• 한국전기전자재료학회논문지
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• 제35권1호
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• pp.80-85
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• 2022

ZnO-based transparent conductive films have been widely studied to achieve high performance optoelectronic devices such as next generation flexible and transparent display systems. In order to achieve a transparent flexible ZnO-based device, a low temperature growth technique using a flexible polymer substrate is required. In this work, high quality flexible ZnO films were grown on colorless polyimide substrate using atomic layer deposition (ALD). Transparent ZnO films grown from 80 to 200℃ were fabricated with a metal-semiconductor-metal structure photodetectors (PDs). As the growth temperature of ZnO film increases, the photocurrent of UV PDs increases, while the sensitivity of that decreases. In addition, it is found that the response times of the PDs become shorter as the growth temperature increases. Based on these results, we suggest that high-quality ZnO film can be grown below 200℃ in an atomic layer deposition system, and can be applied to transparent and flexible UV PDs with very fast response time and high photocurrent.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1943-1950
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• 2009

The development of high voltage Insulated Gate Bipolar Transistor (IGBT) have given new device advantage in the areas where they compete with conventional GTO (Gate Turnoff Thyristor) technology. The IGBT combines the advantages of a power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) and a bipolar power transistor. The change of electrical characteristics for IGBT is mainly coming from the change of characteristics of MOSFET at the input gate and the PNP transistors at the output. The gate oxide structure gives the main influence on the changes in the electrical characteristics affected by environments such as radiation and temperature, etc.. The change of threshold voltage, which is one of the important design parameters, is brought by charge trapping at the gate oxide. In this paper, the electrical characteristics are simulated by SPICE simulation, and the parameters are found to design optimized circuits.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.163-166
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• 2002

We investigated structural and electrical properties of Metal-Oxide-Semiconductor(MOS) structure using Hafnium $oxide(HfO_{2})$ as high-k gate dielectric material. $HfO_{2}$ films are ultrathin gate dielectric material witch have a thickness less than 2.0nm， so it is spotlighted to be substituted $SiO_{2}$ as gate dielectric material. In this paper We have grown $HfO_{2}$ films with pt electrode on P-type Silicon substrate by RF magnetron sputtering system using $HfO_{2}$ target and oserved the property of semiconductor-oxide interface. Using pt electrode, it is necessary to be annealed at ${300^{\circ}C}$. This process is to increase an adhesion ratio between $HfO_{2}$ films with pt electrode. In film deposition process, the deposition time of $HfO_{2}$ films is an important parameter. Structura1 properties are invetigated by AES depth profile, and electrical properties by Capacitance-Voltage characteristic. Interface trap density are measured to observe the interface between $HfO_{2}$ with Si using High-frequency(1MHz) C-V and Quasi - static C-V characteristic.

• 한국세라믹학회지
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• 제33권5호
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• pp.572-582
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• 1996

전류밀도, 70mA/cm2와 전류인가시간, 5초, 10초 조건의 양극반응으로 다공성 실리콘을 제작하여 800~110$0^{\circ}C$에서 열산화시킨 후 AI 전극을 증착시켜 만든 MOS(Metal Oxide Semiconductor) 구조의 C-V(Capacilance-Voltage) 특성을 조사하였다. 800, 90$0^{\circ}C$의 저온과 20~30분 이내의 단시간 산화에서는 산화막의 유전상수가 보통의 열산화막보다 크게 나타나고, 산화온도가 110$0^{\circ}C$의 고온과 60분 이상의 장시간 산화의 경우에는 3.9에 근접한 값을 갖는다. 이는 다공성 실리콘 산화막내에 존재하는 산화되지 않은 silicon들에 의한 효과와 표면적 증가에 의한 정전용량의 증가 효과가 복합적으로 작용하는 것이 그 원인이라 생각된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.268-268
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• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.

• E2M - 전기 전자와 첨단 소재
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• 제9권5호
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• pp.463-469
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• 1996

The double insulating layer consisting of anodic oxide and ZnS was formed for HgCdTe metal insulator semiconductor(MIS) structure. ZnS was evaporated on the anodic oxide grown in H$_{2}$O$_{2}$ electrolyte. Recently, this insulating mechanism for HgCdTe MIS has been deeply studied for improving HgCdTe surface passivation. It was found through TEM observation that an interface layer is formed between ZnS and anodic oxide layers for the first time in the study of this area. EDS analysis of chemical compositions using by electron beam of 20.angs. in diameter and XPS depth composition profile indicated strongly that the new interface is composed of ZnO. Also TEM high resolution image showed that the structure of oxide layer has been changed from the amorphous state to the microsrystalline structure of 100.angs. in diameter after the evaporation of ZnS. The double insulating layer with the resistivity of 10$^{10}$ .ohm.cm was estimated to be proper insulating layer of HgCdTe MIS device. The optical reflectance of about 7% in the region of 5.mu.m showed anti-reflection effect of the insulating layer. The measured C-V curve showed the large shoft of flat band voltage due to the high density of fixed oxide charges about 1.2*10$^{12}$ /cm$^{2}$. The oxygen vacancies and possible cationic state of Zn in the anodic oxide layer are estimated to cause this high density of fixed oxide charges.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.77.1-77.1
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• 2013

