• Transactions on Electrical and Electronic Materials
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• 제12권2호
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• pp.56-59
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• 2011

The characterization of the chemical mechanical polishing (CMP) process for undensified phophosilicate glass (PSG) film is reported using design of experiments (DOE). DOE has been used by experimenters to understand the relationship between the input variables and responses of interest in a simple and efficient way, and it typically is beneficial for determining the appropriatesize of experiments with multiple process variables and making statistical inferences for the responses of interest. The equipment controllable parameters used to operate the machine consist of the down force of the wafer carrier, pressure on the back side wafer, table and spindle speeds (SS), slurry flow (SF) rate, pad condition, etc. None of these are independent ofeach other and, thus, the interaction between the parameters also needs to be understoodfor improved process characterization in CMP. In this study, we selected the five controllable equipment parameters the most recommendedby process engineers, viz. the down force (DF), back pressure (BP), table speed (TS), SS, and SF, for the characterization of the CMP process with respect to the material removal rate and film uniformity in percentage terms. The polished material is undensified PSG which is widely used for the plananization of multi-layered metal interconnects. By statistical modeling and the analysis of the metrology data acquired from a series of $2^{5-1}$ fractional factorial designs with two center points, we showed that the DF, BP and TS have the greatest effect on both the removal rate and film uniformity, as expected. It is revealed that the film uniformity of the polished PSG film contains two and three-way interactions. Therefore, one can easily infer that process control based on a better understanding of the process is the key to success in current semiconductor manufacturing, in which the size of the wafer is approaching 300 mm and is scheduled to continuously increase up to 450 mm in or slightly after 2012.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 INTERNATIONAL SYMPOSIUM ON SOIL & GROUNDWATER ENVIRONMENT
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• pp.59-61
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• 2005

In Korea, hundreds of abandoned and closed coal and metallic mines are present in the steep mountain valleys due to the depression of the mining industry since the late 1980s. From these mines, enormous amounts of coal waste were dumped on the slopes, which causes sedimentation and acid mine drainage (AMD) to be discharged directly into streams causing detrimental effects on soil and water environments. A limestone slurry by-product (lime cake) is produced from the Solvay process in manufacturing soda ash. It has very fine particles, low hydraulic conductivities ($10^{-8}{\sim}10^{-9}cm/sec$), high pH, high EC due to the presence of CaO, MgO and $CaCl_2$ as major components, and traces of heavy metals. Due to these properties, it has potential to be used as a neutralizer for acid-producing materials. A field plot experiment was used to test the application of lime cake for reclaiming coal wastes. Each plot was 20 x 5 m (L x W) in size on a 56% slope. Treatments included a control (waste only), calcite ($CaCO_3$), and lime cake. The lime requirement (LR) for the coal waste to pH 7.0 was determined and treatments consisted of adding 100%, 50%, and 25% of the LR. The lime cake and calcite were also applied in either a layer between the coal waste and topsoil or mixed into the topsoil and coal waste. Each plot was hydroseeded with grasses and planted with trees. In each plot, surface runoff and subsurface water were collected. The lime cake treatments increased the pH of coal waste from 3.5 to 6, and neutralized the pH of the runoff and leachate of the coal waste from 4.3 to 6.7.

• 한국산학기술학회논문지
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• 제9권4호
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• pp.892-898
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• 2008

3차원 쾌속 조형법은 컴퓨터에 저장되어있는 객체 데이터를 이용하여 시제품을 제작하는 기술로써, 기존의 나무나 클레이, 혹은 주조 제작방식과는 달리 원하는 위치에 요구되는 재료를 직접 적층함으로써 원형제품을 제작함을 특징으로 한다. 스테레오리쏘그래피, 용융 점착법, 선택적 레이저 소결법, 판상 제작법 등의 다양한 3차원 쾌속 조형법이 개발되었으나, 그 중에서 잉크젯을 통한 3차원 쾌속 조형법은 잉크화된 조형재료를 통해 구조적으로 기능이 가능한 원형제품의 제작이 가능하다는 특징이 있다. 그러나, 기능성 원형제품의 제작을 위해서는 잉크의 고농도화가 요구되며, 이로 인해 잉크 점도가 상승되어 젯팅 신뢰성이 저하되는 문제점이 있었다. 본 논문에서는 3차원 쾌속 조형법을 위한 최적 젯팅조건을 도출하기 위해 슬러리 타입 세라믹 상변화 잉크의 음파 전달속도 측정과 음파 전달속도가 젯팅에 미치는 영향을 고찰하도록 한다.

