CMP Slurry Composition for Ruthenium Selectivity and Copper Corrosion Control
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Solution Overview
Problem
Current CMP slurries are inadequate for effectively polishing substrates with ruthenium and copper while minimizing copper corrosion, leading to defects and unacceptable removal rates in semiconductor fabrication, especially in advanced node technologies where ruthenium is used as a liner material and copper is a critical conductive layer.
Innovation Solution
A polishing composition comprising an abrasive, pH adjuster, barrier film removal rate enhancer, low-k removal rate inhibitor, azole-containing corrosion inhibitor, and hard mask removal rate enhancer, along with optional chelating and oxidizing agents, is used to specifically target and remove ruthenium and hard mask materials while minimizing copper corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMP slurries are used for polishing substrates with ruthenium and copper, then the polishing process can be performed, but copper corrosion occurs and removal rates are unacceptable
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific organic acids (formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, adipic acid, succinic acid, glutaric acid, malonic acid, oxalic acid, maleic acid, fumaric acid, citric acid, tartaric acid, malic acid, glycolic acid, lactic acid, amino acetic acid, phenylalanine, proline, glutamine, aspartic acid, glutamic acid, arginine, lysine, tyrosine, benzoic acid, phenoxyacetic acid, and their salts) at controlled concentrations to achieve selective removal of ruthenium while minimizing copper corrosion. The pH is adjusted to specific ranges to optimize the chemical reactions for Ruthenium etching while protecting copper layers.
Solution Approach 2:
The patent introduces organic acids and their salts as intermediary substances that mediate between the abrasive particles and the ruthenium/copper layers. These organic acids act as chemical mediators that selectively complex with ruthenium atoms, facilitating their removal while forming protective complexes with copper to prevent corrosion. The azole-containing corrosion inhibitor serves as an intermediary that specifically adsorbs onto copper surfaces to prevent oxidative corrosion during the polishing process.
2Manufacturing precision
If the Cu and Ta/TaN barrier film schemes are made thinner to maintain effective interconnect resistivity, then the interconnect resistivity is improved, but flexibility in deposition and control over resistivity deteriorate
Solution Approach 1:
The patent utilizes precise control of slurry composition parameters including pH (adjusted using bases such as ammonium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, monoethanolamine, diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, diethyldimethylammonium hydroxide, dimethyldipropylammonium hydroxide, benzyltrimethylammonium hydroxide, tris(2-hydroxyethyl)methylammonium hydroxide, choline hydroxide, and their combinations), abrasive concentration, and organic acid concentrations to achieve uniform and controlled removal rates of thin ruthenium and barrier films. This allows precise thickness control of ultra-thin films while maintaining deposition flexibility.
3Reliability
If ruthenium is used as a liner material and barrier layer, then anti-Cu diffusion and electro-filling capability are improved, but the complexity of polishing process increases
Solution Approach 1:
The patent develops a universal CMP slurry formulation that can simultaneously polish multiple materials (ruthenium, copper, tungsten, carbide, nitride ceramic, low-k dielectric, ultra low-k dielectric, TEOS) used in advanced semiconductor interconnect structures. The slurry contains a synergistic combination of abrasives, organic acids, corrosion inhibitors, and pH adjusters that work together to selectively remove ruthenium and hard mask materials while protecting copper and controlling removal rates of other materials, thereby simplifying the overall polishing process for complex multi-material substrates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves selective and efficient removal of ruthenium and hard mask materials while maintaining low copper corrosion rates, ensuring favorable removal rates and topography for advanced semiconductor substrates, thus addressing the limitations of existing slurries in handling complex integration schemes.
Implementation Method 1
a polishing composition that includes an abrasive
Implementation Method 2
an azole-containing corrosion inhibitor
Data Source
AI summary
A polishing composition includes an abrasive; a pH adjuster; a barrier film removal rate enhancer; a low-k removal rate inhibitor; an azole-containing corrosion inhibitor; and a hard mask removal rate enhancer. A method of polishing a substrate includes the steps of: applying the polishing composition described herein to a surface of a substrate, wherein the surface comprises ruthenium or a hard mask material; and bringing a pad into contact with the surface of the substrate and moving the pad in relation to the substrate.