Electrical Evaluation of Ru–W(-N), Ru–Ta(-N) and Ru–Mn films as Cu diffusion barriers

Wojcik, H.; Kaltofen, R.; Merkel, U.; Krien, Cornelia; Strehle, Steffen; Gluch, Jürgen; Knaut, Martin; Wenzel, Christian; Preuße, Axel; Bartha, Johann W.; Geidel, Marion; Adolphi, B.; Neumann, Volker; Liske, R.; Munnik, F.

doi:10.1016/j.mee.2011.03.165

Cited by 32 publications

(13 citation statements)

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“…Ru-Ta alloy has been investigated and the evaluation results of film property such as wettability and barrier property have been reported. [27][28][29][30] However, the filling property of Cu electroplating and the reliability performance z E-mail: torazawa.naoki@jp.panasonic.com with Ru-Ta alloy and RuTa(N) film which is doped with N in RuTa using fine Cu damascene structure have not been reported.In this paper, Ru-Ta alloy was applied as the diffusion barrier layer in fine Cu dual damascene interconnects, and the film property, filling property of Cu electroplating and reliability performances were investigated. The film which Nitrogen (N) was incorporated into Ru-Ta film was also evaluated, and the barrier structure for Ru-Ta alloy was considered on the basis of the film properties.…”

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confidence: 99%

The Development of Cu Filling and Reliability Performance with Ru-Ta Alloy Barrier for Cu Interconnects

Torazawa

Hirao

Kanayama

et al. 2016

J. Electrochem. Soc.

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Ru-Ta alloy was investigated as the diffusion barrier layer in Cu dual damascene interconnects, and Cu filling property and reliability performances with RuTa/RuTa(N) stacked barrier structure were mainly evaluated. RuTa strongly orientated to Ru(002) and the lattice misfit between Ru(002) and Cu(111) was lower than that between Ta(110) and Cu(111). The wettability of Cu seed on RuTa was much better than that on Ta. The barrier property against Cu diffusion of RuTa/RuTa(N) stacked barrier structure kept the equivalent barrier property of conventional Ta/TaN one. Filling property of Cu electroplating was improved by using Ru-Ta alloy barrier, and trenches of 45 nm in width could be filled successfully due to the suppression of the agglomeration of Cu seed on the sidewall of trench. Via resistance with RuTa/RuTa(N) barrier was much lower than that with Ta/TaN one due to its low resistivity. The estimated life time of via electromigration with RuTa/RuTa(N) barrier was longer than that with Ta/TaN one because of the good wettability and filling property inside via. Consequently, Cu filling property and reliability performance can be improved with RuTa/RuTa(N) stacked barrier structure in Cu interconnects. Copper (Cu) interconnects have been applied to ultra large scale integrated circuits (ULSIs) to reduce the resistance of wiring and resistive-capacitive (RC) delay since the introduction of 130 nm complementary metal oxide semiconductors (CMOSs). As the feature size of trench and via continues to shrink, filling the gaps with Cu electroplating becomes more difficult. For perfectly gap filling, the opening of trench and via after the deposition of barrier and Cu seed have to be kept enough by thinning barrier and/or Cu seed. However, thinning Cu seed leads to Cu being agglomerated on the sidewall of both trench and via where Cu seed is too thin due to its poor coverage, resulting in the formation of voids inside trench and via. Therefore, one challenging issue for Cu interconnects is to fill trench and via completely without the agglomeration of Cu seed on the diffusion barrier layer.New barrier metals that have better wettability with Cu than conventional Tantalum (Ta) have been studied to achieve continuous and smooth Cu film on them.1-26 Among them, Cobalt (Co) and Ruthenium (Ru) have been most frequently suggested for suppressing the agglomeration of Cu seed. Co is known to have the good film properties such as the low resistivity, the high melting point and the good adhesion with Cu. However, Co has the serious problems with chemical mechanical polishing (CMP) process and wet etching process. Co is corroded readily during CMP process and wet etching process, and the slits are occurred between Cu wiring and the interlayer dielectric. It results in the degradation of the device yield and reliability performance. As for Ru, the barrier property against Cu diffusion is not enough, and CMP process for Ru is a difficult technology and the scratch occurred during CMP process leads to the degradation of the device yie...