• 한국지반공학회논문집
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• 제19권5호
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• pp.233-241
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• 2003

최근 들어 지오텍스타일 튜브공법은 과거의 임시공법의 한계를 극복하고 다양한 분야에서 주요적용공법으로 활용이 확대되고 있다. 본 연구에서는 수치해석기법을 활용하여 지오텍스타일 튜브의 시공과정에서의 거동에 대하여 연구를 수행하였으며, 수치해석결과를 기존 연구 발표된 현장 모형시험 결과와 비교 분석하였다. 수치해석은 평면변형해석과 3차원 유한요소해석 기법을 이용하여 채움 과정에서 발생하는 정수압에 따른 지오텍스타일 튜브의 형태변화와 실대형 현장실험 결과를 비교 분석하였다. 또한, 3차원 유한요소해석에서는 정수압과 지오텍스타일의 강성변화에 따른 매개변수 해석을 통하여 지오텍스타일 튜브공법의 3차원 유한요소해석 기법을 제시하였다. 평면변형 해석이론에 의한 수치해석은 지오텍스타일 튜브 전용해석 프로그램인 GeoCoPS(version 2.0)를 활용하였으며, 3차원 유한요소 해석은 범용 유한요소해석 프로그램 ABAQUS(version 5.88)를 이용하였다. 평면변형 해석과 3차원 유한요소해석 결과 모두 실대형 현장실험 결과와 근접한 거동을 나타내었으며 적용토사의 종류 및 해석상의 가정사항으로 약간의 차이점들은 발생하지만 평면변형해석 및 3차원 유한요소해석방법을 통하여 채움과정에서의 지오텍스타일 튜브의 거동을 예측할 수 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.136-139
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• 2004

The requirement of planarity, such as with-in-wafer nonuniformity, post thickness range, have become increasingly stringent as critical dimensions of devices are decreased and a better control of a planarity become important. The key factors influencing the planarity capability of the CMP process have been well understood through numerous related experiments. These usually include parameters such as process pressures, relative velocities, slurry temperature, polishing pad materials and polishing head structure. Many study have been done about polishing pad and its groove structure because it's considered as one of the key factors which can decide wafer uniformity directly. But, not many study have been done about polisher head structure, especially about polisher head plate design. The purpose of this paper is to know how the plate structure can affect wafer uniformity and how to deteriorate wafer yield. Furthermore, we studied several new designed plate to improve wafer uniformity and also improve wafer yield.

• Geomechanics and Engineering
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• 제12권3호
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• pp.523-539
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• 2017

Clay soils are typical for their swelling properties upon absorption of water during rains and development of cracks during summer time owing to the profile desorption of water through the inter-connected soil pores by water vapour diffusion leading to evaporation. This type of unstable soil phenomenon by and large poses a serious threat to the strength and stability of structures when rest on such type of soils. Even as lime and cement are extensively used for stabilization of clay soils it has become imperative to find relatively cheaper alternative materials to bring out the desired properties within the clay soil domain. In the present era of catastrophic environmental degradation as a side effect to modernized manufacturing processes, industrialization and urbanization the creative idea would be treating the waste products in a beneficial way for reuse and recycling. Bottom ash and ecosand are construed as a waste product from cement industry. An optimal combination of bottom ash-eco sand can be thought of as a viable alternative to stabilize the clay soils by means of an effective dispersion dynamics associated with the inter connected network of pore spaces. A CATIA model was created and imported to ANSYS Fluent to study the dispersion dynamics. Ion migration from the bottom ash-ecosand pile was facilitated through natural formation of cracks in clay soil subjected to atmospheric conditions. Treated samples collected at different curing days from inner and outer zones at different depths were tested for, plasticity index, Unconfined Compressive Strength (UCS), free swell index, water content, Cation Exchange Capacity (CEC), pH and ion concentration to show the effectiveness of the method in improving the clay soil.

• 대한토목학회논문집
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• 제35권5호
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• pp.1083-1096
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• 2015

본 연구는 준설매립과정에서의 관중혼합 거동을 3차원 전산유체역학(CFD, Computational Fluid Dynamics)을 통해 분석한 연구로 준설토 배송관과 개질재 주입관이 합류하며 발생되는 이상(2-phase)유체의 혼합효율을 사전 평가함으로써 관중혼합 양상을 고찰하는 물리실험의 시행착오를 줄여 경제성을 증진시키는데 연구목적을 두고 있다. 수치해석에 이용된 CFD 코드는 OpenFOAM$^{(R)}$이고, 몇 가지의 기본가정 하에 배송관-주입관의 관경과 합류각을 변화시켜 총 18가지 경우에 대한 삼상(3-phase)유체 거동을 모의하였다. 그 결과 혼합효율에 대한 우열은 있었으나 그 차이는 미미하였고, 모든 경우에서 각 재료 사이의 경계층이 뚜렷하게 형성되었다. 이러한 현상을 극복하기 위한 보완 실험을 통해 경계층 파쇄(破碎)를 위한 관 내 부속 구조물이 고안되었으며, 본 연구에서 제시된 구조물은 단거리 배송관로 내 준설토와 개질재의 혼합효율을 크게 향상시킬 수 있음을 확인할 수 있었다.

