• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.76-80
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• 2019

The characteristics of a titanium oxide layer prepared using a plasma electrolytic oxidation (PEO) process were investigated, using an extended gate ion sensitive field effect transistor (EG-ISFET) to confirm the layer's capability to react with hydrogen ions. The surface morphology and element distribution of the PEO-processed titanium oxide were observed and analyzed using field-emission scanning-electron microscopy (FE-SEM) and energy-distribution spectroscopy (EDS). The titanium oxide prepared by the PEO process was utilized as a hydrogen-ion sensing membrane and an extended gate insulator. A commercially available n-channel enhancement MOS-FET (metal-oxide-semiconductor FET) played a role as a transducer. The responses of the PEO-processed titanium oxide to different pH solutions were analyzed. The output drain current was linearly related to the pH solutions in the range of pH 4 to pH 12. It was confirmed that the titanium-oxide layer prepared by the PEO process could feasibly be used as a hydrogen-ion-sensing membrane for EGFET measurements.

• ETRI Journal
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• v.15 no.2
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• pp.11-25
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• 1993

Interface trap densities at gate oxide/silicon substrate ($SiO_2/Si$) interfaces of metal oxide semiconductor field-effect transistors (MOSFETs) were determined from the substrate bias dependence of the subthreshold slope measurement. This method enables the characterization of interface traps residing in the energy level between the midgap and that corresponding to the strong inversion of small size MOSFET. In consequence of the high accuracy of this method, the energy dependence of the interface trap density can be accurately determined. The application of this technique to a MOSFET showed good agreement with the result obtained through the high-frequency/quasi-static capacitance-voltage (C-V) technique for a MOS capacitor. Furthermore, the effective substrate dopant concentration obtained through this technique also showed good agreement with the result obtained through the body effect measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.150.1-150.1
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• 2015

일부 금속들은 산화물을 형성하여 반도체적 성질을 갖게 되는데 이를 산화물 반도체라 한다. 산화물 반도체는 전자의 전도 특성에 의해 기존에 널리 사용되고 있는 a-Si 반도체 보다 뛰어난 전자 이동도를 갖고 넒은 Band gap energy를 갖기 때문에 누설 전류가 적어 Device 제작 시 저전력 구동이 가능하다는 장점이 있어 관련 연구가 활발히 진행 중이다. 산화물 박막을 증착하는 방법으로는 용액 공정, CVD, Sputtering 등이 있다. 그 중 Sputtering을 이용한 산화물 박막 증착 시 산소 음이온이 기판으로 가속하여 박막에 충돌, 박막 물성에 영향을 준다는 연구결과가 보고되고 있다. 본 연구에서는 Sputtering을 이용하여 ITO를 증착하는 과정에서 발생하는 산소 음이온을 측정하는 장치를 개발하여 산소 음이온 발생여부를 확인해 보았다.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.18-25
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• 1995

건식, 습식, 건식/습식 산화분위기로 성장한 게이트 산화막 위에 AI, 인 도핑된 다결정시리콘, 비정질 실리콘/인 도핑된 다결정 실리콘을 증착하여 제작한 금속-산화물-반도체(metal-oxide-semiconductor:MOS)의 전기적 특성을 순간 절연파괴(TZDB), 정전용량-전압(C-V)과 경시절연파괴(TDDB)로 평가하였다. AI 게이트에서 습식산화막과 건식산화막의 평균 파괴전계는 각각 9.0MV/cm, 7.7MV/cm이였고, 습식산화막의 평균 파괴전계가 8.4MV/cm 이였으며, AI 게이트보다 0.6MV/cm 정도 낮았다. 이것은 다결정 실리콘/습식산화막 계면에서 인(phosphorus) 확산으로 다결정 실리콘의 grain 성장과 산화막의 migration에 의한 roughness 증가에 기인한다. 그러나 다결정 실리콘/건식산화막 계면에서 roughness 증가는 없었다. 다결정 실리콘 게이트에서는 건식/습식 산화막이 건식산화막과 습식산화막보다 평균 파괴전계와 절연파괴전하(QBD)가 높았다. 또한 다결정/비정질 실리콘 게이트에서는 습식산화막의 평균 파괴전계가 8.8MV/cm이였으며, 다결정 실리콘 게이트에서보다 0.4MV/cm 정도 높았다. 다결정/비정질 실리콘 구조는 앞으로 VLSI 적용에 있어서 게이트 전극으로 매우 유용할 것이다.

