Integration Aspects of CoWP Capping Layers for Electromigration Enhancement

Preuße, Axel; Seidel, Robert; Aubel, Oliver; Nopper, Markus; Freudenberg, Benjamin; Schaller, Μ.; Fecher, M.; Letz, T.; Bartsch, Christin; Ott, Andrew W.; Friedemann, M.; Feustel, F.; Meyer, M. A.; Limbecker, Pascal

doi:10.1109/iitc.2008.4546943

Cited by 5 publications

(5 citation statements)

References 3 publications

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“…39,40) When the focus is set on significantly improving reliability performance, metallic cobalt-tungsten-phosphorus (CoWP) layers selectively deposited on top of the Cu lines by electroless plating have been discussed extensively. [41][42][43][44] This process poses some significant challenges. First of all, all relevant chemical parameters in the plating bath have to be closely monitored to ensure stable processing conditions and reproducibility in a manufacturing environment.…”

Section: Process Options and Reliability Concernsmentioning

confidence: 99%

“…44) Also, the clean processes pre and post CoWP deposition are crucial. 43,44) The Cu lines post Cu polish need to be oxidefree to enable a proper initiation of the CoWP deposition. Also, all metallic contamination on the ILD has to be removed prior CoWP deposition for proper selectivity.…”

Section: Process Options and Reliability Concernsmentioning

confidence: 99%

“…Another challenge of this process is the compatibility of CoWP with the post plasma etch wet clean employed when processing subsequent layers. 43,44) This process is necessary for removing etch polymers, but an improper post plasma etch wet clean can completely remove the CoWP layer on the lower metal level. TEM images of two metal levels connected The electrical performance of material with CoWP as compared to interconnects without CoWP cap was evaluated and matching RC values were found.…”

Section: Process Options and Reliability Concernsmentioning

confidence: 99%

“…TEM images of two metal levels connected The electrical performance of material with CoWP as compared to interconnects without CoWP cap was evaluated and matching RC values were found. 43,44) It is possible to obtain a slight R increase for lines capped with CoWP of approximately 3% when using a thicker CoWP layer or when the Cu recess induced by pre-clean processes before CoWP deposition is not properly adjusted. It needs to be noted that this R increase is linewidth independent in contrast to the significant geometry dependence observed for Cu(Mn) interconnects.…”

Section: Process Options and Reliability Concernsmentioning

confidence: 99%

See 3 more Smart Citations

Advanced metallization concepts and impact on reliability

Hauschildt

Hintze

Gall

et al. 2014

Jpn. J. Appl. Phys.

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This study examines several possible back-end-of-line process options for future leading edge, high performance semiconductor devices, discussing effects on electrical and reliability characteristics as well as specific processing challenges. The extendibility of current physical vapor deposition-based processes for barrier layers, based on existing tool sets and therefore representing the most cost-efficient solution, is reviewed. Subsequently, alloying options such as Cu(Mn) in the seed are highlighted, showing excellent reliability, but also leading to challenges with electrical performance. Furthermore, the applicability of atomic layer and chemical vapor deposition processes for barrier applications and their limits are examined. The electro migration advantage of selective metallic capping processes such as electroless cobalt-tungsten-phosphorus deposition and chemically-vapor-deposited cobalt is highlighted, while process challenges are shown. Additionally, the need for careful adjustment of the Cu plating process and evaluation of electro migration performance upon changes to the barrier/liner/seed process is discussed

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Section: Process Options and Reliability Concernsmentioning

confidence: 99%

Section: Process Options and Reliability Concernsmentioning

confidence: 99%

Section: Process Options and Reliability Concernsmentioning

confidence: 99%

Section: Process Options and Reliability Concernsmentioning

confidence: 99%

See 2 more Smart Citations

Advanced metallization concepts and impact on reliability

Hauschildt

Hintze

Gall

et al. 2014

Jpn. J. Appl. Phys.

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“…For metal capping on Cu interconnects, Co-based cap metals have been studied frequently, which were deposited by selective electroless plating. [12][13][14][15][16] TaN 17) deposited by atomic layer deposition (ALD) and W 18) deposited by chemical vapor deposition (CVD) have also been reported. A major problem of Cu alloy interconnects prepared by doping impurities is an increase in line resistance owing to doped metal impurities, which act as an electron scattering factor in Cu lines.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Lifetime Improvements in Electromigration between Ti Barrier Metal and Chemical Vapor Deposition Co Capping

Kakuhara

Yokogawa

Ueno

2010

Jpn. J. Appl. Phys.

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As promising technologies for fabrication of highly reliable Cu interconnects, using Ti barrier metal (Cu/Ti) and chemical vapor deposition (CVD) Co capping (Co/Cu/Ta/TaN) were compared. Both Cu interconnects similarly showed longer electromigration (EM) lifetime and larger activation energy of lifetime than conventional Cu interconnects fabricated using Ta/TaN barrier metal without capping metal (Cu/Ta/TaN). The residual resistance of Cu lines was measured cryogenically. Cu/Ti showed a higher residual resistance than Co/Cu/Ta/TaN and Cu/Ta/TaN, which indicates the presence of more impurities and a higher density of grain boundaries in Cu/Ti. Energy dispersive X-ray spectroscopy (EDX) analysis showed that a large amount of Ti doped into the Cu line segregated mostly at the grain boundaries on the Cu surface. It is suggested that Ti doped into a Cu line suppresses Cu diffusion through only the grain boundaries on the Cu surface. On the other hand, Co capping suppresses Cu diffusion through the entire Cu surface. As Cu/Ti improved EM lifetime significantly, the grain boundaries on the Cu surface are proposed to be a predominant diffusion path in EM. Since the density of grain boundaries probably increases on the Cu surface as interconnects shrink, suppressing the grain boundary diffusion on the Cu surface is highly effective to strengthen EM reliability.

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Alternative ULK integration approach using a sacrificial layer in a standard dual damascene flow

Uhlig

Calvo

Koch

et al. 2015

2015 IEEE International Interconnect Technology Conference and 2015 IEEE Materials for Advanced Metallization Conference (IITC/

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In this work an approach to integrate spin-on deposited ULK in an existing 28 nm BEOL flow is presented. Additionally, this alternative ULK integration avoids any damage by plasma etching, wet cleaning and barrier/seed deposition by employing an alternative integration scheme. This is done by using a sacrificial material and filling the new material in already manufactured dual damascene structures. Critical process steps like the removal of the sacrificial material, filling of the ULK and final planarization are investigated and promising results are presented as a first feasibility study

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Integration Aspects of CoWP Capping Layers for Electromigration Enhancement

Cited by 5 publications

References 3 publications

Advanced metallization concepts and impact on reliability

Advanced metallization concepts and impact on reliability

Comparison of Lifetime Improvements in Electromigration between Ti Barrier Metal and Chemical Vapor Deposition Co Capping

Alternative ULK integration approach using a sacrificial layer in a standard dual damascene flow

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