• Title/Summary/Keyword: Anisotropic etching

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Fabrication of Hollow-type Silicon Microneedle Array Using Microfabrication Technology (반도체 미세공정 기술을 이용한 Hollow형 실리콘 미세바늘 어레이의 제작)

  • Kim, Seung-Kook;Chang, Jong-Hyeon;Kim, Byoung-Min;Yang, Sang-Sik;Hwang, In-Sik;Pak, Jung-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.12
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    • pp.2221-2225
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    • 2007
  • Hollow-type microneedle array can be used for painless, continuous and stable drug delivery through a human skin. The needles must be sharp and have sufficient length in order to penetrate the epidermis. An array of hollow-type silicon microneedles was fabricated by using deep reactive ion etching and HNA wet etching with two oxide masks. Isotropic etching was used to create tapered tips of the needles, and anisotropic etching of Bosch process was used to make the extended length and holes of microneedles. The microneedles were formed by three steps of isotropic, anisotropic, and isotropic etching in order. The holes were made by one anisotropic etching step. The fabricated microneedles have $170{\mu}m$ width, $40{\mu}m$ hole diameter and $230{\mu}m$ length.

Anisotropic Etching Technology of Highly Doped Polysilicon by Mixed Chloroform (클로로포름($CHCl_3$)을 첨가한 고농도 폴리실리콘 이방성 식각 기술)

  • Lee, Jung-Hwan;Seo, Hee-Don;Choi, Se-Gon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.2
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    • pp.101-105
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    • 1998
  • This paper describes anisotropic etching technology of highly doped polysilicon. The main etching gases are $Cl_2$ and $SiCl_4$ for reactive ion etching of polysilicon. The mixed $CHCl_3$ to main etching gas makes polymer on etching side wall, so it prevents side etching of polysilicon. The etch rate of polysilicon is increased with increasing RF power. But the etching rate is decreased as the flow rate of $CHCl_3$ is increased with fixed RF power. The etch selectivity of polysilicon and $SiO_2$ is about 12:1. And that of polysilicon and $Si_3N_4$ is about 19:1. In the main etching gas condition, the slope of polysilicon is same as that of photoresist. But in the mixed $CHCl_3$ condition, the slope of polysilicon is larger than that of photoresist. This represents that the polymer made on side wall by added $CHCl_3$ prevents side etching, so anisotropic etching can be possible by polymer.

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Fabrication of (100), (110), (111) Si Tips using Various Wet Etching Method (다양한 습식식각법을 이용한 (100), (110), (111) Si tip의 제작)

  • Park, Heung-Woo;Ju, Byeong-Kwon;Ko, Chang-Gi;Hong, Soon-Kwan;Oh, Myoung-Hwan;Kim, Chui-Ju
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1250-1253
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    • 1994
  • (100), (110) and (111) Si wafers are etched by isotropic etching method, anisotropic etching method using KOH etchant and EPW etchant and combined two-step etching method to compare the results. Isotopic etching method is effective in fabrication of wedge-shaped tips, especially (110) Si. Anisotropic etching method of (100) Si using EPW etchant can fabricate sharp cone-shaped tips and isotropic etching after anisotropic etching of (100) Si can fabricate wedge-shaped tips.

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Fabrication of a (100) Silicon Master Using Anisotropic Wet Etching for Embossing

  • Jung, Yu-Min;Kim, Yeong-Cheol
    • Journal of the Korean Ceramic Society
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    • v.42 no.10 s.281
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    • pp.645-648
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    • 2005
  • To fabricate a (100) silicon hard master, we used anisotropic wet etching for the embossing. The etching chemical for the sili­con wafer was a TMAH 25$\%$ solution. The anisotropic wet etching produces a smooth sidewall surface inclined at 54.7°, and the surface roughness of the fabricated master is about 1 nm. After spin coating an organic-inorganic sol-gel hybrid resin on a silicon substrate, we used the fabricated master to form patterns on the silicon substrate. Thus, we successfully obtained patterns via the hot embossing technique with the (100) silicon hard master. Moreover, by using a single hydrophobic surface treatment of the master, we succeeded in achieving uniform surface roughness of the embossed patterns for more than ten embossments.

Anisotropic Etching of Silicon in Aqueous TMAH/IPA Solutions (수용성 TMAH/IPA 용액의 실리콘 이방성 식각)

  • 박진성;송승환;정귀상
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.334-337
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    • 1996
  • Si anisotropic etching is a key technology for micromachining. The main advantages of tetramethyl ammonium hydroxide (TMAH)-based solution are their full compatibility with IC process. In this work the anisotropic etching of single crystal Si in a TMAH (($CH_3$)$_4$NOH) based solution was studied. The influence of the addition of IPA to TMAH solution on their etching characteristics was also presented. The crystal planes bounding the etch front and their etch rates were determined as a function of temperature, crystal orientation, and etchant concentration. The etch rates of (100) oriented Si crystal planes decreased linearly with increasing the IPA concentration, The etched (100) planes were covered by Pyramidal-shaped hillocks below 15 wt.%, but very smooth surfaces were obtained above 20 wt.%. The addition of IPA to TMAH solution leads to smoother surfaces of sidewalls etched planes.

