Ammonium Carbonate Buffer Liquid for Substrate pH Control
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Solution Overview
Problem
It is challenging to adjust the pH of dilute ammonia water and carbon dioxide dissolved water to specific values within the range of pH 5 to 9, as the pH of dilute ammonia water changes significantly with ammonia concentration, and carbon dioxide dissolved water's pH is difficult to adjust to values above 5 or below 9.
Innovation Solution
A substrate liquid processing method involving the production of a processing liquid using deionized water, carbon dioxide, and ammonia, where carbon dioxide is dissolved in deionized water to achieve a predetermined resistivity, and then ammonia is added to adjust the pH to a range of 5 to 9, utilizing the buffering properties of the resulting ammonium carbonate solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dilute ammonia water is used as rinse liquid to suppress corrosion of device components, then the pH can be adjusted to protect metal, but the pH changes considerably with ammonia concentration making it difficult to maintain a stable pH value in the range of 5 to 9
Solution Approach 1:
The patent introduces carbon dioxide as an intermediary substance that reacts with ammonia to form ammonium carbonate buffer system. This buffer system acts as a mediator that stabilizes pH in the range of 5 to 9, preventing the considerable pH changes that occur with dilute ammonia water alone. The carbon dioxide-ammonia reaction creates a buffer capacity that resists pH fluctuations while maintaining corrosion protection.
Solution Approach 2:
The patent changes the chemical parameters by introducing carbon dioxide to react with ammonia, transforming the system from simple dilute ammonia water to an ammonium carbonate buffer system. This parameter change enables stable pH control in the 5 to 9 range by utilizing the buffer capacity of the ammonium carbonate system, which resists pH changes upon addition of acids or bases.
2Reliability
If carbon dioxide dissolved water is used as rinse liquid to prevent electrostatic breakdown, then conductivity is controlled, but the pH is difficult to adjust to values of 5 or more
Solution Approach 1:
The patent merges carbon dioxide dissolved water with ammonia to create an ammonium carbonate buffer system. This combination allows the solution to maintain the low pH characteristics of carbon dioxide dissolved water (preventing electrostatic breakdown) while gaining the ability to adjust and stabilize pH to 5 or more through the ammonia component, which neutralizes excess acidity.
Solution Approach 2:
The patent changes the pH parameter by adding ammonia to carbon dioxide dissolved water, transforming it into an ammonium carbonate buffer system with adjustable pH. This parameter change enables the solution to achieve pH values of 5 or more while maintaining the conductivity control benefits of the carbon dioxide system, making it easier to operate within the desired pH range.
3Reliability
If deionized water is used for rinsing to maintain purity, then electrostatic breakdown may occur in device components, but adding substances to adjust pH may introduce contaminants
Solution Approach 1:
The patent uses carbon dioxide and ammonia as intermediary substances that react to form ammonium carbonate, which then serves as the active buffering agent. This intermediary approach allows pH adjustment without introducing heavy metal contaminants or complex organic compounds, maintaining the purity of the rinse liquid while preventing electrostatic breakdown through controlled conductivity.
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 method allows for the stable production of a processing liquid with a desired pH value between 5 and 9, effectively managing resistivity and pH stability, which is crucial for substrate processing to prevent corrosion and electrostatic breakdown.
Implementation Method 1
dissolving carbon dioxide in deionized water until a predetermined resistivity or conductivity is obtained
Implementation Method 2
adding ammonia water to the deionized water in which the carbon dioxide is dissolved, thereby producing a buffer solution
Implementation Method 3
utilizing the buffering properties of the resulting ammonium carbonate solution
Data Source
AI summary
Disclosed is a substrate liquid processing method. The method includes producing a processing liquid including deionized water, carbon dioxide, and ammonia, which has a PH of a predetermined value in a range of pH 5 to 9; and processing a substrate having a metal exposed, using the processing liquid.