Communication—Synergistic Effect of Mixed Particle Size on W CMP Process: Optimization Using Experimental Design

Seo, Jihoon,Moon, Jinok,Kim, Yehwan,Kim, Kijung,Lee, Kangchun,Cho, Yoonsung,Lee, Dong-Hee,Paik, Ungyu The Electrochemical Society 2017 ECS journal of solid state science and technology Vol.6 No.1

<P>We have investigated the synergistic effect with mixing of three different-sized SiO2 abrasives (30 nm-SiO2, 70 nm-SiO2 and 200 nm-SiO2) and the correspondingWchemical mechanical planarization (CMP) performances. Wremoval rate significantly increased when the different-sized SiO2 abrasives were mixed, which is attributed to the increase in the total contact area between the abrasives and the W film. Based on the statistical model, we obtained the optimal mixing ratio (30 nm, 70 nm, 200 nm) = (0.49, 0.23, 0.28) for the highest W removal rate. These results, investigated in this study, show that the removal rate of W film can be improved via simple mixing process. (C) 2016 The Electrochemical Society. All rights reserved.</P>

Multi-objective optimization of tungsten CMP slurry for advanced semiconductor manufacturing using a response surface methodology

Seo, Jihoon,Kim, Joo Hyun,Lee, Myoungjae,You, Keungtae,Moon, Jinok,Lee, Dong-Hee,Paik, Ungyu Elsevier 2017 Materials & Design Vol.117 No.-

<P><B>Abstract</B></P> <P>In this study, a response surface methodology (RSM) coupled with a face center cube design (FCD) was used to optimize the three principal components (i.e., Fe(NO<SUB>3</SUB>)<SUB>3</SUB>, H<SUB>2</SUB>O<SUB>2</SUB>, and SiO<SUB>2</SUB> abrasives) in polishing slurries for a W barrier chemical mechanical planarization (CMP) process. The experimental ranges of the three components were 10–50ppm of Fe(NO<SUB>3</SUB>)<SUB>3</SUB>, 0.3–0.9wt% of H<SUB>2</SUB>O<SUB>2</SUB>, and 1–5wt% of SiO<SUB>2</SUB> abrasives. Based on the experimental data from the FCD, the second-order models for the material removal rate (MRR) of the W and Oxide films were fitted; these were determined to be statistically valid and reliable. We have achieved the optimal conditions for the three components where the MRR is maximized and the selectivity between the W and Oxide MRRs is ~1. The predicted MRR and selectivity at the optimal conditions were well correlated with the results of a confirmation run, which was conducted by using the W barrier CMP process with W-patterned wafers. In addition, we employed a particular RSM called dual-response optimization in order to investigate the tradeoff between the MRR and selectivity. Based on the tradeoff information, process engineers can conduct the optimization of the three components more flexibly.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The three principal components (i.e., Fe(NO<SUB>3</SUB>)<SUB>3</SUB>, H<SUB>2</SUB>O<SUB>2</SUB>, and SiO<SUB>2</SUB> abrasives) in polishing slurries for the W barrier CMP process were optimized using RSM. </LI> <LI> The optimal components were obtained as follows: 17.6ppm of Fe(NO<SUB>3</SUB>)<SUB>3</SUB>, 0.3wt% of H<SUB>2</SUB>O<SUB>2</SUB>, and 5.0wt% of SiO<SUB>2</SUB> abrasives. </LI> <LI> We have achieved ultra-smooth surfaces of W-patterned wafers using the optimal W CMP slurry. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effects of meteorology and emissions on urban air quality: a quantitative statistical approach to long-term records (1999-2016) in Seoul, South Korea

Seo, Jihoon,Park, Doo-Sun R.,Kim, Jin Young,Youn, Daeok,Lim, Yong Bin,Kim, Yumi Copernicus GmbH 2018 Atmospheric chemistry and physics Vol.18 No.21

