Solid-state amorphization at tetragonal-Ta/Cu interfaces

Kwon, Kee-Won; Lee, Hoo-Jeong; Sinclair, Robert

doi:10.1063/1.124559

Cited by 84 publications

(47 citation statements)

References 9 publications

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“…The fcc Cu (111) plane has been reportedly grown heteroepitaxially on the -Ta (002) plane with a lattice mismatch of 7.6%, 34) and the interface between fcc Cu and -Ta exhibited high thermal stability. 18) As previously mentioned for the SK growth mode of the Cu films on -Ta, the formation of one conformal monolayer of Cu can decrease the in-plane compressive strain (or stress) in the Ta barrier and weaken the Cu-thickness dependence of the d Ta002 values of both Ta/Cu and Ta/Cu/Ta, as shown in Fig. 5(b).…”

Section: Resultsmentioning

confidence: 64%

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Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on β-Ta

et al. 2011

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The Cu(111) texture evolution in Cu films sputter-deposited on 35-nm -Ta barrier layers on Si(100) (Ta/Cu) and in those capped by 5-nm Ta (Ta/Cu/Ta) were studied by X-ray diffraction (XRD). The Cu thicknesses (t Cu ) ranged from 5 to 500 nm. For Ta/Cu, the intensity of the Cu 111 reflection exhibited a step-like increase for t Cu between 22 and 33 nm, indicating that subsequent deposition of Cu caused the Cu(111) texture evolution in the already-deposited Cu film (Cu self-capping effect). For Ta/Cu/Ta, the 5-nm Ta capping caused the Cu(111) texture evolution in the already-deposited Cu films for t Cu between 10 and 30 nm (Ta capping effect). These capping effects indicate that the texture evolution took place at room temperature in nanocrystalline Cu films. The capping effects and the initial growth stage of Cu on -Ta are discussed as they relate to Ta and Cu interfacial and grain boundary energies in the nanocrystalline structures.

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Section: Resultsmentioning

confidence: 64%

“…12,[18][19][20][21][22] In our previous work, the Ta barrier layers deposited on Si reed substrates with undulated surfaces consisted of an equilibrium -Ta phase and -Ta phase. 4) In contrast, the Ta barrier layers deposited on Si reed substrates with a mirror surface consisted solely of the -Ta phase.…”

Section: Introductionmentioning

confidence: 99%

Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on β-Ta

et al. 2011

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“…Although too small to be detectable by RBS, even after an 800 C anneal, 4 it is also likely that the reactively sputter-deposited TaN layer is not exactly stoichiometric and will emit a small amount of Ta atoms. Tantalum is known to interact with a Cu surface 20,21 and can, therefore, be expected to interfere with the rearrangement of atoms at the Cu/TaN interface.…”

Section: Electromigration In Cu Interconnects At Elevated Temperatmentioning

confidence: 99%

“…[20][21][22] Such a strong interaction will effectively block surface diffusion at the Cu/Ta interface. This interaction is probably initiated during the PECVD SiN x step at 300 C and is reflected already at RT in the form of the significantly improved EM resistance of the TaN/Cu/Ta interconnect without intentional heat treatment, as shown in Figs.…”

Section: -3 Mardanimentioning

confidence: 99%

Electromigration behavior of Cu metallization interfacing with Ta versus TaN at high temperatures

Mardani

Norström

Smith

et al. 2016

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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High-temperature stability of Cu-based interconnects is of technological importance for electronic circuits based on wide band gap semiconductors. In this study, different metal stack combinations using Ta or TaN as capping-and/or barrier-layer, in the configuration cap/Cu/barrier, are evaluated electrically and morphologically prior to and after high-temperature treatments. The symmetric combinations Ta/Cu/Ta and TaN/Cu/TaN are characterized by a low and stable sheet resistance after annealing up to 700 C. Asymmetric combinations of Ta/Cu/TaN and TaN/Cu/Ta, however, display an increase in sheet resistance values after annealing at 500 C and above. This increase in sheet resistance is considered to result from Ta diffusion into the grain boundaries of the Cu film. The preliminary electromigration studies on the TaN/Cu/Ta and TaN/Cu/TaN structures show a twofold higher activation energy and a tenfold longer lifetime for the former, thus suggesting an important role of the interface between Cu and the cap and/or barrier.

