W/TiN double layers as barrier system for use in Cu metallization

Baumann, J.; Markert, M.; Werner, T.; Ehrlich, Andreas; Rennau, M.; Kaufmann, Ch.; Geßner, Thomas

doi:10.1016/s0167-9317(97)00116-0

Cited by 11 publications

(2 citation statements)

References 12 publications

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“…The higher barrier breakdown temperature of bilayer films compared to that of the corresponding single-layer structure has been primarily attributed to the grain boundary mismatch between the two layers. 19,20 Leu et al 21 reported Ir͑5 nm͒/TaN͑5 nm͒ bilayer barrier to be effective for blocking copper diffusion up to 600°C. The breakdown temperature of Ta/TaN 22 bilayer structure was reported to be as high as 900°C, whereas Ru/ TaN 23 and Mo/W-N 20 barrier structures were stable at least up to 900 and 775°C, respectively.…”

mentioning

confidence: 99%

Reactively Sputtered Mo–V Nitride Thin Films as Ternary Diffusion Barriers for Copper Metallization

Majumder¹,

Takoudis²

2008

J. Electrochem. Soc.

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The effectiveness and performance of Mo-based ternary nitride films as copper diffusion barriers were investigated. Thermally stable Mo-V nitride thin diffusion barrier layers were deposited using radio frequency reactive magnetron sputtering and their barrier capability was evaluated and studied. Cu/Mo-V nitride/Si structures were fabricated and annealed at different temperatures. The agglomeration of Cu and the formation of Cu 3 Si due to high-temperature annealing were probed using scanning electron microscopy/energy-dispersive X-ray spectroscopy. The drastic increase in sheet resistance after annealing at 800°C was found to take place due to the formation of highly resistive Cu 3 Si, also evident from X-ray diffraction patterns. The formation of inverted pyramidal structure of Cu 3 Si at the interface penetrated into the Si substrate corroborated the breakdown of the barrier layer at 800°C. Our results suggest that an 8 nm thick Mo-V nitride barrier can effectively prevent the formation of Cu 3 Si up to high annealing temperatures.The resistance-capacitance ͑RC͒ delay in integrated circuits ͑ICs͒ is becoming inevitable with decreasing dimensions of metal oxide semiconductor devices. In order to address this RC delay, Cu has replaced conventional Al as an interconnect material because the former has low bulk resistivity ͑ϳ1.7 ⍀ cm͒, high melting point, and superior electromigration resistance to that of Al. 1 However, the transition from Al to Cu metallization has given rise to numerous challenges. One of the challenges is to develop a suitable diffusion barrier to restrict the interaction of Cu and Si or SiO 2 that form detrimental Cu silicides at temperatures as low as 200°C. 2,3 The barrier material should ideally have high thermal stability, negligible reactivity with Cu and the underlying Si substrate during the manufacture and operation of the device, low resistivity, and good adhesion to Cu and Si. 4,5 Furthermore, the continuous shrinking of feature sizes in future generations of ICs requires thinner diffusion barrier layers. 6 Various transition metals, their alloys, nitrides, borides, carbides, and ternary barriers have been studied over the past few decades as potential diffusion barriers. Kaloyeros and Eisenbraun 5 reviewed the properties of such barrier materials in detail. They reported that the failure of these barrier layers takes place primarily due to the diffusion of Cu atoms through the barrier grain boundaries and/or bulk defects such as vacancies and dislocations, after annealing at higher temperatures.It is known that bilayer and ternary single-layer barrier structures offer higher thermal stability than that of their corresponding singlelayer metal and metal nitrides. It has been reported that the increase in thermal stability of ternary barrier structure is likely due to the delay in the crystallization of the barrier material upon annealing, because the formation of grain boundaries can be delayed with the addition of a third element. 7,8 Thus, ternary nitride alloys, such as W-B-N,

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mentioning

confidence: 99%

Reactively Sputtered Mo–V Nitride Thin Films as Ternary Diffusion Barriers for Copper Metallization

Majumder¹,

Takoudis²

2008

J. Electrochem. Soc.

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“…The higher thermal stability of a Ta(20 nm)/TaN(10 nm) stacked layer than that of the single layer Ta (30 nm) or TaN (30 nm) was attributed to the grain boundary mismatches between Ta and TaN. A W(20 nm)/TiN(20 nm) layer offered superior thermal stability to that of W or TiN single layer barrier films [12]. Tan et al [13] reported an insignificant increase in sheet resistance of Ru(10 nm)/TaN(10 nm) double layer barrier structures after annealing up to 900 • C, whereas the failure temperature of a single layer Ru was only 600 • C. Although these bilayer barrier nanostructures exhibited better thermal stability than that of their corresponding single layer structures, the total barrier thickness were large enough to meet the present requirements of such barrier films [10].…”

Section: Introductionmentioning

confidence: 99%

Thermal stability of Ti/Mo and Ti/MoN nanostructures for barrier applications in Cu interconnects

Majumder¹,

Takoudis²

2008

Nanotechnology

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This work focuses on the barrier capabilities of sputter deposited Ti/Mo and Ti/MoN nanofilms against diffusion of Cu into Si substrates. The thermal stability of the corresponding bi-layer barrier structures is investigated after annealing Cu/barrier layer/Si samples at different temperatures in N(2) for 5 min. The drastic increase in sheet resistance of Cu and the probing of Cu(3)Si with x-ray diffraction after high temperature annealing indicate the failure of these barrier structures. The formation of Cu(3)Si at the barrier breakdown temperature is also confirmed by scanning electron microscopy and energy dispersive x-ray spectroscopy. Cu diffusion barrier performance analyses show that a Ti(5 nm)/MoN(5 nm) bi-layer nanostructure fails only after annealing at 800 °C; on the other hand, a Ti(5 nm)/Mo(5 nm) barrier stack is found to break down at 700 °C.

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Impact of the Unique Physical Properties of Copper in Silicon on Characterization of Copper Diffusion Barriers

Istratov

Flink

Weber

2000

phys. stat. sol. (b)

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W/TiN double layers as barrier system for use in Cu metallization

Cited by 11 publications

References 12 publications

Reactively Sputtered Mo–V Nitride Thin Films as Ternary Diffusion Barriers for Copper Metallization

Reactively Sputtered Mo–V Nitride Thin Films as Ternary Diffusion Barriers for Copper Metallization

Thermal stability of Ti/Mo and Ti/MoN nanostructures for barrier applications in Cu interconnects

Impact of the Unique Physical Properties of Copper in Silicon on Characterization of Copper Diffusion Barriers

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