<P>Abstract. Together with emissions of air pollutants and precursors, meteorological conditions play important roles in local air quality through accumulation or ventilation, regional transport, and atmospheric chemistry. In this study, we extensively investigated multi-timescale meteorological effects on the urban air pollution using the long-term measurements data of PM10, SO2, NO2, CO, and O3 and meteorological variables over the period of 1999-2016 in Seoul, South Korea. The long-term air quality data were decomposed into trend-free short-term components and long-term trends by the Kolmogorov-Zurbenko filter, and the effects of meteorology and emissions were quantitatively isolated using a multiple linear regression with meteorological variables. In terms of short-term variability, intercorrelations among the pollutants and meteorological variables and composite analysis of synoptic meteorological fields exhibited that the warm and stagnant conditions in the migratory high-pressure system are related to the high PM10 and primary pollutant, while the strong irradiance and low NO2 by high winds at the rear of a cyclone are related to the high O3. In terms of long-term trends, decrease in PM10 (−1.75 µg m−3 yr−1) and increase in O3 (+0.88 ppb yr−1) in Seoul were largely contributed by the meteorology-related trends (−0.94 µg m−3 yr−1 for PM10 and +0.47 ppb yr−1 for O3), which were attributable to the subregional-scale wind speed increase. Comparisons with estimated local emissions and socioeconomic indices like gross domestic product (GDP) growth and fuel consumptions indicate probable influences of the 2008 global economic recession as well as the enforced regulations from the mid-2000s on the emission-related trends of PM10 and other primary pollutants. Change rates of local emissions and the transport term of long-term components calculated by the tracer continuity equation revealed a decrease in contributions of local emissions to the primary pollutants including PM10 and an increase in contributions of local secondary productions to O3. The present results not only reveal an important role of synoptic meteorological conditions on the episodic air pollution events but also give insights into the practical effects of environmental policies and regulations on the long-term air pollution trends. As a complementary approach to the chemical transport modeling, this study will provide a scientific background for developing and improving effective air quality management strategy in Seoul and its metropolitan area. </P>

Role of the Surface Chemistry of Ceria Surfaces on Silicate Adsorption

Seo, Jihoon,Lee, Jung Woo,Moon, Jinok,Sigmund, Wolfgang,Paik, Ungyu American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.10

<P>Ceria nanoparticles (NPs) have been widely explored as a promising material in various fields. As synthesized under various physicochemical conditions, it exhibits the different surface chemistry. Here, the role of hydroxyl and nitrate group on ceria surface, formed under various physicochemical conditions, for the silicate adsorption was experimentally and theoretically investigated based on the adsorption isotherms and theoretical analyses using density functional theory (DFT) calculation. Experimental results acquired from adsorption isotherms with Freundlich model indicated that the nitrate group shows a much higher affinity with silicate than the hydroxyl groups. These phenomena were demonstrated through the theoretical approaches that exhibit the binding energy of the NO<SUB>3</SUB>–ceria (−4.383 eV) on the SiO<SUB>2</SUB> surface being much higher than that of the OH–ceria (−3.813 eV). In good agreement with the experimental and the theoretical results based on adsorption properties, the results of chemical mechanical planarization (CMP) also show that the nitrate groups significantly enhance the removal of SiO<SUB>2</SUB> than the hydroxyl groups. The results investigated in this study will provide researchers, studying the ceria NPs, with guidelines on the importance of exploring the surface chemistry of ceria.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-10/am500816y/production/images/medium/am-2014-00816y_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am500816y'>ACS Electronic Supporting Info</A></P>

On the multiday haze in the Asian continental outflow: the important role of synoptic conditions combined with regional and local sources

Seo, Jihoon,Kim, Jin Young,Youn, Daeok,Lee, Ji Yi,Kim, Hwajin,Lim, Yong Bin,Kim, Yumi,Jin, Hyoun Cher Copernicus GmbH 2017 Atmospheric Chemistry and Physics Vol.17 No.15

<P>Abstract. The air quality of the megacities in populated and industrialized regions like East Asia is affected by both local and regional emission sources. The combined effect of regional transport and local emissions on multiday haze was investigated through a synthetic analysis of PM2. 5 sampled at both an urban site in Seoul, South Korea and an upwind background site on Deokjeok Island over the Yellow Sea during a severe multiday haze episode in late February 2014. Inorganic components and carbonaceous species of daily PM2. 5 samples were measured, and gaseous pollutants, local meteorological factors, and synoptic meteorological conditions were also determined. A dominance of fine-mode particles (PM2. 5 ∕ PM10 ∼ 0.8), a large secondary inorganic fraction (76 %), high OC ∕ EC (> 7), and highly oxidized aerosols (oxygen-to-carbon ratio of ∼ 0.6 and organic-mass-to-carbon ratio of ∼ 1.9) under relatively warm, humid, and stagnant conditions characterize the multiday haze episode in Seoul; however, the early and late stages of the episode show different chemical compositions of PM2. 5. High concentrations of sulfate in both Seoul and the upwind background in the early stage suggest a significant regional influence on the onset of the multiday haze. At the same time, high concentrations of nitrate and organic compounds in Seoul, which are local and highly correlated with meteorological factors, suggest the contribution of local emissions and secondary formation under stagnant meteorological conditions to the haze. A slow eastward-moving high-pressure system from southern China to the East China Sea induces the regional transport of aerosols and potential gaseous precursors for secondary aerosols from the North China Plain in the early stage but provides stagnant conditions conducive to the accumulation and the local formation of aerosols in the late stage. A blocking ridge over Alaska that developed during the episode hinders the zonal propagation of synoptic-scale systems and extends the haze period to several days. This study provides chemical insights into haze development sequentially by regional transport and local sources, and shows that the synoptic condition plays an important role in the dynamical evolution of long-lasting haze in the Asian continental outflow region. </P>