• 대한기계학회논문집A
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• 제38권8호
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• pp.863-867
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• 2014

본 연구에서는 화학 기계 연마(CMP) 공정 중 발생하는 다양한 영역대의 신호를 분석하기 위하여 음향 방출 센서(AE)를 이용하였다. 특히 음향 방출 센서는 공정 중 발생하는 기계적 소음을 전기적 신호로 변환하기 용이하며, 특히 고주파 영역대의 신호를 감지하기에 용이하다. 그래서 본 연구에서는 CMP 장비에 음향 방출 센서를 부착하여 CMP 공정 중 발생하는 신호를 동시에 획득하였다. 본 음향 방출 모니터링 시스템은 CMP 공정 조건 변화 및 패드, 슬러리, 웨이퍼와 같은 소모재의 변화에 따른 신호분석을 하기 위해 제작 되었다. 본 연구에서는 산화막 웨이퍼와 구리막 웨이퍼에 본 시스템을 적용하였다. 음향 방출 센서로 획득한 신호로 Raw 신호 분석, 주파수 분석, 진폭 분석을 통해서 CMP 공정중 발생하는 현상을 분석하였다. 최종적으로 다양한 대역폭의 신호를 음향 방출 센서로 획득하여 CMP 공정 모니터링이 가능함을 확인하고자 하였다.

• 한국정밀공학회지
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• 제16권6호
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• pp.52-57
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• 1999

Funtional metal prototypes are often required in numerous industrial applications. These components are typically needed in the early stage of a project to determine form, fit and function. Recent R/P(Rapid Prototyping) part are made of soft materials such as plastics, wax, paper, these master models cannot be employed durable test in real harsh working environment. Parts by direct metal rapid tooling method, such as laser sintering, by now are hard to get net shape, pores of the green parts of powder casting method must be infiltrated to get proper strength as tool, and new type of 3D direct tooling system combining fabrication welding arc and cutting process is reported by song etc. But a system which can build directly 3D parts of high performance functional material as metal part would need long period of system development, massive investment and other serious obstacles, such as patent. In this paper, through the rapid tooling process as silicon rubber molding using R/P master model, and fabricate wax pattern in that silicon rubber mold using vacuum casting method, then we tranlsated the wax patterns to numerous metal prototypes by new investment casting process combined conventional investment casting with rapid pototyping & rapid tooling process. with this wax-injection-mold-free investment casting, we developed new investment casting process of fabricating numerous functional metal prototypes from one master model, combined 3-D CAD, R/P and conventional investment casting and tried to expect net shape measuring total dimension shrinkage from R/P part to metal part.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권8호
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• pp.348-353
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• 2003

This paper was the research of high voltage suspension insulator (400 [kN]) including pottery stone, feldspar, clay and alumina of 17 [wt%]. The slurry was fabricated after ball milling mixed raw materials. Green compacts were made by the extrusion of jiggering method and were sintered at 1300[$^{\circ}C$] for 50 [min.] in the tunnel kiln. The sintered density was reached to 97% of theoretical density, and the bending strength was 1658 [k $g_{f}$/$\textrm{cm}^2$] and hardness and fracture toughness which was measured by ICL( indentation crack length ) method were 1658 (kgf/$\textrm{cm}^2$) and 27.5 [Gpa], respectively. In measurement of tana and insulation break voltage of 400 (kN) porcelain, tan$\delta$ took some numerical value between 17${\times}$10$_{-3}$ and 61${\times}$10$_{-3}$ and insulation break voltage value was 19.9$\pm$1.4 [㎸/mm]. The test was performed to research whether the shape of pin affect a overvoltage break load or not As a consequence, when a pin was designed a pin diameter 51 [mm] with the bottom form of two-step constructed with straight in the suspension insulator, Insulator showed overvoltage break load 52 [ton] of the highest value and reflected a fine characteristic in aged deterioration test which is one of the accelerated aging test. Also it could be confirmed a fine characteristic through performing the test that electrical property of insulator was established correctly in accordance with IEC 60383-1 standards.s.