Atomic layer deposition (ALD) is known for its self-limiting reaction, which offers atomic-level controllability of the growth of thin films for a wide range of applications. The self-limiting mechanism leads to very useful properties, such as excellent uniformity over a large area and superior conformality on complex structures. These unique features of ALD provide promising opportunities for future electronics. Although the ALD of Al2O3 film (using trimethyl-aluminum and water as a metal precursor and oxygen source, respectively) can be regarded as a representative example of an ideal ALD based on the completely self-limiting reaction, there are many cases deviating from the ideal ALD reaction in recently developed ALD processes. The nonconventional aspects of the ALD reactions may strongly influence the various properties of the functional materials grown by ALD, and the lack of comprehension of these aspects has made ALD difficult to control. In this respect, several dominant factors that complicate ALD reactions, including the types of metal precursors, non-metal precursors (oxygen sources or reducing agents), and substrates, will be discussed in this presentation. Several functional materials for future electronics, such as higher-k dielectrics (TiO2, SrTiO3) for DRAM application, and resistive switching materials (NiO) for RRAM application, will be addressed in this talk. Unwanted supply of oxygen atoms from the substrate or other component oxide to the incoming precursors during the precursor pulse step, and outward diffusion of substrate atoms to the growing film surface even during the steady-state growth influenced the growth, crystal structure, and properties of the various films.

• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.1-6
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• 2002

The hot carried degradation in a metal oxide semiconductor device has been one of the most serious concerns for MOS-ULSI. In this paper, three types of LDD(lightly doped drain) structure for suppression of hot carried degradation, such as decreasing of performance due to spacer-induced degradation and increase of series resistance will be investigated. in this study, LDD-nMOSFETs used had three different drain structure, (1) conventional surface type LDD(SL), (2) Buried type LDD(BL), (3) Surface implantation type LDD(SI). As experimental results, the surface implantation the LDD structure showed that improved hot carrier lifetime to comparison with conventional surface and buried type LDD structures.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.310-310
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• 2016

최근 NAND flash memory는 높은 집적성과 데이터의 비휘발성, 낮은 소비전력, 간단한 입, 출력 등의 장점들로 인해 핸드폰, MP3, USB 등의 휴대용 저장 장치 및 노트북 시장에서 많이 이용되어 왔다. 특히, 최근에는 smart watch, wearable device등과 같은 차세대 디스플레이 소자에 대한 관심이 증가함에 따라 유연하고 투명한 메모리 소자에 대한 연구가 다양하게 진행되고 있다. 대표적인 플래시 메모리 소자의 구조로 charge trapping type flash memory (CTF)가 있다. CTF 메모리 소자는 trap layer의 trap site를 이용하여 메모리 동작을 하는 소자이다. 하지만 작은 window의 크기, trap site의 열화로 인해 메모리 특성이 나빠지는 문제점 등이 있다. 따라서 최근, trap layer에 다양한 물질을 적용하여 CTF 소자의 문제점을 해결하고자 하는 연구들이 진행되고 있다. 특히, 산화물 반도체인 zinc oxide (ZnO)를 trap layer로 하는 CTF 메모리 소자가 최근 몇몇 보고 되었다. 산화물 반도체인 ZnO는 n-type 반도체이며, shallow와 deep trap site를 동시에 가지고 있는 독특한 물질이다. 이 특성으로 인해 메모리 소자의 programming 시에는 deep trap site에 charging이 일어나고, erasing 시에는 shallow trap site에 캐리어들이 쉽게 공급되면서 deep trap site에 갇혀있던 charge가 쉽게 de-trapped 된다는 장점을 가지고 있다. 따라서, 본 실험에서는 산화물 반도체인 ZnO를 trap layer로 하는 CTF 소자의 메모리 특성을 확인하기 위해 간단한 구조인 metal-oxide capacitor (MOSCAP)구조로 제작하여 메모리 특성을 평가하였다. 먼저, RCA cleaning 처리된 n-Si bulk 기판 위에 tunnel layer인 SiO2 5 nm를 rf sputter로 증착한 후 furnace 장비를 이용하여 forming gas annealing을 $450^{\circ}C$에서 실시하였다. 그 후 ZnO를 20 nm, SiO2를 30 nm rf sputter로 증착한 후, 상부전극을 E-beam evaporator 장비를 사용하여 Al 150 nm를 증착하였다. 제작된 소자의 신뢰성 및 내구성 평가를 위해 상온에서 retention과 endurance 측정을 진행하였다. 상온에서의 endurance 측정결과 1000 cycles에서 약 19.08%의 charge loss를 보였으며, Retention 측정결과, 10년 후 약 33.57%의 charge loss를 보여 좋은 메모리 특성을 가지는 것을 확인하였다. 본 실험 결과를 바탕으로, 차세대 메모리 시장에서 trap layer 물질로 산화물 반도체를 사용하는 CTF의 연구 및 계발, 활용가치가 높을 것으로 기대된다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권3호
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• pp.252-258
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• 2013

In this paper, a thermally stable nickel silicide technology using the co-sputtering of nickel and titanium atoms capped with TiN layer is proposed for nano-scale metal oxide semiconductor field effect transistor (MOSFET) applications. The effects of the incorporation of titanium ingredient in the co-sputtered Ni layer are characterized as a function of Ti sputtering power. The difference between the one-step rapid thermal process (RTP) and two-step RTP for the silicidation process has also been studied. It is shown that a certain proportion of titanium incorporation with two-step RTP has the best thermal stability for this structure.