• Journal of the Korean Vacuum Society
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• v.4 no.3
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• pp.301-305
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• 1995

습식 분위기로 성장한 게이트 산화막 위에 다결정 실리콘(poly-Si)과 텅스텐 폴리사이드(WSix/poly-Si)게이트 전극을 형성하여 제작한 금속-산화물-반도체(metal-oxide-semiconductor:MOS)의 전기적 특성을 순간 절연파괴(time zero dielectric breakdown: TZDB)로 평가하였다. 텅스텐 폴리사이드 게이트 전극에 따른 게이트 산화막의 평균 파괴정계는 다결정 실리콘 전극보다 1.93MV/cm 정도 낮았다. 텅스텐 폴리사이드 게이트 전극에서 게이트 산화막의 B model(1-8 MV/cm)불량률은 dry O2 분위기에서 열처리함으로써 증가하였다. 이것은 열처리함으로써 게이트 전극이 silane(SiH4)에 의한 것보다 B mode 불량률이 감소하였다. 그것은 dichlorosilane 환원에 의한 텅스텐 실리사이드내의 불소 농도가 silane에 의한 것보다 낮기 때문이다.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.13-20
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• 2003

Both MgO and $Sc_2O_3$ are shown to provide low interface state densities (in the $10^{11}{\;}eV^{-1}{\;}cm{\;}^{-2}$ range)on n-and p-GaN, making them useful for gate dielectrics for metal-oxide semiconductor(MOS) devices and also as surface passivation layers to mitigate current collapse in GaN/AlGaN high electron mobility transistors(HEMTs).Clear evidence of inversion has been demonstrated in gate-controlled MOS p-GaN diodes using both types of oxide. Charge pumping measurements on diodes undergoing a high temperature implant activation anneal show a total surface state density of $~3{\;}{\times}{\;}10^{12}{\;}cm^{-2}$. On HEMT structures, both oxides provide effective passivation of surface states and these devices show improved output power. The MgO/GaN structures are also found to be quite radiation-resistant, making them attractive for satellite and terrestrial communication systems requiring a high tolerance to high energy(40MeV) protons.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.4
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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.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.14-21
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• 2010

Ge is one of the attractive channel materials for the next generation high speed metal oxide semiconductor field effect transistors (MOSFETs) due to its higher carrier mobility than Si. But the absence of a chemically stable thermal oxide has been the main obstacle hindering the use of Ge channels in MOS devices. Especially, the fabrication of gate oxide on Ge with high quality interface is essential requirement. In this study, $HfO_xN_y$ thin films were prepared by plasma-enhanced atomic layer deposition on Ge substrate. The nitrogen was incorporated in situ during PE-ALD by using the mixture of nitrogen and oxygen plasma as a reactant. The effects of nitrogen to oxygen gas ratio were studied focusing on the improvements on the electrical and interface properties. When the nitrogen to oxygen gas flow ratio was 1, we obtained good quality with 10% EOT reduction. Additional analysis techniques including X-ray photoemission spectroscopy and high resolution transmission electron microscopy were used for chemical and microstructural analysis.

• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.44-49
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• 2020

In this paper, a measuring circuit is designed through analyzing manufacture specification of the sensor based on MOS. And the best input-output polynomial are induced that really gas sensors are used in gas safety management industrial fields. Response characteristics of a MOS gas sensor is analysed by through sensor's output voltages are measured after standard gases with six kinds of concentrations are manufactured and are injected to the sensor. A lookup table is created by relations of sensor's output voltages by injecting gases with other concentrations. Because data of the formed lookup table are equal interval, a polynomial can be induced of method of approximation function. So the 5th polynomial of input-output for a sensor is defined, coefficients are calculated by using least squares method, and the 5th polynomial is completed for representing characteristics of the sensor. If the proposed polynomial is applied to gas leak detectors, an inverse transformation of polynomial and programing of array codes are recreated. In this research, polynomial is implemented with array types that intervals of values of a lookup table are one-fifth sampled and interpolated. The performance of proposed 5th calibration equation is verified that errors are reduced than a linear expression when tests are performed by measurement of concentrations against injection of standard gases.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.829-831
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• 1992

Ultrathin metal-oxide-semiconductor(MOS) gate dielectrics have been fabricated by conventional thermal oxidation in $N_2O$ ambient. Compared to oxides grown in $O_2$, $N_2O$ oxides exhibit significantly low flatband voltage and small shift in flatband voltage. $N_2O$ oxidation induces a slight decrease in mobile ionic charge density($N_m$), fixed charge density($N_f$) and surface state charge density($N_{ss}$). This study establishes that $N_2O$ oxides may have a great impact on future MOS ULSI technology in which ultrathin gate dielectrics are required.