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“…Second, amorphous films can be obtained during growth of Cu/Ta multilayers. [13,14,15] Amorphous metals have high strength, high corrosion resistance, and special magnetic properties suited for communication, aerospace, military, and transport applications. [16,17,18] Cu interconnects require sharp crystalline Cu/Ta interfaces, while amorphization requires highly mixed interfaces.…”

Section: Introductionmentioning

confidence: 99%

Atomically engineering Cu/Ta interfaces.

Webb¹,

Zhou²

2007

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This report summarizes the major research and development accomplishments for the late start LDRD project (investment area: Enable Predictive Simulation) entitled "Atomically Engineering Cu/Ta Interfaces". Two ultimate goals of the project are: (a) use atomistic simulation to explore important atomistic assembly mechanisms during growth of Cu/Ta multilayers; and (b) develop a non-continuum model that has sufficient fidelity and computational efficiency for use as a design tool. Chapters 2 and 3 are essentially two papers that address respectively these two goals.In chapter 2, molecular dynamics simulations were used to study the growth of Cu films on (010) bcc Ta and Cu x Ta 1−x alloy films on (111) fcc Cu. The results indicated that fcc crystalline Cu films with a (111) texture are always formed when Cu is grown on Ta. The Cu films are always polycrystalline even when the Ta substrate is single crystalline. These polycrystalline films are composed of grains with only two different orientations, which are separated by either orientational grain boundaries or misfit dislocations. Periodic misfit dislocations and stacking fault bands are observed. The Cu film surface roughness was found to decrease with increasing adatom energy. Due to a Cu surface segregation effect, the Cu x Ta 1−x films deposited on Cu always have a higher Cu composition than that used in the vapor mixture. When Cu and Ta compositions in the films are comparable, amorphous structures may form. The fundamental origins for all these phenomena have been studied in terms of crystallography and interatomic interactions.In chapter 3, a simplified computational method, diffusional Monte Carlo (dMC) method, was developed to address long time kinetic processes of materials. Long time kinetic processes usually involve material transport by diffusion. The corresponding microstructural evolution of materials can be analyzed by kinetic Monte Carlo simulation methods, which essentially simulate structural evolution by tracing each atomic jump. However, if the simulation is carried out at a high temperature, or a jump mechanism with a very low energy barrier is encountered, the jump frequency may approach the atom vibration frequency, and the computational efficiency of the kinetic Monte Carlo method rapidly decreases to that of a molecular dynamics simulation. The diffusional Monte Carlo method addresses the net effects of many atom jumps over a finite duration, kinetically controlled process. First, atom migration due to both random and non-random jumps is discussed. The concept of dMC is then introduced for random jump diffusion. The validity of the method is demonstrated using several diffusion cases in one-, two-and three-dimensional spaces, including the dissolution of spinodal structures. The application of the non-random diffusion theory to spinodal decomposition is also demonstrated.

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Solid-state amorphization at tetragonal-Ta/Cu interfaces

Cited by 84 publications

References 9 publications

Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on β-Ta

Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on β-Ta

Electromigration behavior of Cu metallization interfacing with Ta versus TaN at high temperatures

Atomically engineering Cu/Ta interfaces.

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Solid-state amorphization at tetragonal-Ta/Cu interfaces

Cited by 84 publications

References 9 publications

Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on &beta;-Ta

Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on &beta;-Ta

Electromigration behavior of Cu metallization interfacing with Ta versus TaN at high temperatures

Atomically engineering Cu/Ta interfaces.

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Product

Resources

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Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on β-Ta

Effects of Cu Self-Capping and Ta Capping on Nanometer-Sized Cu Films Sputter-Deposited on β-Ta