• International Journal of Precision Engineering and Manufacturing
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• 제5권2호
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• pp.39-45
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• 2004

Atomic Force Microscope (AFM) has been widely used in micro/nano-scale studies and applications for the last few decades. In this work, wear characteristics of silicon-based AFM tip was investigated. AFM tip shape was observed using a high resolution SEM and the wear coefficient was approximately calculated based on Archard's wear equation. It was shown that the wear coefficient of Si and ${Si}_3$$N_4$ tips were in the range of ${10}^{-1}$~${10}^{-3}$and ${10}^{-3}$~${10}^{-4}$, respectively. Also, the effect of relative humidity and sliding distance on adhesion-induced tip wear was investigated. It was found that the tip wear has more severe for harder counter surface materials. Finally, the probable wear mechanism was analyzed from the adhesive and abrasive interaction point of view.

• 한국표면공학회지
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• 제47권6호
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• pp.362-367
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• 2014

We report the design, fabrication of a $Si_3N_4$ probe and calculation of its mechanical properties for DPN(dip pen nanolithography), which consists of dual tips. Concept of dual tip probe is to employ individual tips on probe as either an AFM tip for imaging or a writing tip for nano patterning. For this, the dual tip probe is fabricated using low residual stress $Si_3N_4$ material with LPCVD deposition and MEMS fabrication process. On the basis of FEM analysis we show that the functionality of dual tip probe for imaging is dependent on the dimensions of dual tip probe, and high ratio of widths of beam areas is preferred to minimize curvature variation on probe.

• 센서학회지
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• 제9권3호
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• pp.177-181
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• 2000

턴널링 전류는 전극사이의 거리에 지수적으로 비례한다. 따라서 턴널링 전류의 변화측정을 통하여 전극간격의 미세변위를 측정할 수 있다. 본 실험에서는 micro-tip과 membrane사이에 턴널링 전류가 흐르는 피라미드형 실리콘 턴널링소자를 micro-electro-mechanical systems (MEMS) 공정을 이용하여 제조하였다. 단결정 실리콘을 KOH 용액안에서 이방성 에칭 시켜 micro-tip을 제조하였으며, 이때 $SiO_2$막을 마스크로 사용하였다 $Si_3N_4$막으로 membrane을 형성하였다. 마스크 방향에 따른 에칭 진행과정의 차이를 조사하였으며 membrane으로 사용한 $Si_3N_4$막의 stiffness를 측정하였다. 실험으로 측정하기 어려운 영역의 $Si_3N_4$막 stiffness 예측을 위한 모델식을 제시하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.64-64
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• 2009

Atomic force microscopy (AFM) fabrication of oxide patterns is an attractive technique for nanoscale patterns and related device structures, SiC exhibits good performance in high-power, high-frequency, and high-temperature conditions that is comparable to the performance of Si. The AFM fabrication of oxide patterns on SiC is important for electronic applications. However, there has not been much reported investigations on oxidation of SiC using AFM. We achieved the local oxidation of 4H-SiC using the high loading force of ~100 nN, although the oxidation of SiC is generally difficult mainly due to the physical hardness and chemical inactivity. All the experiments were performed using atomic force microscopy (S.I.S. GmbH, Germany) with a Pt/Ir-coated Si tip at ~40% humidity and room temperature. The spring constant and resonance frequency of the tip were around ~3 N/m and ~70 kHz. We fabricated oxide patterns on n-type 4H-SiC ($\sim10^{19}/cm^3$) and n-type Si ($\sim1.9\times10^{16}/cm^3$). In summary, we demonstrated that the oxide patterns can be obtained over the electric field of ${\sim}\times10^7 V/cm$ and the high loading force using the tip as a cathode. The electric field transports the oxyanions (OH-) to the positively biased surface.

• 한국정밀공학회지
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• 제20권5호
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• pp.189-195
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• 2003

Atomic Force Microscope (AFM) has been widely used in micro/nano-scale studies and applications for. the last few decade. In this work, wear characteristics of silicon-based AFM tip was investigated. AFM tip shape was observed using a high resolution SEM and the wear coefficient was approximately calculated based on Archard's wear equation. It was shown that the wear coefficient of silicon and silicon nitride were in the range of ${10}^{-1}$~${10}^{-3}$ and ${10}^{-3}$~${10}^{-4}$, respectively. Also, the effect of relative humidity and sliding distance on adhesion-induced tip wear was discussed. It was found that the tip wear has more severe for harder test materials. Finally, the probable wear mechanism was analyzed from the adhesive and abrasive interaction point of view.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.61-61
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• 1999

