Ruthenium Etchant Composition for Low-RuO4 Patterning
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Solution Overview
Problem
Current ruthenium etchant compositions face challenges in preventing the generation of toxic RuO4 gas during etching, maintaining a high etch rate, and ensuring storage stability at room temperature, particularly when used for forming interconnects and electrodes in semiconductor substrates.
Innovation Solution
A ruthenium etchant composition containing periodic acid and ammonium ions, with a pH range of 6 to 7.5, which inhibits RuO4 gas generation and enhances etch rate and storage stability without the need for additional inhibitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an etchant composition having an excessive high pH is used to reduce RuO4 gas generation, then the stability of periodic acid is lowered and etch rate is reduced
Solution Approach 1:
The patent optimizes the pH parameter to a specific range (6.5-7.5) where periodic acid remains stable while effectively suppressing RuO4 gas generation. This parameter optimization resolves the contradiction by finding the optimal balance point between gas suppression and etching performance.
Solution Approach 2:
The etchant composition uses a composite system containing periodic acid combined with specific additives (ammonium fluorosulfonate and/or ammonium hydrogen sulfate) that work synergistically to maintain periodic acid stability at near-neutral pH while suppressing RuO4 generation, thereby preserving high etch rate.
2Productivity
If reaction temperature is increased to prevent reduction in etch rate, then RuO4 gas generation cannot be solved
Solution Approach 1:
The patent changes the temperature parameter to room temperature (20-25°C) range, which fundamentally alters the reaction kinetics to suppress RuO4 gas generation while maintaining adequate etch rate through the optimized chemical composition rather than thermal activation.
3Object-affected harmful factors
If an alkaline etchant composition with pH 8 or higher is used to inhibit RuO4 gas generation, then etch rate and storage stability are remarkably deteriorated
Solution Approach 1:
The patent shifts the pH parameter from alkaline (pH≥8) to near-neutral range (6.5-7.5), which fundamentally improves storage stability of periodic acid while still effectively suppressing RuO4 gas generation through the synergistic action of periodic acid with ammonium fluorosulfonate and/or ammonium hydrogen sulfate.
Solution Approach 2:
The etchant uses a composite formulation where periodic acid is combined with ammonium fluorosulfonate and/or ammonium hydrogen sulfate, creating a synergistic system that maintains periodic acid stability at lower pH levels, thereby ensuring both high storage stability and effective RuO4 suppression.
4Object-affected harmful factors
If additional RuO4 gas generation inhibitors are added to etchant composition, then RuO4 gas generation is suppressed, but device complexity and process steps increase
Solution Approach 1:
The patent employs periodic acid with ammonium fluorosulfonate and/or ammonium hydrogen sulfate that performs multiple functions simultaneously: it acts as the etching agent, maintains near-neutral pH for stability, and suppresses RuO4 gas generation. This multi-functionality eliminates the need for separate inhibitor additives.
Solution Approach 2:
The etchant composition is self-sufficient as periodic acid combined with ammonium fluorosulfonate and/or ammonium hydrogen sulfate inherently suppresses RuO4 gas generation without requiring external inhibitor additives, thereby simplifying the composition and reducing process complexity.
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 achieves a high etch rate of 200 Å/min or more for ruthenium metal films and maintains stability with a reduction in etch rate of 5% or less after 3 months at room temperature, effectively addressing the limitations of existing etchant compositions.
Implementation Method 1
When a ruthenium metal film is etched with an acidic etchant composition, there are cases where RuO4, which is a toxic gas, is generated
Implementation Method 2
A ruthenium etchant composition containing periodic acid and ammonium ions and having a pH value in a range of 6 to 7.5, which suppresses RuO4 gas generation
Data Source
AI summary
Disclosed is a ruthenium etchant composition containing periodic acid and ammonium ions and having a pH of 6 to 7.5. Further disclosed are a pattern formation method including a step of etching a ruthenium metal film using the etchant composition, a method of manufacturing a display device array substrate by employing the pattern formation method, and a display device array substrate manufactured by the method.