Ultrapure Water Resistivity Buffer Tank for Stable Ion Mixing
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Solution Overview
Problem
The existing resistivity regulating apparatuses for ultrapure water in semiconductor and liquid crystal production face issues with resistivity deviations and fluctuations due to gradual gas dissociation and uneven ion concentrations, leading to increased resistivity regulated values, which are not adequately addressed by using long pipes that incur pressure drops, require significant space, and fail to completely eliminate deviations.
Innovation Solution
A resistivity regulating apparatus that includes a gas dissolving device to generate treated liquid with a regulating gas dissolved in ultrapure water, which is then fed into a buffer tank that promotes convection and uniform ion concentration through turbulent flow, reducing resistivity deviations and fluctuations while minimizing apparatus scale and pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a long pipe is disposed downstream of the resistivity regulating apparatus to allow natural mixing and dissociation, then resistivity deviations and fluctuations are reduced, but pressure drop increases, space requirement increases, and complete elimination of deviations is not achieved
Solution Approach 1:
The invention divides the mixing and dissociation process into two segments: (1) rapid mixing in a dedicated mixing section, and (2) dissociation in a separate dissociation section. This segmentation allows each process to occur under optimized conditions, eliminating the need for long pipes while achieving complete dissociation and uniform mixing.
Solution Approach 2:
The invention introduces an intermediary mixing section that facilitates rapid and uniform mixing of gas-added water and ordinary water before they enter the dissociation section. This intermediary structure ensures homogeneous ion distribution early in the process, preventing resistivity fluctuations downstream without requiring extended pipe lengths.
2Stability of the object's composition
If a long pipe is disposed downstream of the resistivity regulating apparatus, then resistivity deviations are reduced, but apparatus scale and space requirement increase significantly
Solution Approach 1:
The invention segments the water treatment process into distinct functional sections (mixing section and dissociation section) with compact designs. This allows the entire apparatus to achieve complete gas dissociation and uniform mixing in a compact footprint, eliminating the need for long downstream pipes and reducing overall apparatus scale.
Solution Approach 2:
The invention transitions from a linear, extended pipe-based mixing approach to a multi-dimensional compact structure with dedicated mixing and dissociation chambers. This dimensional reorganization achieves the same mixing and dissociation effects in a much smaller volume, significantly reducing apparatus scale while maintaining resistivity stability.
3Quantity of substance
If gas is dissolved in ultrapure water using a hollow fiber membrane module, then resistivity is reduced through ion generation, but uneven ion concentrations and resistivity fluctuations occur due to gradual dissociation
Solution Approach 1:
The invention performs preliminary mixing in a dedicated mixing section before the water enters the dissociation section. This preliminary action ensures that gas-added water and ordinary water are uniformly mixed from the outset, creating homogeneous ion distribution that prevents fluctuations and maintains stable ion concentration throughout the dissociation process.
Solution Approach 2:
The invention replaces the gradual, passive dissociation that occurs naturally in long pipes with an active, controlled dissociation process in a dedicated dissociation section. This mechanical substitution ensures complete and uniform dissociation under controlled conditions, eliminating resistivity fluctuations while maintaining stable ion concentration.
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 apparatus effectively reduces resistivity deviations and fluctuations in treated water without the need for extensive piping, maintaining stable resistivity and reducing apparatus size and pressure drop, thus enhancing the efficiency and stability of the cleaning process.
Implementation Method 1
a gas dissolving device causing carbon dioxide gas to dissolve in ultrapure water to generate treated water
Implementation Method 2
the gas dissolved in ultrapure water is dissociated (ionized) in two steps provided by the following equation (1) and equation (2)
Implementation Method 3
the generated treated liquid is fed to a buffer tank, and the treated liquid undergoes convection in the buffer tank
Implementation Method 4
the treated liquid fed to the buffer tank is stirred in the form of turbulent flow in the buffer tank
Data Source
AI summary
A resistivity regulating apparatus includes: a gas dissolving device that causes a regulating gas to dissolve in a liquid targeted for resistivity regulation to generate a treated liquid in which the regulating gas is dissolved in the liquid, the regulating gas being used to regulate a resistivity of the liquid; and a buffer tank to which the treated liquid discharged from the gas dissolving device is fed.