scholarly journals Curved Structure of Si by Improving Etching Direction Controllability in Magnetically Guided Metal-Assisted Chemical Etching

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 744 ◽  
Author(s):  
Tae Kim ◽  
Jee-Hwan Bae ◽  
Juyoung Kim ◽  
Min Cho ◽  
Yu-Chan Kim ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cost Effectiveness ◽  
External Magnetic Field ◽  
Chemical Etching ◽  
Electronic Devices ◽  
Metal Catalyst ◽  
Fabrication Method ◽  
Electromechanical Systems ◽  
Etching Solution ◽  
Metal Assisted Chemical Etching

Metal-assisted chemical etching (MACE) is widely used to fabricate micro-/nano-structured Si owing to its simplicity and cost-effectiveness. The technique of magnetically guided MACE, involving MACE with a tri-layer metal catalyst, was developed to improve etching speed as well as to adjust the etching direction using an external magnetic field. However, the controllability of the etching direction diminishes with an increase in the etching dimension, owing to the corrosion of Fe due to the etching solution; this impedes the wider application of this approach for the fabrication of complex micro Si structures. In this study, we modified a tri-layer metal catalyst (Au/Fe/Au), wherein the Fe layer was encapsulated to improve direction controllability; this improved controllability was achieved by protecting Fe against the corrosion caused by the etching solution. We demonstrated curved Si microgroove arrays via magnetically guided MACE with Fe encapsulated in the tri-layer catalyst. Furthermore, the curvature in the curved Si microarrays could be modulated via an external magnetic field, indicating that direction controllability could be maintained even for the magnetically guided MACE of bulk Si. The proposed fabrication method developed for producing curved Si microgroove arrays can be applied to electronic devices and micro-electromechanical systems.

Monitoring Hydrogen Peroxide Using Electrochemically Reduced Graphene Oxide Modified Screen Printed Electrodes During Metal Assisted Chemical Etching Processes

2021 ◽  
Author(s):  
Chun-Wen Lan ◽  
Subbiramaniyan Kubendhiran ◽  
Gavin Sison ◽  
Hsiao Ping Hsu
Keyword(s):  
Hydrogen Peroxide ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Electrochemical Method ◽  
Chemical Etching ◽  
Etching Process ◽  
Etching Solution ◽  
Reduced Graphene ◽  
Metal Assisted Chemical Etching ◽  
Screen Printed

Abstract The concentrations of etchant solution substituents in metal assisted chemical etching (MACE) processes control the morphology and reflectivity of subsequently etched wafers. In particular, the concentration of hydrogen peroxide (H2O2) plays a vital role in the MACE process. Unfortunately, the H2O2 concentration is not stable when prolonging the etching process at higher temperatures. As a result, the commercialization of MACE processes for the production of IP texturization has appeared industrially unattractive. Herein, we proposed an innovative method to monitor hydrogen peroxide during the MACE process with an electrochemical method. Reduced graphene oxide (RGO) prepared through an environmentally benign electrochemical method was used to modify a screen-printed electrode (SPE). Under an optimized condition, the RGO/SPE was used to test etching solutions. The MACE process was conducted and the hydrogen peroxide concentration within the etching solution was checked by the RGO/SPE. The RGO/SPE demonstrated excellent electrochemical performance and could record changes to H2O2 concentrations with cyclic voltammetry (CV). Interestingly, the presence of copper (Cu) in the etching solution catalyzed not only the etching process, but also the electrochemical reduction of H2O2. After etching, the reflectivity and structural morphology of the etched wafers were checked. The described modified electrode is disposable, and the fabrication process is rapid and inexpensive, allowing for real time application in, and control of, MACE processes.

Needles and Haystacks: Influence of Catalytic Metal Nanoparticles on Structural and Vibrational Properties and Morphology of Silicon Nanowires Synthesized by Metal-Assisted Chemical Etching

2013 ◽  
Vol 1551 ◽  
pp. 101-110
Author(s):  
M. K. Dawood ◽  
S. Tripathy ◽  
S. B. Dolmanan ◽  
T. H. Ng ◽  
T. Hao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Metal Nanoparticles ◽  
Chemical Etching ◽  
Near Infrared ◽  
Metal Catalyst ◽  
Vibrational Properties ◽  
Si Nanowires ◽  
Wide Range ◽  
Metal Assisted Chemical Etching ◽  
Si Nanostructures

ABSTRACTMetal-assisted chemical etching (MACE) of silicon (Si) is a simple and low-cost process to fabricate Si nanostructures with varying aspect ratio and properties. In this work, we report on the structural and vibrational properties of Si nanostructures synthesized with varying metal catalyst. The morphology of the synthesized nanowires was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical and vibrational properties of the Si nanostructures were studied by photoluminescence and Raman spectroscopy using three different excitation sources (UV, visible and near-infrared) and are correlated to their microstructures. We propose that the excessive injection of holes into Si at the metal-Si interface and its diffusion to the nanowire surfaces facilitate the etching of Si on these surfaces, leading to a mesoporous network of Si nanocrystallites. When etched with catalytic Au nanoparticles, “hay-stacked” mesoporous Si nanowires were obtained. The straighter nanowires etched with Ag nanoparticles, consisted of a single crystalline core with a thin porous layer that decreased in thickness towards the base of the nanowire. This difference is due to the higher catalytic activity of Au compared to Ag for H2O2 decomposition. The SERRS observed during UV and visible Raman with Ag-etched Si nanowires and near-infrared Raman with Au-etched Si nanowires is due to the presence of the sunken metal nanoparticles. In addition, we explored the influence of varying H2O2 and HF concentration as well as the influence of increased etching temperature on the resultant nanostructured Si morphology. Such Si nanostructures may be useful for a wide range of applications such as photovoltaic and biological and chemical sensing.

