Selective Electrochemical Etching of Stainless Steel Using Laser-Patterned Copper Layer

Hong-Shik Shin 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.5

This paper proposes a novel electrochemical etching process without the need for a metal mask or photo-resist mask. The selective electrochemical etching using laser-patterned (SEEL) copper layer process consists of three steps: electrodeposition, laser patterning, and electrochemical etching. In the SEEL copper layer process, a deposited copper layer was formed on stainless steel by an electrodeposition process. A patterned copper layer on stainless steel was formed by laser beam irradiation. A patterned copper layer serves as both a sacrificial layer and a protective mask during the electrochemical etching process. The results were observed via scanning electron microscopy and surface profiler measurement. The appropriate conditions for stable SEEL copper layer process were determined. Finally, selective electrochemical etching with various micro patterns on stainless steel was been successfully performed.

전해에칭 보호 마스크로 활용하기 위한 도금층의 레이저 패터닝

신홍식 한국생산제조학회 2018 한국생산제조학회지 Vol.27 No.1

A through-mask electrochemical etching process involves a selective metal removal process from unprotected areas of a patterned workpiece. A protective mask such as a photo-mask is used in through-mask electrochemical etching. The deposited layer with micro patterns can be fabricated by laser beam irradiation. The deposited layer with micro patterns can act as a protective mask during electrochemical etching. The characteristics of deposited layer with micro patterns are investigated according to the electrodeposition and laser beam conditions. The experimental results were observed by SEM (scanning electron microscope), EDS (energy dispersive spectrometry), and surface profile analysis. Consequently, selective electrochemical etching using the deposited layer was successfully achieved.

Electrochemical Etch-Stop Suitable for MEMS Applications

Chung, Gwiy-Sang,Kim, Sun-Chunl,Kim, Tae-Song The Korean Institute of Electrical and Electronic 2001 Transactions on Electrical and Electronic Material Vol.2 No.2

This paper presents the electrochemical etch-stop characteristics of single-crystal Si(001) wafers in tetramethyl ammonium hydroxide(TMAH):isopropyl alcohol(IPA):pyrazine solutions. The addition of pyrazine to TMAH:IPA solutions increased the etch rate of (100) Si, thus the etching time required by the etch-stop process shortened. The current-voltage(I-V) characteristics of n- and p-type Si in TMAH:IPA:pyrazine solutions were obtained, respectively. Open circuit potential(OCP) and passivation potential(PP) of n- and p-type Si, respectively, were obtained and applied potential was selected between n- and p-type Si PPs. The electrochemical etch-stop method was used to fabricate 801 microdiaphragms of 20 ${\mu}{\textrm}{m}$ thickness on a 5-inch Si wafer. The average thickness of fabricated 801 microdiaphragms on one Si wafer was 20.03 ${\mu}{\textrm}{m}$ and the standard deviation was $\pm$0.26 ${\mu}{\textrm}{m}$. The Si surface of the etch-stopped microdiaphragm was extremely flat with no noticeable taper or nonuniformity.

Fabrication of precisely controlled silicon wire and cone arrays by electrochemical etching

Seo, H.S.,Li, X.,Um, H.D.,Yoo, B.,Kim, J.H.,Kim, K.P.,Cho, Y.W.,Lee, J.H. North-Holland 2009 Materials Letters Vol. No.

There is an exponentially growing need for well-oriented, vertical silicon nano/micro-structure arrays, particularly in high-density integrated electronic devices. Here, we demonstrate that precisely controlled vertical arrays of silicon wires and cones can be fabricated by a combined treatment strategy of electrochemical and chemical etchings. First, a periodically ordered array of silicon wires was readily fabricated at microscale by simple electrochemical etching in which the current density played a critical role in determining the wire diameter and interspacing. The microstructures fabricated by electrochemical etching were more precisely tuned by further chemical etching, thereby transforming into cone arrays with extremely sharp tips where the cone height was controlled by the etching time. This approach could have broad utility in many electronics requiring miniaturization and high-density integration such as field emitters, photovoltaic and thermoelectric devices.

