• 한국재료학회지
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• 제16권5호
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• pp.308-311
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• 2006

The purpose of this study is to investigate the difference of the wafer nanotopography impact on the oxide-film thickness variation between the STI CMP using ceria slurry and STI CMP using fumed silica slurry. The nanotopography impact on the oxide-film thickness variation after STI CMP using ceria slurry is 2.8 times higher than that after STI CMP using fumed silica slurry. It is attributed that the STI CMP using ceria slurry follows non-Prestonian polishing behavior while that using fumed silica slurry follows Prestonian polishing behavior.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.192-194
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• 1993

In this paper, a silicon piezoresistive accelerometer of which the cantilevers have uniform thickness is designed and fabricated with SOI wafer. The accelerometer consists of a seismic mass and four cantilevers, and is fabricated mainly by the anisotropic etching method using EPW etchant. The fabrication processes are that of the frontside processes including the etching of the cantilevers and the doubleside alignment holes, the diffusion of the piezoresisters and patterning of the contact windows, and the metal connection process, and that of the backside processes including the etching of the shallow cavity and the seismic mass. Because of the uniformity of thickness, the performance of the accelerometer fabricated with SOI wafer is expected to be better than that of accelerometer fabricated by the time-controlled etching method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.211-213
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• 1999

In this paper, we documented the controlling oxide removal amount on the pattern wafer using removal rate and removal thickness of blanket wafer. There was the strong correlation relationship for both(correlation factor:0.7109). So, we could confirm the repeatability as applying for STI CMP process from the obtained linear formular. As the result of repeatability test, the difference of calculated polishing time and actual polishing time was 3.48 seconds based on total 50 lots. If this time is converted into the thickness, it is from 104$\AA$ to 167$\AA$. It is possible to be ignored because it is under the process margin.

• 한국시뮬레이션학회논문지
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• 제11권1호
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• pp.23-30
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• 2002

An STI(Shallow Trench Isolation) by using a CMP(Chemical Mechanical Polishing) process has been one of the key issues in the device isolation[1] In this paper we fabricated N, P-MOSFEET tall analyse hump characteristics in various rounding oxdation thickness(ex : Skip, 500, 800, 1000$\AA$). As a result we found that hump occurred at STI channel edge region by field oxide recess. and boron segregation(early turn on due to boron segregatiorn at channel edge). Therefore we improved that hump occurrence by increased oxidation thickness, and control field oxide recess( 20nm), wet oxidation etch time(19HF,30sec), STI nitride wet cleaning time(99HF, 60sec+P 90min) and fate pre-oxidation cleaning time (U10min+19HF, 60sec) to prevent hump occurring at STI channel edge.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2008년도 공동학술대회
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• pp.185-190
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• 2008

한국해양연구원 동해연구소(경상북도 울진군 죽변면) 주변해역에 대하여 다중빔 음향측심기와 천부탄성파탐사를 이용하여 해저지질 및 지하구조에 대한 지구물리 조사를 실시하였다. 다중빔 음향측심기를 이용하여 정밀 해저지형조사 및 해저면 영상조사를 실시하여 정밀 해저지형도와 퇴적층 및 암반의 분포도를 작성하였다. 조사해역의 남동쪽에 뽀족한 암반들이 분포하고 있으며 연구소 주변과 조사해역 북서쪽에 퇴적층이 분포하고 있다. 해안선과 평행하게 수심이 발달되어 있으며 동쪽으로 -60m 까지 깊어진다. 퇴적층은 주로 모래층으로 이루어져 있으며 천부탄성파탐사 결과를 통하여 퇴적층의 두께를 구하였다. 향후 지속적인 지구물리 탐사를 통하여 해저지형, 지하구조 및 퇴적환경에 대하여 모니터링 자료를 확보할 예정이다.

• Geomechanics and Engineering
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• 재33권6호
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• pp.583-596
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• 2023

The interlayers, either softer or stiffer than the surrounding layers, are usually overlooked during field investigation due to the small thickness. They may be neglected through the analysis process for simplicity. However, they may significantly affect the dynamic behavior of the soil-foundation system. In this study, a series of 3D finite-element Direct-solution steady-state harmonic analyses were carried out using ABAQUS/CAE software to investigate the impacts of interlayers on the dynamic response of a cast in place pile group subjected to horizontal harmonic load. The experimental data of a 3×2 pile group testing was used to verify the numerical modeling. The effects of thickness, depth, and shear modulus of the interlayers on the dynamic response of the pile group are investigated. The simulations were conducted on both stiff and soft soils. It was found that the soft interlayers affect the frequency-amplitude curve of the system only in frequencies higher than 70% of the resonant frequency of the base soil. While, the effect of stiff interlayer in soft base soil started at frequency of 35% of the resonant frequency of the base soil. Also, it was observed that a shallow stiff interlayer increased the resonant amplitude by 11%, while a deep one only increased the resonant frequency by 7%. Moreover, a shallow soft interlayer increased the resonant frequency by 20% in soft base soils, whereas, it had an effect as low as 6% on resonant amplitude. Also, the results showed that deep soft interlayers increased the resonant amplitude by 17 to 20% in both soft and stiff base soils due to a reduction in lateral support of the piles. In the cases of deep thick, soft interlayers, the resonant frequency reduced significantly, i.e., 16 to 20%. It was found that the stiff interlayers were most effective on the amplitude and frequency of the pile group.

