• 한국초전도ㆍ저온공학회논문지
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• 제20권4호
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• pp.20-25
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• 2018

Niobium nitride (NbN) superconducting thin films with the thickness of 100 and 400 nm have been deposited on the surfaces of silicon oxide/silicon substrates using a sputtering method. Their superconducting properties have been evaluated in terms of the transition temperature, critical magnetic field, and critical current density. In addition, the NbN films were patterned in a line with a width of $10{\mu}m$ by a reactive ion etching (RIE) process for their characterization. This study proves the applicability of the standard complementary metal-oxide-semiconductor (CMOS) process in the fabrication of superconducting thin films without considerable degradation of superconducting properties.

• 한국안전학회지
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• 제38권2호
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• pp.30-35
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• 2023

Acetone is a widely used Volatile Organic Compound (VOC) in industries and laboratories. However, acetone affects human health adversely and causes fires and explosions. Early acetone detection and improved personnel training in safety and emergency management are necessary to prevent acetone-related accidents. The multi-VOC acetone detectors used currently have a sensitivity and selectivity limit. In this study, we discovered that Pt-loaded iron oxide (a metal oxide semiconductor) conversely, has high detection and selectivity for very low-levels of acetone gas. The loaded Pt catalyzes the reaction between the sensing materials' surface and the oxygen molecules in the air; this optimizes acetone detection and can decrease acetone-related illnesses, fires and explosions.

• 센서학회지
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• 제33권1호
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• pp.48-55
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• 2024

Metal-oxide-based semiconductor gas sensors are widely used because of their advantages, such as high response and simple sensing mechanism. Recently, with the rapid progress in sensor networks, computing power, and microsystem technology, sensor applications are expanding to various fields, such as food quality control, environmental monitoring, healthcare, and artificial olfaction. Therefore, the development of highly selective gas sensors is crucial for practical applications. This article reviews the developments in novel sensor design consisting of sensing films and physical and chemical filters for highly selective gas sensing. Unlike conventional sensors, the sensor structures with filters can separate the sensing and catalytic reactions into independent processes, enabling selective and sensitive gas sensing. The main objectives of this study are directed at introducing the role of various filters in gas-sensing reactions and promising sensor applications. The highly selective gas sensors combined with a functional filter can open new pathways toward the advancement of high-performance gas sensors and electronic noses.

• 한국산학기술학회논문지
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• 제7권3호
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• pp.344-349
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• 2006

[ $60{\sim}70nm$ ] 급의 design rule을 가진 고집적 반도체 소자를 제작하려면, 트랜지스터 형성 이후의 공정에서 thermal budget을 줄이기 위하여 공정의 온도를 낮추는 것이 중요하다. 본 연구에서는 고온의 습식 산화막을 대체할 수 있는 저온의 LPCVD (Low-Pressure Chemical Vapor Deposition) $SiO_2$(LTO : Low-Temperature Oxide) 박막 증착공정을 제시하였으며, ONO (Oxide/Nitride/Oxide) 구조의 커패시터를 형성하여 증착된 LTO 박막의 전기적인 신뢰성을 평가하였다. LTO 박막은 5 MV/cm 이하의 전기장 영역에서는 고온의 습식 산화막과 크게 차이가 없는 누설전류 특성을 보였으나, 더 높은 전기장의 영역에서는 훨씬 더 우수함을 보여주었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.273.2-273.2
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• 2014

Sputtering process has been widely used in Si-based semiconductor industry and it is also an ideal method to deposit transparent oxide materials for thin-film transistors (TFTs). The oxide films grown at low temperature by conventional RF sputtering process are typically amorphous state with low density including a large number of defects such as dangling bonds and oxygen vacancies. Those play a crucial role in the electron conduction in transparent electrode, while those are the origin of instability of semiconducting channel in oxide TFTs due to electron trapping. Therefore, post treatments such as high temperature annealing process have been commonly progressed to obtain high reliability and good stability. In this work, the scheme of electron-assisted RF sputtering process for high quality transparent oxide films was suggested. Through the additional electron supply into the plasma during sputtering process, the working pressure could be kept below $5{\times}10-4Torr$. Therefore, both the mean free path and the mobility of sputtered atoms were increased and the well ordered and the highly dense microstructure could be obtained compared to those of conventional sputtering condition. In this work, the physical properties of transparent oxide films such as conducting indium tin oxide and semiconducting indium gallium zinc oxide films grown by electron-assisted sputtering process will be discussed in detail. Those films showed the high conductivity and the high mobility without additional post annealing process. In addition, oxide TFT characteristics based on IGZO channel and ITO electrode will be shown.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.13.1-13.1
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• 2009

