• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.516-521
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• 2001

Dry etching of Si wafer and $SiO_2$ layers was performed using He/Cl$_2$ mixture plasma by diode-type reactive ion etcher (RIE) system. For Si etching, the Cl molecules react with the Si molecules on the surface and become chemically stable, indicating that the reactants need energetic ion bombardment. During the ion assisted desorption, energetic ions would damage the photoresist (PR) and produce the bad etch Si-profile. Moreover, we have examined the characteristics of the Cl-Si reaction system, and developed the new fabrication procedures with a $Cl_2$/He mixture for Si and $SiO_2$-etching. The developed novel fabrication procedure allows the RIE to be unexpensive and useful a Si deep etching system. Since the etch rate was proved to increase linearly with fHe and the selectivity of Si to $SiO_2$ etch rate was observed to be inversely proportional to fHe.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.66.1-66.1
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• 2010

Microcrystalline silicon at low temperatures has been developed using plasma enhanced chemical vapor deposition (PECVD). It has been found that energetically positive ion and atomic hydrogen collision on to growing surface have important effects on increasing growth rate, and atomic hydrogen density is necessary for the increasing growth rate correspondingly, while keeping ion bombardment is less level. Since the plasma potential is determined by working pressure, the ion energy can be reduced by increasing the deposition pressure of 700-1200 Pa. Also, correlation of the growth rate and crystallinity with deposition parameters such as working pressure, hydrogen flow rate and input power were investigated. Consequently an efficiency of 7.9% was obtained at a high growth rate of 0.92 nm/s at a high RF power 300W using a plasma-enhanced chemical vapor deposition method (27.12MHz).

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.59.2-59.2
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• 2015

Modification of film structure and properties in inductively-coupled plasma (ICP) assisted dc and pulsed dc sputtering has been reported by Oya and Kusano [1] and by Sakamoto, Kusano, and Matsuda [2], showing drastic changes in films structure and properties by the ICP assistance in particular to the pulsed dc discharge. Although mechanisms involved in the modification has been reported to be the increase in energy transferred to the substrate, details of effects of low-energy ion bombardment on the modification and origin of an anomalous increase in the ion quantity by the ICP assistance to the pulsed dc discharge have not been discussed. In this presentation, mechanisms involved in film structure and property modification in ICP assisted dc and pulsed dc sputtering, in which a number of low-energy ions are formed, will be discussed based on ion energy distribution as well as effectiveness of energy transfer to the substrate by low energy particles [3]. The results discussed in this presentation will emphasize the fact that the energetic particles playing an important role in the film structure modification are those to be deposited, but not those of inert gas, when their energies range in less than 100 eV in the pressure range of magnetron sputtering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.679-685
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• 2014

For the measurements of surface shape milled using FIB (focused ion beam), the silicon bulk, $Si_3N_4/Si$, and Al/Si samples are used and observed the shapes milled from different sputtering rates, incident angles of $Ga^+$ ions bombardment, beam current, and target material. These conditions also can be influenced the sputtering rate, raster image, and milled shape. The fundamental ion-solid interactions of FIB milling are discussed and explained using TRIM programs (SRIM, TC, and T-dyn). The damaged layers caused by bombarding of $Ga^+$ ions were observed on the surface of target materials. The simulated results were shown a little bit deviation with the experimental data due to relatively small sputtering rate on the sample surface. The simulation results showed about 10.6% tolerance from the measured data at 200 pA. On the other hand, the improved analytical model of damaged layer was matched well with experimental XTEM (cross-sectional transmission electron microscopy) data.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.586-591
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• 2013

This paper describes the characteristics of thermo-field emission in a freestanding silicon nanomembrane under ion bombardment with various thermal and field conditions. The thermal effect and field effect in thermo-field emission in silicon nanomembrane are investigated by varying kinetic energy of ions and electric field applied to the silicon nanomembrane surface, respectively. We found that thermo-field emission increases linearly as the electric field increases, when the electric field intensity is lower than the threshold. The thermo-field emission (schottky effect) increases proportionally to the power of temperature, which agree well with the predictions of a thermo-field emission model.

• Proceedings of the Korean Vacuum Society Conference
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• 1994.02a
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• pp.35-35
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• 1994

The surface segragation of NiZr, CuZr alloy has been studied wi th X-ray Imotoelectron spectroscopy(XPS), Auger electron spectroscopy(AES) and low energy ion scattering(LEIS). The composition of outmost atomic layer has been determinded by the use of LEIS at several incident energies using Ar+ ion. In the LEIS analysis, the effect of charge exchange has been estimated by a novel measurment of the charge exchange parameters while simul taneous determining the relative concentrations of Ni and Zr and the complementary information obtained will be described. The composition of the clean annealed surface, measured with AES only, will be contrasted wi th the surface concentration of the preferentially sputtered surface. The experimental results has been clearly demonstrated that when the NiZr ruld CuZr alloys are exposed to continuous Ar+ ion bombardment the outermost atomic layer is Zr rich due to preferential sputtering of Ni atoms. where Ni is preferentially sputtered, but the difference in sputtering yields is not sufficient to explain the observed composition. Therefore, it is necessary to consider other processes such as Radiation Induced Segregation(RIS). The surface composition of the heated sample surface predicts that Zr should surface segregate which futher supports the view that part of the Zr enrichment is due to RIS.to RIS.

