Polysilicon CMP Slurry Composition for Uniformity and Removal Rate
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Solution Overview
Problem
The chemical mechanical polishing process for polysilicon layers in semiconductor devices faces issues with low removal rates and uneven polishing, leading to erosion and dishing due to imbalanced chemical and mechanical polishing, which affects the uniformity and efficiency of the process.
Innovation Solution
A slurry composition comprising 4.25 to 18.5 weight percent abrasive, 80 to 95 weight percent deionized water, and 0.05 to 1.5 weight percent additive, with the option of adding a surfactant, is used to enhance the polishing selectivity and rate, preventing erosion and dishing by controlling the pH and composition to optimize mechanical and chemical polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a slurry composition with low removal rate is used, then erosion and dishing are reduced, but polishing time is extended
Solution Approach 1:
The patent applies parameter changes by optimizing the slurry composition parameters including abrasive concentration (4.25-18.5 wt%), pH value (9.5-11.5), and additive content (0.05-1.5 wt%). These parameter adjustments balance the removal rate and polishing uniformity, achieving high removal rate while preventing erosion and dishing through controlled chemical and mechanical action ratios.
2Productivity
If chemical polishing action is increased, then removal rate is improved, but erosion and dishing occur
Solution Approach 1:
The patent applies local quality by creating different functional zones within the slurry composition. The slurry contains abrasive particles for mechanical polishing, chemical additives for controlled chemical etching, and pH buffers for stability. This composition differentiation allows the slurry to perform both high-rate removal and uniform polishing simultaneously by distributing different functions throughout the composition.
Solution Approach 2:
The patent uses composite materials by combining multiple components in the slurry: abrasive particles (silica, alumina, or ceria), chemical additives (amines or quaternary ammonium compounds), pH buffers, and surfactants. This composite composition enables the slurry to provide both strong chemical polishing action for high removal rate and controlled mechanical action for uniformity, preventing erosion and dishing.
3Productivity
If mechanical polishing action is increased, then removal rate is improved, but scratches and uneven polishing occur
Solution Approach 1:
The patent applies the intermediary principle by introducing chemical additives and pH buffers as mediators between the mechanical abrasive action and the polysilicon layer. These intermediaries control the chemical state of the polysilicon surface, making it more susceptible to uniform chemical etching while reducing the need for aggressive mechanical polishing. This mediation achieves high removal rates through chemical action while maintaining surface uniformity.
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 optimized slurry composition achieves higher removal rates of polysilicon layers with improved uniformity, reducing the time required for polishing and preventing erosion and dishing, thereby enhancing the overall efficiency and quality of the chemical mechanical polishing process.
Implementation Method 1
The abrasive of the slurry composition and protrusions of the polishing pad may mechanically polish the surface portion of the semiconductor substrate
Implementation Method 2
the surface portion of the semiconductor substrate is chemically polished by reactions between chemical components included in the slurry composition and ingredients in the surface portion of the semiconductor substrate
Implementation Method 3
A slurry composition including about 4.25 to about 18.5 weight percent of an abrasive, about 80 to about 95 weight percent of deionized water, about 0.01 to about 1.0 weight percent of an additive, and about 0.74 to about 2.0 weight percent of a surfactant
Data Source
AI summary
A slurry composition includes about 4.25 to about 18.5 weight percent of an abrasive, about 80 to about 95 weight percent of deionized water, and about 0.05 to about 1.5 weight percent of an additive. The slurry composition may further include a surfactant. In a polishing method using the slurry composition, a polysilicon layer may be rapidly polished, and also dishing and erosion of the polysilicon layer may be suppressed.