Autocatalysis during Electroless Copper Deposition using Glyoxylic Acid as Reducing Agent

Yu, Lu; Guo, Lian; Preisser, Robert; Akolkar, Rohan

doi:10.1149/2.002312jes

Cited by 35 publications

(28 citation statements)

References 25 publications

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“…3,4 As the above discussion shows in this article, UPD H(ads) is not stable on Cu(111) and as a concentration builds up recombination to form H 2 (g) should be facile. The removal of H(ads) may also be necessary for electroless Cu deposition to proceed.…”

Section: Electochemical Deposition Of H(ads) On Cu(111) and H 2 Evolumentioning

confidence: 80%

Theory of Hydrogen Deposition and Evolution on Cu(111) Electrodes

Zhao¹,

Anderson²

2017

J. Electrochem. Soc.

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The amount of under-potential-deposited (UPD) H(ads), if it forms on Cu(111), is small compared to what forms on Pt(111). According to experimental literature, current density on polycrystalline copper increases slowly in the over-potential-deposited (OPD) potential range beginning at 0 V and rises rapidly at several hundred mV negative potential. Using a comprehensive density functional theory for the electrochemical interface, including Fermi level shifts, in this article we attribute this behavior to calculated weak H adsorption which requires the potential to be reduced to ∼0.0 V(SHE) in order for H(ads) deposition to commence. A literature estimate, based on exchange current densities, of the activation energy for H 2 evolution at 0 V is ∼0.32 eV. As the coverage increases with increasingly negative potentials, we calculate the H adsorption energy decreases at a rate 0.27 eV/V for Cu(111), and this will decrease the effective activation energy. We propose that the observed rapid increase in current density at approximately −0.4 V corresponds to ∼0.5 ML coverage by H(ads) and reflects the decreasing activation energy at more negative potentials. We also relate our calculated findings to the literature for electroless copper deposition and to literature for palladium-doped copper as a heterogeneous hydrogenation catalyst. In this article we used quantum theory to explore hydrogen evolution from Cu(111) electrode surfaces. Hydrogen atoms bond weakly to copper surfaces and for significant hydrogen evolution to take place, an overpotential relative to the 0.0 V standard reversible potential must be applied. The first step is deposition of H(ads). In acidic electrolyte the reaction isand in alkaline electrolyteThere are additional ways in which hydrogen can be introduced to copper surfaces as H(ads). In alkaline electrolytes hydrogen is evolved from copper surfaces when aldehyde groups are oxidized without potential control in alkaline electrolyte, that is at the potentials of zero charge (PZC), during electroless copper deposition. [1][2][3][4] In this case the goal is depositing copper atoms on selected substrates and H 2 , formed from combination of H(ads) on copper, 4 is a secondary product. Hydrogen can also be introduced to copper surfaces as H(ads) by spillover of H bonded to Pd atoms on the copper surface. [5][6][7] In this case H 2 dissociation is activated by the Pd ad-atom and the weakly held spilled-over H(ads) performs hydrogenation of organic molecules.To reduce water to hydrogen in alkaline electrolytes over copper electrodes requires high overpotentials of around 0.2 V. 8,9 This contrasts with the small overpotential over platinum. Exchange current densities for hydrogen evolution in alkaline electrolyte for several transition metals, including copper, have been correlated to theoretically calculated H 2 (g) chemisorption energies in a volcano plot. 9 In the plot Pt is near the peak on the left hand side and Pd, Fe, Ni, Co, and W were also on the left (too strongly adsorbed) and Cu, Au, and Ag wer...

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Section: Electochemical Deposition Of H(ads) On Cu(111) and H 2 Evolumentioning

confidence: 80%

Theory of Hydrogen Deposition and Evolution on Cu(111) Electrodes

Zhao¹,

Anderson²

2017

J. Electrochem. Soc.

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“…Another candidate of reducing agent for the self-catalytic reaction of Cu is glyoxylic acid. [21][22][23][24][25] Yu et al reported on the anodic oxidation of glyoxylic acid on Cu. 22 In addition, in our previous study, it was clarified that glyoxylic acid can show anodic oxidation on both Cu and Ru.…”

Section: Resultsmentioning

confidence: 99%

“…[21][22][23][24][25] Yu et al reported on the anodic oxidation of glyoxylic acid on Cu. 22 In addition, in our previous study, it was clarified that glyoxylic acid can show anodic oxidation on both Cu and Ru. 26 Figure 1 shows linear sweep voltammograms of glyoxylic acid and formaldehyde for a 30 nm Co liner.…”

Section: Resultsmentioning

confidence: 99%

Role of Bath Composition in Electroless Cu Seeding on Co Liner for through-Si Vias

Inoue

Philipsen

Veen

et al. 2014

ECS J. Solid State Sci. Technol.

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To enable Cu fill of through-Si vias (TSV) with a high aspect ratio (diameter 3 μm, depth 50 μm), the electroless deposition of a Cu seed on Co liner material was investigated. The reducing agent glyoxylic acid showed anodic oxidation on Co, which did not appear for the case of formaldehyde. From electrochemical analysis, an optimized bath composition caused limited Co corrosion during the electroless Cu nucleation phase. The concentration ratio of the complexing agent (ethylenediaminetetraacetic acid) and copper was found to strongly impact the liner corrosion; in case free complexing agent is present in the bath, the Co corrosion was assisted by complexation and replacement reactions. A continuous seed layer could be deposited in the entire TSV, which enabled the filling by electrochemical deposition (ECD). The substantially thinner total copper overburden generated for this combination of a wet-chemical seed deposition and an ECD fill process contributes to a cost reduction of its chemical mechanical polishing (CMP).

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“…Electroless Cu plating is used in the electronics industry to obtain conductive layers on bare resins [1][2][3]. High-end applications like plating of integrated circuit (IC) substrate interconnects require finegrained copper to achieve small structures [4].…”

Section: Introductionmentioning

confidence: 99%

Properties of electroless Cu films optimized for horizontal plating as a function of deposit thickness

Sharma

Brüning

Nguyen

et al. 2015

Microelectronic Engineering

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The properties of electroless films produced from a bath designed for horizontal plating, the preferred technology for high production volumes in printed circuit board metallization, are reported. Film thickness, substrate type and electrolyte temperature were varied. Formation of a continuous layer of copper film is correlated with a change in the visual and spectroscopic appearance. Grain orientation is random in thin films and a 〈110〉 texture develops with increasing thickness. The plating solution contains Cu and Ni ions. Nickel co-deposits in copper films in the form of Ni hydroxide, and its concentration decreases from about 6% in the vicinity of the substrate to about 1% at the film surface. Film stress and strain were measured by substrate curvature and X-ray diffraction, respectively. Both stress and strain decrease as the film thickness increases. Stress remains tensile throughout during deposition and during relaxation, promoting film adhesion by preventing blisters. After deposition, stress relaxes first towards compressive and then towards tensile. The stress, the stress relaxation and the Ni concentration are high at the base of the film. We attribute this to the higher volume fraction of grain boundaries (smaller grain size) in this region.

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Autocatalysis during Electroless Copper Deposition using Glyoxylic Acid as Reducing Agent

Cited by 35 publications

References 25 publications

Theory of Hydrogen Deposition and Evolution on Cu(111) Electrodes

Theory of Hydrogen Deposition and Evolution on Cu(111) Electrodes

Role of Bath Composition in Electroless Cu Seeding on Co Liner for through-Si Vias

Properties of electroless Cu films optimized for horizontal plating as a function of deposit thickness

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