• Korean Journal of Metals and Materials
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• v.48 no.11
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• pp.1028-1034
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• 2010

In the development of 3D package, through silicon via (TSV) formation technology by using deep reactive ion etching (DRIE) is one of the key processes. We performed the Bosch process, which consists of sequentially alternating the etch and passivation steps using $SF_6$ with $O_2$ and $C_4F_8$ plasma, respectively. We investigated the effect of changing variables on vias: the gas flow time, the ratio of $O_2$ gas, source and bias power, and process time. Each parameter plays a critical role in obtaining a specified via profile. Analysis of via profiles shows that the gas flow time is the most critical process parameter. A high source power accelerated more etchant species fluorine ions toward the silicon wafer and improved their directionality. With $O_2$ gas addition, there is an optimized condition to form the desired vertical interconnection. Overall, the etching rate decreased when the process time was longer.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.223-223
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• 2012

Surface engineering plays a significant role in fabricating highly functionalized materials applicable to industrial and biomedical fields. Surface wrinkles and folds formed by ion beam or plasma treatment are buckling-induced patterns and controlled formation of those patterns has recently gained considerable attention as a way of creating well-defined surface topographies for a wide range of applications. Surface wrinkles and folds can be observed when a stiff thin layer attached to a compliant substrate undergoes compression and plasma treatment is one of the techniques that can form stiff thin layers on compliant polymeric substrates, such as poly (dimethylsiloxane) (PDMS). Here, we report two effective methods using plasma modification techniques for controlling the formation of surface wrinkles and folds on flat or patterned PDMS substrates. First, we show a method of creating wrinkled diamond-like carbon (DLC) film on grooved PDMS substrates. Grooved PDMS substrates fabricated by a molding method using a grooved master prepared by photolithography and a dry etching process were treated with argon plasma and subsequently coated with DLC film, which resulted in the formation of wrinkled DLC film aligning perpendicular to the steps of the pre-patterned ridges. The wavelength and the amplitude of the wrinkled DLC film exhibited variation in the submicron- to micron-scale range according to the duration of argon plasma pre-treatment. Second, we present a method for controlled formation of folds on flat PDMS substrates treated with oxygen plasma under large compressive strains. Flat PDMS substrates were strained uniaxially and then treated with oxygen plasma, resulting in the formation of surface wrinkles at smaller strain levels, which evolved into surface folds at larger strain levels. Our results demonstrate that we can control the formation and evolution of surface folds simply by controlling the pre-strain applied to the substrates and/or the duration of oxygen plasma treatment.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.190-198
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• 2010

Asymmetric model for plasma uniformity by Ar and $CF_4$ was modeled by the antenna structure, the diameter of chamber, and the distance between source and substrate for the development of plasma equipment for 450 mm wafer. The aspect ratio of chamber was divided by diameter, distance from substrate, and pumping port area. And we found the condition with the optimized plasma uniformity by changing the antenna structure. The drift diffusion and quasi-neutrality for simplification were used, and the ion energy function was activated for the surface recombination and etching reaction. The uniformity of plasma density on substrate surface was improved by being far of the distance between substrate wall and chamber wall, and substrate and plasma source. And when the antenna of only 2 turns was used, the plasma uniformity can improve from 20~30% to 4.7%.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.309-311
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• 2003

The effects of etch parameters on dry etching of BLT thin films were investigated with ICP etch system in $Cl_2$/Ar and $BCl_2/Cl_2$/Ar gas. The etch rate and etch selectivity of BLT films were examined as a function of gas concentration, ICP power, bias power, and pressure. The maximum etch rates of 191.1 nm/min was obtained at the mixed etch condition of $BCl_3(20%)/Cl_2$/Ar, 700 W ICP RF power, 12 mTorr pressure and 400 W substrate RF power. As ICP power and rf power increased, the etch rate of BLT increased. As pressure increased, the etch rate of BLT decreased. The changes of radicals in both $Cl_2$/Ar and $BCl_3/Cl_2$/Ar plasma were measured with using optical emission spectroscopy (OES).

