• Korean Journal of Metals and Materials
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• v.49 no.10
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• pp.797-804
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• 2011

In this study, the mechanisms of the three steps (the polymer deposition step, the polymer etching step and the Si etching step) that constitute the Bosch process were investigated. The effects of radicals and ions on each step were quantitatively analyzed by comparing the simulated aspect ratio dependency of the deposition or etch rate with the experimental results. In the polymer deposition step, fluorocarbon polymer is deposited by chemical reactions of $CF_x$ radicals, of which the reaction probability is 0.13. Although the polymer etching step and the Si etching step were conducted under the same conditions, the etching mechanisms of polymer and Si were found to be quite different. In the polymer etching step, both chemical etching and physical sputter-etching contribute to the polymer etching. Whereas, in the Si etching step, Si is chemically etched by F radicals, of which the reactivity is greatly increased by the bombardment of energetic ions.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.29-35
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• 1999

Inductively coupled plsama etching of platinum thin film was studied using $O_2$ addition to $Cl_2$/Ar gas plasma. In this study, Pt etching mechanism was investigated with Ar/$Cl_2$ /$O_2$ gas plasma by using XPS and QMS. Ion current density was measured with Ar/$Cl_2$ /$O_2$ gas plasma by using single Langmuir probe. It was confirmed by using QMS and single Langmuir probe that Cl and Ar species rapidly decreased and ion current density was also decreased with increasing $O_2$ gas ratios. These results implied that the decrease of Pt etch rate is due to the decrease of reactive species ans ion current density with increasing $O_2$ gas mixing ratios. A maximum etch rate of 150nm/min and the oxide selectivity of 2.5 were obtained at Ar/$Cl_2$ /$O_2$ flow rate of 50 seem, RF power of 600 W, dc bias voltage of 125 V, and the total pressure of 10 mTorr.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.695-699
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• 2001

Cerium dioxide (CeO$_2$) was used as the intermediate layer between the ferroelectric thin film and Si substrate in a metal-ferroelectric-semiconductor field effect transistor (MFSFET), to improve the interface property by preventing the interdiffusion of the ferroelectric material and the Si substrate. In this study, CeO$_2$ thin films were etched with a CF$_4$/Ar gas combination in inductively coupled plasma (ICP). The maximum etch rate of CeO$_2$ thin films was 270$\AA$/min under CF$_4$/(CF$_4$+Ar) of 0.2, 600 W/-200V, 15 mTorr, and $25^{\circ}C$. The selectivities of CeO$_2$ to PR and SBT were 0.21, 0.25, respectively. The surface reaction in the etching of CeO$_2$ thin films was investigated with x-ray photoelectron spectroscopy (XPS). There is a chemical reaction between Ce and F. Compounds such as Ce-F$_{x}$ remains on the surface of CeO$_2$ thin films. Those products can be removed by Ar ion bombardment. The results of secondary ion mass spectrometry (SIMS) were consistent with those of XPS. Scanning electron microscopy (SEM) was used to examine etched profiles of CeO$_2$ thin films. The etch profile of over-etched CeO$_2$ films with the 0.5${\mu}{\textrm}{m}$ line was approximately 65$^{\circ}$.>.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.5
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• pp.265-269
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• 2000

$(Ba, Sr)TiO_3$thin films were etched with a magnetically enhanced inductively coupled plasma (MEICP) at different CF4/Ar gas mixing ratios. Experimental was done by varying the etching parameters such as rf power, dc bias and chamber pressure. The maximum etch rate of the BST films was $1800{AA}/min$ under $CF_4/(CF_4+Ar)$ of 0.1, 600 W/350 V and 5 mTorr. The selectivity of BST to Pt and PR was 0.6, 0.7, respectively. X-ray photoelectron spectroscopy (XPS) results show that surface reaction between Ba, Sr, Ti and C, F radicals occurs during the (Ba, Sr)TiO3 etching. To analyze the composition of surface residue after the etching, films etched with different CF_4/Ar$ gas mixing ratio were investigated using XPS and secondary ion mass spectroscopy (SIMS).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.52-55
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• 2000

In this study, (Ba,Sr)$TiO_3$(BST) thin films were etched with a magnetically enhanced inductively coupled plasma(MEICP) as a function Ar/$CF_4$ gas mixing ratio. Experiment was done by varying the etching parameters such as rf power, dc bias voltage and chamber pressure. The maximum etch rate of the BST films was 1700 ${\AA}/min$ under $CF_4/(CF_4+Ar)$ of 0.1, 600 W/350 V and 5 mTorr. The selectivity of BST to Pt and PR was 0.6, 0.7, respectively. X -ray photoelectron spectroscopy(XPS) studies shows that there are surface reaction between Ba, Sr, Ti and C, F radicals during the etching. To analyze the composition of surface residue remaining after the etching, films etched with different $CF_4$/Ar gas mixing ratio were investigated using XPS.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1637-1643
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• 1989

