Acid Etching Composition for IZTO Oxide Stability
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Solution Overview
Problem
Current liquid etching compositions for oxide semiconductor materials containing indium, zinc, and tin face challenges such as unstable etching rates, deposit generation, and corrosiveness to wiring materials, particularly with hydrochloric acid and oxalic acid-based solutions, which affect the efficiency and reliability of the etching process.
Innovation Solution
A liquid etching composition comprising sulfuric acid, methanesulfonic acid, or their salts, with a pH value of -1 to 3, along with carboxylic acids and polysulfonic acid compounds, is used to achieve a stable etching rate, prevent deposit formation, and minimize corrosiveness to wiring materials like copper, aluminum, and titanium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydrochloric acid or oxalic acid is used as the liquid etching composition, then the etching rate is improved, but deposit is generated and the etching rate becomes unstable
Solution Approach 1:
The patent changes the chemical composition parameters by using sulfuric acid or methanesulfonic acid instead of hydrochloric acid or oxalic acid, and specifically controls the pH value to be 0.5 or lower (highly acidic condition). This parameter change resolves the contradiction by maintaining high etching rate while preventing deposit formation and ensuring stable etching performance throughout the liquid chemical's usage life.
2Ease of manufacture
If conventional liquid etching compositions are used, then the etching process is simple, but the liquid chemical life is short due to deposit generation
Solution Approach 1:
By changing the acid type to sulfuric acid or methanesulfonic acid and controlling pH to 0.5 or lower, the patent prevents deposit formation that would otherwise occur during etching. This allows the liquid etching composition to be used continuously for extended periods without filter clogging or performance degradation, significantly extending liquid chemical life while maintaining process simplicity.
3Productivity
If strong acids are used to achieve high etching rate, then productivity is improved, but corrosiveness to wiring materials increases
Solution Approach 1:
The patent selects specific acids (sulfuric acid or methanesulfonic acid) and controls the pH to be 0.5 or lower, creating a highly acidic environment that provides high etching rate for the oxide semiconductor material. At the same time, this specific acid combination and pH level exhibits reduced corrosiveness to common wiring materials such as copper, aluminum, and titanium, thus resolving the contradiction between productivity and harmful effects.
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 ensures a stable and efficient etching process with a high etching rate, no deposit generation, and reduced corrosiveness to wiring materials, enhancing the longevity and cost-effectiveness of the etching operation.
Implementation Method 1
A liquid etching composition for etching an oxide containing indium, zinc, tin and oxygen, the liquid etching composition comprising: (A) at least one selected from the group consisting of sulfuric acid, methanesulfonic acid, and a salt of any of these acids; and water
Implementation Method 2
The etching step may be performed by a wet method or a dry method. The wet method uses a liquid etching composition
Data Source
AI summary
Provided is a liquid etching composition that etches an oxide comprising indium, zinc, tin and oxygen at a preferable etching rate, without the etching rate being changed much along with the dissolution of the oxide, and with no substantial generation of deposit, and corrodes wiring materials at such a low level to be ignorable. The present invention uses a liquid etching composition comprising (A) at least one selected from the group consisting of sulfuric acid, methanesulfonic acid, and a salt of any of these acids; and water; the liquid etching composition having a pH value of −1 to 3.