Self-annealing characterization of electroplated copper films

Lagrange, Sébastien; Brongersma, Sywert; Judelewicz, Moshe; Saerens, Annelies; Vervoort, Iwan; Richard, E.; Palmans, Roger; Maex, Karen

doi:10.1016/s0167-9317(99)00314-7

Cited by 154 publications

(99 citation statements)

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“…1,2 Since the era of copper interconnects this socalled self-annealing effect came into focus. [3][4][5] Selfannealing has been recognized as an unwanted side effect in the successful manufacturing of copper thin films for applications in microelectronics and postdeposition annealing at elevated temperatures for stabilizing the microstructure has been introduced as an integrated part of the manufacturing process. Even so self-annealing can be prevented by intentional annealing at elevated temperatures, the phenomenon remains of scientific and technological interest, since understanding the kinetics and mechanisms of self-annealing is the essence of tailoring the microstructure.…”

Section: Introductionmentioning

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: Introductionmentioning

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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“…22 Graham et al 23 found that the copper self-annealing is a function of the copper linewidths in that the smaller Cu linewidths require a higher activation energy to achieve full recrystallization than the wider ones. In addition, Lagrange et al 24 investigated the Cu self-annealing phenomenon as a function of the Cu thickness, and found that the self-annealing is slowed down for a thinner Cu layer due to physical restrictions, while the thicker layer approached the grain size of recrystallized copper, forcing growth to proceed in two dimensions (2D). Therefore, the stress relief tends to be lower when the layer is thinner due to the physical limitation.…”

Section: A Geometric Linewidth Dependence Of the Strain In Si Inducementioning

confidence: 99%

Geometric linewidth and the impact of thermal processing on the stress regimes induced by electroless copper metallization for Si integrated circuit interconnect technology

McNally

Kanatharana

Toh

et al. 2004

Journal of Applied Physics

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Mechanical strains and stresses are a major concern in the development of copper-based on-chip metallization. Synchrotron x-ray topography (SXRT), micro-Raman spectroscopy, finite element modeling (FEM), and atomic force microscopy (AFM) have been used to examine the strain fields imposed by electroless Cu metallization on the underlying Si. As expected, we have observed enhanced strain regions close to the metal line edges. These strain fields tend to zero at annealing temperatures approaching 200°C, and thereafter the magnitudes of the strain fields at 300°C and 400°C are much higher, implying a return to a higher strain regime. Although the strain transition point is slightly different from the SXRT result, the FEM results confirm the existence of a zero-strain transition point as a function of thermal anneal. We have also examined the generated stress in Si as a function of Cu linewidth L. We have found that the stress XX due to the electroless copper metallization is empirically related to the Cu linewidth in terms of an exponential distribution. For Cu linewidths less than 20 m, the stress magnitudes increased with decreasing Cu linewidth due to the thermal stress in the absence of self-annealing, whereas the stress decreased with increasing linewidths in the range of 60-100 m due to a relief of the thermal stress possibly via the self-annealing effect. This self-annealing phenomenon was observed using AFM. It is observed that the stresses in the Si shifted to a compressive state after annealing at 400°C.

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“…Such an effect has been observed during Cu electrodeposition for on-chip interconnects. [24][25] Also shown are the EBSD pole figures for each film. These indicate that saccharin changes the film texture from a weak (210) to an appreciable (111) preferred orientation (i.e., the close-packed plane perpendicular to the growth direction).…”

Section: Figures 5a and B Are Tem Micrographs Showing The As-depositementioning

confidence: 99%

Electrodeposition on Ni from a Sulfamate Electrolyte Part 1: Effect of a Stress Relief on Annealing Behavior and Film Metallurgy

Kelly¹

2002

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Ni and Ni alloys are being developed as baseline materials for LIGA technology and prototyping at Sandia National Laboratories. A conventional, additive-free sulfamate electrolyte has been chosen for pure Ni electrodeposition due to its simplicity and ability to produce ductile, low-stress films. When depositing certain Ni alloys, saccharin is typically employed as an electrolyte bath additive. While saccharin is well known and effective as a stress reliever, it has a significant impact on the microstructure of the deposit and its annealing behavior.The electrodeposition of pure Ni in the presence of saccharin is studied here to understand its effects in the absence of an alloying element (such as Co or Fe). The grain structure and Vickers hardness of Ni deposited with and without saccharin on a rotating disk electrode were all found to be consistent with previous studies available in the literature. The following observations were made:1) The fine, columnar morphology obtained without saccharin became an equiaxed, nanosized grain structure with saccharin (from ~1.5 mm to ~40 nm nominal grain size, respectively). The grain refinement resulting from saccharin is not accompanied with an increase in film stress, in contrast to the grain refinement associated with certain Ni alloys. 2) A change in the deposit texture from weak (210) to (111) along the film growth direction with the addition of saccharin. 3) An increase in Vickers hardness by a factor of ~2 (from ~170 to ~320) upon the addition of saccharin. 4) A rapid decrease in hardness with annealing from the high, as-deposited values for films deposited with saccharin to a value lower than that of annealed Ni from an additive-free bath. 5) Accelerated grain growth during annealing for films deposited with saccharin; this has not been observed previously in the literature to the authors' best knowledge. 4ACKNOWLEDGMENT

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Self-annealing characterization of electroplated copper films

Cited by 154 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

Geometric linewidth and the impact of thermal processing on the stress regimes induced by electroless copper metallization for Si integrated circuit interconnect technology

Electrodeposition on Ni from a Sulfamate Electrolyte Part 1: Effect of a Stress Relief on Annealing Behavior and Film Metallurgy

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