Approaches for patterning of aluminum

Frank, Wolfgang E.

doi:10.1016/s0167-9317(96)00034-2

Cited by 25 publications

(10 citation statements)

References 27 publications

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“…For example, an initial deep red mixture (Figure B) of Ti 3 AlC 2 powder (1.0 mmol) suspended in a 2.0 M solution of bromine in cyclohexane (CH) changes to light yellow over 24 h at RT and inert atmosphere, indicating consumption of the reddish-brown Br 2 and production of pale yellow AlBr 3 (Figure C). AlBr 3 ’s high solubility in nonpolar solvents − provides strong driving force for a selective removal of etched Al from the MAX phase surface. The synthetic details are summarized in the Experimental Section.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Halogen-based production of MXene extends beyond Br 2 , due to the generality of the halogen radical etch of metals and their alloys; , Figure summarizes the results using I 2 as well as interhalogen etchants (ICl, IBr) (the procedures are summarized in the Experimental Section). For example, reactions utilizing I 2 are initially deep purple and slowly turn light purple to colorless as the Al is removed.…”

Section: Results and Discussionmentioning

confidence: 99%

“…30 Atomic force microscopy (AFM) indicates ∼2−3 nm thick sheets (Figure S9), where surface adsorbates typically increase observed monolayer heights, as previously reported for other 2D systems. 52−54 Halogen-based production of MXene extends beyond Br 2 , due to the generality of the halogen radical etch of metals and their alloys; 40,45 Figure 4 summarizes the results using I 2 as well as interhalogen etchants (ICl, IBr) (the procedures are summarized in the Experimental Section). For example, reactions utilizing I 2 are initially deep purple and slowly turn light purple to colorless as the Al is removed.…”

Section: Resultsmentioning

confidence: 99%

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Halogen Etch of Ti₃AlC₂ MAX Phase for MXene Fabrication

et al. 2021

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The versatile property suite of two-dimensional MXenes is driving interest in various applications, including energy storage, electromagnetic shielding, and conductive coatings. Conventionally, MXenes are synthesized by a wet-chemical etching of the parent MAX-phase in HF-containing media. The acute toxicity of HF hinders scale-up, and competing surface hydrolysis challenges control of surface composition and grafting methods. Herein, we present an efficient, room-temperature etching method that utilizes halogens (Br 2 , I 2 , ICl, IBr) in anhydrous media to synthesize MXenes from Ti 3 AlC 2 . A radicalmediated process depends strongly on the molar ratio of the halogen to MAX phase, absolute concentration of the halogen, the solvent, and temperature. This etching method provides opportunities for controlled surface chemistries to modulate MXene properties.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Halogen Etch of Ti₃AlC₂ MAX Phase for MXene Fabrication

et al. 2021

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“…Al and other valve metals are typically microstructured by subtractive etching techniques [6][7][8][9][10][11][12][13][14][15] because their formal potentials are too negative to allow for electrodeposition from aqueous solutions. Microstructuring of Al films can be performed by either wet chemical etching (in a mixture of H 3 PO 4 /HNO 3 /H 2 O) [16,17] or chlorine-based plasma etching [18,19]. While wet chemical etching of patterned Al films was used in the microelectronics industry, reactive ion etching (RIE) is now the preferred method for etching of patterned Al substrates.…”

Section: Introductionmentioning

confidence: 99%

Minimization of undercutting in electrochemical micromachining of patterned aluminum–copper films

Cosse

López

Atanassov

et al. 2006

J. Micromech. Microeng.

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Al–0.5%Cu films patterned with an anodization mask of barrier Al2O3 are micromachined by porous-type anodization followed by chemical dissolution of porous Al2O3. Electrochemical micromachining results in well-defined metallic pillars separated by micro-grooves. The trapezoidal shape of the pillars is due to the lateral pore propagation under the anodization mask. Regardless of undercutting, porous-type anodization shows a higher degree of anisotropy than mostly isotropic wet chemical etching. The vertical growth of pores is accelerated with respect to the lateral propagation of pores by increasing the voltage of porous-type anodization. Consequently, the lateral pore propagation is minimized and for ∼3 µm thick Al–0.5%Cu films the etch factor increases from 2.6 to 4.3 when the voltage is increased from 20 V to 60 V. Comparing the results obtained with the micromachining of ∼3 µm and ∼10 µm thick films at the same voltage, the etch factor decreases as the depth of micro-grooves increases. The etch factor depends on the distribution of secondary current density at the pattern scale during porous-type anodization, which is defined by the anodization mask coverage. A higher degree of anisotropy of porous-type anodization (in comparison to wet chemical etching) allows for more accurate shape control of three-dimensional metallic microstructures.

