• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.91-96
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• 1987

Plasma etching can obtain less damaged etch surface than reactive ion etching. This study was performed to get anisotropic etching characteristics of Si using two step etching technique with C2CIF5 and SF6 gas mixture. The results show that the etch rate and aspect ratio of silicon was increased with increment of SF6 contents. The bulging phenomenon on trench side wall in the plasma one-step etching technique was eliminated by the two step etching technique. The anisotropy was decreased from 12(at 120m Torr) to 2.2(at 400m Torr) with increasing the chamber pressure. At the low rf power (350 watts) anisotrpy of silicon was obtained 7 lower than that of high rf power (650 watts. A:~9). In Summary we obtained anisotropic etching profiles of silicon with e 6\ulcornerm depth by using the plasma two-step etching technique.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.276-278
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• 1997

The reliable etching process is one of the essential steps in fabricating GaN based-device. High etch rate is needed to obtain a deeply etched structure and perfect anisotropic etched facet is needed to obtain lasing profile. In the research, therefore, we had proposed a planar inductively coupled plasma etcher (Planar ICP Etcher) as a high density plasma source, and studied the etching mechanism using the $CH_4/H_2$/Ar gas mixture. Dry etching characteristics such as etch rate, anisotropic etching profile and so on, for the III-V nitride layers were investigated using Planar ICP Etcher, based on the plasma characteristic as a variation of plasma process parameters.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.6
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• pp.533-538
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• 2014

We fabricated grooved mushroom structures with anisotropic wettability on silicon substrates using basic MEMS processes. The geometry of these grooved mushroom structures could be changed by controlling the additional IPA solution during Si etching by TMAH solution. To understand anisotropic wettability, contact angles (CAs) of hexadecane droplets were measured in the orthogonal and parallel directions to grooved lines. The CA measurement results displayed anisotropic wetting on the grooved mushroom structures. However, specimens with $80{\mu}m$ distance between top layers displayed isotropic and superoleophobic wetting. This study demonstrates that the thickness of the top layer is more critical than the width or height of the ridge when determining the wettability of organic solvent. Despite the wide distance between top layers ($80{\mu}m$), the specimen with a thin top layer (100 nm) showed highly anisotropic wetting and low CA due to the pinning of droplets at the edge of the top layer.

• Journal of the Korean Electrochemical Society
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• v.16 no.1
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• pp.1-8
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• 2013

This review article summarizes metal-assisted chemical etching (MAC etch or MACE), an anisotropic etching method for Si, and describes principles, main factors, and recent achievements in literature. In 1990, it was discovered that, with metal catalyst on surface and $H_2O_2$/HF as etchant, Si substrate can be etched anisotropically, in even in solution. In contrast to high-cost vacuum-based dry etching methods, MAC etch enables to fabricate a variety of high aspect ratio nanostructures through wet etching process.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.4
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• pp.51-56
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• 2012

In order to fabricate through-Si-vias for thermal vias by using wet etching process, anisotropic etching behavior of Si substrate was investigated as functions of concentration and temperature of TMAH solution in this study. The etching rate of 5 wt%, 10 wt%, and 25 wt% TMAH solutions, of which temperature was maintained at $80^{\circ}C$, was $0.76{\mu}m/min$, $0.75{\mu}m/min$, and $0.30{\mu}m/min$, respectively. With changing the temperature of 10 wt% TMAH solution to $20^{\circ}C$ and $50^{\circ}C$, the etching rate was reduced to $0.067{\mu}m/min$ and $0.233{\mu}m/min$, respectively. Through-Si-vias of $500{\mu}m$-depth could be fabricated by etching a Si substrate for 5 hours in 10 wt% TMAH solution at $80^{\circ}C$ after forming same via-pattern on each side of the Si substrate.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.9-14
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• 2004

In this study, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ ammonium persulfate(AP)/isopropyl alcohol(IPA) solutions were investigated to realize the optimum structure of a diaphragm for the piezoresistive pressure sensor application. Due to its low toxicity and its high compatibility with the CMOS processing, TMAH was used as Si anisotropic etchants. The variations of Si etch rate on the etching temperature, TMAH concentration, and etching time were obtained. With increasing the etching temperature and decreasing TMAH concentrations, the Si etch rate is increased while a significant non-unifonnity exists on the etched surface because of formation of hillocks on the (100) surface. The addition of IPA to TMAH solution leads to smoother etched surfaces but, makes the Si etch rate lower. However, with the addition of AP to TMAH solution, the Si etch rate is increased and an improvement in flatness on the etching front is observed. The Si etch rate is also maximized with increasing the number of addition of AP to TMAH solution per one hour. The Si square membranes of 20${\mu}{\textrm}{m}$ thickness and l00-400${\mu}{\textrm}{m}$ one-side length were fabricated successfully by applying optimum Si etching conditions of TMAH/AP solutions.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.89-96
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• 2006

In this study, fabrication of the large area silicon mirror is accomplished by anisotropic wet etching using micromachining technology for implementation of integrated slim optical pickup and the process condition is also established for improving the mirror surface roughness. Until now, few results have been reported about the production of highly stepped $9.74^{\circ}$ off-axis-cut silicon wafers using wet etching. In addition rough surface of the mirror is achieved in case of tong etching time. Hence a novel method called magnetorheolocal finishing is applied to enhance the surface quality of the mirror plane. Finally, areal peak to valley surface roughness of mirror plane is reduced about 100nm in large area of $mm^2$ and it is applicable to optical pickup using infrared wavelength.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.11a
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• pp.5.2-5.2
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• 2008

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.26-26
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• 1997

• Journal of the Korean Ceramic Society
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• v.34 no.10
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• pp.1021-1026
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• 1997

RuO2 thin film has reasonably good conductivity and stiffness and it is thought to substitute for the cantilever beam made up of Pt and Si3N4 double layers in microactuators. Therefore, anisotopic Si etching was performed using RuO2 thin film as a mask layer in 25 wt. % TMAH water solution. In the etching temperature ranging from 6$0^{\circ}C$ to 75$^{\circ}C$, the etch rates of all the crystallographic directions increased linearly as the etching temperature increased. The etch rate ratio(selectivity) of [111]/[100] which varied from 0.08 to 0.14, was not sensitive to temperature. The activation energies for [110] direction, [100] direction and [111] direction were 0.50, 0.66 and 1.04eV, respectively. RuO2 cantilever beam with a clean surface was formed at the etching temperatures of 6$0^{\circ}C$ and $65^{\circ}C$. But the damages due to formation of pin holes on RuO2 surface were observed beyond 7$0^{\circ}C$. The tensile stress of RuO2 thin films caused the cantilever bending upward. As a result, it was demonstrated that the formation of conducting oxide RuO2 cantilever beam which can replace the role of an electrode and supporting layer could be possible by TMAH solution.