In this study, phosphosilicate glass(PSG) film was deposited by the oxidation of phosphine (PH3) and silane(SiH4) in nitrogen ambient with a conventional conveyerized Atmospheric Pressure Chemical Vapor Deposition(APCVD)system and phosphorus concentration is measured by using FT-IR technique. The flow characteirstics and etch rate variations ofthe films, depending on phosphorus concentrations, are investigated. Special emphasis is focused on the yield variations of NMOS-based 256K DRAM with 1.2\ulcorner metallization spacing with increasing phosphorus concentrations. As a result, the data indicates that the fairly good yield can be obtained within the range of between 8 and 10wt% phosphorus concentration, which result in a slope of flow within 45\ulcorner10\ulcorner The analysi of failure mechanism is also accompanied.

• Korean Membrane Journal
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• v.5 no.1
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• pp.54-60
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• 2003

The rejection properties and flux rates of silica nanoparticles in ultrafiltration membranes has been investigated. Cross-flow permeation experiments were conducted using polycarbonate track-etch flat membranes with pore sizes of 30 and 50 nm, and a silica nanoparticle solute with particle sizes of 5 and 18 nm with narrow size distributions. The fluxes and rejection factors were investigated at various particle concentrations, cross-flow velocities, pH, and ionic strengths of solution. Even though the size of the silica nanoparticles was much smaller than that of the membrane pores, the observed rejection rates were very high compared with those for a similar-sized polymer (dextran). The observed rejection rate decreased with increasing ionic strength, which implies that the transport mechanism of the silica nanoparticles is significantly influenced by electrostatic repulsion between particles and membranes.

• Transactions on Electrical and Electronic Materials
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• v.9 no.2
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• pp.62-66
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• 2008

We report on the growth mechanism of vertically aligned carbon nanotubes (VACNTs) using ultra thin Ni catalysts and direct current plasma enhanced chemical vapor deposition (PECVD) system. The CNTs were grown with -600 V bias to substrate electrode and catalyst thickness variation of 0.07 nm to 3 nm. The CNT density was reduced with catalyst thickness reduction and increased growth time. Cone like CNTs were grown with ultra thin Ni thickness, and it results from an etch of carbon network by reactive etchant species and continuous carbon precipitation on CNT walls. Vertically aligned sparse CNTs can be grown with ultra thin Ni catalyst.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1380-1381
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• 2006

본 연구는 MgO 박막을 유도 결합 플라즈마를 이용하여, $CF_4/Ar$ 가스 혼합비로 식각하였고, RF 전력, DC-bais 전압과 Process Pressure를 변경하면서 실험하였다. 빛 방출 분석(optical emission spectroscopy, OES)을 이용하여, 플라즈마 진단과 식각 특성과의 관계를 분석하였다. OES 결과로부터 $CF_4$ 첨가비를 50%까지는 증가시킴에 따라 식각률이 증가하였고, 그 후에 Ar 이온이 감소함으로써 식각률이 감소하였다. MgO 박막의 최고 식각률은 50%의 $CF_4/(CF_{4}+Ar)$에서 700 W의 RF 전력, -150 V의 DC-bias 전압, 반응로 압력은 15 mTorr, 기판 온도는 $30^{\circ}C$로 고정시켰을 때 29nm/min이었다. 이 조건에서 MgO 박막과 $SiO_2$의 선택비는 0.06 이었다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.11
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• pp.18-24
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• 2000

(Ba,Sr)$TiO_3$ thin films have attracted great interest as new dielectric materials of capacitors for ultra-large-scale integrated dynamic random access memories (ULSI-DRAMs) such as 1 Gbit or 4 Gbit. In this study, inductively coupled $BCl_3/Cl_2/Ar$ plasmas was used to etch (Ba,Sr)$TiO_3$ thin films. RF power/dc bias voltage=600 W/-250 V and chamber pressure was 10 mTorr. The $Cl_2/(Cl_2+Ar)$ was fixed at 0.2 the (Ba,Sr)$TiO_3$ thin films were etched adding $BCl_3$. The highest (Ba,Sr)$TiO_3$ etch rate is $480{\AA}/min$ at 10 % $BCl_3$ to $Cl_2/Ar$. The change of Cl, B radical density measured by optical emission spectroscopy(OES) as a function of $BCl_3$ percentage in $Cl_2/Ar$. The highest Cl radical density was shown at the addition of 10% $BCl_3$ to $Cl_2/Ar$. To study on the surface reaction of (Ba, Sr)$TiO_3$ thin films was investigated by XPS analysis. Ion bombardment etching is necessary to break Ba-O bond and to remove $BaCl_2$. There is a little chemical reaction between Sr and Cl, but Sr is removed by physical sputtering. There is a chemical reaction between Ti and Cl, and $TiCl_4$ is removed with ease. The cross-sectional of (Ba,Sr)$TiO_3$ thin film was investigated by scanning electron microscopy (SEM), the etch slope is about 65~70$^{\circ}$.