저항이 5$\Omega$-cm인 n-type Si(100) 웨이퍼를 실리콘 식각시 마스크로 사용하기 위하여 습식 열산화법을 이용하여 100$0^{\circ}C$에서 SiO2을 2400$\AA$ 성장시킨 후, OPCVD 공정을 통해 785$^{\circ}C$서 SiH2Cl2 가스 30sccm과 NH3가스 100sccm을 이용하여 Si3N4를 3000$\AA$ 증착시켰다. 이 웨이퍼를 포토-리쏘그라피 공정을 거쳐 지름 2$\mu\textrm{m}$의 포토레지스트 패턴을 제작한 후 600W의 RF power하에서 CF4 가스 10sccm, CHF3 가스 15sccm, O2가스 8sccm 및 Ar가스 10sccm을 이용하여 MERIE 방법으로 Si3N4를 식각한 다음, 7:1 BHF 용액내에서 30초간의 습식식각을 통해 40wt.%의 KOH 용액내에 8$0^{\circ}C$에서 30초간의 이방성 식각을 통해 피라미드 모양의 Si FEA(field emitter array)를 제작하였다. 본 실험은 다음과 같이 완성된 Si FEA를 샤프닝 산화 후 산화막 식각을 통해 마스크를 제거한 다음, tip의 열화학적 내구성을 증가시키고 장시간 구동시 안정성과 전계방출 전류밀도를 높이기 위해 tip의 표면에 Ti를 sputter 방법으로 약 300$\AA$ 증착시킨 후, RTA 장비를 이용하여 2단계 열처리 (first annealing:$600^{\circ}C$/30sec, second annealing : 85$0^{\circ}C$/15sec)를 통해 Si FEA의 경우보다 낮은 turn-on 전압과 높은 전계방출 특성을 나타낼 것으로 기대된다.

• Tribology and Lubricants
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• 제17권3호
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• pp.191-197
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• 2001

Nano adhesion and friction characteristics between SPM(scanning electron microscope) tips and flat plates of different materials were experimentally studied. Tests were performed to measure adhesion and friction in AFM(atomic force microscope) and LFM(lateral force microscope) modes in different conditions of relative humidity. Three different Si$_3$N$_4$ tips (rdaii : 15nm, 22nm and 50 nm) and three different flat plates of Si-wafer(100), W-DLC(tungsten-incorporated diamond-like carbon) and DLC were used. Results generally showed that adhesion and friction increased with the tip radius, and W-DLC and DLC surfaces were superior to Si-wafer. But the adhesion force of Si-wafer showed non linearity with the tip radius while W-DLC and DLC surfaces showed good correlation to the “JKR model”. It was found that high adhesion force between Si-wafer and a large radius of tip was caused by a capillary action due to the condensed water.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.149-154
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• 2004

This paper presents a silicon probe tip for vertical probe card application. The silicon probe tip was fabricated using MEMS technology such as porous silicon micromachining and deep- RIE (reactive ion etching). The thickness of the silicon epitaxial layers was 5 ${\mu}{\textrm}{m}$ and 7 ${\mu}{\textrm}{m}$, respectively. The width and length were 40 ${\mu}{\textrm}{m}$ and 600 ${\mu}{\textrm}{m}$, respectively. The probe structure was a multilayered structure and was composed of Au/Ni-Cr/Si$_3$N$_4$/n-epi layers. The height of the curled probe tip was measured as a function of the annealing temperature and time. Resistance characteristics of the probe tip were measured using a touchdown test.

• 한국재료학회지
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• 제10권4호
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• pp.301-304
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• 2000

Si FEA로 부터 tip의 표면을 Co 금속으로 silicidation한 새로운 3극형 Co-silicided Si FEA를 제작하고 이의 전계 방출특성을 조사하였다. $10^{-8}Torr$의 고진공상태에서 제작된 소자의 단위 pixel(pixel 면적 : $250{\mu\textrm{m}}{\times}250{\mu\textrm{m}}$, tip 어레이 : $45{\times}45$)를 통해 측정된 turn-on 전압은 약 35V로, 아노드 전류는 $V_A=500V,\;V_G=55V$ 바이어스 아래에서 약 $1.2{\mu\textrm{A}}(0.6nA/tip)$로 나타났다. 제작된 소자는 초기 과도상태를 제외하면 장시간의 동작을 통해 전계방출 전류의 감소없이 매우 안정된 전기적 특성을 나타내었다. Co-silicided Si FFA 의 낮은 turn-on 전압과 높은 전류안전성은 Si tip 표면에 형성된 실리사이드 박막의 열화학적 안전성과 낮은 일함수에 기인하는 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.79-80
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• 2009

The local oxidation using an atomic force microscopy (AFM) is useful for Si-base fabrication of nanoscale structures and devices. SiC is a wide band-gap material that has advantages such as high-power, high-temperature and high-frequency in applications, and among several SiC poly types, 4H-SiC is the most attractive poly type due to the high electron mobility. However, the AFM local oxidation of 4H-SiC for fabrication is still difficult, mainly due to the physical hardness and chemical inactivity of SiC. In this paper, we investigated the local oxidation of 4H-SiC surface using an AFM. We fabricated oxide patterns using a contact mode AFM with a Pt/Ir-coated Si tip (N-type, $0.01{\sim}0.025\;{\Omega}cm$) at room temperature, and the relative humidity ranged from 40 to 50%. The height of the fabricated oxide pattern ($1{\sim}3\;nm$) on SiC is similar to that of typically obtained on Si ($10^{15}{\sim}10^{17}\;cm^{-3}$). We perform the 2-D simulation to further analyze the electric field between the tip and the surface. Whereas the simulated electric field on Si surface is constant ($5\;{\times}\;10^7\;V/m$), the electric field on SiC surface increases with increasing the doping concentration from ${\sim}10^{15}$ to ${\sim}10^{17}\;cm^{-3}$. We demonstrated that a specific electric field ($4\;{\times}\;10^7\;V/m$) and a doping concentration (${\sim}10^{17}\;cm^{-3}$) is sufficient to switch on/off the growth of the local oxide on SiC.