나노갭 트렌치 공정을 이용한 가속도센서 제작

김현철(Hyeon-Cheol Kim),권희준(Hee-jun Kwon) 한국정보전자통신기술학회 2016 한국정보전자통신기술학회논문지 Vol.9 No.2

본 논문은 광 도움 전기화학적 식각으로 나노갭 트렌치 구조를 형성하고 이를 이용해서 정전 용량형 가속도 센서를 설계하고 제작한 것에 대한 연구이다. 정전 용량형 가속도 센서의 감도를 증가시키기 위해 스프링에 연결된 관성질량과 연결된 전극과 감지전극 사이의 간격을 좁혀 커패시턴스의 변화량을 증가시키고 있다. 이를 실현시키기 위해 광-도움 전기화학적 식각을 이용하였고 ANSYS 프로그램을 이용하여 구조해석을 실시하여 1㎜×1㎜ 크기의 초소형 정전 용량형 가속도 센서를 설계하였다. 광-도움 전기화학적 식각의 실험 변수인 빛의 세기, dc 전압, 용액의 조성, 피치 등을 고려하여 가속도 센서는 제작 되었다. 최적 공정 조건은 dc전압 2V, Blue LED 20mA, 49wt%HF:DMF:D.I.Water=1:20:10, 피치 20μm이며, 폭 344nm, 깊이 11.627μm의 나노갭 트렌치가 형성되었다. This paper proposes a novel fabrication method for a capacitive type micro-accelerometer with uniform nano-gap using photo-assisted electro-chemical etching. The sensitivity of the accelerometer should be improved while the electrodes between the inertial mass and the sensing comb should be narrowed. In this paper the nano-gap trench structure is fabricated using the photo-assisted electrochemical etching method. The sensor was designed and analysed using ANSYS simulator. The characteristics of the etching were observed according to the dc bias, the light intensity, the composition of the solution, the temperature of the solution, and the pattern pitch variation. The optimum etching conditions were dc bias of 2V, Blue LED of 20mA, 49wt% HF:DMF:D.I.Water=1:20:10, the pattern pitch of 20μm. Uniform trench structure with width of 344nm and depth of 11.627μm are formed using the optimum condition.

인가 바이어스 조건이 전기화학적 식각정지 특성에 미치는 영향

정귀상,강경두,김태송,이원재,송재성 한국전기전자재료학회 2001 전기전자재료학회논문지 Vol.14 No.4

This paper describes the effects of applied bias conditions on electrochemical etch-stop characteristics. THere are a number of key issues such as diode leakage and ohmic losses which arise when applying the conventional 3-electrochemical etch-stop to fabricated some of he MEMS(microelectro mechanical system) and SOI(Si-on-insulator) structures which employ SDB(Si-wafer direct bonding). This work allows to perform anin situ diagnostic to predict whether or not an electrochemical etch-stop would fail due to diode-leakage-induced premature passivation. In addition, it presents technology which takes into account the effects of ohmic losses and allows to calculate the appropriate bias necessary to obtain a successful electrochemical etch-stop.

전기화학적 식각정지에 의한 고수율 실리콘 박막 멤브레인 제작

정귀상,박진상,이원재,송재성 한국전기전자재료학회 2001 전기전자재료학회논문지 Vol.14 No.3

In this paper, the authors present the fabrication of high-yield Si thin-membranes by electrochemical etch-stop in tetramethyl ammonium hydroxide (TMAH): isopropyl alcohol (IPA):pyrazine solutions. The current-voltage (I-V) characteristics of n- and p-type Si in TMAH:IPA;pyrazine solutions were analysed, repsectively. Open circuit potential (OCP)and passivation potential (PP) of n- and p-type Si, respectively, were obtained and applied potential was selected between n- and p-type Si PPs. The electrochemical etch-stop method was applied to the fabrication of 801 micro-membranes with 20.0 $\mu\textrm{m}$ thickness on a 5" Si wafer. The average thickness of fabricated 801 micro-membranes on one wafer 20.03$\mu\textrm{m}$ and the standard deviation was ${\pm}$0.26$\mu\textrm{m}$. The Si surface of the etch-stopped micro-membranes was extremely flat with no noticeable taper or nonuniformity. The results indicate that use of the electrochemical etch-stop method for the etching of Si in TMAH:IPA;pyrazine solutions provides a powerful and versatile alternative process for fabricating high-yield Si micro-membranes.

