Reliability Improvement by Adopting Ti-barrier Metal B for Porous Low-k IL Structure

Sakata, A.; Yamashita, Shota; Omoto, S.; Hatano, M.; Wada, J.; Higashi, Katsumi; Yamaguchi, Hideyo; Yosho, T.; lmamizu, K.; Yamada, Masayuki; Hasunuma, M.; Takahashi, S.; Yamada, A.; Hasegawa, T.; Kaneko, H.

doi:10.1109/iitc.2006.1648658

Cited by 11 publications

(6 citation statements)

References 2 publications

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“…N doping in RuTa degrades the wettability of Cu on the barrier layer. As RuTa(N) film was annealed, N desorbed easily from RuTa(N) film due to its low thermal stability and crystal ECS Journal of Solid State Science and Technology, 5 (7) P433-P437 (2016) P437 size became larger due to the recrystallization. RuTa(N) had the poor barrier property against Cu diffusion in the BEOL process compared to RuTa one due to the structure of high-angle grain boundaries despite the crystal size of RuTa(N) increased and the density of grain boundaries decreased after annealing.…”

Section: Discussionmentioning

confidence: 99%

Effects of N Doping in Ru-Ta on Barrier Property and Reliability Performance for Cu Interconnects

Torazawa

Hinomura

Hirao

et al. 2016

ECS J. Solid State Sci. Technol.

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The effects of N doping in Ru-Ta alloy on film property, barrier property against Cu diffusion and reliability performance in Cu interconnects were investigated. RuTa(N) film which was doped with N in Ru-Ta alloy was applied as a diffusion barrier layer in Cu interconnects, and barrier property and reliability performance with RuTa(N) barrier were mainly evaluated. As RuTa(N) film was annealed, N desorbed easily from RuTa(N) film due to its low thermal stability and the crystal size became larger because of the recrystallization. RuTa(N) film had the poor barrier property against Cu diffusion due to the structure of high-angle grain boundaries despite the crystal size of RuTa(N) increases and the density of grain boundaries decreases after annealing. Reliability performance of via electromigration could be improved by using Ru-Ta based alloy barrier. However, there was remarkable difference of reliability performance between RuTa and RuTa(N) barrier, and RuTa(N) had inferior reliability performance of via electromigration. On the other hand, RuTa had both good barrier property and superior reliability performance. It was found that doping N in Ru-Ta alloy degraded barrier property and reliability performance. Consequently, it is appropriate to apply RuTa single film as the diffusion barrier layer for 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 gapped filling, the opening of trench and via after the deposition of barrier and Cu seed have to be kept far 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 the 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.1-23 Among them, Ruthenium (Ru) has been most frequently suggested as a layer for suppressing the agglomeration of Cu seed. The barrier property against Cu diffusion of pure Ru and Ru-N is not enough. [22][23][24] In addition, chemical mechanical polishing (CMP) process for Ru is a difficult technology and the scratch occurred during CMP process leads to the degradation of the device yield and time dependent dielectric breakdown (TDDB) reliability performance. However, Ru has the good wettability with Cu and can improve the filling property of Cu electroplating, and has another possibility in Cu interconnects such as the seed layer for direct plating onto R...

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Section: Discussionmentioning

confidence: 99%

Effects of N Doping in Ru-Ta on Barrier Property and Reliability Performance for Cu Interconnects

Torazawa

Hinomura

Hirao

et al. 2016

ECS J. Solid State Sci. Technol.

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“…Recently, Ti-based barrier layers have been re-visited and extensively investigated for use in copper dual damascene interconnects, since compared to conventional Ta-based barrier films, Ti is able to achieve lower resistance and higher reliability at a lower overall cost of ownership. [1][2][3] Previous work has been performed to study the effect of copper ions and oxidants in the slurry on Ti CMP performance. [4][5][6][7] It is important to note that temperature also plays a critical role in CMP due to its significant influence on pad surface properties and slurry chemistry.…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature in titanium chemical mechanical planarization

Jiao

Sampurno

et al. 2015

Jpn. J. Appl. Phys.

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The effect of temperature on the tribological and kinetic attributes of Ti chemical mechanical planarization (CMP) was investigated. Results indicated that processes at platen temperatures of 25 and 50 °C behaved similarly in terms of their tribological mechanism. At both temperatures, average coefficient of friction (COF) ranged from 0.19 to 0.41, indicating that boundary lubrication was the dominant tribological mechanism. Results also showed that average COF decreased with increasing platen temperature likely due to softening of pad asperities and lower slurry viscosity at the higher temperature. Due to exponentially accelerated chemical effects, Ti removal rate was higher when platen temperature was set at 50 °C. A two-step modified Langmuir-Hinshelwood model was used to simulate Ti removal rate and the chemical and mechanical rate constants under different polishing conditions. Simulated values of removal rate agreed well with experimental data. Simulated chemical rate to mechanical rate constant ratios suggested that the removal mechanism shifted from a more chemically-controlled to a more mechanicallycontrolled process as platen temperature was raised.

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“…Sputtering is an alternative to electroplating as a Cu filling method. [8][9][10][11][12][13] Sputtering has the advantages of producing highly reliable results since the era of Al wiring and being accomplished with equipment that is easy to operate. Even now, it is used to form trench barrier layers 14,15) and Cu seed layers.…”

Section: Introductionmentioning

confidence: 99%

Cu filling of 10 nm trenches by high-magnetic-field magnetron sputtering

Itoh

Uhara

Saito

2014

Jpn. J. Appl. Phys.

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Ru and Cu sputterings were performed with two different high-vacuum sputtering systems. The Ru sputtering was performed by high-vacuum sputtering. On the other hand, the Cu sputtering was performed by high-magnetic-field sputtering. High-magnetic-field sputtering, which entails a Cu deposition rate of 80 nm/min (target-substrate distance: 200 mm) at a sputtering pressure of 7 ' 10 %2 Pa, is used for the Cu filling of 10-nmwide Ru-lined trenches with an aspect ratio of 6.5. The complete Cu filling of trenches is accomplished within 1 min of sputtering time using a 1 at. % N 2 -Ar sputtering gas. The reason for the complete Cu filling is considered in terms of the capillary theory, focusing on the wettability of Cu on Ru. The improvement in Cu wettability with the use of a N 2 additive is also evaluated in terms of the contact angle for Cu on Ru and surface shape.

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Reliability Improvement by Adopting Ti-barrier Metal B for Porous Low-k IL Structure

Cited by 11 publications

References 2 publications

Effects of N Doping in Ru-Ta on Barrier Property and Reliability Performance for Cu Interconnects

Effects of N Doping in Ru-Ta on Barrier Property and Reliability Performance for Cu Interconnects

Effect of temperature in titanium chemical mechanical planarization

Cu filling of 10 nm trenches by high-magnetic-field magnetron sputtering

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