Synergistic effect of 1,2,4-triazole and phytic acid as inhibitors on copper film CMP for ruthenium - based copper interconnected and the surface action mechanism analysis

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For Ruthenium (Ru)-based copper (Cu) interconnects Cu film chemical mechanical polishing (CMP), it is crucial to select appropriate pH regulators in the slurry to ensure the chemical reactions and maintain the stability of the polishing chemical environment. In this study, the effects of inorganic pH regulator KOH, organic pH regulator diethanolamine (DEA), and 2-amino-2-methyl-1-propanol (AMP) on CMP and slurry properties of Cu film were compared. It was found when using AMP as a pH regulator, the Cu/Ru removal rate selectivity (RRS) can reach 598:1, the surface roughness of Cu film decreased to 0.76 nm, and the slurry can remain stable for at least 7 days. The performance order of the three pH regulators is AMP＞KOH＞DEA. Meanwhile, through experimental results and test analysis, it has been confirmed that AMP can also play a multifunctional role as a complexing agent, dispersant, and surfactant. Therefore, AMP can replace KOH as a new pH regulator in weak alkaline slurries. This result plays an important role in guiding the selection of organic pH regulators in the optimization of Cu film CMP slurry.

Section: Methodsmentioning

confidence: 99%

“…The composition of the slurry was based on the previous research results. 29 At the same time, the action mechanism of the three pH regulators was analyzed by UV-Visible and XPS tests.…”

mentioning

confidence: 99%

Effect of Novel pH Regulators on Copper film Chemical Mechanical Polishing for Ruthenium-Based Copper Interconnect under Weak Alkalinity Conditions

Dong,

Niu,

Liu

et al. 2024

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“…Among the materials mentioned above, ruthenium gathers favorable comments and widespread attention because of its high melting point, lower resistivity compared to tantalum, good adhesion and wettability with copper, and exceptional barrier properties. 17,[26][27][28] It is also feasible to accomplish conformal electroplating of copper on the ruthenium surface without copper seed layer, while there is no intermetallic compound between copper and ruthenium even after annealing at 800 °C. 27 Although ruthenium, being a promising barrier material, has many of the aforementioned advantages, chemical mechanical polishing(CMP) after deposition of ruthenium barrier is challenging as a consequence of its high mechanical hardness(6.5 Mohs) and strong chemical inertness, which pushes the approach to actualize high removal rate of ruthenium towards screening for powerful and valid oxidizers.…”

mentioning

confidence: 99%

Effect of Potassium Ferrocyanide on CMP Performance of Ruthenium in H₂O₂-based Slurries

Liu,

Xu,

Liu

et al. 2024

As feature size of integrated circuits develops to 7 nm, ruthenium is considered the preferred material to replace traditional Ta/TaN barrier layers. Ruthenium can be electroplated without the need for copper seed crystal layers. However, the removal of the ruthenium barrier layer during the polishing process must be addressed. Therefore, this article studies the promoting effect of potassium ferrocyanide (K4Fe(CN)6) and hydrogen peroxide (H2O2) containing silicon slurries on the rate of ruthenium chemical mechanical polishing. Experiments have shown that the polishing rate of ruthenium is significantly improved by the combined action of K4Fe(CN)6 and H2O2. The stronger hydroxyl radicals is the main factor in achieving a high Ru polishing rate, which accelerates the dissolution and removal of Ru layers by converting the hard Ru layer into softer RuO2 and RuO3 oxide layers. The dependencies of the chemical properties (such as electrochemical impedance spectroscopy and surface morphology) proved that the CMP mechanism using Fenton reaction principally performs chemical oxidation and etching dominant CMP simultaneously. This study is expected to provide ideas and insights for the development and design of a new alkaline polishing solution for ruthenium, which is beneficial for the wider application of ruthenium in the field of integrated circuits.

“…When the technology node is less than 14 nm, the one-step polishing method is implemented instead of the previous two-step polishing, which needs to stop on the barrier layer while removing Cu completely. 4 The role of the slurry is critical in the CMP process. In general, the slurry mainly includes abrasives, oxidants, complexing agents, surfactants, and corrosion inhibitors.…”

mentioning

confidence: 99%

Surface Interaction Effect and Mechanism of Methionine Derivatives as Novel Inhibitors for Alkaline Copper CMP: Insights from Molecular Simulation and Experimental Analysis

Zhan,

Niu,

Liu

et al. 2023

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To prevent excessive corrosion caused by the slurry in the copper (Cu) chemical mechanical polishing (CMP) process, a corrosion inhibitor is normally required. In this study, the methionine (Met) derivative FMOC-L-Methionine (Fmoc-Met-OH) was explored as a corrosion inhibitor for Cu film CMP in weak alkaline conditions (pH = 8.5). A comprehensive evaluation was conducted to confirm the efficiency of Fmoc-Met-OH as a corrosion inhibitor, combining experiments and theoretical calculations. The results showed that Fmoc-Met-OH could effectively inhibit the corrosion of Cu, with a high inhibition efficiency (IE) of 78.26% while maintaining a high removal rate (RR) of 5703 Å min−1, a low static etch rate (SER) of 676 Å min−1, and a low surface root mean square deviation (Sq) of 1.41 nm. Simultaneously, the results of X-ray photoelectron spectroscopy (XPS) tests and electrochemical analysis confirm that Fmoc-Met-OH molecules can form a dense and ordered adsorption film on the Cu surface. According to the density functional theory (DFT) calculations and molecular dynamics (MD) simulation, it was verified that Fmoc-Met-OH exhibited strong chemical adsorption on Cu substrates, as evidenced by the high binding energy (E Binding) value, low energy gap (ΔE), and radial distribution function (RDF) analysis. The findings provided theoretical evidence of the better inhibition effectiveness of Fmoc-Met-OH at a molecular or atomic level.