• E2M - 전기 전자와 첨단 소재
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• 제10권5호
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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.

• 대한전자공학회논문지SD
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• 제41권3호
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• pp.9-14
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• 2004

본 논문에서는 압저항 압력센서 응용을 위한 최적의 멤브레인 구조를 만들기 위하여 tetramethylammonium hydroxide (TMAH)/ammonium persulfate (AP)/isopropyl alcoho 1(IPA) 용액의 Si 이방성 식각 특성을 연구하였다. 독성이 적고 CMOS 공정과의 높은 호환성 때문에 TMAH를 Si 이방성 식각용액으로 사용하였다. 식각온도, TMAH농도 및 식각시간에 따른 Si 식각률의 변화를 측정하였다. 식각온도를 증가 시키고 TMAH농도를 감소시킴에 따라 Si 식각률은 증가한 반면에 (100)면에 hillock 이 생겨 식각표면의 평탄도가 감소하였다. TMAH 에 IPA 용액을 첨가하면 식각표면의 평탄도를 증가 시키나 Si의 식각률을 감소 시켰다. 그러나, TMAH 에 AP 용액을 첨가하면 Si의 식각률과 식각표면의 평탄도 모두를 증가시켰다. 또한 시간당의 AP 첨가 횟수를 증가시킴으로서 Si 식각률을 최대화시킬 수 있었다. TMAH/AP 용액의 최적의 Si 식각조건을 적용하여 한변의 길이가 100∼400㎛이고 두께가 20㎛인 정사각형 모양의 Si 멤브레인을 성공적으로 제작하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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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.

• 한국군사과학기술학회지
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• 제14권2호
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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.

• 반도체디스플레이기술학회지
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• 제2권4호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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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 %.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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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.

• Transactions on Electrical and Electronic Materials
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• 제2권2호
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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.