Electroplated Cu Recrystallization in Damascene Structures at Elevated Temperatures

Jiang, Qing-Tang; Thomas, Michael E.; Bersuker, G.; Foran, Brendan; Mikkola, Robert; Carpenter, Brad; Ormando, J.

doi:10.1557/proc-564-429

Cited by 12 publications

(17 citation statements)

References 1 publication

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“…A similar thickness dependence of the selfannealing kinetics has been observed previously. 6,7,[24][25][26][27] Supported by the observation of even slower kinetics observed for Cu deposited in damascene trenches, 8,28,29 the thickness dependence has been attributed to geometrical constraints due to trench and via structures and/or the interface and surface of the film. 8 This, however, does not explain the complete absence of self-annealing in the thinnest Cu layer, as observed in the present study, since the as-deposited crystallite sizes are considerably smaller than the layer thickness.…”

Section: B Kinetics Of Self-annealingmentioning

confidence: 99%

In situ investigation of the microstructure evolution in nanocrystalline copper electrodeposits at room temperature

Pantleon

Somers

2006

Journal of Applied Physics

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The microstructure evolution in copper electrodeposits at room temperature ͑self-annealing͒ was investigated by means of x-ray diffraction analysis and simultaneous measurements of the electrical resistivity as a function of time. In situ studies were started immediately after deposition of the various thick layers and continued with a unique time resolution until stabilization of the recorded data occurred. Independent of the copper layer thickness, the as-deposited microstructure consisted of nanocrystalline grains with orientation dependent crystallite sizes. Orientation dependent grain growth, crystallographic texture changes by multiple twinning, and a decrease of the electrical resistivity occurred as a function of time at room temperature. The kinetics of self-annealing is strongly affected by the layer thickness: the thinner the layer, the slower the microstructure evolution is, and self-annealing is suppressed completely for a thin layer with 0.4 m. The preferred crystallographic orientation of the as-deposited crystallites is suggested to cause the observed thickness dependence of the self-annealing kinetics.

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Section: B Kinetics Of Self-annealingmentioning

confidence: 99%

In situ investigation of the microstructure evolution in nanocrystalline copper electrodeposits at room temperature

Pantleon

Somers

2006

Journal of Applied Physics

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“…Although this behaviour of electroplated copper is intriguing, the kinetics are hard to study, since the as-deposited grain structure and impurity content of the film strongly depend on the electroplating bath chemistry. Several research groups have reported that the resistivity of as-deposited electroplated copper exceeds the bulk value of 1.67µΩcm by 10-30%, but after a transient period of hours at room temperature, the resistivity decreases to near-bulk values [90][91][92][93][94][95]. The observed sheet resistance decline during self-annealing is attributed to the elimination of electron scattering at the grain boundaries due to the reducing number of grain boundaries as grain growth proceeds.…”

Section: Self-annealing In Electroplated and Sputtered Copper Filmsmentioning

confidence: 99%

Increasing the mean grain size in copper films and features

et al. 2008

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A new grain-growth mode is observed in thick sputtered copper films. This new grain-growth mode, also referred to in this work as super secondary grain growth (SSGG) leads to highly concentric grain growth with grain diameters of many tens of micrometers, and drives the system toward a {100} texture. The appearance, growth dynamics, final grain size, and self-annealing time of this new grain-growth mode strongly depends on the applied bias voltage during deposition of these sputtered films, the film thickness, the post-deposition annealing temperature, and the properties of the copper diffusion barrier layers used in this work. Moreover, a clear rivalry between this new growth mode and the regularly observed secondary grain-growth mode in sputtered copper films was found. The microstructure and texture evolution in these films is explained in terms of surface/interface energy and strain-energy density minimizing driving forces, where the latter seems to be an important driving force for the observed new growth mode. By combining these sputtered copper films with electrochemically deposited (ECD) copper films of different thickness, the SSGG growth mode could also be introduced in ECD copper, but this led to a reduced final SSGG grain size for thicker ECD films. The knowledge about the thin-film level is used to also implement this new growth mode in small copper features by slightly modifying the standard deposition process. It is shown that the SSGG growth mode can be introduced in narrow structures, but optimizations are still necessary to further increase the mean grain size in features.

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“…Dramatic changes in preferred grain orientations were observed for Cu layers over a period of hours or weeks after electrochemical deposition. [3][4][5] Consequently, the properties of Cu electrodeposits, applied e.g., as interconnect lines in microelectronics, change due to the course of self-annealing; a decrease of internal stress level 6 and microhardness 7,8 as well as electrical resistivity 6,9,10 have been reported. A direct comparison of crystallographic texture of electrodeposits reported in the literature is difficult, if possible at all, because the interaction between very different electrolyte compositions and deposition parameters as well as the extent of self-annealing has to be considered.…”

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confidence: 99%

Interpretation of Quantitative Crystallographic Texture in Copper Electrodeposits on Amorphous Substrates

Pantleon

Jensen

Somers

2004

J. Electrochem. Soc.

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Crystallographic texture and morphology in Cu electrodeposits was studied in relation to the current density and the content of the organic levelling additive 3-mercapto-1-propanesulfonate. The substrate onto which Cu was electrodeposited consisted of amorphous Ni-P in order to allow substrate-unbiased texture development in the electrodeposit. Comprehensive X-ray diffraction studies of the crystallographic texture, including calculations of the three-dimensional orientation distribution function, were performed and accompanied by investigations of the deposit morphology by means of light optical microscopy. Electrodeposits with totally different microstructures having the same main crystallographic orientation of grains were observed. For interpretation of the results, not only the original growth behavior in direct dependence on the applied process parameters, but also process dependent self-annealing effects ͑recrystallization͒ of the as-deposited layers were considered.

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Electroplated Cu Recrystallization in Damascene Structures at Elevated Temperatures

Cited by 12 publications

References 1 publication

In situ investigation of the microstructure evolution in nanocrystalline copper electrodeposits at room temperature

In situ investigation of the microstructure evolution in nanocrystalline copper electrodeposits at room temperature

Increasing the mean grain size in copper films and features

Interpretation of Quantitative Crystallographic Texture in Copper Electrodeposits on Amorphous Substrates

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