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The Effect of Pyrazine on TMAH:IPA Single-crystal Silicon Anisotropic Etching Properties

  • Gwiy-Sang Chung;Tae-Song Kim
    • Transactions on Electrical and Electronic Materials
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    • v.2 no.2
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    • pp.21-25
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    • 2001
  • This paper presents the effect of pyrazine on tetramethylammonium hydroxide (TMAH):isopropyl alcohol (IPA) single-crystal silicon anisotropic etching properties. With the addition of IPA to TMAH solutions, etching characteristics are exhibited an improvement in flatness on the etching front and a reduction in undercutting, but the etch rate on (100) silicon is decreased. The (100) silicon etch rate is improved by the addition of pyrazine. An etch rate on (100) silicon of 0.8 ${\mu}{\textrm}{m}$/min, which is faster by 13% than a 20 wt.% solution of pure TMAH, is obtained using 20 wt.% TMAH: 0.5 g/100 ml pyrazine solutions, but the etch rate on (100) silicon is decreased when more pyrazine is added. With the addition of pyrazine to a 25 wt.% TMAH solution, variations in flatness on the etching front are not observed and the undercutting ratio is reduced by 30~50%. These results indicate that anisotropic etching technology using TMAH:IPA:pyrazine solutions provides a powerful and versatile method for realizing of microelectromechanical systems.

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Photoelectrochemical Hydrogen Production on Textured Silicon Photocathode

  • Oh, Il-Whan
    • Journal of the Korean Electrochemical Society
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    • v.14 no.4
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    • pp.191-195
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    • 2011
  • Wet chemical etching methods were utilized to conduct Si surface texturing, which could enhance photoelectrochemical hydrogen generation rate. Two different etching methods tested, which were anisotropic metal-catalyzed electroless etching and isotropic etching. The Si nano-texture that was fabricated by the anisotropic etching showed ~25% increase in photocurrent for H2 generation. The photocurrent enhancement was attributed to the reduced reflection loss at the nano-textured Si surface, which provided a layer of intermediate density between water and the Si substrate.

Si Anisotropic Etching Characteristics of TMAH/IPA (TMAH/IPA의 실리콘 이방성 식각특성)

  • 정귀상;박진성;최영규
    • Electrical & Electronic Materials
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    • v.10 no.5
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    • pp.481-486
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    • 1997
  • This paper describes the anisotropic etching characteristics of Si in acqueous TMAH/IPA solutions. The etch rates of (100) oriented Si crystal planes decrease with increasing TMAH concentration and IPA concentration. Etchant concentration and etch temperature have a large effect on hillock density. Hillock density strongly increase with lower TMAH concentration and higher etch temperature. The etched (100) planes are covered by pyramidal-shaped hillocks below TMAH 15 wt.%, but very smooth surface is obtained TMAH 25 wt.%. The addition of IPA to TMAH solution leads to smoother surfaces of sidewalls etched planes. Undercutting ratio of pure TMAH solution is much higher than KOH. But, addition of IPA to TMAh the underrcutting ratio reduces by a factor of 3∼4. Therefore, acqueous TMAH/IPA solution is able to use as anisotropic etchant of Si because of full compability with IC fabrication process.

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Fabrication of Electrostatically Driven Comb Actuator Using (110) Oriented Si Anisotropic Etching ((110) 실리콘의 이방성 식각을 이용한 빗 모양 액츄에이터의 제작)

  • Lim, Hyung-Taek;Lee, Sang-Hun;Kim, Seong-Hyok;Kim, Yong-Kweon;Lee, Seung-Ki
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1974-1976
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    • 1996
  • An electrostatically driven comb actuator with $525{\mu}m$ height was fabricated using (110) Si anisotropic etching in the Potassium Hydroxide(KOH) solution. The etch-rate and etch-rate ratio are strongly dependent on the weight % and temperature of KOH solution. We developed the optimal condition for the anisotropic etching on (110) wafer with varying these conditions. The force that the comb-drive actuator generates is inversely proportional to the distance of gap and proportional to the height of the comb electrodes. The electrodes must have the high aspect ratio. The (110) Si anisotropic etching is very useful to get a high aspect ratio structure.

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A Study of Micro Freestanding Structure Fabrication using Nickel Electroless Plating And Silicon Anisotropic Etching (무전해 니켈 도금과 실리콘의 이방성 식각을 이용한 미세 가동 구조물의 제작방법에 관한 연구)

  • Kim, Seong-Hyok;Kim, Yong-Kweon;Lee, Jae-Ho;Huh, Jin
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.6
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    • pp.367-374
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    • 2000
  • This paper presents a method to fabricate freestanding structures by (100) silicon anisotropic etching and nickel electroless plating. The electroless plating process is simpler than the electroplating, and provides good coating uniformity and improved mechanical properties. Furthermore, the (100) silicon anisotropic etching in KOH solution with being aligned to <100> direction provides vertical (100) sidewalls on etched (100) surface. In this paper, the effects of the nickel electroless plating condition on the properties of electroless plated metal structures are investigated to apply fabrication of micro structures and then various micro structures are fabricated by nickel electroless plating. And then, the structures are released by silicon anisotropic etching in KOH solution with a large gap between the structure and the substrate. The fabricated cantilever structures are $210\mum$. wide, $5\mum$. thick and $15\mum$. over the silicon substrate, and the comb structure has the comb electrodes which are $4\mum$. wide and $4.3\mum$. thick separated by$1\mum$. It is released by silicon anisotropic etching in KOH solution. The gap between the structure and the substrate is $2.5\mum$.

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