Silica CMP Slurry for Selective Carbon Film Polishing
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Solution Overview
Problem
Current chemical-mechanical polishing compositions for carbon-based films in shallow trench isolation processes face challenges in achieving high removal rates while maintaining planarization efficiency, often resulting in trench erosion and increased device defectivity due to rapid polishing rates.
Innovation Solution
A chemical-mechanical polishing composition comprising silica abrasive with a negative zeta potential, an iron cation, and a surfactant, which enhances the polishing process by improving the interaction with carbon-based films, thereby achieving higher removal rates and reduced defectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the polishing rate is increased to improve device throughput, then the removal rate of carbon-based film is improved, but trench erosion and device defectivity increase
Solution Approach 1:
The patent modifies the chemical composition parameters of the polishing slurry by incorporating iron cations (Fe2+ or Fe3+) at concentrations of 0.1-100 ppm, along with specific surfactants and chelating agents. These parameter changes alter the chemical reactivity of the slurry to achieve selective removal of carbon-based films while controlling the removal rate of oxide materials in trenches, thus resolving the contradiction between high throughput and trench erosion control
Solution Approach 2:
The patent creates a composite polishing slurry system combining silica abrasive particles (0.1-10 µm), iron cations, surfactants (e.g., Triton X-100, SDS), and chelating agents (e.g., EDTA, citric acid). This composite formulation works synergistically to achieve differential polishing rates: the iron cations enhance carbon film removal through chemical reaction, while the surfactants and chelating agents moderate oxide removal, thereby resolving the contradiction between productivity and manufacturing precision
2Productivity
If the polishing rate is increased to remove excess dielectric material faster, then planarization speed is improved, but selectivity between carbon-based film and oxide is reduced
Solution Approach 1:
The patent adjusts the chemical parameters of the polishing slurry by introducing iron cations at optimized concentrations (0.1-100 ppm) alongside specific surfactants and chelating agents. These parameter modifications create a chemically selective environment where carbon-based films are removed at high rates through iron-catalyzed reactions, while oxide removal is controlled, thus achieving both high planarization speed and maintained selectivity
Solution Approach 2:
The patent introduces surfactants (e.g., Triton X-100, SDS at 0.01-1 wt%) and chelating agents (e.g., EDTA, citric acid at 0.01-1 wt%) as intermediary substances in the polishing slurry. These intermediaries modulate the chemical interactions between the abrasive and the materials being polished, enhancing the differential removal rates between carbon-based films and oxide, thereby maintaining selectivity while improving planarization speed
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 a balanced high removal rate for carbon-based films while minimizing trench erosion and device defectivity, ensuring efficient planarization and improved semiconductor performance.
Implementation Method 1
wherein the silica abrasive has a negative zeta potential in the chemical-mechanical polishing composition
Implementation Method 2
the silica abrasive has a negative zeta potential in the chemical-mechanical polishing composition
Implementation Method 3
an iron cation; (d) optionally a ligand
Implementation Method 4
a surfactant; (c) an iron cation
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising: (a) a silica abrasive, (b) a surfactant, (c) an iron cation, (d) optionally a ligand, and (e) water, wherein the silica abrasive has a negative zeta potential in the chemical-mechanical polishing composition. The invention also provides a method of chemically-mechanically polishing a substrate, especially a substrate comprising a carbon-based film, using said composition.