Characteristics of Thermally Robust 5 nm Ru–C Diffusion Barrier/Cu Seed Layer in Cu Metallization

Chen, Chun-Wei; Chen, J. S.; Jeng, Jiann-Shing

doi:10.1149/1.3160549

Cited by 13 publications

(17 citation statements)

References 22 publications

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“…Redistribution subject to ECS terms of use (see 138.251.14. 35 Downloaded on 2015-03-14 to IP majority of the inner film of both the as-deposited and annealed film is composed of metallic Cu. It has been reported that Ar + sputtering can reduce oxide to its metallic form.…”

Section: Resultsmentioning

confidence: 99%

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The Inhibition of Enhanced Cu Oxidation on Ruthenium∕Diffusion Barrier Layers for Cu Interconnects by Carbon Alloying into Ru

Xie

Müeller

Waechtler

et al. 2011

J. Electrochem. Soc.

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The inhibition of Cu oxidation by alloying C into the Ru/TaN barrier stack is investigated. By using in-situ XRD measurement, severe copper oxide formation was observed for the Cu/Ru/barrier system during annealing process in He atmosphere. This phenomenon is explained using thermodynamics from the viewpoint of Gibbs free energy of oxide formation. The Cu oxidation can be inhibited by alloying C into the Ru layer, and the more C content in the RuC layer, the more evident the inhibition effect. The RuC/TaN stack also shows better diffusion barrier properties than the Ru/TaN bi-layer. Atomic layer deposition of Cu 2 O on the RuC substrate was carried out and reduction of the Cu 2 O to Cu was observed. The mechanism of inhibition of Cu oxidation on C alloyed Ru was investigated by a first principles calculation based on the density functional theory.As the interconnect line width continually scales down, the reliability problem induced by stress induced voiding (SiV) and electromigration (EM) becomes severe. 1-6 The SiV and EM problem are mainly caused by poor adhesion between Cu and the glue layer or capping layer. 1, 6-11 It is found that the oxidation of Cu or barrier layer will degrade the adhesion between Cu and the glue layer, 1, 12-14 resulting in delamination during chemical mechanical polishing (CMP) and reliability problems. Cu oxidation Cu can also increase the line resistance and thus increase the RC delay and degrade the performance of the devices. During the back end of line (BEOL) manufacturing process, Cu oxidation is easily observed because of many thermal processes and the unavoidable oxygen processes such as electrochemical deposition (ECD) of Cu. In order to inhibit Cu oxidation and improve the reliability of Cu interconnects, many methods have been proposed, such as using Ti instead of Ta as the Cu adhesion layer, 9 or adding an oxygen adsorption layer, such as Al 1 or Ti 15 on the pure ECD-Cu film before annealing.Recently, novel materials such as Ru 16,17,19 and Co 16, 20 etc. with low resistivity have been proposed to replace Ta as Cu adhesion layer because of the ability of direct ECD of Cu on their surface, which is beneficial for conformal ECD Cu gap filling. [16][17][18] Ru is considered as one of the most promising material as Cu adhesion layer in the future technology node. 17,19,21,22 It is reported that the predicted circuitperformance using the Ru based barrier was 10% higher than that with a Ta barrier and the operating-speed distribution was estimated to be less than 5% for the 22 nm-node CMOS generation. 19 However, there are still some concerns such as severe oxidation of copper and galvanic corrosion during the CMP process. 16 In this work, the effect of Ru on enhanced Cu oxidation was studied and by adding C into Ru, the inhibition of Cu oxidation and promotion of Cu 2 O reduction were studied.Experimental P-type Si (100) substrates were loaded into the vacuum chamber through a loadlock after standard chemical cleaning. The base pressure of the vacuum was 2 × 10 −7 mbar. TaCN a...

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Section: Resultsmentioning

confidence: 99%

“…ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14 35. Downloaded on 2015-03-14 to IP…”

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confidence: 99%

The Inhibition of Enhanced Cu Oxidation on Ruthenium∕Diffusion Barrier Layers for Cu Interconnects by Carbon Alloying into Ru

Xie

Müeller

Waechtler

et al. 2011

J. Electrochem. Soc.

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“…[3,5,14]) between Cu and SiO 2 or Si, the sharp increase in sheet resistance of the 700 • C annealed sample cannot be attributed to the interdiffusions and reactions in the Cu/Ni-Al-N/SiO 2 /Si heterostructure. Very recently, it was reported that agglomeration of Cu could occur due to the internal stress of Cu film itself and thermal stress of interface between Cu and its underlayer [14,15]. In this case, holes and hills exist in Cu film so that Cu film is no longer continuous, leading to a strong electron scattering and thus increasing noticeably the sheet resistance of the samples.To further confirm the failure mechanism of Ni-Al-N barrier, surface morphologies of the Cu/Ni-Al-N/SiO 2 /Si heterostructures annealed at various temperatures from 500 to 700 • C were investigated using an atomic force microscope.…”

Section: Resultsmentioning

confidence: 99%

Investigation of amorphous Ni–Al–N film as diffusion barrier between Cu and SiO2

Liu

Chen

et al. 2011

Journal of Alloys and Compounds

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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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Characteristics of Thermally Robust 5 nm Ru–C Diffusion Barrier/Cu Seed Layer in Cu Metallization

Cited by 13 publications

References 22 publications

The Inhibition of Enhanced Cu Oxidation on Ruthenium∕Diffusion Barrier Layers for Cu Interconnects by Carbon Alloying into Ru

The Inhibition of Enhanced Cu Oxidation on Ruthenium∕Diffusion Barrier Layers for Cu Interconnects by Carbon Alloying into Ru

Investigation of amorphous Ni–Al–N film as diffusion barrier between Cu and SiO2

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

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