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Role of the Oxidizing Agent in the Etching of 4H-SiC Substrates with Molten KOH
Moonkyong Na,In-Ho Kang,Jeong Hyun Moon,Wook Bahng 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.11
A novel etching solution using molten potassium hydroxide (KOH) for the identification of dislocation types in a silicon-carbide (SiC) epilayer is identified. Threading screw dislocations (TSDs) and threading edge dislocations (TEDs) are rarely useful for size-based differentiation of etch pits in highly nitrogen (N)-doped SiC through conventional KOH etching. In this study, we report the role of sodium peroxide (Na2O2) and potassium dioxide (KO2) as oxidizing agent additives to the etchant for identifying the dislocation types in highly N-doped 4H-SiC. A Na2O2-KOH phase diagram was calculated to predict the chemical composition of the etchant. Solid-phase Na2O2 remained in the system when added to the etchant at concentrations greater than 13-wt% Na2O2, and it provided excess oxygen to the etchant. We experimentally confirmed that etch pit shapes became more hexagonal and that the etch pit sizes of TSDs and TEDs differed more greatly when more than 20-wt% Na2O2 was added to the etchant. We also found that the size distribution of TEDs was much smaller than that of TSDs after etching using Na2O2-KOH. Dissolved oxygen played an essential role in enhancing the anisotropic etching of highly N-doped SiC and allowed the dislocation types to be identified.
광대역 고온용 SAW filter 소자용 $La_3Ga_5SiO_{14}$ 단결정의 고밀도 플라즈마 식각
조현,Cho, Hyun 한국결정성장학회 2005 한국결정성장학회지 Vol.15 No.6
Effects of plasma composition, ion flux and ion energy on the etch rate, surface morphology and near surface stoichiometry of a single crystalline $La_3Ga_5SiO_{14}$ wafer have been examined in $Cl_2/Ar$ inductively coupled plasma (ICP) discharges. Maximum etch rate ${\sim}1600{\AA}/min$ was achieved either at relatively high source power $({\sim}1000W)$ or high $Cl_2$ content conditions in $Cl_2/Ar$ discharges. The etched surfaces showed similar or better RMS roughness values than those of the unetched control sample and the near surface stoichiometry was found not to be affected by ICP etching. [ $Cl_2/Ar$ ] 유도결합 플라즈마(ICP)내의 플라즈마 조성, 이온 flux 및 이온 에너지가 $La_3Ga_5SiO_{14}$ 단결정 wafer의 식각속도, 표면 양상 및 화학량론적 조성에 미치는 영향을 조사하였다. 비교적 높은 ICP source power$({\sim}1000W)$ 또는 높은 $Cl_2$ gas 유량 비율 조건으로부터 최고 약 $1600{\AA}/min$의 실용적이고 조절이 용이한 식각속도를 확보하였다. 식각된 $La_3Ga_5SiO_{14}$ 표면은 식각 이전과 비슷하거나 더 낮은 표면 조도 특성을 나타내었으며 식각 공정 전, 후 표면의 화학량론적 조성에 있어서의 변화는 없는 것으로 조사되었다.
STI--CMP 공정에서 Torn oxide 결함 해결에 관한 연구
서용진,정헌상,김상용,이우선,이강현,장의구 한국전기전자재료학회 2001 전기전자재료학회논문지 Vol.14 No.1
STI(shallow trench isolation)-CMP(chemical mechanical polishing) process have been substituted for LOCOS(local oxidation of silicon) process to obtain global planarization in the below sub-0.5㎛ technology. However TI-CMP process, especially TI-CMP with RIE(reactive ion etching) etch back process, has some kinds of defect like nitride residue, torn oxide defect, etc. In this paper, we studied how to reduced torn oxide defects after STI-CMP with RIE etch back processed. Although torn oxide defects which can occur on trench area is not deep and not severe, torn oxide defects on moat area is not deep and not severe, torn oxide defects on moat area is sometimes very deep and makes the yield loss. Thus, we did test on pattern wafers which go through trench process, APECVD process, and RIE etch back process by using an IPEC 472 polisher, IC1000/SUVA4 PAD and KOH base slurry to reduce the number of torn defects and to study what is the origin of torn oxide defects.
