• Title/Summary/Keyword: silicon oxide

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Hydrodynamic effects of heater lengths on pool boiling critical heat flux (히터 길이가 수조비등 임계열유속에 미치는 수력학적 영향)

  • Su Cheong Park;Do Yeon Kim;Seon Ho Choi;Chang Hoon Lee;Younghun Lim;Chi Young Lee;Yeon Won Lee;Dong In Yu
    • Journal of the Korean Society of Visualization
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    • v.21 no.1
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    • pp.67-73
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    • 2023
  • In the study, pool boing critical heat flux (CHF) was experimentally investigated depending on the length of heaters. A smooth silicon oxide surfaces are used as the boiling surfaces. As the results of pool boiling experiments based on distilled water in ambient pressure condition, the CHF decreased as the length of the heater increased. By the high speed imaging, it was shown that the number of vapor columns increased as the length of the heater increased. Comparing the number of vapor columns and the CHF according to the heater length, the change in the CHF according to the heater length was analyzed based on the hydrodynamic instability.

Thin Film Characterization on Refractive Index of PECVD SiO2 Thin Films

  • Woo Hyuck Kong;In Cheon Yoon;Seung Jae Lee;Yun Jeong Choi;Sang Jeen Hong
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.2
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    • pp.35-39
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    • 2023
  • Silicon oxide thin films have been deposited by plasma-enhanced chemical vapor deposition in SiH4 and N2O plasma along the variation of the gas flow ratio. Optical emission spectroscopy was employed to monitor the plasma and ellipsometry was employed to obtain refractive index of the deposited thin film. The atomic ratio of Si, O, and N in the film was obtained using XPS depth profiling. Fourier Transform Infrared Spectroscopy was used to analyze structures of the films. RI decreased with the increase in N2O/SiH4 gas flow ratio. We noticed the increase in the Si-O-Si bond angles as the N2O/SiH4 gas flow ratio increased, according to the analysis of the Si-O-Si stretching peak between 950 and 1,150 cm-1 in the wavenumber. We observed a correlation between the optical emission intensity ratio of (ISi+ISiH)/IO. The OES intensity ratio is also related with the measured refractive index and chemical composition ratio of the deposited thin film. Therefore, we report the added value of OES data analysis from the plasma related to the thin film characteristics in the PECVD process.

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Research Progress on NF3 Substitute Gas of PECVD Chamber Cleaning Process for Carbon Neutrality (반도체·디스플레이 탄소중립을 위한 PECVD 챔버세정용 NF3대체가스 개발연구)

  • Seyun Jo;Sang Jeen Hong
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.4
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    • pp.72-75
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    • 2023
  • Carbon neutrality has been emerged as important mission for all the manufacturing industry to reduce energy usage and carbon emission equivalent. Korean semiconductor and display manufacturing industries are also in huge interest by minimize the energy usage as well as to find a less global warming product gases in both etch and cleaning. In addition, Korean government is also investing long term research and development plan for the safe environment in various ways. In this paper, we revisit previous research activities on carbon emission equivalent and current research activities performed in semiconductor process diagnosis research center at Myongji University with respect to the reduction of NF3 usage for the PECVD chamber cleaning, and we present the analytical result of the exhaust gas with residual gas analysis in both 6 inches and 12 inches PECVD equipment. The presented result can be a reference study of the development of new substitution gas in near future to compare the cleaning rate of the silicon oxide deposition chamber.

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A Study on the Thickness Dependence of p-type Organic Layer on the Current of Small Molecule-based Organic Photodiode (저분자 유기 광다이오드 소자의 p형 유기물 두께에 따른 전류 특성에 관한 연구)

  • Young Woo Kim;Dong Woon Lee;Yongmin Jeon;Eou-sik Cho;Sang Jik Kwon
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.3
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    • pp.101-105
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    • 2023
  • Organic photo Diodes (OPDi) give multiple advantages in the growing interest of the flexible optoelectronic devices. Organic semiconductors are freeform as they can deposit on any substrate, so it could be flexible. But the inorganic material photodiodes (PDs) are usually fabricated on silicon wafers which are solid. So, normally PDs are inflexible. By those reasons, we decided to make the vacuum deposited small molecule OPDi. We have investigated the OPDi's J-V characteristic by changing the thickness of p-type layer of OPDi. This device consists of indium-tin-oxide (ITO) / 2,3:6,7-dibenzanthracene (pentacene) / buckminsterfullerene (C60) / aluminum (Al). Its J-V characteristics were measured in the probe station(4156C) that can give dark condition while measuring. And for the luminance characteristics, the photocurrent was measured with the bright halogen lamp and a probe station.

