Direct-on-barrier copper electroplating on ruthenium from the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide

D’Urzo, Lucia; Schaltin, Stijn; Shkurankov, Andrey; Plank, Harald; Kothleitner, Gerald; Gspan, Christian; Binnemans, Koen; Fransaer, Jan

doi:10.1007/s10854-011-0525-4

Cited by 14 publications

(6 citation statements)

References 26 publications

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“…Ruthenium (Ru), a novel barrier layer material, the application of which is quite promising in the new generation of integrated circuit. 1 A thin film of Ru (several nanometers) often lies between Cu and the low-k dielectric material, preventing interfacial diffusion between Cu and the substrate. 2,3 Since the polishing solutions used in the CMP process are corrosive and abrasive, the galvanic corrosion at the Cu/Ru interface is unavoidable and detrimental.…”

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Galvanic Corrosion Inhibitors for Cu/Ru Couple during Chemical Mechanical Polishing of Ru

Cheng

Wang

2016

ECS J. Solid State Sci. Technol.

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Galvanic corrosion of Cu is a critical issue during the chemical mechanical polishing (CMP) process of barrier layer, especially when KIO 4 is used as the oxidant in the polishing slurry. This paper focuses on the investigation of galvanic corrosion inhibitors (BTA and 1, 2, 4-triazole) for Cu/Ru couple in the KIO 4 -based solutions. The galvanic corrosion current of Cu was directly measured, and the corrosion inhibition efficiencies (CIE) were calculated. Results show that both BTA and 1, 2, 4-triazole are effective galvanic corrosion inhibitors of Cu. The CIE of 5 mM BTA and 2 mM 1, 2, 4-triazole is up to 69.4 and 59.7, respectively. On this basis, the corrosion inhibition mechanism was proposed. BTA forms a complete and tight three-dimensional multilayer structure on Cu when the concentration is over 0.5 mM. With regard to 1, 2, 4-triazole, the protective film on Cu is two-dimensional, and excessive dosage of 1, 2, 4-triazole will reduce the stability of the surface film, as well as the corrosion inhibition efficiency of Cu. © 2016 The Electrochemical Society. [DOI: 10.1149/2.0181701jss] All rights reserved.Manuscript submitted November 1, 2016; revised manuscript received December 7, 2016. Published December 30, 2016 Corrosion plays a critical role in diverse industrial fields, and consequently, in the chemical mechanical polishing process (CMP) of the chip manufacturing process. During the CMP process, dissimilar metal surfaces are exposed to the polishing solutions, which could provide electrolyte-conducting paths for the corrosion and galvanic corrosion between Cu wiring and the directly contacting barrier metals. Ruthenium (Ru), a novel barrier layer material, the application of which is quite promising in the new generation of integrated circuit. 1A thin film of Ru (several nanometers) often lies between Cu and the low-k dielectric material, preventing interfacial diffusion between Cu and the substrate.2,3 Since the polishing solutions used in the CMP process are corrosive and abrasive, the galvanic corrosion at the Cu/Ru interface is unavoidable and detrimental. It has been reported that the resulting interfacial defects from galvanic corrosion could cause severe Cu pitting and dishing problems, and even affect the reliability of Cu interconnection. 4 Galvanic corrosion refers to the accelerated corrosion of Cu when connected with Ru, occurring at the mixed potential between the corrosion potentials of Cu and Ru under uncoupled conditions. Ru is much nobler than Cu, thus acting as the cathode and Cu acting as the anode, comparatively. It is commonly recognized that a bigger corrosion potential difference ( E cor ) between two metals will cause a serious trend of galvanic corrosion, and therefore a minimizing E cor is the goal when evaluating the corrosion inhibition effect of various inhibitors in most of the relevant researches.5-7 However, practical corrosion process is influenced by many other factors such as the area ratio of anode/cathode, and the properties of the surface passive film. 8,9 Theref...

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Galvanic Corrosion Inhibitors for Cu/Ru Couple during Chemical Mechanical Polishing of Ru

Cheng

Wang

2016

ECS J. Solid State Sci. Technol.

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“…However, at a P-ratio of 6 with a high concentration of Cu ions, the overpotential was relatively low due to the high conductivity of the solution. It was reported that the Cu nucleation density on the barrier layer decreases as the overpotential decreases [11]. When the Cu nucleation density was low, the adhesion of the Cu plated on the Ti surface as a barrier layer could be poor [12].…”

Section: Effects Of the P-ratio And Current Densitymentioning

confidence: 99%

Seed step-coverage enhancement process for a high-aspect-ratio through-silicon via using a pyrophosphate solution

Jin

Lee

et al. 2015

Met. Mater. Int.

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A seed step-coverage enhancement process (SSEP) was investigated in order to improve the poor stepcoverage of the Cu seed layer when it is deposited by physical vapor deposition with a high-aspect-ratio through-silicon via (TSV) to inhibit void generation during a subsequent electroplating TSV gap-fill process. The SSEP was performed by means of electroplating after the deposition of the Cu seed layer in TSV using an alkaline pyrophosphate solution, which is effective when used to prevent the dissolution of the Cu seed layer. The molar ratio of pyrophosphate ions to Cu ions in the plating solution and the current density were optimized for the SSEP by considering the surface uniformity of the electroplated Cu film through electroplating on the defective seed layer. In order to improve the wettability of the pyrophosphate solution in the TSV pattern, polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether was added to the solution. Finally, we significantly strengthened the seed step-coverage at the bottom-corner of the TSV, the weakest point in terms of seed step-coverage, and achieved a void-free filling of the TSV in the subsequent TSV gap-fill process.

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“…Copper electrodeposition has good agreement with HDI microvias metallization due to its void-free filling in the features, minimal topography of the final copper surface, and controllable impurity incorporation in the plated copper film [3][4][5].…”

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Characterization and application of aggregated porous copper oxide flakes for cupric source of copper electrodeposition

et al. 2015

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Direct-on-barrier copper electroplating on ruthenium from the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide

Cited by 14 publications

References 26 publications

Galvanic Corrosion Inhibitors for Cu/Ru Couple during Chemical Mechanical Polishing of Ru

Galvanic Corrosion Inhibitors for Cu/Ru Couple during Chemical Mechanical Polishing of Ru

Seed step-coverage enhancement process for a high-aspect-ratio through-silicon via using a pyrophosphate solution

Characterization and application of aggregated porous copper oxide flakes for cupric source of copper electrodeposition

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