CMP Slurry Chemistry for High-Rate Polishing of Hard Materials
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) processes face challenges in achieving high removal rates for hard materials like diamond, carbides, nitrides, and amorphous carbon with low friction and minimal surface defects, while also managing temperature rise during the polishing process.
Innovation Solution
A CMP slurry comprising an aqueous liquid carrier, a transition metal oxy compound, and a per-based oxidizer is used, which includes oxy-nitrates, oxy-chlorides, oxy-sulfates, and oxy-carbonates, allowing for high removal rates with reduced abrasive content and controlled temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP processes use high abrasive content and high pressure/velocity to increase removal rate for hard materials, then material removal rate improves, but temperature rise increases and surface defects are generated
Solution Approach 1:
The invention changes the chemical parameters of the slurry by introducing per-based oxidizers (peroxide, persulfate, permanganate, periodate, or perchlorate) in combination with transition metal salts. This chemical parameter change enables high removal rates for hard materials through enhanced chemical reactivity rather than relying solely on mechanical abrasion, thereby avoiding the temperature rise and surface defects associated with high pressure and velocity mechanical polishing
Solution Approach 2:
The invention substitutes the purely mechanical abrasion system with a chemical-mechanical hybrid system. The per-based oxidizer provides strong chemical oxidation capability that works synergistically with mild mechanical action, replacing the need for high-intensity mechanical polishing and thereby reducing temperature generation and surface damage
2Productivity
If conventional CMP processes increase pressure and velocity to achieve high removal rates, then productivity improves, but friction increases and surface defects are generated
Solution Approach 1:
The invention changes the chemical composition parameters by adding per-based oxidizers and transition metal salts to the slurry. This chemical enhancement allows the polishing process to achieve high removal rates through chemical reaction rather than intense mechanical force, thereby preventing surface defects such as scratches, pits, and other polishing-induced damage
Solution Approach 2:
The invention replaces the mechanical removal mechanism with a chemical oxidation mechanism assisted by mild mechanical action. The per-based oxidizer chemically modifies the hard material surface, making it easier to remove with minimal mechanical stress, thus eliminating the harmful surface defects that result from high-pressure mechanical polishing
3Productivity
If conventional CMP processes use high abrasive content to achieve high removal rates, then productivity improves, but the complexity of the slurry composition and process control increases
Solution Approach 1:
The invention changes the slurry composition parameters by using per-based oxidizers in combination with transition metal salts at controlled concentrations. This chemical approach achieves high removal rates without requiring high abrasive content, and the parameter ranges provided in the patent (e.g., per-based oxidizer at 0.01-10 wt%, transition metal salt at 0.01-5 wt%) simplify process control while maintaining high 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 slurry achieves high removal rates for hard materials with selectivity over silica films and low temperature rise, enhancing the stability and reproducibility of the polishing process.
Implementation Method 1
a per-based oxidizer
Implementation Method 2
a transition metal oxy compound chosen from oxy-nitrates, oxy-chlorides, oxy-sulfates, oxy-carbonates, and C2-C10 oxy-alkanoates
Implementation Method 3
CMP involves applying slurry, e.g., a solution of an abrasive and an active chemistry, to a polishing pad that buffs the surface of a microelectronic device wafer
Implementation Method 4
as the pressure and velocity during polishing is increased, there is a need to decrease the temperature rise during the polishing process
Data Source
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.