• Journal of the Korean Vacuum Society
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• v.3 no.1
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• pp.77-93
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• 1994

플라즈마 식각 공정에서의 미세구조 식각 연구를 위하여 두종류의 미세식각 진전 모델을 제시하 였다. 모델 1에서는 Knudsen 확산 정도를 나타내는 Thiele 계수($\Phi$2) 의 변화와 마스크의 하전에 의한 이온의 회적이 식각 패턴에 미치는 영향을 고찰하였으며 모델 2에서는 이온의 충돌에 의한 분산 효과가 식각 패턴에 미치는 영향을 살펴보았다. 반응성 라디칼과 확산저항이 수직방향으로의 긱각깊이를 감소 시켜 RIE Lag를 일으키며 마스크의 하전에 의한 이온의 회절에 의하여 "dovetailing"형태의 식각 패턴 형성의 원인 이 됨을 알 수 있었다. 모델 2의 결과로부터 쉬스 지역에서의 이온의 분산이 심화될수록 "bowing" 형태의 식각패턴이 두드러졌으며 RIE Laggus상이 증가하는 것으로 나타났다.gus상이 증가하는 것으로 나타났다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.1-6
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• 2004

Dry etch characteristics of polysilicon with HBr/O$_2$ inductively coupled plasma (ICP) have been investigated. We determined etch late, uniformity, etch profiles, and selectivity with analyzing the cross-sectional scanning electron microscopy images obtained from top, center, bottom, right, and left positions. The etch rate of polysilicon was about 2500 $\AA$/min, which meets with the mass production for devices. The wafer level etch uniformity was within $\pm$5 ％. Etch profile showed 90$^{\circ}$ slopes without notches. The selectivity over photoresist was between 2:1∼4.5:1, depending on $O_2$ flow rate. The HBr-ICP etching showed higher PR selectivity, and sharper profile than the conventional Cl$_2$-RIE.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.770-772
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• 1998

The highest etch rate of Pt film was obtained at 10% $Cl_2$/90% Ar gas mixing ratio in our previous investigation. However, the problems such as the etch residues(fence) remained on the pattern sidewall, low selectivity to oxide as mask and low etch slope were presented. In this paper, the etching by additive $O_2$ gas to 10% $Cl_2$/90% Ar gas base was examined. As a result, the fence-free pattern and high etch slope was observed and the selectivity to oxide increased without decreasing of the etch rate. And the reasons for this phenomenon was investigated by XPS(x-ray photoelectron spectroscopy) surface analysis and plasma characteristic.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.27-29
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• 2005

Using a generalized regression neural network, etch microtrenching was modeled. All neurons in the pattern layer were equipped with multi-factored spreads and their complex effects on the prediction performance were optimized by means of a genetic algorithm. For comparison, GRNN model was constructed in a conventional way. Comparison result revealed that GA-GRNN model was more accurate than GRNN model by about 30%. The microtrenching data were collected during the etching of silicon oxynitride film and the etch process was characterized by a statistical experimental design.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.496-500
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to significantly impact terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (RIE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi-Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7% efficiency of mono-crystalline silicon solar cell and 10.2% multi-crystalline silicon solar cell.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1271-1276
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• 2004

Two-dimensionally arrayed nanocolumn lattices were fabricated by using double-exposure laser holographic method. The hexagonal lattice was formed by rotating the sample with 60 degree while the square lattice by 90 degree before the second laser-exposure. The reactive ion etching for a typical time of 30 min using CH$_4$/H$_2$ plasma enhanced the aspect-ratio by more than 1.5 with a slight increase of the bottom width of columns. The etch-damage was observed by photoluminescence (PL) spectroscopy which was removed by the wet chemical etching using HBr/$H_2O$$_2$/$H_2O$ solution, leading into the enhanced PL intensities of the PCs.