Electrochemical Reactions During Ru Chemical Mechanical Planarization and Safety Considerations

Shima, Shohei; Wada, Yutaka; Tokushige, Katsuhiko; Fukunaga, Atsushi; Tsujimura, Manabu

doi:10.1143/jjap.50.05ec04

Cited by 6 publications

(7 citation statements)

References 8 publications

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“…[3][4][5][6] Ru is more conductive than both TaN and Ta, and can serve as a substrate for scalable electrodeposition of Cu lines without requiring Cu seed layers. [1][2][3] However, in the commonly used dual damascene approach, integration of Ru lines in Cu interconnects requires chemical mechanical planarization (CMP), [3][4][5][6][7][8][9][10] and the chemical component of Ru-CMP tends to be rather weak. Furthermore, since Ru is electrochemically noble compared to Cu, the Cu lines adjacent to Ru in the reactive environment of wet CMP remain susceptible to galvanic corrosion.…”

mentioning

confidence: 99%

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Türk¹,

Rock²,

Amanapu

et al. 2013

ECS J. Solid State Sci. Technol.

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Chemical mechanical planarization (CMP) of Ru barrier lines is expected to become a critical processing step in the fabrication of the new interconnect-structures. However, due to its noble metal characteristics, Ru induces galvanic corrosion in its adjacent Cu lines in the wet CMP environment, and resists chemical surface modifications that are necessary to support CMP. The present work reports a slurry formulation to address these challenges of Ru-CMP, and explores the considerations for residual Cu removal using the same slurry. This alkaline (pH = 10) slurry with colloidal silica abrasives uses sodium percarbonate as an oxidizer/complexing agent in the CMP of both Ru and Cu. L-ascorbic acid is employed as a surface modifier to regulate the material removal rates of CMP, and benzotriazole is used to control galvanic corrosion of the Ru-Cu couple. With this slurry, wafer polish rates of ∼10 and ∼80 nm min−1 are measured for Ru and Cu, respectively, resulting in defect-free processed samples. Electrochemical measurements of open circuit potentials, potentiodynamic polarization and impedance spectroscopy are performed to investigate the detailed surface reactions of Ru and Cu that facilitate material removal and control corrosion during the CMP of these metals.

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mentioning

confidence: 99%

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Türk¹,

Rock²,

Amanapu

et al. 2013

ECS J. Solid State Sci. Technol.

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“…In CMP, the mechanical removal of material exposes the surface of the wafer for slurry passivation, which results in a higher anodic current as the surface is improved; therefore, Faraday's law can be applied to calculate the copper removed per unit time due to pure chemical dissolution during CMP [27][28][29] ( )…”

Section: Effects Of Chemical Dissolution On the Mrr Of Copper Thin Fi...mentioning

confidence: 99%

Analyzing the effects of pad asperity on chemical mechanical polishing of copper thin film wafer

Quoc

Lin

Chen

2022

Jpn. J. Appl. Phys.

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Copper thin film has been identified as a promising material for multi-level interconnecting materials in IC fabrication due to its unique electrical properties and high electrical conductivity. However, it is very challenging to manufacture superior planar surface with low dishing and minimal erosion of copper thin film in chemical mechanical polishing (CMP) process. In this study, micro-topography model of soft polishing pad is performed using X-ray micro computed tomography scan combined with finite element method simulation to evaluate the contact area between the CMP pad and wafer during CMP process. Additionally, material removal rate (MRR) model for copper wafer is calibrated based on wear of material between abrasive particles and wafer surface. The results of this study not only investigate the effect of CMP pad asperities during CMP process, but they also provide new method for fully calibrating MRR in comparison with CMP experiments for verification of model parameters.

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“…A new characterization technique using Kelvin probe force microscopy (KFM) was proposed. 15,16) KFM is founded on atomic force microscopy (AFM), which allows us to obtain not only topographic images but also potential images based on the Kelvin method. 17) Dominget et al 15) attempted KFM observation with Cu interconnect patterns of various widths (0.18-9.0 m) for the first time and found that potential differences between Cu lines and spaces depended on the pattern width.…”

Section: Kfm and Efm Studiesmentioning

confidence: 99%

“…17) Dominget et al 15) attempted KFM observation with Cu interconnect patterns of various widths (0.18-9.0 m) for the first time and found that potential differences between Cu lines and spaces depended on the pattern width. Shima et al 16) evaluated patterndependent corrosion in a Sematech test pattern by KFM and found that the isolated line connected to a pad was especially recessed during Cu CMP. In addition, their KFM measurement after 0.5M H 2 SO 4 dipping revealed that the KFM potential at the isolated line was 160 mV higher than that of the surrounding area.…”

Section: Kfm and Efm Studiesmentioning

confidence: 99%

“…Recently, they have also reported that electrostatic force microscopy (EFM) is useful for detecting surface charge. 18) However, the potential with fine narrow interconnects attached to a transistor has not been reported yet. In this study, we attempted to clarify the effect of the interconnect potential on corrosion by KFM and EFM measurements with a fine interconnect pattern fixed to pads and/or transistors.…”

Section: Kfm and Efm Studiesmentioning

confidence: 99%

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Potential Characterization of Interconnect Corrosion by Kelvin Probe and Electrostatic Force Microscopies

Kodera

Yoshimizu

Uchida

2012

Jpn. J. Appl. Phys.

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The fine-scale potential observation was performed by Kelvin probe force microscopy (KFM) and electrostatic force microscopy (EFM) using tungsten interconnects in which the minimum width was 43 nm. It was confirmed that the line connected to pads and/or a transistor has a peculiar KFM potential by comparing it with the surrounding pattern. Only the plugs attached to this line were corroded, while the other plugs remained intact. By comparing the results of KFM and EFM observations, the peculiar potential of the line can be attributed to the electron charge up in the bulk of the sample. Charged electrons induced corrosion not only in the line itself but also in the connected structure. It was also revealed that the particular potential can be suppressed by a wet treatment.

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Electrochemical Reactions During Ru Chemical Mechanical Planarization and Safety Considerations

Cited by 6 publications

References 8 publications

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Analyzing the effects of pad asperity on chemical mechanical polishing of copper thin film wafer

Potential Characterization of Interconnect Corrosion by Kelvin Probe and Electrostatic Force Microscopies

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