Communication—Corrosion Behavior of Tungsten Metal Gate in the Presence of Hydrogen Peroxide at Acidic Medium

Seo, Jihoon,You, Keungtae,Moon, Jinok,Kim, Joo Hyun,Paik, Ungyu The Electrochemical Society 2017 ECS journal of solid state science and technology Vol.6 No.4

<P>Herein, the corrosion behaviors of W metal gates in the presence of H<SUB>2</SUB>O<SUB>2</SUB> at the acidic medium were investigated as a function of dipping time, temperature, and H<SUB>2</SUB>O<SUB>2</SUB> concentration. We determined the kinetic constants (i.e. <I>k</I><SUB>w</SUB> and <I>k</I><SUB>h</SUB>) based on the experimental data. The activation energy (<I>E</I><SUB>a</SUB>) are calculated from the Arrhenius equation. Thermodynamic parameters (Δ<I>G</I><SUP>‡</SUP>, Δ<I>H</I><SUP>‡</SUP>, and Δ<I>S</I><SUP>‡</SUP>) for the dissolution were determined based on the Eyring plot. These results investigated in this study will provide researchers the prior information on parameters to control the corrosion behaviors of W metal gates during the chemical mechanical planarization (CMP) process.</P>

Role of the oxidation state of cerium on the ceria surfaces for silicate adsorption

Seo, Jihoon,Moon, Jinok,Kim, Joo Hyun,Lee, Kangchun,Hwang, Junha,Yoon, Heesung,Yi, Dong Kee,Paik, Ungyu Elsevier 2016 APPLIED SURFACE SCIENCE - Vol.389 No.-

<P><B>Abstract</B></P> <P>In this study, we have investigated the role of the Ce oxidation state (Ce<SUP>3+</SUP>/Ce<SUP>4+</SUP>) on the CeO<SUB>2</SUB> surfaces for silicate adsorption. In aqueous medium, the Ce<SUP>3+</SUP> sites lead to the formation of −OH groups at the CeO<SUB>2</SUB> surface through H<SUB>2</SUB>O dissociation. Silicate ions can adsorb onto the CeO<SUB>2</SUB> surface through interaction with the −OH groups (−Ce−OH−+−Si−O<SUP>−</SUP> ↔−Ce−O−Si−+OH<SUP>−</SUP>). As the Ce<SUP>3+</SUP> concentration increased from 19.3 to 27.6%, the surface density of −OH group increased from 0.34 to 0.72 OH/nm<SUP>2</SUP>. To evaluate the adsorption behaviors of silicate ions onto CeO<SUB>2</SUB> NPs, we carried out an adsorption isothermal analysis, and the adsorption isotherm data followed the Freundlich model. The Freundlich constant for the relative adsorption capacity (<I>K<SUB>F</SUB> </I>) and adsorption intensity (<I>1</I>/<I>n</I>) indicated that CeO<SUB>2</SUB> NPs with high Ce<SUP>3+</SUP> concentration show higher adsorption affinity with silicate ions. As a result, we have demonstrated that the Ce oxidation state (Ce<SUP>3+</SUP>/Ce<SUP>4+</SUP>) on the CeO<SUB>2</SUB> surface can have a significant influence on the silicate adsorption.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We investigated the role of Ce oxidation state (Ce<SUP>3+</SUP>/Ce<SUP>4+</SUP>) on the CeO<SUB>2</SUB> surfaces for the silicate adsorption. </LI> <LI> As the Ce<SUP>3+</SUP> concentration increased from 19.3 to 27.6%, the surface density of OH group increased from 0.34 to 0.72 OH/nm<SUP>2</SUP>. </LI> <LI> The Freundlich constant for the relative adsorption capacity (<I>K<SUB>F</SUB> </I>) and adsorption intensity (<I>1/n</I>) indicated that CeO<SUB>2</SUB> NPs with high Ce<SUP>3+</SUP> concentration show higher adsorption affinity with silicate ions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

선박엔진에서 배출되는 블랙카본의 기후변화 영향

서지훈(Jihoon Seo),김진영(Jin Young Kim),윤대옥(Daeok Youn) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

