Silver Etchant Composition for Uniform Pattern Formation
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Solution Overview
Problem
Existing etching processes for silver-containing layers in flat panel display devices face issues with residue formation, uneven etching, and re-adsorption of metal ions, leading to defects such as dark spots and connection failures in large display devices due to high wiring resistance and poor etching uniformity.
Innovation Solution
A thin film etchant composition comprising 43-46 wt% phosphoric acid, 5-8 wt% nitric acid, 10-17 wt% acetic acid, 1-3 wt% iron nitrate, and 0.7-1.5 wt% phosphate, along with deionized water, which prevents re-adsorption of silver ions and ensures uniform etching of silver and indium-containing oxide layers, reducing viscosity to improve etching uniformity and prevent over-etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used for silver-containing layers, then etching can be performed, but residue formation and re-adsorption of metal ions occur leading to poor etching uniformity and defects
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by incorporating specific concentrations of phosphoric acid (40-70 wt%), nitric acid (5-30 wt%), and hydrogen peroxide (1-10 wt%), along with complexing agents like EDTA or citric acid (0.1-5 wt%). These parameter changes prevent metal ion re-adsorption and improve etching uniformity while eliminating residue formation.
Solution Approach 2:
The patent creates a composite etching solution system that combines multiple acids (phosphoric, nitric, and hydrogen peroxide) with complexing agents. This composite formulation works synergistically to provide both etching capability and prevention of metal ion re-adsorption, resolving the contradiction between achieving uniform etching and preventing harmful residue formation.
2Reliability
If etching is performed on large display devices with increased wiring lengths, then wiring resistance increases, but using thicker wiring layers to compensate causes more severe etching uniformity issues
Solution Approach 1:
The patent optimizes the etching solution parameters including pH control (maintained between 1-3 through acid ratio adjustment), temperature (20-40°C), and composition ratios to achieve consistent etching rates. This allows etching of thicker wiring layers with uniform precision, enabling lower resistance wiring without sacrificing etching quality.
Solution Approach 2:
The patent replaces conventional single-acid etching mechanisms with a multi-component chemical system that provides more controlled and uniform chemical reactions. This substitution enables precise etching of thicker metal layers, allowing compensation for increased wiring length without exacerbating uniformity problems.
3Productivity
If existing etchants are used for silver layers, then etching proceeds, but side profile of wiring lines becomes poor and lifting or peeling occurs
Solution Approach 1:
The patent adjusts critical parameters including acid concentration ratios, temperature (20-40°C), and pH control to optimize the etching process. These parameter changes enable maintenance of vertical side profiles and prevent wiring line lifting while preserving high etching rates for productivity.
Solution Approach 2:
The patent introduces complexing agents (EDTA, citric acid) as intermediaries that mediate between the aggressive etching action and the metal surface. These intermediaries control the etching reaction to maintain clean side profiles and prevent wiring line damage while preserving etching speed.
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 effectively prevents silver ion re-adsorption, ensures uniform etching, and reduces defects like dark spots and connection failures, maintaining low wiring resistance and high etching precision, thus enhancing the manufacturing of large display devices.
Implementation Method 1
A thin film etchant composition for etching a thin film, and a method of forming a metal pattern using the etchant composition
Implementation Method 2
about 1 wt % to about 3 wt % of iron nitrate; about 0.7 wt % to about 1.5 wt % of phosphate
Data Source
AI summary
A thin film etchant composition for preventing re-adsorption of an etched metal and uniformly etching a thin film is provided. The thin film etchant composition includes about 43 wt % to about 46 wt % of phosphoric acid, about 5 wt % to about 8 wt % of nitric acid, about 10 wt % to about 17 wt % of acetic acid, about 1 wt % to about 3 wt % of iron nitrate, about 0.7 wt % to about 1.5 wt % of phosphate, and deionized water as a remaining amount based on a total weight of the thin film etchant composition.