Self-stopping Polishing Composition for 3D NAND Planarization
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Solution Overview
Problem
Current self-stopping CMP compositions face limitations in step height reduction rates due to electrostatic repulsion between abrasives and silicon oxide surfaces, particularly in complex semiconductor devices and 3D NAND technology, necessitating improved polishing compositions and methods for silicon oxide-containing substrates that offer high removal rates with low trench loss and enhanced planarization efficiency.
Innovation Solution
A chemical-mechanical polishing composition comprising an abrasive, a self-stopping agent with specific structural features, and an aqueous carrier, optimized to provide high pattern removal rates that transition to low blanket removal rates, thereby reducing trench loss and improving planarization efficiency, using ceria as the abrasive and incorporating compounds like kojic acid, crotonic acid, or maltol as self-stopping agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions are used to increase removal rate, then productivity improves, but trench loss increases and manufacturing precision deteriorates
Solution Approach 1:
The polishing composition dynamically adjusts its removal rate based on the polishing stage: during patterned substrate polishing, the composition maintains high removal rate for productivity, and during blanket substrate polishing, the self-stopping agent reduces removal rate to prevent trench loss. This dynamic behavior resolves the contradiction between productivity and precision.
Solution Approach 2:
The composition changes its chemical parameters through the self-stopping agent (kojic acid, crotonic acid, or maltol) which modifies the polishing chemistry based on substrate conditions. The agent causes the removal rate to naturally transition from high to low as polishing progresses, enabling high productivity during pattern removal while preventing over-polishing and trench loss during blanket polishing.
2Productivity
If high removal rate polishing is used to improve productivity, then manufacturing efficiency increases, but planarization efficiency deteriorates due to excessive material removal
Solution Approach 1:
The self-stopping agent provides inherent feedback control in the polishing process. As the substrate surface transitions from patterned to blanket topology, the chemical environment changes, causing the removal rate to automatically decrease. This feedback mechanism ensures high productivity during pattern removal while preventing excessive material removal that would reduce planarization efficiency.
Solution Approach 2:
The polishing composition exhibits dynamic removal rate characteristics that adapt to the polishing stage. The self-stopping agent causes the composition to transition from aggressive removal (high productivity) to gentle removal (high planarization efficiency), resolving the contradiction between manufacturing efficiency and planarization quality.
3Manufacturing precision
If electrostatic repulsion between abrasives and silicon oxide is present, then manufacturing precision is maintained, but productivity decreases due to reduced removal rate
Solution Approach 1:
The self-stopping agent acts as an intermediary that mediates between the electrostatic repulsion (which maintains precision) and the need for high removal rate (productivity). The agent (kojic acid, crotonic acid, or maltol) modifies the chemical interaction at the polishing interface, enabling high removal rate during pattern polishing while maintaining the precision-controlting electrostatic effects during blanket polishing.
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 proposed composition achieves significant step height reduction with minimal trench loss, enhancing planarization efficiency and device throughput by maintaining high removal rates for patterned areas while reducing overpolishing and trench erosion, thus improving the manufacturing process for advanced semiconductor technologies.
Implementation Method 1
The polishing of the substrate typically is further aided by the mechanical activity of an abrasive suspended in the polishing composition
Implementation Method 2
Current self-stopping CMP compositions face limitations in step height reduction rates due to electrostatic repulsion between abrasives and silicon oxide surfaces
Implementation Method 3
The polishing of the substrate typically is further aided by the chemical activity of the polishing composition
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising an abrasive, a self-stopping agent, an aqueous carrier, and a cationic polymer. This invention additionally provides a method suitable for polishing a dielectric substrate.