Effect of a metal interlayer under Au catalyst for the preparation of microscale holes in Si substrate by metal-assisted chemical etching

Shimizu, Tomohiro; Niwa, Ryosuke; Ito, Tetsuo; Shingubara, Shoso

doi:10.7567/1347-4065/aaec15

Cited by 5 publications

(6 citation statements)

References 29 publications

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“…The Ti layer under the Au catalyst acts as an adhesion layer and as a diffusion barrier layer to suppress interdiffusion between the Au catalyst and the Si substrate before the MacEtch. 20) The Ti layer was etched away at the initial stage of the MacEtch process, and the layer itself did not contribute to etching of the Si as a catalyst. The PEG (MW 1000) was added to the etching solution and MacEtch of the Si substrate with patterned Au was performed in the etching solution at 40 °C for 120 min.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, metal-assisted chemical etching (MacEtch) has attracted attention for the fabrication of nano/microscale structures in Si substrates, such as nanowires and nanohole array. [13][14][15][16][17][18][19][20][21] In this method, a noble metal is used as a catalyst, and only Si is selectively etched under the catalyst in the etching solution. 22) Generally, Au is used as this catalyst, and the Au can be removed by nitrohydrochloric, iodine or cyanogen systems after the MacEtch process.…”

Section: Introductionmentioning

confidence: 99%

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Effect of additives on preparation of vertical holes in Si substrate using metal-assisted chemical etching

Shimizu¹,

Niwa²,

Ito³

et al. 2019

Jpn. J. Appl. Phys.

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The influence of a polyethylene glycol (PEG) additive on the morphology of 10 μm diameter holes in a Si(001) substrate formed by metal-assisted chemical etching (MacEtch) was investigated. The addition of PEG to the etching solution suppressed deformation of the Au catalyst film, so that the verticality of the etched holes was significantly improved. There was a strong correlation between the deformation of the thin (10 nm) Au catalyst film and the bending of etched holes during the MacEtch process.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of additives on preparation of vertical holes in Si substrate using metal-assisted chemical etching

Shimizu¹,

Niwa²,

Ito³

et al. 2019

Jpn. J. Appl. Phys.

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“…[331] Similarly, one can apply porous entity, either substrate or metal stamp, to fabricate macroscale Si features successfully by MaCE. One can make lithographically defined nanoscale (≈200 nm in diameter) pores array in larger (≈10 µm) metal layer, [126,332] which facilitate mass transport of etchant/ by-products during MaCE for the fabrication of macroscale Si features, as shown in Figure 6d. Also, porous network of metal catalyst mold, prepared by sintering of metal powder at high temperature and pressure, can be used for the MaCE; in this case, the porous mold can supply paths for mass transport of etchant/by-products.…”

Section: Mass Transport In Macementioning

confidence: 99%

“…During the MaCE for the fabrication of macroscale Si features, it is inevitable that there remain unwanted micro/nanostructures on the etched Si surface when a porous, permeable metal catalyst is used. [125,126,131,326,330,332,336] Pores in metal catalyst layer can be widened during MaCE, and can lead to the mechanical rupture of catalyst in the extreme case. Then, the unwanted Si structures can be generated where there are widened pores, often called sprouts.…”