Investigation of the Electrical Resistivity of 20μm-Gap Gold-DNA-Gold Structure: Exploiting the Current-Voltage Characteristics under a Variable External Magnetic Field

2014 ◽  
Vol 554 ◽  
pp. 155-159 ◽  
Author(s):  
Nadia Mahmoudi Khatir ◽  
Zulkurnain Abdul-Malek ◽  
Seyedeh Maryam Banihashemian
Keyword(s):  
Magnetic Field ◽  
Electrical Resistivity ◽  
External Magnetic Field ◽  
Molecular Electronics ◽  
Electronic Devices ◽  
Charge Carriers ◽  
Current Voltage ◽  
Dna Strands ◽  
Pcr Method ◽  
Current Voltage Characteristics

Deoxyribonucleic acid (DNA), as the most important molecule in nature, holds promise as a key element of the molecular electronics as its utilization in the synthesis of electronic devices such as micro and nanosensors has increased remarkably during the recent years. Our work is devoted to an experimental study of the electrical resistivity of a gold-DNA-gold (GDG) structure in the presence of a variable external magnetic field. The DNA strands, extracted by the PCR method, were used to fabricate the GDG structures. The resistivity of the structure was found to rise sharply with the magnitude of the exerted magnetic field due to onset and progression of the cyclotron effects in charge carriers. Such a distinct current-voltage signature can possibly be employed for realization of an accurate magnetic sensor.

Study of metal-assisted chemical etching of silicon as an alternative to dry etching for the development of vertical comb-drives

2021 ◽  
pp. 251659842110334
Author(s):  
Varun P. Sharma ◽  
Rahul Shukla ◽  
C. Mukherjee ◽  
Pragya Tiwari ◽  
A. K. Sinha
Keyword(s):  
Surface Tension ◽  
Chemical Etching ◽  
Surface Defects ◽  
Metal Catalyst ◽  
Etching Time ◽  
Etch Depth ◽  
Au Catalyst ◽  
Comb Drives ◽  
Side Walls ◽  
Metal Assisted Chemical Etching

Metal-assisted chemical etching (MaCEtch) has recently emerged as a promising technique to etch anisotropic nano- and microstructures in silicon by metal catalysts. It is an economical wet chemical etching method, which can be a good alternative to deep-reactive ion etching (DRIE) process in terms of verticality and etch depth. In the present study, gold is used as a metal catalyst and deposited using physical vapour deposition. It has already been demonstrated that (100) p-type Si wafer can be etched with vertical and smooth side walls. Effects of varying concentrations of etchant constituents and various other parameters, that is, porosity of deposited Au, surface contaminants, oxide formation, metal catalyst, etching time, role of surface tension of additives on the etch depth and surface defects are studied and discussed in detail. By increasing the hydrofluoric acid (HF) concentration from 7.5 M to 10 M, lateral etching is reduced and the microstructure’s width is increased from 17 µm to 18 µm. Porous defects are suppressed by decreasing the hydrogen peroxide (H2O2) concentration from 1.5 M to 1 M. On increasing the etching time from 30 min to 60 min, the microstructures are over-etched laterally. Smoother side walls are fabricated by using the low-surface-tension additive ethanol. The maximum etch depth of 2.6 µm is achieved for Au catalyst in 30 min. The results are encouraging and useful for the development of vertical comb-drives and Micro-Electro-Mechanical Systems (MEMS).

Reduced porosity in metal-assisted chemical etching of vertical Si nanowire arrays by an induced magnetic field

2016 ◽  
Vol 213 (6) ◽  
pp. 1572-1576
Author(s):  
Seokhun Yun ◽  
Chan Ho Choi ◽  
Dipali S. Patil ◽  
Doo Gun Kim ◽  
Taikjin Lee ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Chemical Etching ◽  
Nanowire Arrays ◽  
Induced Magnetic Field ◽  
Si Nanowire ◽  
Metal Assisted Chemical Etching

In-plane and out-of-plane mass transport during metal-assisted chemical etching of GaAs

2014 ◽  
Vol 2 (29) ◽  
pp. 11017-11021 ◽  
Author(s):  
Yunwon Song ◽  
Bugeun Ki ◽  
Keorock Choi ◽  
Ilwhan Oh ◽  
Jungwoo Oh
Keyword(s):  
Mass Transport ◽  
Chemical Etching ◽  
Redox Reactions ◽  
Metal Catalyst ◽  
Diffusion Pathway ◽  
Out Of Plane ◽  
Metal Assisted Chemical Etching ◽  
Catalytic Effects

We have demonstrated the dependence of the metal-assisted chemical etching of GaAs on catalyst thickness. For ultra-thin (3~10 nm) Au catalysts, we found that electrochemically generated nano-pinholes in the metal catalyst not only enhance important catalytic effects in redox reactions, but also act as a diffusion pathway for the reactants (H2SO4) and products (Ga3+ and Asn+ ions) for chemical etching oxidized GaAs.

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