• Transactions on Electrical and Electronic Materials
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• v.11 no.3
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• pp.116-119
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• 2010

The etching characteristics of zinc oxide (ZnO) were investigated, including the etch rate and the selectivity of ZnO in a $Cl_2/BCl_3$/Ar plasma. It was found that the ZnO etch rate, the RF power, and the gas pressure showed non-monotonic behaviors with an increasing Cl2 fraction in the $Cl_2/BCl_3$/Ar plasma, a gas mixture of $Cl_2$(3 sccm)/$BCl_3$(16 sccm)/Ar (4 sccm) resulted in a maximum ZnO etch rate of 53 nm/min and a maximum etch selectivity of 0.89 for ZnO/$SiO_2$. We used atomic force microscopy to determine the roughness of the surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the plasmas. Due to the relatively low volatility of the by-products formed during etching with $Cl_2/BCl_3$/Ar plasma, ion bombardment and physical sputtering were required to obtain the high ZnO etch rate. The chemical states of the etched surfaces were investigated using X-ray photoelectron spectroscopy (XPS). This data suggested that the ZnO etch mechanism was due to ion enhanced chemical etching.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.21-26
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• 2003

4H-SiC Schottky rectifiers were exposed to pure Ar discharges in a planar coil Inductively Coupled Plasma system, as a function of source power, of chuck power and process pressure. The reverse breakdown voltage ($V_B$) decreased as a result of plasma exposure due to the creation of surface defects associated with the ion bombardment. The magnitude of the decrease was a function of both ion flux and ion energy. The forward turn-on voltage ($V_F$), on-state resistance ($R_{ON}$) and diode ideality factor (n) all increased after plasma exposure. The changes in all of the rectifier parameters were minimized at low power, high pressure plasma conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.175-175
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• 1999

Circumventing problems lying in the conventional lithographic techniques, we devised a new method for the fabrication of nanometer scale metal wires inspired by the unique characteristics of carbon nanotubes (CNTs). Since carbon nanotubes could act as masks when CNT-coated thin Au/Ti layer on a SiO2 surface was physically etched by low energy argon ion bombardment 9ion milling), Au/Ti nano-wires were successfully formed just below the CNTs exactly duplicating their lateral shapes. Cross-sectional analysis by transmission electron microscopy revealed that the edge of the metal wire was very sharply developed indicating the great difference in the milling rates between the CNTs and the metal layer as well as the good directionality of the ion milling. We could easily find a few nanometer-wide Au/Ti wires among the wires of various width. After the formation of nano-wires, the CNTs could be pushed away from the metal nano-wire by atomic force microscopy, The lateral force for the removal of the CNTs are dependent upon the width and shape of the wires. Resistance of the metal nano-wires without the CNTs was also measured through the micro-contacts definted by electron beam lithography. since this CNT-based lithographic technique is, in principle, applicable to any kinds of materials, it can be very useful in exploring the fields of nano-science and technology, especially when it is combines with the CNT manipulation techniques.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.584-584
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• 2012

결정형 실리콘 태양전지 공정 중 표면 texturing 공정은 표면에 요철을 형성시켜 반사되는 빛 손실을 줄여서, 증가된 빛 흡수 양에 의해 단락전류(Isc)를 증가시키는데 그 목적이 있다. 표면 texturing 공정은 습식 식각과 건식 식각에 의한 방법으로 나눌 수 있다. 습식 식각은 KOH, TMAH, HNA 등의 실리콘 식각 용액을 사용하여 공정상의 위험도가 크고, 사용 후 용액의 폐기물에 의한 환경오염 문제가 있다. 건식 식각은 습식 식각과 달리 폐기물의 처리가 없고 미량의 가스를 이용한다. 그리고 다결정 실리콘 웨이퍼처럼 불규칙적인 결정방향에도 영향을 받지 않는 장점을 가지고 있어서 건식 식각을 이용한 표면 texturing 공정에 관한 많은 연구가 진행되고 있으며, 특히 RIE(reactive ion etching)를 이용한 태양전지 texturing 공정이 가장 주목을 받고 있다. 하지만 기존의 RIE를 이용하여 표면 texturing 공정을 하게 되면 500 nm 이하의 needle-like 구조의 표면이 만들어진다. Needle-like 구조의 표면은 전극을 형성할 때에 접촉 면적이 좁기 때문에 adhesion이 좋지 않은 것과 단파장 대역에서 광 손실이 많다는 단점이 있다. 본 논문에서는 기존의 RIE texturing의 단점을 보완하기 위해 챔버 내부에 metal-mesh를 장착한 후 RIE를 이용하여 $1{\mu}m$의 피라미드 구조를 형성하였고, RIE 공정 시 ion bombardment에 의한 표면 손상을 제거(RIE damage remove etching)하기 위하여 10초간 TMAH(Tetramethyl -ammonium hydroxide, 25 %) 식각 공정을 하였다.