Metal Surface Chemical Composition and Morphology

Park, Jin-Goo; Paluvai, Nagarjuna Reddy; Venkatesh, R.

doi:10.1016/b978-0-323-51084-4.00010-1

Cited by 2 publications

(2 citation statements)

References 169 publications

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“…5 to 7. 34,35,37,39 Co H O Co H O ads 5 The corresponding reduction reaction in the alkaline region is given below [18][19][20] ClO H O 2e Cl 2OH 10…”

Section: Comentioning

confidence: 99%

Formulation of Sodium Hypochlorite Based Slurry for Copper-Cobalt Chemical Mechanical Planarization Process

Hazarika

Rajaraman

2020

ECS J. Solid State Sci. Technol.

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Chemical mechanical planarization of interconnect metal copper and barrier metal cobalt using NaOCl based slurry is investigated in this study. The slurry consists of 2 wt% silica, 0.5 wt% NaOCl and 5 mM BTA as inhibitor. The formulated slurry gives a combination of low etch rates and comparatively fair removal rates along with selectivity of ∼1:1.006 at pH 9, which are desired to be used in semiconductor industry. A decrease in removal rates for both Cu and Co is observed as the pH regime changes from acidic to alkaline. At acidic pH, the passive layer if any formed on the surface becomes very unstable resulting in higher polish rates. However, at neutral and alkaline medium, the passivation layer comprising of Co (II) oxide/hydroxides is formed which subsequently decreases the polish rate. A highly stable and dense passivation layer of Co (III) oxides comprising of mostly Co 3 O 4 and CoOOH is formed at the highly alkaline region explaining the reason behind lower removal rates. The variation in turntable speed and down force pressure does not have any significant impact on selectivity obtained at optimum conditions. XRD analysis reveals the formation of oxide on Co surface after etching at pH 9.

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“…5 to 7. 34,35,37,39 Co H O Co H O ads 5 The corresponding reduction reaction in the alkaline region is given below [18][19][20] ClO H O 2e Cl 2OH 10…”

Section: Comentioning

confidence: 99%

Formulation of Sodium Hypochlorite Based Slurry for Copper-Cobalt Chemical Mechanical Planarization Process

Hazarika

Rajaraman

2020

ECS J. Solid State Sci. Technol.

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“…From the studies done till date, it was observed that Co is more prone to corrosion owing to the fact of having lower reduction potential than Cu. 4,33 Hence, the selected slurry should be capable enough to passivate the surface as well as inhibit galvanic corrosion.…”

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confidence: 99%

Controlling Galvanic Corrosion with Oxalic Acid and Imidazole for Chemical Mechanical Planarization of Cobalt-Copper Interface

Hazarika

Gupta

Rajaraman

2022

ECS J. Solid State Sci. Technol.

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This work focuses on the investigation of Co/Cu removal rate (RR) selectivity and reduction of galvanic corrosion associated with Co and Cu by using oxalic acid (weak acid) as the complexing agent and imidazole as an inhibitor in hydrogen peroxide (H2O2) and fumed silica-based slurry. The results obtained from a dissolution study, polishing experiments, and potentiodynamic polarization measurements revealed that the proposed chemistry can achieve a desirable Co/Cu RR selectivity and a significant decrease in corrosion potential of Co and Cu (pH 9) to be used in the semiconductor industry. The corrosion potential difference (CuEcorr - CoEcorr) was reduced to 12 mV by using 0.1 wt.% H2O2 + 0.02 M oxalic acid + 5 ppm imidazole solution at pH 9. Meanwhile, a removal rate of ~147 nm/min for Co and ~140 nm/min for Cu was achieved using the same composition in a fumed silica slurry which resulted in Co/Cu selectivity ratio of 1.05:1, which is acceptable for cobalt barrier and copper interconnect CMP. Based on Fourier transform infrared and ultraviolet spectra, the dissolution mechanism in the proposed chemistry is also discussed.

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Metal Surface Chemical Composition and Morphology

Cited by 2 publications

References 169 publications

Formulation of Sodium Hypochlorite Based Slurry for Copper-Cobalt Chemical Mechanical Planarization Process

Formulation of Sodium Hypochlorite Based Slurry for Copper-Cobalt Chemical Mechanical Planarization Process

Controlling Galvanic Corrosion with Oxalic Acid and Imidazole for Chemical Mechanical Planarization of Cobalt-Copper Interface

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