Low-resistivity PVD α-tantalum: phase formation and integration in ultra-low k dielectric/copper damascene structures

Donohue, H.; Gris, H.; Yeoh, J. C.; Buchanan, Keith

doi:10.1109/iitc.2002.1014926

Cited by 6 publications

(14 citation statements)

References 2 publications

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“…Due to their chemical and mechanical stability, Ta metal and its compounds have become the material of choice for diffusion barrier applications in 1C Cuinterconnects [1], However, the desirable diffusion barrier properties of such materials depend on their crystal structure, chemical composition as well as surface roughness [1,2]. Therefore the development of metrology techniques for characterizing such properties is critical for successful process development and quality control.…”

Section: Introductionmentioning

confidence: 99%

“…Ta can exist in two different phases, a (bcc), and P (tetragonal). The a-phase is preferable because its resistivity is approximately one tenth of that of the Pphase [1], and in addition study also had shown that the a-phase could promote the growth of the preferred (111) orientation in subsequent ECP Cu deposition [2]. When Ta is deposited on Si or SiO 2 directly using PVD process, it will form the less desirable p-phase unless additional process steps are introduced [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…The a-phase is preferable because its resistivity is approximately one tenth of that of the Pphase [1], and in addition study also had shown that the a-phase could promote the growth of the preferred (111) orientation in subsequent ECP Cu deposition [2]. When Ta is deposited on Si or SiO 2 directly using PVD process, it will form the less desirable p-phase unless additional process steps are introduced [2,3]. On the other hand, it was recently reported that the introduction of low-& dielectrics has enabled the formation of a-phase Ta directly on the dielectrics surfaces [2].…”

Section: Introductionmentioning

confidence: 99%

“…When Ta is deposited on Si or SiO 2 directly using PVD process, it will form the less desirable p-phase unless additional process steps are introduced [2,3]. On the other hand, it was recently reported that the introduction of low-& dielectrics has enabled the formation of a-phase Ta directly on the dielectrics surfaces [2]. The study reported here concerns mainly the crystal phase determination by XRD and the surface roughness measurement by AFM of the Ta barrier layer deposited by PVD on several dielectric materials.…”

Section: Introductionmentioning

confidence: 99%

“…These three samples are included in the study for baseline purposes. It was pointed out in the introduction that, when Ta is deposited directly on SiO 2 , p-phase Ta forms spontaneously [2]. It has also been shown in the literature that as Ta is deposited on a TaN surface, the low-resistivity a-phase Ta is formed [1].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Characterization of Barrier Layer Phase and Morphology As a Function of Differing Dielectric Substrate Conditions by AFM and Grazing Angle XRD

Wang¹,

Lai²,

Brundle³

et al. 2003

AIP Conference Proceedings

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Tantalum (Ta) metal has emerged as one of the leading materials of choice for diffusion barrier applications in Cu-damascene interconnects. For successful implementation, the microstructure, the electrical property and the surface roughness of the barrier layer have to be controlled. To satisfy such needs, atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques have been employed to monitor the surface roughness and crystal phase of the PVD Ta thin film deposited on low-£ dielectrics. XRD results show that the population of the two different Ta crystal phases, a and p, depends on substrate material, surface pretreatment prior to thin film deposition and deposition conditions. AFM results reveal that surface roughness of the thin barrier layer is mainly determined by the starting substrate surface roughness. Also, AFM surface imaging discovered that each Ta crystal phase possesses a unique surface morphology. Therefore, the population of the Ta crystal phases can be crudely quantified by performing image analysis on the AFM images. The Ta phase population obtained from AFM images correlates very well with the XRD results.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Characterization of Barrier Layer Phase and Morphology As a Function of Differing Dielectric Substrate Conditions by AFM and Grazing Angle XRD

Wang¹,

Lai²,

Brundle³

et al. 2003

AIP Conference Proceedings

View full text Add to dashboard Cite

show abstract

Low-loss α-tantalum coplanar waveguide resonators on silicon wafers: fabrication, characterization and surface modification

Lozano,

Mongillo,

Piao

et al. 2024

Mater. Quantum. Technol.

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The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric loss at different interfaces. α-tantalum is a superconductor that has proven effective in reducing dielectric loss and improving device performance due to its thin low-loss oxide. Here, we demonstrate the fabrication of high-quality factor α-tantalum coplanar-waveguide resonators directly on pristine 300 mm silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. Additionally, we apply a surface treatment based on hydrofluoric acid that allows us to modify different resonators surfaces, leading to a reduction in two-level system (TLS) loss in the devices by a factor of three. This loss reduction can be entirely attributed to the removal of surface oxides. Our study indicates that large scale manufacturing of low-loss superconducting circuits should indeed be feasible and suggests a viable avenue to materials-driven advancements in superconducting circuit performance.

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Via Resistance Reduction using “Cool” PVD-Ta Processing

Seet¹,

Zhang²,

Yong³

et al. 2003

J. Electrochem. Soc.

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Different processes, including ''cool'' physical vapor deposition ͑PVD͒, of Ta barrier and Cu seed deposition were compared in Cu interconnect development. In the cool Ta process, the substrate temperature was Ͻ50°C, compared to a temperature of about Ͼ100°C in the standard process. With the cool process, via resistance ͑0.19 m in via size͒ was reduced by about 25%, although 40% thicker Ta was measured at the via bottom. This was not in agreement with the common understanding that the thicker the Ta film is, the higher the via resistance. Blank film studies suggested that a mixed texture of ␣and ␤-Ta was formed at via bottom in the new Ta/Cu process. X-ray diffraction spectra clearly exhibited the existence of ␣-Ta in addition to the ␤-Ta, where the latter is usually observed in the standard process. Electron diffraction spectra further supported the claim of mixed ␣-/␤-Ta formation at via bottom. Moreover, Rutherford backscattering data suggested that the mixed ␣-/␤-Ta had even higher thermal stability.

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Low-resistivity PVD α-tantalum: phase formation and integration in ultra-low k dielectric/copper damascene structures

Cited by 6 publications

References 2 publications

Characterization of Barrier Layer Phase and Morphology As a Function of Differing Dielectric Substrate Conditions by AFM and Grazing Angle XRD

Characterization of Barrier Layer Phase and Morphology As a Function of Differing Dielectric Substrate Conditions by AFM and Grazing Angle XRD

Low-loss α-tantalum coplanar waveguide resonators on silicon wafers: fabrication, characterization and surface modification

Via Resistance Reduction using “Cool” PVD-Ta Processing

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