Compositionally bilayered feature of interfacial voids in a porous anodic alumina template directly formed on Si

Seo, Hong-Seok; Jung, Yang-Gyoo; Jee, Sang-Won; Yang, Jun Mo; Lee, Jung-Ho

doi:10.1016/j.scriptamat.2007.06.067

Cited by 15 publications

(10 citation statements)

References 9 publications

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“…Figure 3a shows the barrier layer of AAO with the thickness of 15 nm before the etching which is caused by the stress pushing upward at the interface of silicon and AAO pore during the anodization. 21 As shown in Figs. 3b and 3c, when AAO was etched using pure Cl 2 , the barrier layer was not easily removed even though the AAO top layer was significantly etched and the size of the AAO pore appeared to be decreased by blocking the sidewall of the hole with an etch residue.…”

Section: Resultsmentioning

confidence: 79%

Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl₂/BCl₃ Neutral Beam Etching

Yeon

Lim

Park

et al. 2011

J. Electrochem. Soc.

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The barrier layer of anodic aluminum oxide (AAO) formed on the silicon substrate was etched with Cl 2 /BCl 3 gas mixtures by a neutral beam and the results were compared with the AAO etched by an ion beam. The etch rate of AAO itself was increased with the increase of BCl 3 in Cl 2 /BCl 3 up to 60% in the gas mixture. And, the etching of AAO itself was related to the Cl radical density in the plasma and the formation of volatile BO x Cl y on the AAO surface for both the neutral beam etching and the ion beam etching. The AAO itself could be etched by both the neutral beam and the ion beam in all Cl 2 /BCl 3 gas mixtures. However, the barrier layer of the AAO located near the bottom of the AAO pore could not be etched using the ion beam etching due to the charging of the nanometer size AAO pore similar to the case of conventional reactive ion etching. Using the neutral beam etching, the barrier layer of AAO pore could be successfully etched with BCl 3 -rich BCl 3 /Cl 2 gas mixtures by removing the barrier layer without charging the AAO pore and by the forming volatile BO x Cl y .Anodization is a technology transforming metal into metal oxide by electrochemical oxidation and it has been actively investigated for the fabrication of nanostructure of various sizes. Especially, the anodic aluminum oxide (AAO) obtained by the anodization of aluminum film is being used as the template and mask for deposition, etching, doping, etc. in the fabrication of various nano devices such as magnetic data storage devices, optoelectronic devices, nano sensors, etc. [1][2][3][4] In general, AAO can be fabricated with various porous nano-hole spacing and diameter in the range of 10-500 and 4-200 nm by controlling anodization voltage and, also by using indentation method, various shapes of AAO such as hexagonal, square, and triangular shaped AAO can be fabricated. 5-7 When the AAO is used as the solid mask, due to the strong bonding of Al 2 O 3 , it shows superior mechanical properties compared to other porous mask materials. 8 Especially, compared to the patterning using electron-beam lithography and block co-polymer, the patterning using AAO is cheaper, more reliable, and easier in controlling the size and shape. 9 In addition, it can be applied to fabricate various two-dimensional lateral superlattice structures by using highly ordered AAO templates. 10 However, due to the stress at the interface between the aluminum and the substrate, the alumina barrier layer is formed at the bottom of the AAO holes during the formation of AAO and it prevents direct physical and electrical contact to the substrate, and it is known to be one of the biggest problems in the formation of AAO. 11,12 To remove the barrier layer, various techniques such as pore widening, cathodic polarization, voltage drop, plasma assisted etching, etc. are investigated. [13][14][15] In the case of pore widening and cathodic polarization, even though the barrier layer can be removed reliably and reproducibily, due to the chemical attack of the sidewall of AAO by OH-formed...

