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산화막 CMP 공정에서 슬러리 온도 변화에 따른 연마 특성
고필주,박성우,김남훈,서용진,이우선,Ko, Pil-Ju,Park, Sung-Woo,Kim, Nam-Hoon,Seo, Yong-Jin,Lee, Woo-Sun 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.3
To investigate the effects of slurry temperature on the chemical mechanical polishing(CMP) performance of oxide film with silica and ceria slurries, we have studied slurry properties as a function of different slurry temperature. Also, the effects of each input parameter of slurry on the oxide CMP characteristics were investigated. The pH showed a slight tendency of decrease, the conductivity in slurries showed an increased tendency, the mean particle size in slurry decreased, and the zeta potential of slurry decreased with temperature. The removal rates significantly increased and maintained at the specific levels over 4$0^{\circ}C$. The better surface morphology of oxide films could be obtained at 40 $^{\circ}C$ of silica slurry and at 90 $^{\circ}C$ of ceria slurry. It is found that the CMP performance of oxide film could be significantly improved or controlled by change of slurry temperature.
고필주(Pil-Ju Ko),김남훈(Nam-Hoon Kim),이우선(Woo-Sun Lee) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
Pb(Zr,Ti)O₃ is one of the most attractive ferroelectric materials for realizing the FeRAM due to its higher remanant polarization and the ability to withstand higher coercive fields. Generally, the ferroelectric materials were patterned by a plasma etching process for high-density FeRAM. The applicable possibility of CMP process to pattern Pb(Zr,Ti)O₃ instead of plasma etching process was investigated in our previous study for improvement of an angled sidewall which prevents the densification of ferroelectric memory and is apt to receive the plasma damage. Our previous study showed that good removal rate with the excellent surface roughness compared to plasma etching process were obtained by CMP process for the patterning of Pb(Zr,Ti)O₃. The suitable selectivity to TEOS without any damage to the structural property of Pb(Zr,Ti)O₃ was also guaranteed. In this study, the removal mechanism of Pb<SUB>1.1</SUB>(Zr<SUB>0.52</SUB>Ti<SUB>0.48</SUB>)O₃ coated by sol-gel method was investigated. Surface analysis of polished specimens at the best and worst conditions was carried out by XPS.
고필주(Pil-Ju Ko),김남훈(Nam-Hoon Kim),이우선(Woo-Sun Lee) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
Platinum is a candidate of top and bottom electrode in ferroelectric random access memory and dynamic random access memory. High dielectric materials and ferroelectric materials were generally patterned by plasma etching, however, the low etch rate and low etching profile were repoted. We proposed the damascene process of high dielectric materials and ferroelectric materials for patterning process through the chemical mechanical polishing process. At this time, platinum as a top electrode was used for the stopper for the end-point detection as Igarashi model. Therefore, the control of removal rate in platinum chemical mechanical polishing process was required. In this study, an addition of H₂O₂ oxidizer to alumina slurry could control the removal rate of platinum. The removal rate of platinum rapidly increased with an addition of 10wt% H₂O₂ oxidizer from 24.81㎚/min to 113.59㎚/min. Within-wafer non-uniformity of platinum after chemical mechanical polishing process was 9.93% with an addition of 5wt% H₂O₂ oxidizer.
Damascene 공정을 이용한 Pb(Zr,Ti)O₃ 캐패시터 제조 연구
고필주(Pil-Ju Ko),이우선(Woo-Sun Lee) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.10
The ferroelectric materials of the PZT, SBT attracted much attention for application to ferroelectric random access memory (PRAM) devices. Through the last decade, the lead zircon ate titanate (PZT) is one of the most attractive perovskite-tvpe materials for the ferroelectric products due to its higher remanant polarization and the ability to withstand higher coercive fields. FRAM has been currently receiving increasing attention for one of future memory devices due to its ideal memory properties such as non-volatility, high charge storage, and faster switching operations. In this study, we first applied the damascene process using chemical mechanical polishing (CMP) to the fabricate the Pb<SUB>1.1</SUB> (Zr<SUB>0.52</SUB>Ti<SUB>0.48</SUB>)O₃ thin film capacitor in order to solve the problems of plasma etching such as low etching profile and ion charging. The structural characteristics were compared with specimens before and after CMP process of PZT films. The scanning electron microscopy (SEM) analysis was performed to compare the morphology surface characteristics of Pb<SUB>1.1</SUB>(Zr<SUB>0.52</SUB>Ti<SUB>0.48</SUB>)O₃ capacitors. The densification by the vertical sidewall patterning and charging-free ferroelectric capacitor could be obtained by the damascene process without remarkable difference of the characteristics.
2차원 층상 구조 전이금속 칼코겐화합물의 레이저 식각에 의한 직접-간접 띠간격 구조 연구
문은아,고필주,Moon, Eun-A,Ko, Pil-Ju 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.9
Single-layered transition metal dichalcogenides (TMDs) exhibit more interesting physical properties than those of bulk TMDs owing to the indirect to direct bandgap transition occurring due to quantum confinement. In this research, we demonstrate that layer-by-layer laser etching of molybdenum diselenide ($MoSe_2$) flakes could be controlled by varying the parameters employed in laser irradiation (time, intensity, interval, etc.). We observed a dramatic increase in the photoluminescence (PL) intensity (1.54 eV peak) after etching the samples, indicating that the removal of several layers of $MoSe_2$ led to a change from indirect to direct bandgap. The laser-etched $MoSe_2$ exhibited the single $MoSe_2$ Raman vibration modes at ${\sim}239.4cm^{-1}$ and ${\sim}295cm^{-1}$, associated to out-of-plane $A_{1g}$ and in-plane ${E^1}_{2g}$ Raman modes, respectively. These results indicate that controlling the number of $MoSe_2$ layers by laser etching method could be employed for optimizing the performance of nano-electronic devices.