Stable, amphiphobic, and electrically conductive coating on flexible polyimide substrate
전현수,Wenhui Yao,Kyeong-Hwan Kim,심준형,조영래 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-
A flexible electrode material, with good surface amphiphobicity and mechanical and chemical stability,was fabricated herein using a simple process. A superhydrophilic nanopillar array with a high aspect ratiowas formed on a flexible polyimide substrate by radio-frequency plasma etching using a sputtering system. A superhydrophobic and electrically conductive silver nanopillar array was constructed by sequentiallydepositing Ag thin films without breaking the vacuum. Good surface amphiphobicity was achievedby fluorination on the Ag nanopillar arrays using 1H,1H,2H,2H-perfluorodecanethiol (PFDT) solution. Forthe optimal sample, the contact angles for water and ethanol were approximately 166 and 120, respectively. The water sliding angle and contact angle hysteresis were 3 and 1, respectively, indicating thepotential of the arrays to perform well in self-cleaning tests. Fingerprints were not observed after pressingthe thumb on the surface, indicating the excellent anti-fingerprint property. Even after 10,000 bendingcycles, the change in the electrical resistance was close to unity, and the surface amphiphobicity waswell maintained, indicating the excellent mechanical durability. The superior electrical stability wasexhibited even after immersion in different solutions such as water and acid. The superior performancesrender the Ag nanopillar array with PFDT a good candidate for use as a flexible electrode material.
Wafer size effect on material removal rate in copper CMP process
유민종,장수천,박인호,정해도 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6
The semiconductor industry has employed the Chemical mechanical planarization (CMP) to enable surface topography control. Copperhas been used to build interconnects because of its low-resistivity and high-electromigration. In this study, the effect of wafer size onthe Material removal rate (MRR) in copper CMP process was investigated. CMP experiments were conducted using copper blanket waferswith diameter of 100, 150, 200 and 300 mm, while temperature and friction force were measured by infrared and piezoelectric sensors. The MRR increases with an increase in wafer size under the same process conditions. The wafer size increased the sliding distanceof pad, resulting in an increase in the process temperature. This increased the process temperature, accelerating the chemical etching rateand the dynamic etch rate. The sliding distance of the pad was proportional to the square of the wafer radius; it may be used to predictCMP results and design a CMP machine.
Mechanical strength enhancement of carbon fibers by hybrid surface treatments
김관우,정진수,안계혁,김병주 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
In this study, surface defects and surface layer etching of CF were attempted by using electrochemical oxidation method and surface oxidation treatment was performed. Also, the microstructure was strengthened by the electron beam method and the change of the mechanical strength (tensile properties, interfacial shear strength) was investigated. Depending on the hybrid surface treatment of the carbon fibers, the diameter of the fibers decreased from the initial 7 μm to 6.5 μ m. The hybrid surface treatment of carbon fiber, which has a structure similar to onion skin, causes repetitive changes in the crystal structure due to the repetitive pattern of oxidation (1st amorphous oxidation, 2nd disordered graphitic structure oxidation) and also reduces the diameter of the carbon fibers. The development of hybrid surface treatments is expected to gradually increase the tensile strength of carbon fibers by more than 50%.
Seo, Yong-Jin,Lee, Kyoung-Jin,Kim, Sang-Yong,Lee, Woo-Sun The Korean Institute of Electrical Engineers 2003 KIEE International Transactions on Electrophysics Vol.3C No.1
In this paper, we have studied the in-situ end point detection (EPD) for direct chemical mechanical polishing (CMP) of shallow trench isolation (STI) structures without the reverse moat etch process. In this case, we applied a high selectivity $1n (HSS) that improves the silicon oxide removal rate and maximizes oxide to nitride selectivity Quite reproducible EPD results were obtained, and the wafer-to-wafer thickness variation was significantly reduced compared with the conventional predetermined polishing time method without EPD. Therefore, it is possible to achieve a global planarization without the complicated reverse moat etch process. As a result, the STI-CMP process can be simplified and improved using the new EPD method.
Paul-Chang Lin,Jin-Hai Xu,Hong-Liang Lu,David Wei Zhang,Pei Li 대한전자공학회 2017 Journal of semiconductor technology and science Vol.17 No.3
Through silicon via (TSV) technology is extensively used in 3D IC integrations. The special structure of the TSV is realized by CMP (Chemically Mechanical Polishing) process with a high Cu removal rate and, low dishing, yielding fine topography without defects. In this study, we investigated the electrochemical behavior of copper slurries with various inhibitors in the Cu CMP process for advanced TSV applications. One of the slurries was carried out for the most promising process with a high removal rate (~18000 Å/Min @ 3 psi) and low dishing (~800 Å), providing good microstructure. The effects of pH value and H₂O₂ concentration on the slurry corrosion potential and Cu static etching rate (SER) were also examined. The slurry formula with a pH of 6 and 2% H₂O₂, hadthe lowest SER (~75 Å/Min) and was the best for TSV CMP. A novel Cu TSV CMP process was developed with two CMPs and an additional annealing step after some of the bulk Cu had been removed, effectively improving the condition of the TSV Cu surface and preventing the formation of crack defects by variations in wafer stress during TSV process integration.