SDB와 전기화학적 식각정지에 의한 벌크 마이크로머신용 3차원 미세구조물 제작

정귀상,김재민,윤석진 한국전기전자재료학회 2002 전기전자재료학회논문지 Vol.15 No.11

This paper reports on the fabrication of free-standing microstructures by DRIE (deep reactive ion etching). SOI (Si-on-insulator) structures with buried cavities are fabricated by SDB (Si-wafer direct bonding) technology and electrochemical etch-stop. The cavity was formed the upper handling wafer by Si anisotropic etch technique. SDB process was performed to seal the formed cavity under vacuum condition at -760 mmHg. In the SDB process, captured air and moisture inside of the cavities were removed by making channels towards outside. After annealing (100$0^{\circ}C$, 60 min.), the SDB SOI structure with a accurate thickness and a good roughness was thinned by electrochemical etch-stop in TMAH solution. Finally, it was fabricated free-standing microstructures by DRIE. This result indicates that the fabrication technology of free-standing microstructures by combination SDB, electrochemical etch-stop and DRIE provides a powerful and versatile alternative process for high-performance bulk micromachining in MEMS fields.

Efficient Fabrication of Gold Tips by Electrochemical Etching for Tip-Enhanced Raman Spectroscopy

허태원,안효석,한규범,반우진 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.2

Tip-enhanced Raman Spectroscopy (TERS) is a powerful tool for analyzing physical and chemical properties of material at the nanoscale. The most widely used probes for TERS have metal(Au or Ag)-coated AFM tips. However, the durability of metal-coated AFM tips are limited because the coating layers can be easily worn out during the measurement. Furthermore, the Ag-coated tip is oxidized when it is exposed to air. To overcome these limitations, we propose a method of fabricating a Au tip for TERS with a Au wire by electrochemical etching. Pulse waves generated by pulse width modulation was applied to an electrochemical etching system, and it was optimized by controlling etching parameters (voltage, duty cycle, frequency and immersion depth) to achieve a smoothly etched surface with a tip radius of around 20 nm. With optimized etching parameters, a Au probe tip having a desired tip radius was successfully fabricated with a yield rate of approximately 85 %. Finally, a tuning fork-based Au probe for TERS was fabricated by attaching the Au tip to a tuning fork, and its operation was confirmed by obtaining a topographical image and Raman maps of carbon-nanotubes (CNTs).

Effect of electrolyte solution in the morphology control of polycrystalline W nanotip

Bishwa Chandra Adhikari,Jun Sung Kim,Pradeep Lamichhane,Ramhari Paneru,Eun Ha Choi 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2

The consistency in the shape and reproducibility of the ultra-sharp nanotips are important for both commercial application and research. In this study, a polycrystalline tungsten wire of diameter 150 ㎛ was used to fabricate the nanotip below the 10 nm by static process of electrochemical etching. The static electrochemical etching process was a common process in which electrolyte solution of NaOH, and KOH varied from 2N to 8N. The taper length, a radius of curvature, and the etching current of nanotips were observed and compared between 4N of NaOH and KOH, respectively. The drop off process quickly occurred in the aqueous solution of 4N of NaOH than in the KOH solution because of high conductivity. The field emission electron beam stability, I-V curve, Fowler-Nordheim (FN) plot are compared between 4N of NaOH and KOH, respectively. Furthermore, the scanning electron microscopy (SEM), field ion microscopy (FIM), field emission microscopy (FEM) image was compared between two nanotips prepared by 4N of NaOH and KOH, respectively.