fast crystallization of GBT, we were able to reduce the speed to less than 26 ns while maintaining endurance characteristics up to 109 cycles. Our results indicate that the scalable PRAM device enabling the use of PRAM in dynamic RAM and storage class memory applications can be realized using CVD GBT.

We investigated the evolution of microstructures and the #electrical properties of CeO 2 thin films deposited by the reactive DC magnetron sputtering method on the (100) silicon substrate upon annealing in the O 2 gas ambient. The CeO 2 thin films deposited at 300°C were polycrystalline. After annealing in ambient O 2 gas, the crystallinity of the CeO 2 film was improved and becomes more dense with annealing time and temperature. The maximum accumulation capacitance of CeO 2 thin film annealed above 700°C in the ambient O 2 gas decreased due to the growth of the interfacial SiO 2 layer between CeO 2 film and silicon substrate by the diffusion of oxidizing species through CeO 2 thin film from the ambient gas.

The effect of interfacial reactions on the electrical properties of a polycrystalline (poly) Si1−xGex/HfO2 gate stack were evaluated in terms of annealing conditions and the results were compared with those of a conventional poly-Si/HfO2 system. In the poly-Si0.4Ge0.6/HfO2 gate stack, silicate formation was the dominant reaction at the poly-Si0.4Ge0.6/HfO2 interface after annealing at 900 °C, resulting in the significant decrease in leakage current. From x-ray photoelectron spectroscopy analysis, the binding states of Hf silicates were clearly observed at a binding energy of about 16.1 eV in Hf 4f spectra and 102.7 eV in Si 2p spectra. However, in the poly-Si/HfO2 gate stack, the accumulation capacitance became undeterminable and the leakage current increased suddenly after annealing at 900 °C due to silicide formation at the poly-Si/HfO2 interface. The differences in reactions between a poly-Si/HfO2 interface and a poly-Si0.4Ge0.6/HfO2 interface are attributed to the accumulation of Ge.

We investigated the pressure dependence of the inductive coupled plasma (ICP) oxidation on the electrical characteristics of the thin oxide films. Activation energies and electron temperatures with different pressures were estimated. To demonstrate the pressure effect on the plasma oxide quality, simple N type metal-oxide-semiconductor (NMOS) transistors were fabricated and investigated in a few electrical properties. At higher pressure than 200mTorr, plasma oxide has a slightly higher on-current and a lower interfacial trap density. The on-current gain seems to be related to the field mobility increase and the lower defective interface to the electron temperature during oxidation.

A highly robust gap-fill process technology of spin-on glass (SOG) was developed for the interlayer dielectric (ILD) in sub-30nm devices. We revealed that the filling behavior of SOG within gaps during spin-coating is mainly dependent on the capillary effect. The highly wettable surface treatment prior to SOG coating was found to enhance the gap-fill performance remarkably. This technique plays a key role in maximizing capillary effect by raising surface wettability. The filling capability was also improved by optimization of baking temperature to minimize the viscosity of SOG. It was finally found that the defects of contact bridges due to poor filling of SOG were reduced to be almost free by those unique process refinements.

To improve the IPD reliability of NAND flash memory, plasma oxidation was introduced as the post-treatment process of ONO (Oxide/Nitride/Oxide) IPD. The LP-CVD SiO2 modified by plasma oxidation showed the excellent electrical properties. e.g., low leakage current, high breakdown voltage etc. By the analysis of Tof-SIMS and XRR, we could observe the several changes of physical characteristics such as the reduction of impurities (H, N etc.), the increase of oxide density, and the improvement of oxide surface roughness. We found out the appropriate treatment condition to be able to densify oxide layer without the addition of ONO Equivalent Oxide Thickness (EOT). The LP-CVD SiO2 prepared by plasma oxidation was used for the ONO IPD of 50nm NAND flash device and also compared with the conventional LP-CVD SiO2 in the aspect of the IPD reliability.

We studied factors which affect cell Vth variation in the floating gate flash memory. By simulation and experiment, we showed that the shape of STI (shallow trench isolation) and the tunnel oxide thickness in the STI edge were the main control factors. For example, sharp and thin oxide in the STI edge caused an uncontrolled F-N gate current in the program or erase operation, which directly indicated the amount of threshold voltage in the flash memory. Furthermore, we found that tunnel oxide thinning was closely related to the activation energy in the oxidation process. Smaller activation energy resulted in better thinning and better cell Vth distribution.

Abnormal gate oxide thickening at active edge (GOTAE) has been investigated in dynamic random access memories (DRAMs) with SiN-lineared shallow trench isolation (STI). 1% of gaseous HCl, which is added during dry oxidation, plays a major role in inducing abnormal GOTAE by the mechanical interaction with thin SiN layers in STI. Other structural parameters, such as the thickness of trench sidewall oxide, liner SiN and sacrificial oxide, are believed to influence the amount of oxide thickening. In order to avoid abnormal GOTAE, wet oxidation is introduced and shown to be effective in suppressing it. Electrical properties, which are susceptible to the extent of GOTAE, are also presented in this paper.

The oxidation characteristics of tungsten line pattern during the carbon-based mask-layer removal process using oxygen plasmas have been investigated for sub-50 nm patterning processes, in addition to the reduction characteristics of the WOx layer formed on the tungsten line surface using hydrogen plasmas. The surface oxidation of tungsten lines during the mask layer removal process could be minimized by using low-temperature (300 K) plasma processing for the removal of the carbon-based material. Using this technique, the thickness of WOx on the tungsten line could be decreased to 25% compared to results from high-temperature processing. The WOx layer could also be completely removed at a low temperature of 300 K using a hydrogen plasma by supplying bias power to the tungsten substrate to provide a activation energy for the reduction. When this oxidation and reduction technique was applied to actual 40-nm-CD device processing, the complete removal of WOx formed on the sidewall of tungsten line could be observed.

We investigated interfacial stabilities of ZrO 2 films with Al and Pt electrodes formed by magnetron sputtering upon annealing and consequent changes of their metal-oxide-semiconductor capacitor characteristics. The as-deposited ZrO 2 films deposited using a sputtering power of 300 W were amorphous, while after annealing in N 2 at 600°C for 5 min the films became polycrystalline with a mixture of monoclinic and tetragonal phases. After the deposition of electrodes, we found that the amorphous interlayer which is presumed to be Al 2 O 3 was formed at the ZrO 2 /Al interface, while platinum (Pt) electrodes showed no interlayer at the interface with ZrO 2 films. The value of the capacitance equivalent thickness for the ZrO 2 film with the Al electrode was larger than that of the case with the Pt electrode by about 12 A, which is due to the presence of the additional Al 2 O 3 interlayer at the Al/ZrO 2 interface. The capacitance-voltage measurement showed that the difference in fiatband voltage (V FB ) between the ZrO 2 films and the two different electrodes is about 1.2 V, which is due to the work function difference between the two electrode materials.