Display Substrate Oxide Removal Using HF-Ammonia Gas Etching
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Solution Overview
Problem
Existing methods for removing oxide layers from display apparatus substrates often result in the formation of impurities, such as water marks, due to the use of wet cleaning techniques, which are not effective and can degrade device characteristics.
Innovation Solution
A method involving an etching operation using a hydrofluoric acid and ammonia gas mixture to form and then decompose a salt layer on the substrate, followed by thermal treatment, effectively removing the oxide layer without generating impurities, utilizing a specific gas flow ratio and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet cleaning techniques are used to remove oxide layers, then cleaning effectiveness is improved, but impurities such as water marks are generated
Solution Approach 1:
The patent replaces wet cleaning techniques with a chemical etching process using hydrofluoric acid gas and ammonia gas. This substitution eliminates the need for liquid cleaning agents that cause water marks, while effectively removing oxide layers through controlled chemical reactions that form volatile salts.
Solution Approach 2:
The patent changes the physical state of the cleaning medium from liquid (wet cleaning) to gas phase (hydrofluoric acid gas and ammonia gas). This parameter change allows for effective oxide layer removal without leaving residual impurities, as the gaseous reagents can be completely evaporated after reaction.
2Productivity
If hydrofluoric acid gas and ammonia gas are used in etching operation, then oxide layer removal efficiency is improved, but residual fluorine may remain on substrate
Solution Approach 1:
The patent extracts residual fluorine from the substrate surface through a thermal treatment process. By heating the substrate to 150-350°C, the residual fluorine compounds are decomposed and removed, leaving a clean surface without harmful residues.
Solution Approach 2:
The patent converts the potentially harmful residual fluorine into beneficial volatile compounds through thermal decomposition. The residual fluorine reacts with ammonia to form ammonium fluoride, which then decomposes at elevated temperatures to release harmless gases, turning a contamination problem into a self-cleaning mechanism.
3Manufacturing precision
If thermal treatment is performed at high temperature to remove residual fluorine, then substrate purity is improved, but energy consumption increases
Solution Approach 1:
The patent applies partial thermal treatment at a moderate temperature range (150-350°C) rather than extreme high temperatures. This partial action is sufficient to remove residual fluorine and complete the etching process, achieving substrate purity without excessive energy consumption that would result from higher temperature treatment.
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
This approach improves the removal efficiency of the oxide layer, reducing residual fluorine and enhancing the characteristics of thin-film transistors and voltage-current performance, while avoiding the formation of impurities like water marks.
Implementation Method 1
The oxide layer may be removed by a salt formation reaction in the etching operation
Implementation Method 2
The formed salt may be removed by a salt decomposition reaction in the thermal treatment operation
Implementation Method 3
an etching operation of removing an oxide layer formed on a surface of a substrate by utilizing a hydrofluoric acid gas and an ammonia gas
Implementation Method 4
a thermal treatment operation of thermally treating the substrate from which the oxide layer has been removed
Data Source
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AI summary
A method of manufacturing a display apparatus, the method includes removing an oxide layer formed on a surface of a substrate by utilizing a hydrofluoric acid gas and an ammonia gas, and thermally treating the substrate from which the oxide layer has been removed. A flow ratio between the hydrofluoric acid gas and the ammonia gas is about 0.8:1 to about 1:1.