CMP Slurry Chemistry for High-Rate Polishing of Hard Materials
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Solution Overview
Problem
There is a need to improve the chemical mechanical polishing (CMP) rate of hard materials such as diamond, carbides, nitrides, and amorphous carbon, while maintaining low friction and avoiding polishing defects. Additionally, the process should minimize temperature rise to ensure stability and reproducibility.
Innovation Solution
A slurry for CMP is developed, comprising an aqueous liquid carrier, a transition metal oxy compound, and a per-based oxidizer. This slurry is effective for polishing various hard substrates, including diamond, silicon carbide, gallium nitride, and amorphous carbon, with high removal rates and selectivity over silica films, even with reduced or zero abrasive content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions are used on hard materials, then polishing can proceed, but the polishing rate is insufficient and the composition cannot effectively remove material
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by adjusting pH to highly acidic conditions (pH 0-3) and modifying oxidant concentration and type. This enables the composition to effectively polish hard materials like sapphire and silicon carbide that conventional compositions cannot handle, simultaneously improving both polishing rate and effective material removal
Solution Approach 2:
The patent creates a composite polishing system combining multiple oxidants (potassium ferricyanide, ammonium persulfate, hydrogen peroxide), acidic components (nitric acid, acetic acid), and abrasive particles (alumina, silica). This composite approach synergistically enhances the polishing performance on hard materials, achieving both high productivity and reliable material removal
2Manufacturing precision
If conventional CMP compositions are used, then the composition remains stable, but it causes excessive scratching and cannot achieve high-quality optical surfaces
Solution Approach 1:
The patent modifies the chemical parameters by introducing specific organic additives and controlling pH within 0-3 range, which changes the polishing mechanism from mechanical abrasion to chemical-mechanical removal. This reduces scratching while maintaining surface quality, achieving high manufacturing precision for optical surfaces
Solution Approach 2:
The patent employs porous abrasive particles with controlled pore structures that allow reactant penetration and product egress. This porous structure enables more uniform material removal and reduces surface scratching, improving overall surface quality
3Productivity
If the composition is made more aggressive to increase polishing rate, then productivity improves, but the composition becomes unstable and difficult to control
Solution Approach 1:
The patent optimizes the concentration ranges of all components: oxidants (0.1-5 M), acids (0.1-5 M), and additives (0.01-1 M). This precise parameter control maintains composition stability while achieving high polishing rates through enhanced chemical reactivity
Solution Approach 2:
The patent incorporates pH buffers and redox potential controllers that provide feedback control of the polishing chemistry. This maintains stable composition conditions during polishing, preventing runaway reactions while sustaining high material removal rates
4Adaptability or versatility
If existing oxidant systems are used, then the composition is simple, but it cannot effectively polish materials like sapphire and silicon carbide
Solution Approach 1:
The patent develops a composite oxidant system combining potassium ferricyanide, ammonium persulfate, and hydrogen peroxide. This multi-component oxidant system provides the necessary chemical capability to polish hard materials like sapphire and silicon carbide, achieving broad material compatibility
Solution Approach 2:
The patent creates a universal polishing composition that can handle multiple hard materials (sapphire, silicon carbide, diamond, quartz) with a single formulation. The composition's multi-functional chemistry allows it to adapt to different material types without requiring separate formulations
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 CMP slurry achieves high removal rates for amorphous carbon with selectivity over silica films, while maintaining low abrasive content and minimizing temperature rise during the polishing process, thus enhancing the stability and reproducibility of the CMP process.
Implementation Method 1
compositions for polishing hard materials... comprising an oxidizing agent
Implementation Method 2
compositions for polishing hard materials
Data Source
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AI summary
A slurry for chemical mechanical polishing (CMP) includes an aqueous liquid carrier, an oxygen and anion containing transition metal compound or polyatomic cations including a transition metal and oxygen or hydrogen, and a per-based oxidizer. The anion for the oxygen and anion containing transition metal compound can include oxynitrate, oxychloride, oxyhydroxide, oxyacetate, oxysulfide, or oxysulfate. The per-based oxidizer can be a permanganate compound.