Tungsten CMP Slurry Composition for Uniform Polishing and Low Dishing
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Solution Overview
Problem
Current tungsten chemical mechanical polishing (CMP) slurries face challenges in achieving planarity and reducing defects, such as excessive localized corrosion and array erosion, while also being cost-effective and stable, especially as semiconductor feature sizes shrink.
Innovation Solution
A CMP composition comprising a water-based liquid carrier with cationic abrasive particles, a combination of tungsten corrosion inhibitors with different isoelectric points, and optional iron-containing accelerators and hydrogen peroxide, maintaining a pH between 1 and 5 to enhance stability and reduce tungsten etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP slurry compositions are used for tungsten CMP, then the polishing process can proceed, but dishing defects occur and polishing uniformity is poor
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, or butyric acid) at controlled concentrations (0.1-10 wt%), along with peroxide precursors and catalysts. These parameter changes in the slurry composition enable effective tungsten polishing while preventing dishing defects and improving polishing uniformity.
Solution Approach 2:
The patent creates a composite slurry system combining multiple components: organic acids, peroxide precursors (H2O2, organic peroxycarboxylic acids), catalysts (metal salts like Fe, Cu, Mn, Co, Ni), and buffering agents. This composite material approach synergistically combines the functions of each component to achieve both high polishing uniformity and defect prevention in tungsten CMP processes.
2Productivity
If polishing speed is increased for tungsten CMP, then productivity improves, but polishing uniformity deteriorates
Solution Approach 1:
The patent optimizes the concentration parameters of reactive components in the slurry, specifically adjusting organic acid concentration (0.1-10 wt%), peroxide precursor concentration (0.1-20 wt%), and catalyst concentration (0.01-1 wt%). These parameter optimizations enable the system to maintain high polishing speeds while preserving polishing uniformity through controlled chemical reactivity.
Solution Approach 2:
The patent establishes a continuous chemical reaction mechanism through the combination of peroxide precursors and catalysts that continuously generate reactive oxygen species during polishing. This continuous chemical action ensures consistent material removal rates and maintains polishing uniformity even at high polishing speeds, preventing the deterioration of quality that typically accompanies increased productivity.
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 provides improved chemical and colloidal stability, reduced tungsten etching, and better planarity, leading to increased throughput and extended shelf life with reduced defects in tungsten CMP operations.
Implementation Method 1
chemical-mechanical polishing (CMP) process utilizes a slurry and a polishing pad to mechanically and chemically remove material from a substrate
Implementation Method 2
chemical-mechanical polishing (CMP) process utilizes a slurry and a polishing pad to mechanically and chemically remove material from a substrate
Data Source
AI summary
A chemical mechanical polishing composition includes a water based liquid carrier, cationic abrasive particles dispersed in the liquid carrier, a first amino acid compound having an isoelectric point of less than 7 and a second amino acid compound having an isoelectric point of greater than 7. The pH of the composition is in a range from about 1 to about 5. A method for chemical mechanical polishing a substrate including a tungsten layer includes contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.