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Enhancement of SiO2 Uniformity by High-Pressure Deuterium Annealing (고압 중수소 어닐링을 통한 SiO2 절연체의 균일성 개선)

  • Yong-Sik Kim;Dae-Han Jung;Hyo-Jun Park;Ju-Won Yeon;Tae-Hyun Kil;Jun-Young Park
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.2
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    • pp.148-153
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    • 2024
  • As complementary metal-oxide semiconductor (CMOS) is scaled down to achieve higher chip density, thin-film layers have been deposited iteratively. The poor film uniformity resulting from deposition or chemical mechanical planarization (CMP) significantly affects chip yield. Therefore, the development of novel fabrication processes to enhance film uniformity is required. In this context, high-pressure deuterium annealing (HPDA) is proposed to reduce the surface roughness resulting from the CMP. The HPDA is carried out in a diluted deuterium atmosphere to achieve cost-effectiveness while maintaining high pressure. To confirm the effectiveness of HPDA, time-of-flight secondary-ion mass spectrometry (ToF-SIMS) and atomic force microscopy (AFM) are employed. It is confirmed that the absorbed deuterium gas facilitates the diffusion of silicon atoms, thereby reducing surface roughness.

Radiation-hardened-by-design preamplifier with binary weighted current source for radiation detector

  • Minuk Seung;Jong-Gyun Choi ;Woo-young Choi;Inyong Kwon
    • Nuclear Engineering and Technology
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    • v.56 no.1
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    • pp.189-194
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    • 2024
  • This paper presents a radiation-hardened-by-design preamplifier that utilizes a self-compensation technique with a charge-sensitive amplifier (CSA) and replica for total ionizing dose (TID) effects. The CSA consists of an operational amplifier (OPAMP) with a 6-bit binary weighted current source (BWCS) and feedback network. The replica circuit is utilized to compensate for the TID effects of the CSA. Two comparators can detect the operating point of the replica OPAMP and generate appropriate signals to control the switches of the BWCS. The proposed preamplifier was fabricated using a general-purpose complementary metal-oxide-silicon field effect transistor 0.18 ㎛ process and verified through a test up to 230 kGy (SiO2) at a rate of 10.46 kGy (SiO2)/h. The code of the BWCS control circuit varied with the total radiation dose. During the verification test, the initial value of the digital code was 39, and a final value of 30 was observed. Furthermore, the preamplifier output exhibited a maximum variation error of 2.39%, while the maximum rise-time error was 1.96%. A minimum signal-to-noise ratio of 49.64 dB was measured.

Characteristics of amorphous IZTO-based transparent thin film transistors (비정질 IZTO기반의 투명 박막 트렌지스터 특성)

  • Shin, Han-Jae;Lee, Keun-Young;Han, Dong-Cheul;Lee, Do-Kyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.151-151
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    • 2009
  • Recently, there has been increasing interest in amorphous oxide semiconductors to find alternative materials for an amorphous silicon or organic semiconductor layer as a channel in thin film transistors(TFTs) for transparent electronic devices owing to their high mobility and low photo-sensitivity. The fabriction of amorphous oxide-based TFTs at room temperature on plastic substrates is a key technology to realize transparent flexible electronics. Amorphous oxides allows for controllable conductivity, which permits it to be used both as a transparent semiconductor or conductor, and so to be used both as active and source/drain layers in TFTs. One of the materials that is being responsible for this revolution in the electronics is indium-zinc-tin oxide(IZTO). Since this is relatively new material, it is important to study the properties of room-temperature deposited IZTO thin films and exploration in a possible integration of the material in flexible TFT devices. In this research, we deposited IZTO thin films on polyethylene naphthalate substrate at room temperature by using magnetron sputtering system and investigated their properties. Furthermore, we revealed the fabrication and characteristics of top-gate-type transparent TFTs with IZTO layers, seen in Fig. 1. The experimental results show that by varying the oxygen flow rate during deposition, it can be prepared the IZTO thin films of two-types; One a conductive film that exhibits a resistivity of $2\times10^{-4}$ ohm${\cdot}$cm; the other, semiconductor film with a resistivity of 9 ohm${\cdot}$cm. The TFT devices with IZTO layers are optically transparent in visible region and operate in enhancement mode. The threshold voltage, field effect mobility, on-off current ratio, and sub-threshold slope of the TFT are -0.5 V, $7.2\;cm^2/Vs$, $\sim10^7$ and 0.2 V/decade, respectively. These results will contribute to applications of select TFT to transparent flexible electronics.

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RF and Optical properties of Graphene Oxide

