Substrate Liquid Processing Apparatus Concentration Control
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Solution Overview
Problem
Existing substrate liquid processing systems face challenges in precisely controlling the concentration of processing liquids, leading to inconsistent supply of processing liquids to substrates, as raw material liquids may not be sufficiently mixed before being supplied, resulting in inadequate concentration management.
Innovation Solution
A substrate liquid processing apparatus with a tank, circulation line, processing liquid producing mechanism, concentration measuring device, and control device that measures and adjusts the concentration of processing liquids by controlling the mixing ratio of raw material liquids, ensuring the processing liquid is supplied at a precise concentration through a processing liquid supply line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If raw material liquids are supplied to the tank from independent supply lines and mixed in the tank, then the processing liquid can be stored and circulated to multiple liquid processing units, but the processing liquid may flow out from the tank before the raw material liquids are mixed sufficiently, resulting in inadequate concentration control
Solution Approach 1:
The system separates the mixing function from the storage function by introducing a dedicated mixing tank distinct from the storage tank. Raw material liquids are mixed in the mixing tank before being supplied to the storage tank, ensuring sufficient mixing occurs before the processing liquid is stored and circulated to multiple liquid processing units. This segmentation resolves the contradiction by enabling both efficient multi-unit supply and precise concentration control.
2Ease of operation
If a liquid flow controller (LFC) is provided in each raw material liquid supply line to control supply amount, then the supply flow rate and time can be regulated, but the supply amount may be insufficiently managed when low concentration or precise concentration control is required
Solution Approach 1:
The system incorporates a concentration measuring device that continuously monitors the concentration of the processing liquid and provides feedback to the control device. The control device adjusts the supply amounts of raw material liquids based on this feedback, enabling precise concentration control. This feedback mechanism resolves the contradiction by transforming the open-loop LFC control into a closed-loop system that can achieve both ease of operation and high measurement precision.
Solution Approach 2:
The system replaces the purely mechanical LFC control with an integrated control system that combines mechanical flow control with electronic concentration measurement and automated feedback control. The concentration measuring device and control device work together to substitute manual or simple mechanical regulation with an intelligent control system that achieves precise concentration management while maintaining ease of operation.
3Duration of action of stationary object
If the processing liquid is adjusted by mixing in the tank, then the processing liquid can be stored for circulation, but the mixing may not be sufficient before supply, leading to concentration variations
Solution Approach 1:
The system segments the liquid handling process into distinct mixing and storage phases by using separate mixing tank and storage tank. The mixing tank is dedicated to thorough mixing of raw material liquids, while the storage tank is dedicated to storing the uniformly mixed processing liquid for circulation. This segmentation ensures that sufficient mixing occurs before storage, maintaining composition stability throughout the storage and circulation period.
Solution Approach 2:
The system performs preliminary mixing in the mixing tank before the processing liquid is supplied to the storage tank. This preliminary action ensures that raw material liquids are thoroughly mixed and reach uniform concentration before being stored and circulated to multiple liquid processing units, thereby maintaining composition stability throughout the system.
Data Source
AI summary
A substrate liquid processing apparatus includes a tank; a circulation line; a processing unit connected to the circulation line through a branch line and configured to perform a liquid processing on a substrate using a processing liquid flowing through the circulation line; a processing liquid producing mechanism configured to produce the processing liquid by mixing at least two kinds of raw material liquids supplied from respective raw material liquid sources at a controlled mixing ratio; a concentration measuring device configured to measure a concentration of the processing liquid flowing through the circulation line and a concentration of the processing liquid flowing through the processing liquid supply line; and a control device configured to control the processing liquid producing mechanism based on the measured concentrations of the processing liquid.