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Section: Resultsmentioning

confidence: 79%

Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl₂/BCl₃ Neutral Beam Etching

Yeon

Lim

Park

et al. 2011

J. Electrochem. Soc.

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“…An interesting and unique situation of barrier layer formation takes place during the anodization of aluminum deposited on the other substrates. The notable feature here is the inverted barrier layer morphology due to the formation of interfacial voids at the aluminum-substrate interface [104]. Such interfacial voids were observed when Si wafer, glass, and glass substrates with an ITO interlayer were used as the substrate [105,106].…”

Section: Pore Wall and Barrier Layer Thicknessmentioning

confidence: 89%

“…The quantitative analysis of the local Al concentration around voids carried out using nanoprobe energy dispersive spectroscopy revealed that the voids were surrounded by a thin Al-rich layer (Figure 4e-g). The compositional morphology surrounding these voids revealed a bi-layered feature with thin aluminum-rich and thick aluminum-poor areas, suggesting that these voids are formed physically and not chemically [104]. Additionally, the two-dimensional reconstruction of Al profiles obtained from EDS (Figure 4h) displayed that the Al concentration decreased from void top to the bottom edges of the void.…”

Section: Pore Wall and Barrier Layer Thicknessmentioning

confidence: 98%

“…The genesis of this was attributed to several reasons. One of the reasons was the mechanical stress pushing the alumina barrier layer upward and inducing the inversion in curvature [104,107]. The other reason suggested was the dissolution of alumina owing to the local temperature rise [108] or oxygen bubble formation [105].…”

Section: Pore Wall and Barrier Layer Thicknessmentioning

confidence: 99%

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Recent Progress in the Fabrication and Optical Properties of Nanoporous Anodic Alumina

et al. 2022

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The fabrication of a thick oxide layer onto an aluminum surface via anodization has been a subject of intense research activity for more than a century, largely due to protective and decorative applications. The capability to create well-defined pores via a cost-effective electrochemical oxidation technique onto the surface has made a major renaissance in the field, as the porous surfaces exhibit remarkably different properties compared to a bulk oxide layer. Amongst the various nanoporous structures being investigated, nanoporous anodic alumina (NAA) with well-organized and highly ordered hexagonal honeycomb-like pores has emerged as the most popular nanomaterial due to its wide range of applications, ranging from corrosion resistance to bacterial repelling surfaces. As compared to conventional nanostructure fabrication, the electrochemical anodization route of NAA with well-controlled pore parameters offers an economical route for fabricating nanoscale materials. The review comprehensively reflects the progress made in the fabrication route of NAA to obtain the material with desired pore properties, with a special emphasis on self-organization and pore growth kinetics. Detailed accounts of the various conditions that can play an important role in pore growth kinetics and pore parameters are presented. Further, recent developments in the field of controlling optical properties of NAA are discussed. A critical outlook on the future trends of the fabrication of NAA and its optical properties on the emerging nanomaterials, sensors, and devices are also outlined.

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“…1b shows a zoom of the alumina/Si interface revealing an inverted barrier layer (IBL) of around 25 nm consisting in voids beneath the pores separated by a thin alumina part, as typically observed for anodization on substrate 21,22 . It might originates from mechanical stress pushing the barrier layer upward and inducing a curvature inversion 23 , alumina dissolution due to local temperature increase 21 or oxygen bubbles formation 22 .…”

mentioning

confidence: 99%

Duplex nanoporous alumina and polyelectrolyte adsorption: more insights from a combined neutron reflectivity and electron microscopy study

et al. 2019

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Compositionally bilayered feature of interfacial voids in a porous anodic alumina template directly formed on Si

Cited by 15 publications

References 9 publications

Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl₂/BCl₃ Neutral Beam Etching

Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl₂/BCl₃ Neutral Beam Etching

Recent Progress in the Fabrication and Optical Properties of Nanoporous Anodic Alumina

Duplex nanoporous alumina and polyelectrolyte adsorption: more insights from a combined neutron reflectivity and electron microscopy study

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Compositionally bilayered feature of interfacial voids in a porous anodic alumina template directly formed on Si

Cited by 15 publications

References 9 publications

Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl2/BCl3 Neutral Beam Etching

Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl2/BCl3 Neutral Beam Etching

Recent Progress in the Fabrication and Optical Properties of Nanoporous Anodic Alumina

Duplex nanoporous alumina and polyelectrolyte adsorption: more insights from a combined neutron reflectivity and electron microscopy study

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Product

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Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl₂/BCl₃ Neutral Beam Etching

Removal of Anodic Aluminum Oxide Barrier Layer on Silicon Substrate by using Cl₂/BCl₃ Neutral Beam Etching