Comparison of dicarboxylic acids as complexing agents for abrasive-free chemical mechanical planarization of copper

Ramakrishnan, Suresh; Janjam, S. V. S. B.; Patri, Udaya B.; Roy, D.; Babu, S. V.

doi:10.1016/j.mee.2006.08.011

Cited by 57 publications

(32 citation statements)

References 18 publications

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“…The passive film formation can also be seen from measurements of the open circuit potential (Fig. 21) [96], which increases with the peroxide concentration.…”

Section: Oxidizing and Complexing Agentsmentioning

confidence: 82%

Colloid aspects of chemical–mechanical planarization

Matijević

Babu

2008

Journal of Colloid and Interface Science

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“…The passive film formation can also be seen from measurements of the open circuit potential (Fig. 21) [96], which increases with the peroxide concentration.…”

Section: Oxidizing and Complexing Agentsmentioning

confidence: 82%

Colloid aspects of chemical–mechanical planarization

Matijević

Babu

2008

Journal of Colloid and Interface Science

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“…[36][37][38][39][40][41] Citric acid is a tricarboxylic acid widely used in Cu-CMP slurries 37,42 since it can form water soluble complexes with metal oxides and hydroxides. It has also been recently used as a complexant in a post-CMP cleaning solution for Co substrates.…”

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confidence: 99%

Citric Acid as a Complexing Agent in Chemical Mechanical Polishing Slurries for Cobalt Films for Interconnect Applications

Popuri

Sagi

Alety

et al. 2017

ECS J. Solid State Sci. Technol.

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A colloidal silica-based slurry (3-10 wt%) containing H 2 O 2 (1 wt%) and citric acid (50 mM) was found to polish chemical vapordeposited (CVD) cobalt (Co) films with removal rates (RRs) of ∼180-500 nm/min and a dissolution rate (DR) of ∼0 nm/min at pH 8 along with an RMS roughness of ∼0.5 nm and a corrosion current of ∼50 μA/cm 2 . Our results suggest that, in the presence of H 2 O 2 , the Co film surface was covered with a passive film of CoO in acidic conditions and Co 3 O 4 in alkaline conditions. However, in the presence of H 2 O 2 and citric acid in acidic conditions, formation of the soluble complex [Co(C 6 H 5 O 7 ) 2 ] 3− from abraded Co enhanced the RRs significantly. The roles of H 2 O 2 , citric acid, and silica abrasives as well as the pH on the Co material removal process are discussed and a removal mechanism is proposed. Two inhibitors namely, 1, 2, 4-Triazole (TAZ) and Benzotriazole (BTA), were tested in the presence of 50 mM citric acid at pH 8 but were found to be ineffective even at concentrations of 100 mM in reducing the E corr of Co-Ti couple to minimize galvanic corrosion that is essential when the Co/Ti structure is polished after the removal of bulk of Co and requires further study. Sub-10 nm devices face several challenges with copper as an interconnect material for back-end-of-the-line (BEOL) processes during the manufacture of integrated circuits. These include increasing resistivity with decreasing thickness, 1 non-conformal deposition at narrow trench widths ∼20 nm or less, 2 and scaling limitations of the diffusion barrier/liner.3 This led to the investigation of new trench filling materials. Cobalt is a promising alternative to meet the challenges of interconnect lines at these lower nodes for the first two metal layers M1 and M2, due to its lower resistivity at smaller dimensions (∼10 nm) compared to copper. [4][5][6] Kamineni et al. 7 proposed the use of chemical vapor deposited (CVD) cobalt to replace the widely used tungsten for local interconnects for 10 nm and smaller nodes. They emphasized two main advantages of CVD Co metallization which are a) CVD Co precursors do not damage the Ti liner enabling barrier scaling and b) it achieves void free fill in high aspect ratio features without defects, something that is difficult to achieve with a conventional physical vapor deposited (PVD) Co process. 8,9 Hence, CVD-based Co metallization is an attractive option for the technology nodes below 10 nm.CVD-based cobalt has also gained prominence in the advanced copper interconnects below 22 nm as liner [10][11][12][13][14][15][16][17] to improve adhesion between the barrier (TaN, TiN) and Cu seed layer where the Co film thickness is only ∼2 nm. Several authors 18-26 have investigated cobalt polishing for such applications where RR requirements are typically <20 nm/min and Co loss due to corrosion has to be as close to zero as possible, since even a minute loss of Co material can degrade the device reliability significantly. Hence, since the potential gap between Co and Cu is a large ∼0...

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“…Other additives may be included in the chemical composition for a better control of the slurry stability and of the tungsten layer formation and removal kinetics [12][13][14]. The addition of carboxylic acids as complexing agents or stabilizers has been proposed in order to reduce the kinetics of the iron catalyzed oxidation [12,14,15]. The addition of surfactants also helps to stabilize the polishing slurry and prevents settling, flocculation and decomposition of the silica particles [16].…”

Section: Introductionmentioning

confidence: 99%