Substrate Treating Device Concentration Control
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Solution Overview
Problem
Existing substrate treating devices face challenges in maintaining the concentration of treating liquids within a suitable range for semiconductor wafer etching and washing treatments due to evaporation and decomposition, leading to divergences between apparent and actual concentrations.
Innovation Solution
A substrate treating device with a treating-liquid exchange unit, detecting unit, concentration control unit, and target-value change unit that adjusts the target concentration based on detected concentrations and treatment conditions to maintain optimal liquid concentrations, including increasing the target concentration during the life time of the treating liquid and setting an upper limit to prevent excessive changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If concentration control is performed using a concentration meter in the circulation line, then the apparent concentration can be maintained at a target value, but the actual concentration diverges from the apparent concentration over time due to measurement errors influenced by the treating liquid state
Solution Approach 1:
The patent introduces an intermediary calculation process that uses multiple detection values (including conductivity and other parameters) to calculate the actual concentration, rather than relying solely on the concentration meter reading. This intermediary calculation acts as a mediator between the apparent measurement and the actual concentration value, correcting for measurement errors and divergence over time.
Solution Approach 2:
The system implements feedback control by continuously monitoring the treating liquid state through multiple parameters, calculating the actual concentration, and adjusting the treating liquid composition accordingly. The feedback mechanism compares the calculated actual concentration with the target concentration and makes real-time adjustments to maintain accuracy.
2Device complexity
If the treating liquid concentration is controlled without considering volatility differences between components, then the control process is simple, but the concentration cannot be maintained within the suitable range due to evaporation and decomposition
Solution Approach 1:
The patent changes the control parameter from simple concentration reading to a multi-parameter approach that includes conductivity and other characteristics. By monitoring multiple parameters simultaneously, the system can detect changes in liquid composition due to evaporation and decomposition, and adjust the treating liquid to maintain the suitable concentration range.
Solution Approach 2:
The system performs preliminary calculation of the actual concentration based on multiple detection values before making adjustments. This preliminary action allows the system to anticipate concentration deviations caused by volatility differences and take corrective measures before the concentration falls outside the suitable range.
3Productivity
If feedback control is used to maintain apparent concentration at target value, then short-term concentration control is effective, but long-term concentration accuracy deteriorates due to cumulative measurement errors
Solution Approach 1:
The patent introduces an intermediary calculation that uses multiple detection values to determine the actual concentration, serving as a mediator between the apparent concentration reading and the true concentration value. This intermediary process corrects cumulative measurement errors by referencing additional parameters that are less susceptible to the same errors.
Solution Approach 2:
The system periodically recalculates the actual concentration using multiple detection values and adjusts the treating liquid composition accordingly. This periodic action prevents cumulative errors from building up over time by regularly resetting the concentration baseline through multi-parameter verification.
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 configuration allows for precise control of treating liquid concentrations, ensuring accurate and stable performance of etching and washing treatments by canceling divergences and maintaining optimal conditions throughout the treatment process.
Implementation Method 1
a detecting unit that detects a concentration of the pure water or of other predetermined components in the treating liquid
Implementation Method 2
a concentration control unit that controls, based on the concentration detected by the detecting unit, the concentration such that the concentration becomes a predetermined target concentration, by supplying the pure water or the other predetermined components to the treating liquid in the treating tank
Implementation Method 3
a treating-liquid exchange unit that exchanges the treating liquid based on a life time of the treating liquid in the treating tank
Data Source
AI summary
A substrate treating device immerses substrates in a mixed-acid aqueous solution, and performs an etching treatment on the substrates. The substrate treating device includes: a treating tank that stores the mixed-acid aqueous solution; a treating-liquid exchange unit that performs a total liquid exchange of the mixed-acid aqueous solution based on a life time of the mixed-acid aqueous solution in the treating tank; a detecting unit that detects a pure-water concentration of the mixed-acid aqueous solution; a concentration control unit that controls, based on the pure-water concentration detected by the detecting unit, the pure-water concentration such that the pure-water concentration becomes a predetermined target concentration by supplying pure water to the mixed-acid aqueous solution in the treating tank; and a target-value change unit that changes a lower-side standard value (a target concentration).