• Earthquakes and Structures
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• 제12권2호
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• pp.153-163
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• 2017

The underlying goal of the present paper is to investigate soil and structural uncertainties on impedance functions and structural response of soil-shallow foundation-structure (SSFS) system using Monte Carlo simulations. The impedance functions of a rigid massless circular foundation resting on the surface of a random soil layer underlain by a homogeneous half-space are obtained using 1-D wave propagation in cones with reflection and refraction occurring at the layer-basement interface and free surface. Firstly, two distribution functions (lognormal and gamma) were used to generate random numbers of soil parameters (layer's thickness and shear wave velocity) for both horizontal and rocking modes of vibration with coefficients of variation ranging between 5 and 20%, for each distribution and each parameter. Secondly, the influence of uncertainties of soil parameters (layer's thickness, and shear wave velocity), as well as structural parameters (height of the superstructure, and radius of the foundation) on the response of the coupled system using lognormal distribution was investigated. This study illustrated that uncertainties on soil and structure properties, especially shear wave velocity and thickness of the layer, height of the structure and the foundation radius significantly affect the impedance functions, and in same time the response of the coupled system.

• JSTS:Journal of Semiconductor Technology and Science
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• 제4권1호
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• pp.45-51
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• 2004

We have proposed a new shallow trench isolation (STI) process using flowable oxide (F-oxide) chemical vapor deposition (CVD) for DRAM application and it was successfully developed. The combination of F-oxide CVD and HDP CVD is thought to be the superior STI gap-filling process for next generation DRAM fabrication because F-oxide not only improves STI gap-filling capability, but also the reduced local stress by F-oxide in narrow trenches leads to decrease in junction leakage and gate induced drain leakage (GIDL) current. Finally, this process increased data retention time of DRAM compared to HDP STI. However, a serious failure occurred by symphonizing its structural dependency of deposited thickness with poor resistance against HF chemicals. It could be suppressed by reducing the flow time during F-oxide deposition. It was investigated collectively in terms of device yield. In conclusion, the combination of F-oxide and HDP oxide is the very promising technology for STI gap filling process of sub-100nm DRAM technology.

• 한국지열·수열에너지학회논문집
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• 제12권3호
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• pp.24-32
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• 2016

Commercial buildings and institutions are generally cooling-dominated and therefore reject more heat to a borehole ground heat exchanger (BHE) than they extract over the annual cycle. Shallow ponds can provide a cost-effective means to balance the thermal loads to the ground and to reduce the length of BHE. This paper presents the analysis results of the impact of design parameters on the length of SWHE pipe and its application effect on geothermal heat pump (GHP) system using BHE. In order to analysis, we applied ${\varepsilon}-NTU$ method on designing the length of SWHE pipe. Analysis results show that the required pipe length of SWHE was decreased with the increase of approach temperature difference and with the decrease of pipe wall thickness. In addition, when the SWHE was applied to the GHP system, the temperature of BHE was more stable than that of standalone BHE system.

• E2M - 전기 전자와 첨단 소재
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• 제8권6호
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• pp.737-743
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• 1995

Two step RTD(Rapid Thermal Diffussion) of P into silicon wafer using tungsten halogen lamp was used to fabricated very shallow n$^{+}$p junction. 1st RTD was performed in the temperature range of 800.deg. C for 60 see and the heating rate was in the 50.deg. C/sec. Phosphrous solid source was transfered on the silicon surface. 2nd RTD process was performed in the temperature range 1050.deg. C, 10sec. Using 2 step RTD we can obtain a shallow junction 0.13.mu.m in depth. After RTD, the Ti-silicide process was performed by the two step RTA(Rapid Thermal Annealing) to reduced the electric resistance and to improve the n$^{+}$p junction diode. The titanium thickness was 300.angs.. The condition of lst RTA process was 600.deg. C of 30sec and that of 2nd RTA process was varied in the range 700.deg. C, 750.deg. C, 800.deg. C for 10sec-60sec. After 2 step RTA, sheet resistance was 46.ohm../[]. Ti-silicide n+p junction diode was fabricated and I-V characteristics were measured.red.