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confidence: 99%

The Development of Cu Filling and Reliability Performance with Ru-Ta Alloy Barrier for Cu Interconnects

Torazawa

Hirao

Kanayama

et al. 2016

J. Electrochem. Soc.

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“…Ru has drawn much attention lately as adhesion layer and possible diffusion barrier for Cu interconnects in VLSI circuits. While the diffusion barrier properties of sputtered Ru layers are less attractive, wetting and adhesion experiments have shown promising results [5][6][7][8]. In all cases presented here, except if noted elsewise, a thin Ti layer is deposited prior to the diffusion barrier to imitate the Ti or Ti-Si contacts to the active device areas.…”

Section: Introductionmentioning

confidence: 91%

The influence of liners with Ti, Ta or Ru finish on thin Cu films

Gross

Haag

Schuster

et al. 2014

Microelectronics Reliability

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“…Ru is chemically inert and stable, contrasting with its counterparts, such as Co, which is prone to dissolution during conventional acidic electroplating, requiring electrolyte modification to be used in seedless diffusion barrier systems [11,12]. However, similar to other candidates, Ru alone is not effective as a diffusion barrier [13], thus, driving the research on coupling Ru with other species to improve the barrier properties against Cu diffusion, including Ru-Co [14], Ru-Cr [15], Ru-Mn [16][17][18], Ru-N [19], Ru-P [20,21], Ru-Ta(-N) [16,22,23], and Ru-W(-N) [16,24,25] compositions.…”

Section: Introductionmentioning

confidence: 99%

“…Bias temperature stress measurements by H. Wojcik et al [16] showed that Ru 50 -W 50 has an outstanding performance up to 600 • C; however, the best seedless Cu electroplating lies in the Ru-rich layers. Several studies were successful in electroplating Cu directly on Ru [26][27][28][29][30], but attempts on seedless Cu electroplating on Ru-W, particularly on Ru 50 -W 50 , are still scarce in the literature.…”

Section: Introductionmentioning

confidence: 99%

Seedless Cu Electroplating on Ru-W Thin Films for Metallisation of Advanced Interconnects

Santos

Oliveira

Savaris

et al. 2022

IJMS

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For decades, Ta/TaN has been the industry standard for a diffusion barrier against Cu in interconnect metallisation. The continuous miniaturisation of transistors and interconnects into the nanoscale are pushing conventional materials to their physical limits and creating the need to replace them. Binary metallic systems, such as Ru-W, have attracted considerable attention as possible replacements due to a combination of electrical and diffusion barrier properties and the capability of direct Cu electroplating. The process of Cu electrodeposition on Ru-W is of fundamental importance in order to create thin, continuous, and adherent films for advanced interconnect metallisation. This work investigates the effects of the current density and application method on the electro-crystallisation behaviour of Cu. The film structure, morphology, and chemical composition were assessed by digital microscopy, atomic force microscopy, scanning and transmission electron microscopies, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The results show that it was possible to form a thin Cu film on Ru-W with interfacial continuity for current densities higher than 5 mA·cm−2; however, the substrate regions around large Cu particles remained uncovered. Pulse-reverse current application appears to be more beneficial than direct current as it decreased the average Cu particle size.

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Electrical Evaluation of Ru–W(-N), Ru–Ta(-N) and Ru–Mn films as Cu diffusion barriers

Cited by 32 publications

References 9 publications

The Development of Cu Filling and Reliability Performance with Ru-Ta Alloy Barrier for Cu Interconnects

The Development of Cu Filling and Reliability Performance with Ru-Ta Alloy Barrier for Cu Interconnects

The influence of liners with Ti, Ta or Ru finish on thin Cu films

Seedless Cu Electroplating on Ru-W Thin Films for Metallisation of Advanced Interconnects

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