Aluminum bulk micromachining through an anodic oxide mask by electrochemical etching in an acetic acid/perchloric acid solution

Kikuchi, Tatsuya; Wachi, Yuhta; Sakairi, Masatoshi; Suzuki, Ryosuke O.

doi:10.1016/j.mee.2013.05.007

Cited by 34 publications

(25 citation statements)

References 27 publications

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“…Figure 8a shows the schematic models of the vertical cross-section of the anodic porous oxide films formed by self-ordering anodizing. Generally, the aluminum specimen is electropolished in a solution of a mixture of HClO 4 /CH 3 COOH or HClO 4 /C 2 H 5 OH before the anodizing [117][118]. During subsequent self-ordering anodizing, the nanopores are formed in a disorderly fashion in the oxide film in the initial stages, and then well-ordered nanopore structures are formed at the interface between the anodic oxide and the aluminum substrate [119].…”

Section: Fabrication Of Highly Ordered Porous Aluminum Oxidementioning

confidence: 99%

Porous Aluminum Oxide Formed by Anodizing in Various Electrolyte Species

Kikuchi¹,

Nakajima²,

Nishinaga³

et al. 2015

CNANO

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Anodizing of aluminum and its alloys is widely investigated and used for corrosion protection, electronic devices, and micro-/nanostructure fabrication. Anodizing of aluminum in acidic solutions causes formation of porous aluminum oxide films, which consists of numerous hexagonal cells perpendicular to the aluminum substrate, and each cell has nanoscale pores at its center. Recently, highly ordered porous aluminum oxide has been widely investigated for various novel nanoapplications. In this review article, we introduce the fundamentals of anodic oxide films including barrier and porous oxides. Then, we summarize the electrolyte species used so far for porous oxide fabrication and describe the self-ordering conditions during anodizing in these electrolyte solutions. Fabrication of highly ordered porous oxides through the vertical section can be achieved by a two-step anodizing and nanoimprint technique. Various nanoapplications based on the ordered porous oxide are also introduced.

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Section: Fabrication Of Highly Ordered Porous Aluminum Oxidementioning

confidence: 99%

Porous Aluminum Oxide Formed by Anodizing in Various Electrolyte Species

Kikuchi¹,

Nakajima²,

Nishinaga³

et al. 2015

CNANO

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“…Barrier anodic oxide films and porous anodic oxide films on aluminum have been widely investigated by many researchers in the fields of surface finishing [1][2][3], electrolytic capacitor application [4][5][6], and micro-and nano-structure fabrication [7][8][9]. Recently, highly ordered anodic porous alumina with a cell size on the scale of 10-100 nm has been studied for potential use in various ordered-nanostructure applications [10][11][12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Self-Ordering Behavior of Anodic Porous Alumina via Selenic Acid Anodizing

Kikuchi

Nishinaga

Natsui

et al. 2014

Electrochimica Acta

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The self-ordering behavior of anodic porous alumina that was formed by anodizing in selenic acid electrolyte (H 2 SeO 4 ) at various concentrations and voltages was investigated with SEM and AFM imaging. A high purity aluminum foil was anodized in 0.1-3.0 M selenic acid solutions at 273 K and at constant cell voltages in the range of 37 to 51 V. The regularity of the cell arrangement increased with increasing anodizing voltage and selenic acid concentration under conditions of steady oxide growth without burning. Anodizing at 42-46 V in 3.0 M selenic acid produced highly ordered porous alumina. By selective dissolution of the anodic porous alumina, highly ordered convex nanostructures of aluminum with diameters of 20 nm and heights of 40 nm were exposed at the apexes of each hexagonal dimple array. Highly ordered anodic porous alumina with a cell size of 102 nm from top to bottom can be fabricated by a two-step selenic acid anodizing process, that includes the first anodizing step, the selective oxide dissolution, and the second anodizing step.Key words: Aluminum; Anodizing; Anodic Porous Alumina; Selenic Acid IntroductionBarrier anodic oxide films and porous anodic oxide films on aluminum have been widely investigated by many researchers in the fields of surface finishing [1][2][3], electrolytic capacitor application [4][5][6], and micro-and nano-structure fabrication [7][8][9]. Recently, highly ordered anodic porous alumina with a cell size on the scale of 10-100 nm has been studied for potential use in various ordered-nanostructure applications [10][11][12][13][14][15][16][17][18][19][20][21]. Anodic porous alumina is typically fabricated on an aluminum substrate using electrochemical anodizing (or anodization) [22][23][24][25][26]. In several acidic electrolyte solutions, the porous alumina fabricated by anodizing is self-ordered when prepared at the appropriate electrochemical conditions, including appropriate concentrations, temperatures, and voltages (or electrochemical potentials) [27][28][29][30] [50], and acetylenedicarboxylic (HOOC-C≡C-COOH) [51] acids have also been reported as electrolytes used to fabricate porous alumina that has characteristic nanostructure morphologies.In addition to these acidic electrolytes, alkaline and neutral solutions used for porous alumina fabrication were reported by several research groups. Takahashi et al. reported that a porous anodic oxide film could be formed by anodizing in an H 3 BO 3 /Na 2 B 4 O 7 neutral borate solution at a high temperature [52]. Baron-Wiechec et al. investigated aluminum anodizing in a borax (Na 2 B 4 O 7 ) solution at 333 K and successfully obtained porous alumina [53]. Noguchi et al. investigated the anodizing behavior of aluminum in propylenediamine and choline alkaline solutions containing ammonium fluoride, ammonium tartrate, ammonium carbonate, and ammonium tetraborate, and obtained anodic porous alumina with nanopores that were 10-150 nm in diameter [54]. However, it is difficult to form a highly ordered porous alumina by anodiz...