Transparent electronics has attracted many interests, for it can open new applications for consumer electronics, transportation, business, and military. Among them, display backplane, thin film transistor (TFT) array would be the most attractive application. Many researchers have been investigating oxide semiconductors for transparent channel material of TFT since the report for transparent amorphous oxide semiconductor (TAOS) TFT by Hosono group and ZnO TFT by Wager group. Especially, oxide TFTs have been intensively investigated during a couple of years since the first demonstration of ZnO-TFT driving AM-OLED. Many papers regarding the fabrication and performance of oxide TFTs, and active matrix display driven by oxide TFTs have been reported. Now lots of people have confidence in the competitiveness of oxide TFTs for the backplane of AM-Display. Especially, high mobility, uniformity, fairly good stability, and low cost process make oxide TFTs applied even to a large size AM-OLED. Last year, Samsung mobile display, former SID, reported 12" AM-OLED driven by IZGO-TFT and it seems that the remained issue for the mass production is the bias temperature stability. Here, we will introduce the application of oxide TFT and important issue for oxide TFT to be used for the direct printing.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.434-435
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• 2012

Plasma enhanced chemical vapor deposition (PECVD) silicon dioxide thin films have many applications in semiconductor manufacturing such as inter-level dielectric and gate dielectric metal oxide semiconductor field effect transistors (MOSFETs). Fundamental chemical reaction for the formation of SiO2 includes SiH4 and O2, but mixture of SiH4 and N2O is preferable because of lower hydrogen concentration in the deposited film [1]. It is also known that binding energy of N-N is higher than that of N-O, so the particle generation by molecular reaction can be reduced by reducing reactive nitrogen during the deposition process. However, nitrous oxide (N2O) gives rise to nitric oxide (NO) on reaction with oxygen atoms, which in turn reacts with ozone. NO became a greenhouse gas which is naturally occurred regulating of stratospheric ozone. In fact, it takes global warming effect about 300 times higher than carbon dioxide (CO2). Industries regard that N2O is inevitable for their device fabrication; however, it is worthwhile to develop a marginable nitrous oxide free process for university lab classes considering educational and environmental purpose. In this paper, we developed environmental friendly and material cost efficient SiO2 deposition process by substituting N2O with O2 targeting university hands-on laboratory course. Experiment was performed by two level statistical design of experiment (DOE) with three process parameters including RF power, susceptor temperature, and oxygen gas flow. Responses of interests to optimize the process were deposition rate, film uniformity, surface roughness, and electrical dielectric property. We observed some power like particle formation on wafer in some experiment, and we postulate that the thermal and electrical energy to dissociate gas molecule was relatively lower than other runs. However, we were able to find a marginable process region with less than 3% uniformity requirement in our process optimization goal. Surface roughness measured by atomic force microscopy (AFM) presented some evidence of the agglomeration of silane related particles, and the result was still satisfactory for the purpose of this research. This newly developed SiO2 deposition process is currently under verification with repeated experimental run on 4 inches wafer, and it will be adopted to Semiconductor Material and Process course offered in the Department of Electronic Engineering at Myongji University from spring semester in 2012.

• 한국진공학회지
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• 제15권6호
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• pp.630-636
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• 2006

플래시 메모리 반도체의 고집적화와 고밀도화가 진행함에 따라 플래시 메모리의 트랜지스터 안 선폭을 중심으로 게이트 패턴의 미세화가 진행 중이다. 최근 100 nm 이하의 선폭을 구현하기 위해서 ONO(oxide-nitride-oxide)를 사용하기 위한 연구가 개발 중이고, 이러한 100 nm이하의 미세 선폭으로 갈수록 식각 속도와 식각의 프로파일은 중요한 요인으로 작용하고 있다. ICP 식각 장비를 이용하여, power를 50 W 증가 하였을 때, 각각 식각 속도와 포토레지스트와의 선택비를 확인 한 결과 platen power를 100 W로 올렸을 경우 가장 좋은 결과를 나타내었다. 100 W에서 HBr가스의 유량에 변화를 주었을 경우 가스의 양을 증가 할수록 식각 속도는 감소하였지만, 포토레지스트와의 선택비는 증가함을 보였다. 유도결합 플라즈마 식각 장비를 가지고 platen power를 100 W, HBr gas를 35 sccm 공급하여 하부 층에 노치가 형성이 안되고, 식각 속도 320 nm/min, 감광액과의 선택비 3.5:1, 측면식각 프로파일이 수직인 공정 조건을 찾았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.206.1-206.1
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• 2015

