Cubic TaN diffusion barrier for Cu interconnects using an ultra-thin TiN seed layer

Araujo, Roy A.; Yoon, Jungho; Zhang, Xinghang; Wang, Haiyan

doi:10.1016/j.tsf.2007.12.144

Cited by 15 publications

(11 citation statements)

References 16 publications

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“…Therefore, we decide to include three Cu ͑111͒ layers on top of Ta ͑110͒ substrate in the interfacial diffusion calculations. fcc TaN was reported to be a metastable structure 16,27 but it is believed to be the most effective diffusion barrier material among all TaN compounds. 27 The surface orientation of fcc TaN differs depending on the methods of fabrication; 28 it is reported however that the densely packed ͑111͒ orientation is considered the most effective orientation for barrier materials.…”

Section: Crystal Structure and Computational Methodsmentioning

confidence: 99%

“…fcc TaN was reported to be a metastable structure 16,27 but it is believed to be the most effective diffusion barrier material among all TaN compounds. 27 The surface orientation of fcc TaN differs depending on the methods of fabrication; 28 it is reported however that the densely packed ͑111͒ orientation is considered the most effective orientation for barrier materials. The Cu/ fcc-TaN interface structures remain unclear experimentally except that Cu ͑111͒ has been reported as preferred orientation on fcc-TaN substrate.…”

Section: Crystal Structure and Computational Methodsmentioning

confidence: 99%

“…The Cu/ fcc-TaN interface structures remain unclear experimentally except that Cu ͑111͒ has been reported as preferred orientation on fcc-TaN substrate. [8][9][10][11][12][13][14]27,28 Therefore, we will study Cu ͑111͒/fcc-TaN ͑111͒ interfaces by including three Cu ͑111͒ layers on top of TaN ͑111͒ substrate in the firstprinciples calculations. [29][30][31][32] All calculations in this paper are carried out based on first-principles density-functional theory ͑DFT͒ with planewave basis and the projector augmented-wave method as implemented in the Vienna Ab initio Simulation Package.…”

Section: Crystal Structure and Computational Methodsmentioning

confidence: 99%

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First-principles simulations of copper diffusion in tantalum and tantalum nitride

Zhao

Lü

2009

Phys. Rev. B

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To explore potential applications of tantalum and tantalum nitrides ͑TaN͒ as diffusion barrier materials in integrated circuits with Cu interconnects, we carry out detailed first-principles simulations of Cu/Ta and Cu/TaN systems. Various interfacial structures between Cu-and Ta-based compounds are examined by considering different surface orientations, in-plane arrangements, surface terminations, and chemical compositions. The coexistence of strong Cu-N ionic bonding and Ta-Cu covalent/metallic bonding dictates the stable interfacial structures. Using nudged elastic band method, we calculate the diffusion energy barriers of Cu to the pre-existing vacancies across Cu/Ta, Cu/TaN interfaces, and in bulk TaN compounds. As a comparison, Cu diffusion in Si is also studied. It was found that Cu can easily diffuse into Si either spontaneously or with small energy barriers. On the other hand, although the Cu/Ta interfacial diffusion barrier is low, the high vacancy formation energy in Ta renders Cu diffusion difficult. We find that fcc TaN is an excellent candidate for diffusion barrier material owing to its extremely high interfacial diffusion energy barrier. The bulk diffusion barrier of Cu in fcc TaN is also very high.

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Section: Crystal Structure and Computational Methodsmentioning

confidence: 99%

Section: Crystal Structure and Computational Methodsmentioning

confidence: 99%

Section: Crystal Structure and Computational Methodsmentioning

confidence: 99%

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First-principles simulations of copper diffusion in tantalum and tantalum nitride

Zhao

Lü

2009

Phys. Rev. B

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“…It has been expected that the TaN/Ta barrier material will fail at such a small dimension. 7,8 To enable continuous downward scaling of the Cu interconnect, it requires researchers to develop the ultra-thin layer (<1 nm) with high resistance to Cu species migration inside the low-k dielectrics.…”

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confidence: 99%

Mass Transport Mechanism of Cu Species at the Metal/Dielectric Interfaces with a Graphene Barrier

et al. 2014

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The interface between the metal and dielectric is an indispensable part in various electronic devices. The migration of metallic species into the dielectric can adversely affect the reliability of the insulating dielectric and can also form a functional solid-state electrolyte device. In this work, we insert graphene between Cu and SiO2 as a barrier layer and investigate the mass transport mechanism of Cu species through the graphene barrier using density functional theory calculations, second-ion mass spectroscopy (SIMS), capacitance-voltage measurement, and cyclic voltammetry. Our theoretical calculations suggest that the major migration path for Cu species to penetrate through the multiple-layered graphene is the overlapped defects larger than 0.25 nm2. The depth-profile SIMS characterizations indicate that the "critical" thickness of the graphene barrier for completely blocking the Cu migration is 5 times smaller than that of the conventional TaN barrier. Capacitance-voltage and cyclic voltammetry measurement reveal that the electrochemical reactions at the Cu/SiO2 interface become a rate-limiting factor during the bias-temperature stressing process with the use of a graphene barrier. These studies provide a distinct roadmap for designing controllable mass transport in solid-state electrolyte devices with the use of a graphene barrier.

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“…It is well known that copper is a faster diffuser in Si and SiO 2 , which makes diffusion barrier layer so important in Cu metallization [1][2]. Thetantalum (Ta) and tantalum nitride (TaN) [3] barrier layers have been widely used as diffusion barriers and thin film resistors in the microelectronics industry due to their good diffusion barrier properties [1,4,5] and relatively stable electrical properties [6][7][8]. TiN have also received much attention as diffusion barrier [9][10][11] due to its mechanical stability [9,12] and low resistivity [10,11].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characteristics of the Reactive Sputtered Ta-N Thin Films with Ti Addition

Chung¹

2018

J Nanosci Adv Tech

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The combination of TaN and TiN is expected to create a range of muti-functional materials because of the composition dependent resistivity and thermal coefficient of resistance for the applications in microelectronics and thermal sensors industry. In this article, adding Ti into the TaN thin film has been investigated by various sputtering conditions to create the possibility with varied electrical property which can be good for resistor and sensor application. A series of TaN (0Ti%) and Ta-TiN thin films were deposited by DC magnetron sputtering. The microstructure, composition, morphology and electrical properties of the films were characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, scanning electron microscopy and four point probe method. The crystal structures of Ta, Ti and Ta-Ti alloys are based on bcc α-Ta and bcc β-Ti. XRD patterns showed TaN is qusi-amorphous structure with high N 2 flow ratio of 20% while Ta-TiN is preferred to form polycrystalline phase. The resistivity of both kinds of thin films decreases with increasing temperatures for the nature of negative temperature coefficient of resistance (N-TCR). The magnitude of both resistivity and N-TCR increases with increasing N 2 flow ratio. The wide range of resistivity and TCR can be used for applications in thermally based micro sensors (high TCR)and thin-film resistor (low TCR).

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Cubic TaN diffusion barrier for Cu interconnects using an ultra-thin TiN seed layer

Cited by 15 publications

References 16 publications

First-principles simulations of copper diffusion in tantalum and tantalum nitride

First-principles simulations of copper diffusion in tantalum and tantalum nitride

Mass Transport Mechanism of Cu Species at the Metal/Dielectric Interfaces with a Graphene Barrier

Fabrication and Characteristics of the Reactive Sputtered Ta-N Thin Films with Ti Addition

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