Etching Liquid for Copper/Titanium Multilayer Films
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Solution Overview
Problem
Existing etching liquids for multilayer thin films containing copper and titanium layers fail to achieve high processing accuracy, low residue, and uniform etching, which are essential for the size enlargement and resolution enhancement of displays, due to issues with adhesiveness and diffusion of copper and insufficient etching profiles.
Innovation Solution
An etching liquid comprising hydrogen peroxide, nitric acid, a fluoride ion source, an azole, a quaternary ammonium hydroxide, and a hydrogen peroxide stabilizer, with a pH of 1.5 to 2.5, is used to etch multilayer thin films, optimizing the etching process by controlling etching rates and preventing corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching liquids are used for copper/titanium multilayer films, then the etching process can be performed, but the processing accuracy is insufficient and etching residues remain
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching liquid by incorporating specific concentrations of hydrogen peroxide (3-10% by mass), nitric acid (2-10% by mass), and fluoride ions (0.05-1% by mass), along with specific additives like azole compounds and quaternary ammonium hydroxides. These parameter changes enable selective etching of copper while protecting titanium, achieving high processing accuracy and minimal residues
Solution Approach 2:
The patent introduces intermediary substances including azole compounds (such as benzotriazole) and quaternary ammonium hydroxides that act as mediators in the etching process. These intermediaries facilitate selective chemical reactions, enhance etching uniformity, and prevent unwanted side reactions, thereby improving processing accuracy and reducing residues
2Manufacturing precision
If conventional etching liquids are used, then etching can proceed, but etching unevenness occurs and profile control is poor
Solution Approach 1:
The patent optimizes multiple parameters including pH value (maintained between 1.5-2.5 through quaternary ammonium hydroxide addition), oxidizer concentration ratios, and additive concentrations to achieve uniform etching rates across the substrate. This results in controlled taper angles between 20-60 degrees and consistent wiring profiles
Solution Approach 2:
The patent employs feedback mechanisms through the use of buffer systems and stabilizing agents that maintain constant etching conditions throughout the process. The quaternary ammonium hydroxide and hydrogen peroxide stabilizer provide continuous feedback control, adjusting local pH and reaction rates to ensure uniform etching and consistent profile formation
3Productivity
If existing etching liquids are used for copper etching, then copper removal can occur, but adhesion problems and diffusion into silicon occur
Solution Approach 1:
The patent applies local quality control by making the etching liquid selectively reactive - it is designed to etch copper at high rates while being inert or minimally reactive toward titanium and silicon. This is achieved through the specific combination of oxidizers and complexing agents that target copper atoms while leaving other materials unaffected, ensuring adhesion integrity and preventing diffusion
Solution Approach 2:
The patent converts the potential harm of aggressive copper etching (which could damage adjacent materials) into a benefit by using the fluoride ion-copper complex formation mechanism. The fluoride ions form stable complexes with copper ions, driving the etching reaction forward while the azole compounds provide protective adsorption on titanium surfaces, thus enabling high copper removal rates without compromising adhesion or causing diffusion
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 etching liquid provides high processing accuracy, minimal residue, and a stable etching profile, enabling effective size enlargement and resolution enhancement of displays with a long bath life and reduced glass corrosion.
Implementation Method 1
hydrogen peroxide, nitric acid, a fluoride ion source, an azole, a quaternary ammonium hydroxide, and a hydrogen peroxide stabilizer
Implementation Method 2
hydrogen peroxide, nitric acid, a fluoride ion source, an azole, a quaternary ammonium hydroxide, and a hydrogen peroxide stabilizer
Implementation Method 3
hydrogen peroxide, nitric acid, a fluoride ion source, an azole, a quaternary ammonium hydroxide, and a hydrogen peroxide stabilizer
Data Source
AI summary
The present invention provides an etching liquid for a multilayer thin film containing a copper layer and a titanium layer, and a method of using it for etching a multilayer thin film containing a copper layer and a titanium layer, that is, an etching liquid for a multilayer thin film containing a copper layer and a titanium layer, which comprises (A) hydrogen peroxide, (B) nitric acid, (C) a fluoride ion source, (D) an azole, (E) a quaternary ammonium hydroxide and (F) a hydrogen peroxide stabilizer and has a pH of from 1.5 to 2.5, and a etching method of using it.