Development of plasma-enhanced atomic layer deposition grown Ru–WCN mixed phase films for nanoscale diffusion barrier and copper direct-plate applications

Greenslit, Daniel; Chakraborty, Tonmoy; Eisenbraun, Eric

doi:10.1116/1.3097856

Cited by 15 publications

(12 citation statements)

References 22 publications

(17 reference statements)

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“…30 The effect of C on inhibition of Cu oxidation.-The fact that the Cu 2 O XRD peak is less intense for the Cu/Ru/Ta 0.44 C 0.19 N 0.37 / Si sample indicates that C doped in the TaN layer may inhibit Cu oxidation. Although C-containing barrier, such as WCN, 31 Ta-Si-C, 32 Ru-WCN mixed layer 33 have been reported as good barrier, but the C effect on the Cu oxidation was not studied. We further alloyed C into the Ru layer and studied the effect of C on the Cu oxidation.…”

Section: Resultsmentioning

confidence: 98%

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: 98%

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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“…In particular cases, a low-resistivity barrier and adhesion layer could also simultaneously act as a seed-layer for the electrochemical deposition process of Cu. 161,166,[180][181][182][183]220,240 Triggered by these challenges, Rossnagel and co-workers at IBM developed plasma-assisted ALD processes of Ta and Ti using the metal halides TaCl 5 and TiCl 4 as precursors and an H 2 plasma as a reducing agent. 206 As mentioned in Sec.…”

Section: A Back-end-of-line Processingmentioning

confidence: 99%

Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges

Profijt

Potts

Sanden

et al. 2011

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

729

537

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Plasma-assisted atomic layer deposition (ALD) is an energy-enhanced method for the synthesis of ultra-thin films with Å-level resolution in which a plasma is employed during one step of the cyclic deposition process. The use of plasma species as reactants allows for more freedom in processing conditions and for a wider range of material properties compared with the conventional thermally-driven ALD method. Due to the continuous miniaturization in the microelectronics industry and the increasing relevance of ultra-thin films in many other applications, the deposition method has rapidly gained popularity in recent years, as is apparent from the increased number of articles published on the topic and plasma-assisted ALD reactors installed. To address the main differences between plasma-assisted ALD and thermal ALD, some basic aspects related to processing plasmas are presented in this review article. The plasma species and their role in the surface chemistry are addressed and different equipment configurations, including radical-enhanced ALD, direct plasma ALD, and remote plasma ALD, are described. The benefits and challenges provided by the use of a plasma step are presented and it is shown that the use of a plasma leads to a wider choice in material properties, substrate temperature, choice of precursors, and processing conditions, but that the processing can also be compromised by reduced film conformality and plasma damage. Finally, several reported emerging applications of plasma-assisted ALD are reviewed. It is expected that the merits offered by plasma-assisted ALD will further increase the interest of equipment manufacturers for developing industrial-scale deposition configurations such that the method will find its use in several manufacturing applications.

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“…Both subfilms can be deposited by PEALD to form a mixed-phase Ru-TaN barrier, with a composition of an Ru:Ta ratio of 12 found to exhibit both a good diffusion barrier and direct-plate characteristics [204]. Ru-WC x N y [193]. Ru-WC x N y [193].…”

Section: Figure 69 Tem Bright-field Images (Left) As Well As N and Rmentioning

confidence: 99%

Diffusion Barriers

Hecker¹,

Hübner²

2012

Advanced Interconnects for ULSI Technology

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Development of plasma-enhanced atomic layer deposition grown Ru–WCN mixed phase films for nanoscale diffusion barrier and copper direct-plate applications

Cited by 15 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

Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges

Diffusion Barriers

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