Bottom-up Filling of Damascene Trenches with Gold in a Sulfite Electrolyte

Josell, Daniel; Moffat, Thomas P.

doi:10.1149/2.0041901jes

Cited by 13 publications

(66 citation statements)

References 47 publications

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“…2019, 166, D3022−D3034. 1 This study details the f irst demonstration of bottom-up gold f illing of recessed features and explores key electrochemical and feature f illing attributes of the chemistry and process.…”

Section: ■ Key Referencesmentioning

confidence: 99%

“…Copyright 2019 Electrochemical Society). (e) Multicycle cyclic voltammogram capturing the impact of the switching potential at the positive vertex, (f) cyclic voltammograms capturing the impact of the switching potential at the negative vertex, and (g) linear sweep voltammograms capturing the impact of scan rate on activation of the RDE surface (Reproduced with permission from ref . Copyright 2019 Electrochemical Society).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Bottom-up superconformal gold electrodeposition in high aspect ratio recessed features from a sulfite electrolyte containing a Bi 3+ additive has been detailed in a series of recent reports, − the most recent including simulations from a mechanistic model of the filling process . The experimental work details filling of recessed features on metallized substrates including high aspect ratio trenches, vias, and fractal patterns followed by self-termination of growth with minimal deposition on the overlying field.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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Section: ■ Key Referencesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extreme Bottom-up Gold Filling of High Aspect Ratio Features

Josell

Moffat

2023

Acc. Chem. Res.

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Implementation of a dual-phase grating interferometer for multi-scale characterization of building materials by tunable dark-field imaging

Organista,

Tang,

Shi

et al. 2024

Sci Rep

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The multi-scale characterization of building materials is necessary to understand complex mechanical processes, with the goal of developing new more sustainable materials. To that end, imaging methods are often used in materials science to characterize the microscale. However, these methods compromise the volume of interest to achieve a higher resolution. Dark-field (DF) contrast imaging is being investigated to characterize building materials in length scales smaller than the resolution of the imaging system, allowing a direct comparison of features in the nano-scale range and overcoming the scale limitations of the established characterization methods. This work extends the implementation of a dual-phase X-ray grating interferometer (DP-XGI) for DF imaging in a lab-based setup. The interferometer was developed to operate at two different design energies of 22.0 keV and 40.8 keV and was designed to characterize nanoscale-size features in millimeter-sized material samples. The good performance of the interferometer in the low energy range (LER) is demonstrated by the DF retrieval of natural wood samples. In addition, a high energy range (HER) configuration is proposed, resulting in higher mean visibility and good sensitivity over a wider range of correlation lengths in the nanoscale range. Its potential for the characterization of mineral building materials is illustrated by the DF imaging of a Ketton limestone. Additionally, the capability of the DP-XGI to differentiate features in the nanoscale range is proven with the dark-field of Silica nanoparticles at different correlation lengths of calibrated sizes of 106 nm, 261 nm, and 507 nm.

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Pushing the Limits of Bottom-Up Gold Filling for X-ray Grating Interferometry

Josell

Shi

Jefimovs

et al. 2020

J. Electrochem. Soc.

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The application of superconformal Bi-catalyzed Au electrodeposition for void-free filling of recessed trenches in X-ray gratings used in phase contrast imaging is detailed. Filling of trenches with aspect ratio (height divided by width) up to 55 is demonstrated. Uniform bottom-up filling of patterned trench arrays across 100 mm (4 inch) diameter Si wafer is accomplished using a welldefined hydrodynamic flow field across the wafer surface. The filling process and microstructure are examined by scanning electron microscopy of cross-sectioned specimens. The importance of process optimization, from the design of potential (current) programming to electrolyte pH and concentrations of Na 3 Au(SO 3 ) 2 and Bi 3+ , for the filling of high aspect ratio trenches is demonstrated. X-ray phase contrast imaging is used to assay the quality and uniformity of the as-formed gratings as well as demonstrate their application to imaging biological tissue. Successful void-free Au filling of micrometer range pitch, high aspect ratio trenches in Si gratings promises to advance X-ray grating interferometry and its application to X-ray phase contrast imaging.

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Bottom-up Filling of Damascene Trenches with Gold in a Sulfite Electrolyte

Abstract: Superconformal Au deposition is demonstrated in a Na 3 Au(SO 3 ) 2 + Na 2 SO 3 electrolyte using Bi species to catalyze the reduction of Au(SO 3 ) 2 3− . Micromolar additions of Bi 3+ to the sulfite-based electrolyte accelerate the reduction of Au(SO 3 ) 2 3− … Show more

Cited by 13 publications

References 47 publications

Extreme Bottom-up Gold Filling of High Aspect Ratio Features

Extreme Bottom-up Gold Filling of High Aspect Ratio Features

Implementation of a dual-phase grating interferometer for multi-scale characterization of building materials by tunable dark-field imaging

Pushing the Limits of Bottom-Up Gold Filling for X-ray Grating Interferometry

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