• Title/Summary/Keyword: TMAH

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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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A Study on Anisotropic Etching Characteristics of Silicon in TMAH/AP/IPA Solutions for Piezoresistive Pressure Sensor Applications (압저항 압력센서 응용을 위한 TMAH/AP/IPA 용액의 실리콘 이방성 식각특성에 대한 연구)

  • 윤의중;김좌연;이태범;이석태
    • 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.

TMAH/IPA Anisotropic Etching Characteristics with Addition of Pyrazine (Pyrazine이 첨가된 TMAH/IPA 이방성 식각특성)

  • 박진성;정귀상
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1997.04a
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    • pp.23-26
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    • 1997
  • This work presents the TMAH/IPA anisotropic etching characteristics with addition of Pyrazine. (100) Si etching rate of 0.747 ${\mu}{\textrm}{m}$/min at 8$0^{\circ}C$ was obtained using TMAH 25 wt.% / IPA 17 vol.% / pyrazine 0.1 g. The etching rate of (100) Si is increased about 52% compare to pure TMAH 25 wt.%. But etching rate of (100) Si is decreased with increasing Pyrazine additive. Activation energy of TMAH/IPA/pyrazine is much lower than TMAH and TMAH/IPA solutions. Addition of Pyrazine does not effect on surface flatness and decreases undercutting ratio about 20 %. Therefore, TMAH/IPA/pyrazine is an attractive anisotropic etchant because of alkaline-ion free.

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Application of TMAH-based Pyrolysis Mass Spectrometry to a Biological Detection System (TMAH에 기반한 열분해 질량분석법의 생물 탐지체계 적용)

  • Kim, Ju-Hyun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.2
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    • pp.289-298
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    • 2011
  • TMAH-based Py-MS has been investigated to apply for a real-time classification of biological agents in the field. Acquiring reproducible data from mass spectrometry is a key to biological detection in the field. Nevertheless, it has been little studied on what factors could affect to the reproducibility of the TMAH-based Py-MS spectrum patterns. Given the TMAH-based Py-MS applied to the field system, several factors which could affect to the reproducible pattern of TMAH-based Py-MS spectra are needed to be examined, including changes in TMAH injection volume, growth temperature for microorganism, and number of cells collected in pyrolyzer, and implication of stabilizer used for lyophilization. This study showed that the reproducibility of the spectrum patterns was significantly hindered by changes in TMAH concentration and cell number, and stabilizer implication but not by growth temperature. Among those at low TMAH concentration(0.015m) was not observed the significant alterations of the spectrum pattern even when its injection volume was changed, yet was in different cell numbers and stabilizer implication.

The Etching Characteristics of TMAH/AP for the Diaphragm Fabrication of Pressure Sensors (압력센서용 다이아프램 제작을 위한 TMAH/AP 식각특성)

  • 윤의중;김좌연
    • Journal of the Semiconductor & Display Technology
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    • v.2 no.4
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    • pp.19-22
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    • 2003
  • In this paper, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ammonium persulfate (AP) 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-uniformity exists on the etched surface because of formation of hillocks on the <100> surface. 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 diaphragms of 20$\mu\textrm{m}$ thickness and 100-400 $\mu\textrm{m}$ one-side length were fabricated successfully by adding AP of (5/6)g to 800 ml TMAH solution every 10 minutes.

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Selective Etching of Silicon in TMAH:IPA:Pyrazine Solutions (TMAH:IPA:Pyrazine 용액에서 실리콘의 선택식각)

  • Chung, Gwiy-Sang;Lee, Chae-Bong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04b
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    • pp.112-116
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    • 2000
  • This paper presents anisotropic ethcing characteristics of single-crystal silicon in tetramethylammonium hydroxide(TMAH):isopropyl alcohol(IPA) solutions containing pyrazine. With the addition of IPA to TMAH solutions, etching characteristics are exhibited that indicate 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 $0.8\;{\mu}m/min$, 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 if more pyrazine is added. With the addition of pyrazine to a 25 wt.% TMAH solution, variations in flatness on the etching front were not observed and the undercutting ratio was reduced by 30 ~ 50 %.

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A Study on Anisotropic Etching Characteristics of Silicon in TMAH/AP Solutions and Fabrication of a Diaphragm (TMAH/AP 용액의 실리콘 이방성 식각특성 및 다이아프램 제작에 대한 연구)

  • 윤의중;김좌연;이태범;이석태
    • Proceedings of the IEEK Conference
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    • 2003.07b
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    • pp.1033-1036
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    • 2003
  • In this paper, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ ammonium persulfate (AP) 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-uniformity exists on the etched surface because of formation of hillocks on the <100> surface. 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 diaphragms of 20${\mu}{\textrm}{m}$ thickness and 100~400${\mu}{\textrm}{m}$ one-side length were fabricated successfully by applying optimum Si etching conditions of TMAH/AP solutions.

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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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Micromachining of Si substrate Using Electrochemical Etch-Stop in Aqueous TMAH/IPA/pyrazine Solution (TMAH/IPA/Pyrazine 수용액에서 전기화학적 식각정지법을 이용한 Si 기판의 미세가공)

  • 박진성;정귀상
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1997.11a
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    • pp.397-400
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    • 1997
  • This paper presentes the characteristics of Si anisotropic etching and electrochemical etch-stop in aqueous TMAH/IPA/pyrazine solution. (100) Si etching rate of 0.747 $\mu\textrm{m}$/min which faster 86% than TMAH 25 wt.%/IPA 17 vol.% solution was obtained using best etching condition at TMAH 25 wt.%/IPA 17 vol.%/pyrazine 0.1 g and the etching rate of (100) Si was decreased with more additive quantity of pyrazine. I-V curve of p-type Si in TMAH/IPA/pyrazine was obtained. OCP(Open Circuit Potential) and PP(Passivation Potential) were -2 V and -0.9 V, respectively. Si diaphragms were obtained by electrochemical etch-stop in aqueous TMAH/IPA/pyrazine solution.

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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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