Section: Generation and Removal Of Unwanted Micro/ Nanostructuresmentioning

confidence: 99%

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Srivastava

Khang

2021

Advanced Materials

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classified into two common approaches: bottom-up chemical synthesis, such as vapor-liquid-solid growth, [16][17][18][19][20] and topdown fabrication schemes. [21][22][23] This review will focus on the top-down fabrication of Si structures using a wet chemical etching technique aided with a metal catalyst, called metal-assisted chemical etching (MaCE). [24][25][26][27][28][29][30][31][32] In comparison with top down fabrication methods based on dry etching using a reactive plasma in vacuum, MaCE is less expensive and less complex. [33][34][35] MaCE is a nano-scale reductionoxidation (redox) process that usually occurs in aqueous solution where the sample to be etched is in contact with the etchant. MaCE is a simple, cost-effective, and versatile method to produce Si nanostructures; due to these attractive features, there have been many good review articles published on the process. [36][37][38][39][40][41][42] With two-decades of research of the MaCE and its innovative variations, recent studies have focused on the various applications of Si nanostructures prepared by MaCE, including photovoltaics, [43,44] thermoelectrics and piezoelectric nanogenerators, [45] energy storage, [46][47][48] nanophotonics and optoelectronics, [49] and biosensors and biomedical applications. [50][51][52] In this review, we provide an overview of the recent advances in MaCE processes and their novel applications. To differentiate this review from previous review articles, the main emphasis is on the recently developed novel MaCE processes and the macroscale structuring of Si by MaCE. We begin the review by describing new MaCE processes, particularly catalysts for MaCE. In contrast to well-known noble metal catalysts, such as Ag, Au, and Pt, carbon-based catalysts, such as graphene, graphene oxide, and carbon nanotubes, have been successfully applied as catalysts for MaCE. In addition, TiN has been found to be a catalyst for MaCE, making the whole process CMOS-compatible. Different types of etch additives, such as various alcohols and chlorides, have also been discussed, which enhance etch uniformity by increasing the wettability of etchants and suppressing the random diffusion of excessive (holes) h + by trapping them for better etch control. Recent novel variations of the MaCE process have been introduced, such as MaCE with externally applied electric or magnetic fields. The external field has a profound effect on the output of MaCE, by controlling the etch directionality and etch rate. In addition, MaCE can be combined with unconventional patterning techniques, StructuringSi, ranging from nanoscale to macroscale feature dimensions, is essential for many applications. Metal-assisted chemical etching (MaCE) has been developed as a simple, low-cost, and scalable method to produce structures across widely different dimensions. The process involves various parameters, such as catalyst, substrate doping type and level, crystallography, etchant formulation, and etch additives. Careful optimization of these parameters is the key to the succe...

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“…6 This technique has also a capability to fabricate helical structures, [7][8][9][10][11][12][13] cone-shaped structures, [14][15][16][17][18] and zigzag structures. [19][20][21] The metalassisted etching process has been increasingly applied in a wide range of fields, e.g., solar cells, 3,[22][23][24][25][26] lithium-ion batteries, 27,28 adhesive metal film formation, 29,30 through-silicon via, [31][32][33] X-ray optics, [34][35][36] laser-based analyses, [37][38][39][40][41][42] and biomedicine 43 including biosensors, tissue engineering, and drug delivery, whereas the mechanism of etching remains to be fully elucidated. In platinum (Pt)-particle-assisted etching, for example, a characteristic composite structure of macropores and a thick mesoporous (and/or microporous) layer can be produced.…”

mentioning

confidence: 99%

Electrochemical Investigation of the Effect of Hydrogen Peroxide Concentration on Platinum-Particle-Assisted Etching of p-Type Silicon in a Hydrofluoric Acid Solution

Matsumoto¹,

Furukawa²,

Majima³

et al. 2021

J. Electrochem. Soc.

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Metal-assisted etching (metal-assisted chemical etching) has attracted increasing attention as a low-cost and versatile microfabrication technique of semiconductors. In platinum (Pt)-particle-assisted etching of silicon (Si), a composite structure of straight macropores and a mesoporous layer can be produced, but the mechanism of the structure formation is still open to discussion. We employed an electrochemical approach to investigate the composite structure formation by the Pt-assisted etching. Polarization curves of Pt-deposited Si and bare Si were measured in hydrofluoric acid (HF) solutions containing different concentrations of hydrogen peroxide (H 2 O 2 ). The open circuit potential during the Pt-assisted etching was more positive than that of the bare Si and it shifted in the positive direction with increasing the H 2 O 2 concentration as a consequence of the enhancement of the H 2 O 2 reduction reaction. For the structure observation, both the macropore depth and the mesoporous layer thickness increased with increasing the H 2 O 2 concentration, while the ratio between them changed. We discussed the structure change on the basis of the polarization characteristics. The mesoporous layer formation can be explained by the hole consumption at the Si surface under the positive potential which is determined by mixed potential theory.

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Effect of a metal interlayer under Au catalyst for the preparation of microscale holes in Si substrate by metal-assisted chemical etching

Cited by 5 publications

References 29 publications

Effect of additives on preparation of vertical holes in Si substrate using metal-assisted chemical etching

Effect of additives on preparation of vertical holes in Si substrate using metal-assisted chemical etching

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Electrochemical Investigation of the Effect of Hydrogen Peroxide Concentration on Platinum-Particle-Assisted Etching of p-Type Silicon in a Hydrofluoric Acid Solution

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