  • Im, Ju-Hwan;Rani, J.R.;Yun, Hyeong-Seo;O, Ju-Yeong;Jeong, Yeong-Mo;Park, Hyeong-Gu;Jeon, Seong-Chan
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2012.05a
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    • pp.68.1-68.1
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    • 2012
  • The best part of graphene is - charge-carriers in it are mass less particles which move in near relativistic speeds. Comparing to other materials, electrons in graphene travel much faster - at speeds of $10^8cm/s$. A graphene sheet is pure enough to ensure that electrons can travel a fair distance before colliding. Electronic devices few nanometers long that would be able to transmit charge at breath taking speeds for a fraction of power compared to present day CMOS transistors. Many researches try to check a possibility to make it a perfect replacement for silicon based devices. Graphene has shown high potential to be used as interconnects in the field of high frequency electrical devices. With all those advantages of graphene, we demonstrate characteristics of electrical and optical properties of graphene such as the effect of graphene geometry on the microwave properties using the measurements of S-parameter in range of 500 MHz - 40 GHz at room temperature condition. We confirm that impedance and resistance decrease with increasing the number of graphene layer and w/L ratio. This result shows proper geometry of graphene to be used as high frequency interconnects. This study also presents the optical properties of graphene oxide (GO), which were deposited in different substrate, or influenced by oxygen plasma, were confirmed using different characterization techniques. 4-6 layers of the polycrystalline GO layers, which were confirmed by High resolution transmission electron microscopy (HRTEM) and electron diffraction analysis, were shown short range order of crystallization by the substrate as well as interlayer effect with an increase in interplanar spacing, which can be attributed to the presence of oxygen functional groups on its layers. X-ray photoelectron Spectroscopy (XPS) and Raman spectroscopy confirms the presence of the $sp^2$ and $sp^3$ hybridization due to the disordered crystal structures of the carbon atoms results from oxidation, and Fourier Transform Infrared spectroscopy (FTIR) and XPS analysis shows the changes in oxygen functional groups with nature of substrate. Moreover, the photoluminescent (PL) peak emission wavelength varies with substrate and the broad energy level distribution produces excitation dependent PL emission in a broad wavelength ranging from 400 to 650 nm. The structural and optical properties of oxygen plasma treated GO films for possible optoelectronic applications were also investigated using various characterization techniques. HRTEM and electron diffraction analysis confirmed that the oxygen plasma treatment results short range order crystallization in GO films with an increase in interplanar spacing, which can be attributed to the presence of oxygen functional groups. In addition, Electron energy loss spectroscopy (EELS) and Raman spectroscopy confirms the presence of the $sp^2$ and $sp^3$ hybridization due to the disordered crystal structures of the carbon atoms results from oxidation and XPS analysis shows that epoxy pairs convert to more stable C=O and O-C=O groups with oxygen plasma treatment. The broad energy level distribution resulting from the broad size distribution of the $sp^2$ clusters produces excitation dependent PL emission in a broad wavelength range from 400 to 650 nm. Our results suggest that substrate influenced, or oxygen treatment GO has higher potential for future optoelectronic devices by its various optical properties and visible PL emission.

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Current Sensing Trench Gate Power MOSFET for Motor Driver Applications (모터구동 회로 응용을 위한 대전력 전류 센싱 트렌치 게이트 MOSFET)

  • Kim, Sang-Gi;Park, Hoon-Soo;Won, Jong-Il;Koo, Jin-Gun;Roh, Tae-Moon;Yang, Yil-Suk;Park, Jong-Moon
    • Journal of IKEEE
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    • v.20 no.3
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    • pp.220-225
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    • 2016
  • In this paer, low on-resistance and high-power trench gate MOSFET (Metal-Oxide-Silicon Field Effect Transistor) incorporating current sensing FET (Field Effect Transistor) is proposed and evaluated. The trench gate power MOSFET was fabricated with $0.6{\mu}m$ trench width and $3.0{\mu}m$ cell pitch. Compared with the main switching MOSFET, the on-chip current sensing FET has the same device structure and geometry. In order to improve cell density and device reliability, self-aligned trench etching and hydrogen annealing techniques were performed. Moreover, maintaining low threshold voltage and simultaneously improving gate oxide relialility, the stacked gate oxide structure combining thermal and CVD (chemical vapor deposition) oxides was adopted. The on-resistance and breakdown voltage of the high density trench gate device were evaluated $24m{\Omega}$ and 100 V, respectively. The measured current sensing ratio and it's variation depending on the gate voltage were approximately 70:1 and less than 5.6 %.

Improved Degradation Characteristics in n-TFT of Novel Structure using Hydrogenated Poly-Silicon under Low Temperature (낮은 온도 하에서 수소처리 시킨 다결정 실리콘을 사용한 새로운 구조의 n-TFT에서 개선된 열화특성)

  • Song, Jae-Ryul;Lee, Jong-Hyung;Han, Dae-Hyun;Lee, Yong-Jae
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2008.05a
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    • pp.105-110
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    • 2008
  • We have proposed a new structure of poly-silicon thin film transistor(TFT) which was fabricated the LDD region using doping oxide with graded spacer by etching shape retio. The devices of n-channel poly-si TFT's hydrogenated by $H_2$ and $HT_2$/plasma processes are fabricated for the devices reliability. We have biased the devices under the gate voltage stress conditions of maximum leakage current. The parametric characteristics caused by gate voltage stress conditions in hydrogenated devices are investigated by measuring /analyzing the drain current, leakage current, threshold voltage($V_{th}$), sub-threshold slope(S) and transconductance($G_m$) values. As a analyzed results of characteristics parameters, the degradation characteristics in hydrogenated n-channel polysilicon TFT's are mainly caused by the enhancement of dangling bonds at the poly-Si/$SiO_2$ interface and the poly-Si Brain boundary due to dissolution of Si-H bonds. The structure of novel proposed poly-Si TFT's are the simplity of the fabrication process steps and the decrease of leakage current by reduced lateral electric field near the drain region.

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