최근에 금속산화물을 증착하는 방법으로 용액공정이 주목 받고 있다. 용액 공정은 대기압에서 매우 간단한 방법으로 복잡한 공정과정을 요구하지 않기 때문에 박막을 경제적으로 간단하게 형성할 수 있다. 하지만 용액공정을 통해 형성한 박막에는 소자의 특성을 열화 시키는 solvent와 탄소계열의 불순물을 많이 포함하고 있어 고온의 열처리가 필수적이다. 박막의 품질을 향상시키기 위해서 다양한 열처리 방법들이 이용되고 있으며, 일반적인 열처리 방법으로는 furnace를 이용한 conventional thermal annealing (CTA)이 많이 이용되고 있다. 하지만, 최근에는 microwave를 이용한 공정이 주목 받고 있다. Microwave energy는 CTA보다 효과적으로 비교적 낮은 온도에서 높은 열처리 효과를 나타낸다. 본 실험은 n-type Silicon 기판에 solution-ZrO2 산화막을 형성 후, oven baking을 한 뒤, CTA와 microwave를 이용하여 solvent와 불순물을 제거 하였다. 전기적 특성을 확인하기 위해 solution ZrO2 산화막 위에 E-beam evaporator를 이용해 Ti 금속 전극을 증착하여 Metal-Oxide-Semiconductor (MOS) capacitor를 제작하였다. 다음으로, PRECISION SEMICONDUCTOR PARAMETER ANALYZER (4156B)를 이용하여, capacitance-voltage (C-V) 특성 및 current-voltage (I-V) 특성을 비교하였다. 다음으로, CTA를 통하여 제작한 소자와 전기적 특성을 비교하였다. 그 결과, Microwave irradiation으로 열처리한 MOS capacitor 소자에서 capacitance 값과 flat band voltage, hysteresis 등이 개선되는 효과를 확인하였다. Microwave irradiation 열처리는 100oC 미만의 온도에서 공정이 이루어짐에도 불구하고 시료 내에서의 microwave 에너지의 흡수가 CTA 공정에서의 열에너지 흡수보다 훨씬 효율적으로 이루어지며, 결과적으로 ZrO2 용액의 불순물과 solvent를 낮은 온도에서 제거하여 고품질 박막 형성에 매우 효과적이라는 것을 나타낸다. 따라서, microwave irradiation 열처리 방법은 비정질 산화막이 포함되는 박막 transistor 소자 제작에 대하여 결정적인 열처리 방법이 될 것으로 기대한다.

• 한국전기전자재료학회논문지
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• 제26권4호
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• pp.271-274
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• 2013

Power Metal Oxide Semiconductor Field Effect Transistor's (MOSFETs) are well known for superior switching speed, and they require very little gate drive power because of the insulated gate. In these respects, power MOSFETs approach the characteristics of an "ideal switch". The main drawback is on-resistance RDS(on) and its strong positive temperature coefficient. While this process has been driven by market place competition with operating parameters determined by products, manufacturing technology innovations that have not necessarily followed such a consistent path have enabled it. This treatise briefly examines metal oxide semiconductor (MOS) device characteristics and elucidates important future issues which semiconductor technologists face as they attempt to continue the rate of progress to the identified terminus of the technology shrink path in about 2020. We could find at the electrical property as variation p base dose. Ultimately, its ON state voltage drop was enhanced also shrink chip size. To obtain an optimized parameter and design, we have simulated over 500 V Field ring using 8 Field rings. Field ring width was $3{\mu}m$ and P base dose was $1e15cm^2$. Also the numerical multiple $2.52cm^2$ was obtained which indicates the doping limit of the original device. We have simulated diffusion condition was split from $1,150^{\circ}C$ to $1,200^{\circ}C$. And then $1,150^{\circ}C$ diffusion time was best condition for break down voltage.