산화제 첨가에 따른 WO<sub>3</sub> 박막의 CMP 평탄화 특성
이우선,고필주,김남훈,서용진,Lee, Woo-Sun,Ko, Pil-Ju,Kim, Nam-Hoon,Seo, Yong-Jin 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.1
Chemical mechanical polishing (CMP) process is one of the most useful methods for improving the surface roughness of films. The effects of CMP on the surface morphology of WO$_3$ films prepared by RF sputtering system were investigated in this paper. A removal rate of films increased, and the uniformity performance of surface decreased with the addition of an oxidizer to the tungsten slurry. Non-uniformity performance of surface was superior as its value was below 5 % when oxidizers of 5.0 vol% and 2.5 vol%, respectively, were added to the tungsten slurry. The optimized oxidizer concentration, reflected both the improved roughness values and hillock-free surface with the good uniformity performance, was 5.0 vol% as an atomic force microscopy(AFM) analysis of thin film topographies. Our CMP results will be a useful reference for advanced technology of thin films for gas sensor applications in the near future.
Bi<SUB>3.25</SUB>La<SUB>0.75</SUB>Ti₃O₁₂(BLT) 박막의 CMP 메커니즘 연구
신상헌(Sang-Hun Shin),고필주(Pil-Ju Ko),김남훈(Nam-Hoon Kim),이우선(Woo-Sun Lee) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
In this paper, we first applied the chemical mechanical polishing (CMP) process to the planarization of ferroelectric film in order to obtain a good planarity of electrode/ferroelectric film interface. Bi<SUB>3.25</SUB>La<SUB>0.75</SUB>Ti₃O₁₂ (BLT) ferroelectric film was fabricated by the sol-gel method. Removal rate and non-uniformity (WIWNU%) were examined by change of silica slurries pH(10.3, 11.3, 12.3). Surface roughness of BLT thin films before and after CMP process was inquired into by atomic force microscopy (AFM). Effects of silica slurries pH(10.3, 11.3, 12.3) were investigated on the CMP performance of BLT film by the surface analysis of X-ray photoelectron spectroscopy(XPS).
고집적 메모리 커패시터의 Vertical Sidewall Patterning을 위한 BTO 박막의 CMP 특성
徐龍辰(Yong-Jin Seo),高必周(Pil-Ju Ko),朴成祐(Sung-Woo Park),李康淵(Lee Kang Yeon),李愚宣(Woo-Sun Lee) 대한전기학회 2006 전기학회논문지C Vol.55 No.3
Most high-k materials are well known not to be etched easily, Some problems such as low etch rate poor sidewall angle, plasma damage, and process complexity were emerged from the high-density DRAM fabrication. Chemical mechanical polishing (CMP) by a damascene process was proposed to pattern this high-k material was polished with some commercial silica slurry as a function of pH variation. Sufficient removal rate with adequate selectivity to realize the pattern mask of tera-ethyl ortho-silicate (TEOS) film for the vertical sidewall angle were obtained. The changes of X-ray diffraction pattern and dielectric constant by CMP process were negligible. The planarization was also achieved for the subsequent multi-level processes. Our new CMP approach will provide a guideline for effective patterning of high-k material by CMP technique.
열처리공정에 따른 층상 ReSe<sub>2</sub> 디바이스의 접촉 저항 개선 연구
정판검 ( Pan Gum Jung ),이동진 ( Dong Jin Lee ),고필주 ( Pil Ju Ko ) 조선대학교 공학기술연구원 2017 공학기술논문지 Vol.10 No.1
The two-dimensional(2D) materials, including graphene, h-BN, layered transition metal-chalcogenides (TMC) and layered transition metal-dichalcogenides(TMDCs) are the next generation of the opto-electronic devices. In this paper, we report on the opto-electronic properties of back-gated field effect transistor(FET) based on ∼ 200 layered ReSe<sub>2</sub> at before and after annealing. After the annealing, the transition from schottky to ohmic contact in the Ti electrodes and ReSe<sub>2</sub> was observed, and the external quantum efficiency (EQE) of the ReSe<sub>2</sub> device was by increased 10% due to the improvement of the contact resistance between the electrodes and ReSe<sub>2</sub>. We obtained an EQE of 18.8% and 8.2% using 532 nm laser excitation, and ReSe<sub>2</sub> device is a good candidate for 2D material based ultra-thin opto-electronic device applications.
양호한 유기발광소자의 광학적 특성 개선을 위한 Anode 표면특성에 관한 연구
이우선(Woo-Sun Lee),최권우(Gwon-Woo Choi),고필주(Pil-Ju Ko),박주선(Ju-Sun Park),나한용(Han-Yong Na) 한국조명·전기설비학회 2008 한국조명·전기설비학회 학술대회논문집 Vol.2008 No.5월
ITO thin film is generally fabricated by various. methods such as spray, CVD, evaporation, electron gun deposition, direct current electroplating, high frequency sputtering, and reactive DC sputtering. However, some problems such as peaks, bumps, large particles, and pin-holes on the surface of ITO thin film were reported, which caused the destruction of color quality, the reduction of device life time, and short-circuit. Chemical mechanical polishing (CMF) process is one of the suitable solutions which could solve the problems