Etchant Composition for IGZO Wiring Corrosion Control
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Solution Overview
Problem
Existing etchants fail to effectively etch wiring materials without damaging indium gallium zinc oxide (IGZO), which is essential for advanced display panel technologies like 4K and 8K panels, as they require dense and high-aspect-ratio wiring patterns, and current low-pH etchants do not provide sufficient corrosion protection or processability.
Innovation Solution
An etchant composition comprising hydroxyethanediphosphonic acid, specific phosphonic acids, hydrogen peroxide, nitric acid, a fluorine compound, an azole, and an alkali, with carefully controlled ratios, that prevents IGZO corrosion and allows for etching with high taper angles without a protective layer, suitable for multilayer thin films including copper and titanium layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etchants are used to etch wiring materials, then etching performance is achieved, but IGZO corrosion occurs
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant by incorporating specific phosphonic acids (diethylenetriaminepentaacetic acid, N,N,N′,N′-ethylenediaminetetraacetic acid, or aminotrimethylene phosphonic acid) at controlled concentrations (0.003-0.04% by mass) alongside hydroxyethanediphosphonic acid (0.01-0.1% by mass), hydrogen peroxide, nitric acid, fluorine compound, azole, and alkali. This parameter modification enables the etchant to selectively etch wiring materials while suppressing IGZO corrosion through optimized chemical interactions.
Solution Approach 2:
The patent creates a composite etchant formulation that combines multiple chemical components with specific functions: phosphonic acids for corrosion inhibition, hydrogen peroxide for oxidation enhancement, nitric acid for etching, fluorine compound for selectivity, azole for stability, and alkali for pH control. This composite composition achieves synergistic effects that simultaneously provide etching capability and IGZO protection.
2Object-affected harmful factors
If a protective layer is formed on IGZO to prevent corrosion, then IGZO corrosion is suppressed, but production complexity increases
Solution Approach 1:
The patent extracts and eliminates the protective layer step from the manufacturing process by developing an etchant that inherently provides corrosion protection through its chemical composition. The phosphonic acids and other components in the etchant formulation create a protective chemical environment that prevents IGZO corrosion during etching, allowing direct etching without additional protective layer formation, deposition, or removal steps.
Solution Approach 2:
The etchant formulation provides self-protection functionality by incorporating corrosion-inhibiting phosphonic acids that automatically protect IGZO surfaces during the etching process. The etchant itself performs the dual function of etching wiring materials and protecting IGZO, eliminating the need for separate protective layer processes and simplifying the overall manufacturing workflow.
3Loss of energy
If wiring width is reduced to suppress light loss, then light loss is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent modifies the etching process parameters through its unique chemical formulation, achieving high aspect ratio etching with precise sidewall control. The combination of phosphonic acids, hydrogen peroxide, and other components enables controlled etching that maintains vertical sidewalls and precise dimensions even for narrow wiring patterns, allowing reduced wiring width without sacrificing manufacturing precision.
4Reliability
If wiring cross-sectional area is increased to ensure current flow, then current capacity is improved, but taper angle control becomes more difficult
Solution Approach 1:
The patent achieves precise taper angle control through its optimized chemical composition, enabling the formation of high aspect ratio wiring structures with controlled geometry. The phosphonic acid-based formulation regulates etching kinetics to produce consistent taper angles even for wide wiring patterns requiring high current capacity, maintaining manufacturing precision while achieving the desired current carrying capability.
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 etchant composition significantly reduces production costs by preventing IGZO corrosion, enabling the formation of substrates with high taper angle wiring structures while maintaining etching performance, effectively applicable to structures with copper and titanium layers.
Implementation Method 1
the phosphonic acid (B) comprises at least one phosphonic acid selected from the group consisting of diethylenetriaminepentamethylenephosphonic acid, N,N,N′,N′-ethylenediaminetetrakismethylenephosphonic acid and aminotrimethylenephosphonic acid
Implementation Method 2
hydrogen peroxide (C)
Implementation Method 3
nitric acid (D)
Implementation Method 4
a fluorine compound (E)
Data Source
AI summary
The present invention provides an etchant less causing damage to IGZOs. The etchant of the present invention comprises hydroxyethanediphosphonic acid (A), one or more phosphonic acids (B), hydrogen peroxide (C), nitric acid (D), a fluorine compound (E), an azole (F), and an alkali (G), and is characterized in that the phosphoric acids (B) comprise one or more phosphonic acids selected from the group consisting of diethylenetriaminepentamethylenephosphonic acid, N,N,N′,N′-ethylenediaminetetrakismethylenephosphonic acid, and aminotrimethylenephosphonic acid and that the proportion of the hydroxyethanediphosphonic acid (A) is in the range of 0.01-0.1 mass % and the proportion of the phosphonic acids (B) is in the range of 0.003-0.04 mass %.