Ruthenium CMP Slurry Chemistry for High Removal Without Pitting
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Solution Overview
Problem
Conventional ruthenium etch and chemical-mechanical polishing (CMP) processes face challenges with surface corrosion, pitting, and low material removal rates due to the nobility of ruthenium, which makes it difficult to planarize and etch effectively, and the use of strong oxidizers leads to rough post-etch surfaces and contamination hazards.
Innovation Solution
A new ruthenium CMP slurry chemistry using halogenation to form ruthenium halide or oxyhalide surface intermediates, combined with ligand-assisted reactive dissolution, which controls pitting and enhances material removal rates by adjusting the kinetics of halogenation and dissolution, and includes a halogenation agent and a ligand in a non-aqueous solvent with a catalyst to facilitate chemical removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strong oxidizers are used to etch ruthenium, then material removal rate is improved, but surface roughness increases and metal contamination occurs
Solution Approach 1:
The patent changes the chemical mechanism from oxidation to halogenation, transforming the reaction pathway while maintaining high material removal rates. This parameter change in the chemical reaction type allows effective ruthenium removal without the surface roughness and contamination issues associated with strong oxidizers
Solution Approach 2:
The patent introduces halogenation agents as intermediaries that facilitate ruthenium removal through a different chemical pathway. These halogenation intermediaries enable material removal while avoiding the harmful effects of strong oxidizers, acting as a mediator between the etching goal and surface quality requirements
2Productivity
If conventional oxidizers are used for ruthenium CMP, then material removal is achieved, but pitting occurs at grain boundaries
Solution Approach 1:
The patent changes the chemical reaction parameter from oxidation to halogenation, which fundamentally alters how the chemical interacts with ruthenium grain boundaries. This parameter change eliminates the preferential reaction at grain boundaries that causes pitting, while maintaining effective material removal across the surface
3Manufacturing precision
If less aggressive oxidizers are used to reduce pitting, then surface uniformity improves, but material removal rate decreases substantially
Solution Approach 1:
The patent introduces halogenation chemistry as an intermediary mechanism that decouples the relationship between surface uniformity and material removal rate. This intermediary chemical pathway enables both uniform surface treatment and high material removal rates simultaneously, breaking the trade-off that exists with oxidizer-based approaches
4Productivity
If strong oxidizers are used to create soluble ruthenium compounds, then etching effectiveness is improved, but metal contamination hazard increases
Solution Approach 1:
The patent changes the chemical reaction type from oxidation to halogenation, which fundamentally alters the byproducts formed during ruthenium removal. This parameter change eliminates the metal contamination hazards associated with strong oxidizers while maintaining effective etching through the halogenation pathway
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 solution improves the smoothing of post-etch ruthenium surfaces while maintaining high material removal rates, reducing pitting, and avoiding the use of strong oxidizers, thus providing a more effective and controlled CMP process for ruthenium.
Implementation Method 1
a halogenation agent that halogenates the ruthenium surface to form a halogenated ruthenium surface
Implementation Method 2
a ligand that reacts with the halogenated ruthenium surface to dissolve the halogenated ruthenium surface
Implementation Method 3
a catalyst that increases a rate of a ligand exchange reaction with the halogenated ruthenium surface
Data Source
AI summary
The present disclosure provides a new corrosion control chemistry for use in ruthenium (Ru) chemical-mechanical polishing (CMP) processes. More specifically, the present disclosure provides an improved CMP slurry chemistry and CMP process for planarizing a ruthenium surface. In the CMP process disclosed herein, a ruthenium surface (e.g., a post-etch ruthenium surface) is exposed to a CMP slurry containing a halogenation reagent, which reacts with the ruthenium surface to create a halogenated ruthenium surface, and a ligand for ligand-assisted reactive dissolution of the halogenated ruthenium surface. Relative amounts of the halogenation agent and the ligand can be controlled in the CMP slurry, so as to provide a diffusion-limited etch process that improves pos-etch surface morphology, while providing high material removal rates.