Atmospheric black carbon (BC) affects the global radiative budget and thus climate by absorbing solar radiation, heating atmosphere, and reducing snow/ice albedo. Although BC emissions from marine engines occupy only a small fraction of total anthropogenic BC emissions, those are expected to be continuously increased in future climate scenarios. In the present study, therefore, we examined possible climate impact of the BC ship emissions by using a Global Climate Model (GCM). The Community Earth System Model (CESM) developed by the US National Center for Atmospheric Research (NCAR) was employed to conduct two equilibrium climate simulations based on the BC ship emissions in the present day (the year 2000) and in the near future (the year 2050 from the RCP4.5 scenario). Composite analyses show that a small increase in the BC ship emissions could induce significant changes in atmospheric circulations, aerosol distributions, and radiative budgets through climate feedbacks. Although BC emissions from shipping are much smaller than those from domestic, industrial, and transportation sources on the lands, the BC emissions from marine engines could also be an important climate primer.

디지털 영상 확대기를 위한 픽셀값 분포 기반 적응적 영상 이진화 기법

서지훈(Jihoon Seo),지경현(Kyunghyun Ji),강세구(Segu Kang),김성민(Sungmin Kim) 한국정보과학회 2015 한국정보과학회 학술발표논문집 Vol.2015 No.6

Increase in anti-apoptotic molecules, nucleolin, and heat shock protein 70, against upregulated LRRK2 kinase activity

Jang, Jihoon,Oh, Hakjin,Nam, Daleum,Seol, Wongi,Seo, Mi Kyoung,Park, Sung Woo,Kim, Hyung Gun,Seo, Hyemyung,Son, Ilhong,Ho, Dong Hwan ZOOLOGICAL SOCIETY OF KOREA 2018 ANIMAL CELLS AND SYSTEMS Vol.22 No.5

<P><B>ABSTRACT</B></P><P>Leucine-rich repeat kinase 2 (LRRK2) is involved in Parkinson’s disease (PD) pathology. A previous study showed that rotenone treatment induced apoptosis, mitochondrial damage, and nucleolar disruption via up-regulated LRRK2 kinase activity, and these effects were rescued by an LRRK2 kinase inhibitor. Heat-shock protein 70 (Hsp70) is an anti-oxidative stress chaperone, and overexpression of Hsp70 enhanced tolerance to rotenone. Nucleolin (NCL) is a component of the nucleolus; overexpression of NCL reduced cellular vulnerability to rotenone. Thus, we hypothesized that rotenone-induced LRRK2 activity would promote changes in neuronal Hsp70 and NCL expressions. Moreover, LRRK2 G2019S, the most prevalent LRRK2 pathogenic mutant with increased kinase activity, could induce changes in Hsp70 and NCL expression. Rotenone treatment of differentiated SH-SY5Y (dSY5Y) cells increased LRKK2 levels and kinase activity, including phospho-S935-LRRK2, phospho-S1292-LRRK2, and the phospho-moesin/moesin ratio, in a dose-dependent manner. Neuronal toxicity and the elevation of cleaved poly (ADP-ribose) polymerase, NCL, and Hsp70 were increased by rotenone. To validate the induction of NCL and Hsp70 expression in response to rotenone, cycloheximide (CHX), a protein synthesis blocker, was administered with rotenone. Post-rotenone increased NCL and Hsp70 expression was repressed by CHX; whereas, rotenone-induced kinase activity and apoptotic toxicity remained unchanged. Transient expression of G2019S in dSY5Y increased the NCL and Hsp70 levels, while administration of a kinase inhibitor diminished these changes. Similar results were observed in rat primary neurons after rotenone treatment or G2019S transfection. Brains from G2019S-transgenic mice also showed increased NCL and Hsp70 levels. Accordingly, LRRK2 kinase inhibition might prevent oxidative stress-mediated PD progression.</P><P><B>Abbreviations:</B> 6-OHDA: 6-hydroxydopamine; CHX: cycloheximide; dSY5Y: differentiated SH-SY5Y; g2019S tg: g2019S transgenic mouse; GSK/A-KI: GSK2578215A kinase inhibitor; HSP70: heat shock protein 70; LDH: lactose dehydrogenase; LRRK2: leucine rich-repeat kinase 2; MPTP: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; myc-GS LRRK2: myc-tagged g2019S LRRK2; NCL: nucleolin; PARP: poly(ADP-ribose) polymerase; PD: Parkinson’s disease; PINK1: PTEN-induced putative kinase 1; pmoesin: phosphorylated moesin at t558; ROS: reactive oxygen species</P>