Citrate Complexes of Copper in Acid Solutions

Choe

et al. 2015

J. Electrochem. Soc.

The electrolyte for Cu superfilling generally consists of copper sulfate, sulfuric acid, a chloride ion, an accelerator, and a suppressor. In this study, the characteristics of citric acid-based electrolytes and the interaction between citrate species and accelerators are investigated, with the ultimate goal being the replacement of both sulfuric acid and the suppressor with citric acid. Electrochemical impedance measurements were adopted to measure the changes in solution and charge transfer resistances with respect to citric acid and accelerator concentrations. In addition to a decrease in solution resistance resulting from the addition of citric acid, charge transfer inhibition was observed during Cu electrodeposition, which is likely the result of adsorption of citrate species onto Cu surface. A competitive adsorption between the citrate species and the accelerator was also observed and the new additive system was applied to the feature filling in the absence of the conventional polyethylene glycol suppressor. Using this new copper sulfate, citric acid, chloride ion, and accelerator system, trenches were successfully bottom-up filled, resulting in no internal defects.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Electrochemical Behavior of Citric Acid and Its Influence on Cu Electrodeposition for Damascene Metallization

Choe

et al. 2015

J. Electrochem. Soc.

“…It was found that electrolytes operating at pH 4.12 and 4.06 were unstable due to the formation of an insoluble citrate complex dihydrate, usually formulated as Cu 2 C 6 H 4 O 7 AE 2H 2 O [89,90], which formed a blue precipitate after a few days. In some experiments, citrate solutions at pH 6.0 proved to be stable.…”

Section: Influence Of Electrochemical Conditionsmentioning

confidence: 99%

Recent developments in the electrodeposition of nickel and some nickel-based alloys

Oriňáková¹,

Turoňová²,

Kladeková³

et al. 2006

J Appl Electrochem

207

The numerous theoretical and practical studies of the electrodeposition of nickel and its binary and selected ternary alloys with copper and cobalt over the last 10-15 years are reviewed. The reported mechanisms of the electrodeposition processes and accompanying evolution of hydrogen are considered. The complex influence of different bath compositions, pHs, current densities or potential ranges and temperature on the formation of single or multiple deposition layers are compared. The determination of the structure and morphology of the deposits on different substrates, including solid surfaces and particulate materials, using a range of analytical techniques are reported.

“…Citric acid is known to form a stable complex with trace copper (Parry & Du Bois, 1952). Therefore, the stability of ascorbic acid in the citrate buffer should be at a maximum due to the unavailability of the catalytic copper ions.…”

Section: Discussionmentioning

confidence: 99%

“…The stability of ascorbic acid in fruit and vegetable products is known to vary and several naturally occurring flavonoid substances have been reported to be protective (Davidek, 1960;Samarodova-Bianki, 1965).…”

Section: Introductionmentioning

confidence: 99%

The phenolic compounds of blackcurrant juice and their protective effect on ascorbic acid

Clegg¹,

Morton²

1968

Int J of Food Sci Tech

Model systems of ascorbic acid in citrate buffer have been used to investigate the antioxidant effect of flavonols, phenolic acids, anthocyanins and extracts of blackcurrant juice for ascorbic acid. In the presence and absence of added copper salts the flavonol aglycones, and quercetin in particular, gave positive protection to the ascorbic acid, but the anthocyanins showed no antioxidant properties except in the presence of copper. The stability of ascorbic acid in blackcurrant juice has been discussed.