Suppressing Sulfite Dimerization at a Polarized Gold Electrode/Water Solution Interface for High-Quality Gold Electrodeposition

Yang, Jixing; Jin, Lei; Xiao, Yuan-Hui; Yu, Haijiang; Yang, Fang‐Zu; Zhan, Dongping; Wu, De‐Yin; Zhang, Tian

doi:10.1021/acs.langmuir.1c01595

Cited by 5 publications

(3 citation statements)

References 35 publications

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“…Molecular additives, such as hydroxyethylene disphosphonic acid (HEDP), that interfere with sulfite dimerization are observed to facilitate the deposition of bright Au films. 23 Furthermore, the heavy metal p-block ion additives + Tl , + Pb 2 and + Bi , 3 reduced to their elemental form, strongly accelerate the Au deposition rate by altering the intrinsic blocking character of the sulfite based adlayer to also yield bright and smooth Au films.…”

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confidence: 99%

Mechanism of Bismuth Stimulated Bottom-up Gold Feature Filling

Josell

Braun

Moffat

2022

J. Electrochem. Soc.

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The mechanism underlying 〖Bi〗^(3+)-stimulated bottom-up Au filling and self-passivation in trenches and vias in slightly alkaline 〖Na〗_3 Au(〖SO〗_3 )_2+〖Na〗_2 〖SO〗_3 electrolytes is explored. The impacts of electrolyte components 〖Na〗_3 Au(〖SO〗_3 )_2, 〖Na〗_2 〖SO〗_3 and 〖Bi〗^(3+) and potential-dependent kinetic factors on the rate of Au electrodeposition are quantified experimentally. Derived parameters are applied within the surfactant conservation curvature enhanced accelerator coverage model to simulate the filling of high aspect ratio trenches. It is observed that Bi adsorption accelerates the Au deposition rate with a non-linear dependence occurring around a critical coverage. Further, the impact of electrolyte composition is such that gradients of Au(〖SO〗_3 )_2^(3-) and SO_3^(2-) derived from reduction of Au(〖SO〗_3 )_2^(3-) during deposition accentuate deposition farther from the feature opening. These factors and surface area reduction at the bottoms of filling features localize active deposition to feature bottoms. Ultimately, weakening of the concentration gradients and associated kinetics as bottom-up feature filling progresses reduces the Bi coverage on the growth front below the critical value and bottom-up growth terminates. Good agreement is observed with key experimental features including the incubation period of conformal deposition, transition to bottom-up growth, subsequent bottom-up filling and finally self-passivation as the growth front nears the field.

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confidence: 99%

Mechanism of Bismuth Stimulated Bottom-up Gold Feature Filling

Josell

Braun

Moffat

2022

J. Electrochem. Soc.

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“…25 Gold deposition in the neat electrolyte is inhibited by adsorption of sulfite and its dimerization product S 2 O 5 2− with formation of the latter associated with the growth of optically rough films. 26 Heavy metal p-block ion additives, Tl + , Pb 2+ , and Bi 3+ , once reduced and adsorbed in the elemental form, can individually accelerate the Au deposition rate by lifting the intrinsic blocking character of the sulfite-based adlayer to yield bright and smooth Au films, with analogous effects seen in cyanide electrolytes. 27 The use of Tl + can improve the uniformity and smoothness of Au deposits, 28−31 while Pb 2+ additions help attenuate roughness and even give rise to superconformal feature filling in trenches of modest aspect ratio.…”

Section: Electrolyte and Additivesmentioning

confidence: 99%

“…Deposition is typically performed in near neutral, slightly alkaline pH where Au(SO 3 ) 2 3– and SO 3 2– are the dominant anions . Gold deposition in the neat electrolyte is inhibited by adsorption of sulfite and its dimerization product S 2 O 5 2– with formation of the latter associated with the growth of optically rough films . Heavy metal p-block ion additives, Tl + , Pb 2+ , and Bi 3+ , once reduced and adsorbed in the elemental form, can individually accelerate the Au deposition rate by lifting the intrinsic blocking character of the sulfite-based adlayer to yield bright and smooth Au films, with analogous effects seen in cyanide electrolytes .…”

Section: Introductionmentioning

confidence: 99%

Extreme Bottom-up Gold Filling of High Aspect Ratio Features

Josell

Moffat

2023

Acc. Chem. Res.

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Conspectus Where copper interconnects fabricated using superconformal electrodeposition processes have enabled dramatic advances in microelectronics over the past quarter century, gold filled gratings fabricated using superconformal Bi3+-mediated bottom-up filling electrodeposition processes promise to enable a new generation of X-ray imaging and microsystem technologies. Indeed, bottom-up Au-filled gratings have demonstrated excellent performance in X-ray phase contrast imaging of biological soft tissue and other low Z element samples even as studies using gratings with inferior Au fill have captured the potential for broader biomedical application. Four years ago, the Bi-stimulated bottom-up Au electrodeposition process was a scientific novelty where gold deposition was localized entirely on the bottoms of metallized trenches 3-μm-deep and 2-μm-wide, an aspect ratio of only 1.5, on centimeter scale fragments of patterned silicon wafers. Today the room-temperature processes routinely yield uniformly void-free filling of metallized trenches 60-μm-deep and 1-μm-wide, an aspect ratio 60, in gratings patterned across 100 mm Si wafers. Four distinctive characteristics of the evolution of void-free filling in the Bi3+-containing electrolyte are seen in experimental Au filling of fully metallized recessed features such as trenches and vias: (1) an “incubation period” of conformal deposition, (2) subsequent Bi-activated deposition localized on the bottom surface of features, (3) sustained bottom-up deposition that yields void-free filling, and (4) self-passivation of the active growth front at a distance from the feature opening defined by operating conditions. A recent model captures and explains all four features. The electrolyte solutions are simple and nontoxic, being near-neutral pH and composed of Na3Au(SO3)2 + Na2SO3 containing micromolar concentrations of Bi3+ additive, the latter generally introduced through electrodissolution from the metal. The influences of additive concentration, metal ion concentration, electrolyte pH, convection, and applied potential have been examined in some depth using both electroanalytical measurements on planar rotating disk electrodes and studies of feature filling, thereby defining and elucidating relatively wide processing windows for defect-free filling. The process control for bottom-up Au filling processes is observed to be quite flexible, with online changes of potential as well as concentration and pH adjustments during the course of filling compatible with processing. Furthermore, monitoring has enabled optimization of the filling evolution, including to shorten the incubation period for accelerated filling and to fill features of ever higher aspect ratio. The results to date indicate that the demonstrated filling of trenches with an aspect ratio of 60 represents a lower bound, a value determined only by the features presently available.

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Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS): Techniques, Applications, and Future Perspectives

Murugasenapathi,

Palanisamy

2024

Springer Series in Optical Sciences

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Suppressing Sulfite Dimerization at a Polarized Gold Electrode/Water Solution Interface for High-Quality Gold Electrodeposition

Cited by 5 publications

References 35 publications

Mechanism of Bismuth Stimulated Bottom-up Gold Feature Filling

Mechanism of Bismuth Stimulated Bottom-up Gold Feature Filling

Extreme Bottom-up Gold Filling of High Aspect Ratio Features

Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS): Techniques, Applications, and Future Perspectives

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