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“…Porous anodic oxide films of aluminum (anodic porous alumina) have been widely investigated as nanotemplates and resist films with good insulating properties for various micro-and nano-technology applications, such as magnetic recording media [1,2], electronic devices [3], biosensors [4], photonic crystals [5][6][7], microlens arrays [8,9], plasmonic devices [10][11][12], three-dimensional microstructures [13][14][15] and other basic nanodevices [16]. When aluminum is anodized in appropriate acidic electrolytes, porous alumina develops, which exhibits a uniform array of hexagonal cells, each containing a uniform cylindrical nanopore at the center [17][18][19][20][21][22] (lower right in Fig.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

Kikuchi¹,

Yamamoto²,

Natsui³

et al. 2014

Electrochimica Acta

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The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M squaric acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200-400 nm and sub-100-nm-scale pore diameter was successfully fabricated by anodizing in squaric acid. The cell size of the anodic oxide increased with anodizing time because of the uneven growth of the porous layer. The anodic porous alumina obtained by squaric acid anodizing consists of amorphous Al 2 O 3 containing 5-6 at% carbon from the electrolyte. Fig. 1). The morphology of anodic porous alumina, especially its cell size (identical meaning to interpore distance) and pore diameter in the porous layer, is limited by the electrolyte and voltage (electrochemical potential) applied during anodizing [23,24]. Fig. 1 summarizes the anodizing electrolytes that have been reported to date for porous alumina fabrication. Sulfuric (H 2 SO 4 ), oxalic ((COOH) 2 ), and phosphoric (H 3 PO 4 ) acids are well-known, self-ordering anodizing solutions for porous alumina fabrication, and highly ordered porous alumina can be obtained by anodizing in these solutions at constant voltages of 18-25 V, 40 V, and 160-195 V, respectively [24-29]. Malonic acid (HOOC-CH 2 -COOH) and tartaric acid (HOOC-(CHOH) 2 -COOH), typical dicarboxylic acids, have also been reported to support the fabrication of highly ordered porous alumina fabrication at 120 V and 195 V, respectively [30,31]. In addition, several other electrolytes, such as chromic (H 2 CrO 4 ) [32,33], malic (HOOC-CH(OH)-CH 2 -COOH) [23,34], citric (HOCO-CH 2 -C(OH)(COOH)-COOH)) [23], and glycolic (CH 2 OH-COOH) [23] acids, have been reported as anodizing electrolytes to date. However, the formation of thick porous alumina with straight nanopores by anodizing in chromic acid is difficult because of branching and colony-forming nanopores [35]. Although citric acid anodizing has already been used for nanostructure fabrication [36], other organic electrolytes, including malic and glycolic acid solutions, cause the formation of non-uniform anodic porous alumina [23,34]. Therefore, five self-ordering electrolytes, namely, sulfuric, oxalic, and phosphoric acids, are generally selected for anodic porous alumina fabrication by many researchers.In recent years, new anodizing procedures using an effective experimental approach and optimal anodizing conditions have been reported by several researchers to control the nano-scale features of anodic porous alumina. Lee et al. studied the rapid formation of ordered porous alumina by a hard anodizing procedure involving a powerful cooling stage and obtained an ultra-high aspect ratio (>1,000) of anodic porous alumina by anodizing in oxalic acid at 120-150...

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Aluminum bulk micromachining through an anodic oxide mask by electrochemical etching in an acetic acid/perchloric acid solution

Cited by 34 publications

References 27 publications

Porous Aluminum Oxide Formed by Anodizing in Various Electrolyte Species

Porous Aluminum Oxide Formed by Anodizing in Various Electrolyte Species

Self-Ordering Behavior of Anodic Porous Alumina via Selenic Acid Anodizing

Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

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