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“…To prevent the problem of hillock or whisker formation during thermal processing, certain metals such as Ti, Ta, Si, Cu, and Nd are embedded in Al alloys or multilayers. [2][3][4][5][6] Among these aluminum alloys, the addition of 2% Nd in aluminum has been applied extensively for metal deposition on glass within TFT processes. In addition, because Mo is capable of suppressing hillocks and improving taper angles simultaneously, metal-capped structures of Mo/Al and Mo/Al/Mo are the major construction in metal line processes.…”

mentioning

confidence: 99%

Synergetic Effect of Aluminum and Mo/Al Etching in Phosphoric Acid-Based Etchant with Nitric Acid

Wang

Chen

et al. 2011

J. Electrochem. Soc.

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This study examined the etching behaviors and electrochemical characteristics of aluminum in phosphoric acid-based etchants. The etchant used for the research was composed primarily of phosphoric acid and nitric acid. Surface analysis of the etched aluminum sample revealed the existence of Al 2 O 3 , AlO(OH), and PO 4 3− . Other than the contribution of phosphate ions, the experimental results showed that hydrogen ions in the etchant influenced the etching rate substantially. Inclusion of nitric acid in the etchant caused a synergetic effect on the etching rate. Hence, this study proposes an etching mechanism in which hydronium ions and phosphate ions separately dissolve the passivated film. In the etchant, aluminum becomes passivated AlO(OH) and a dissolvable complex simultaneously. The adsorbed H (ads) produced on the Al surface is removed by nitric acid, which leads to acceleration in etching rate. In the study of electrochemical impedance measurements, an equivalent-circuit model with two capacitor elements has been established. In addition, this study investigated the etching behavior of Mo/Al. The dramatic change in open-circuit potential explained the different aspects for discrete etching durations.Materials used as interconnections in thin film transistor liquid crystal displays (TFT-LCDs) require low resistivity, high adhesion to glass, resistance to stress migration, and good patternability with proper taper angles. With the advantages of high electrical conductivity, low material cost, high adhesion, and good responses to patterning, aluminum and its alloys have been used widely in TFT-LCDs as data lines, gate materials, and source-drain electrodes. 1 Within manufacturing, aluminum has been widely used because the sputtering target cost is cheaper and is easier to handle than copper. To prevent the problem of hillock or whisker formation during thermal processing, certain metals such as Ti, Ta, Si, Cu, and Nd are embedded in Al alloys or multilayers. 2-6 Among these aluminum alloys, the addition of 2% Nd in aluminum has been applied extensively for metal deposition on glass within TFT processes. In addition, because Mo is capable of suppressing hillocks and improving taper angles simultaneously, metal-capped structures of Mo/Al and Mo/Al/Mo are the major construction in metal line processes. 7,8 Within industries, phosphoric acid-based etchants comprising phosphoric acid, nitric acid, acetic acid, and water are applied widely in aluminum alloy etching. In addition, Mo/Al stacked metal can be taper-etched easily with the phosphoric acid-based etchants. 9 Previous studies 10 showed that the dissolution rate of Mo increases in conjunction with nitric acid content. However, the adoption of Mo/Al and Mo/Al/Mo metal depositions in etching processes is complicating etching behavior. For example, the control of the taper angle is difficult because of the overhang structure and galvanic corrosion between Mo and Al. Although relevant studies have presented discussions on the kinetics and characteristics of alum...

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Approaches for patterning of aluminum

Cited by 25 publications

References 27 publications

Halogen Etch of Ti₃AlC₂ MAX Phase for MXene Fabrication

Halogen Etch of Ti₃AlC₂ MAX Phase for MXene Fabrication

Minimization of undercutting in electrochemical micromachining of patterned aluminum–copper films

Synergetic Effect of Aluminum and Mo/Al Etching in Phosphoric Acid-Based Etchant with Nitric Acid

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Approaches for patterning of aluminum

Cited by 25 publications

References 27 publications

Halogen Etch of Ti3AlC2 MAX Phase for MXene Fabrication

Halogen Etch of Ti3AlC2 MAX Phase for MXene Fabrication

Minimization of undercutting in electrochemical micromachining of patterned aluminum–copper films

Synergetic Effect of Aluminum and Mo/Al Etching in Phosphoric Acid-Based Etchant with Nitric Acid

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Halogen Etch of Ti₃AlC₂ MAX Phase for MXene Fabrication

Halogen Etch of Ti₃AlC₂ MAX Phase for MXene Fabrication