Substrate Processing Apparatus Concentration Control
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Solution Overview
Problem
The presence of zero-point deviation in differential pressure flowmeters used in substrate processing apparatuses can lead to discrepancies in chemical concentration, affecting processing performance, as the flow rate measurements become inaccurate, causing a drift between measured and displayed values without error output.
Innovation Solution
A substrate processing apparatus is designed with dual flow rate regulation units, each equipped with differential pressure flowmeters, a concentration meter, and a controller that adjusts flow rates to maintain a conforming concentration and flow rate, even if zero-point deviation occurs, ensuring accurate chemical mixing and supply to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential pressure flowmeters are used to measure flow rates, then flow rate regulation is achieved, but zero-point deviation causes measurement inaccuracy and concentration drift
Solution Approach 1:
The patent implements a feedback mechanism where the actual concentration of the mixed liquid is measured and compared with the target concentration. Based on this comparison, the controller automatically adjusts the flow rates of the first and second liquids to eliminate concentration deviations, thereby resolving the reliability issue caused by flowmeter zero-point drift.
Solution Approach 2:
The patent replaces reliance on mechanical differential pressure flowmeters with an optical concentration measurement system. By using a concentration meter (optical measurement) to directly measure the mixed liquid concentration and substituting mechanical flow rate-based control with optical concentration-based feedback control, the system achieves higher reliability independent of flowmeter accuracy.
2Ease of operation
If flow rate controllers with differential pressure flowmeters are used, then flow rate regulation is possible, but zero-point deviation leads to drift between measured and displayed flow rates without error output
Solution Approach 1:
The patent introduces concentration as an intermediary parameter between flow rate control and processing quality. Instead of directly relying on flow rate measurements from potentially inaccurate flowmeters, the system uses concentration measurement as an intermediate feedback to indirectly ensure accurate flow rate control, thus preventing loss of accurate control information.
Solution Approach 2:
The patent changes the control parameter from flow rate (measured by unreliable differential pressure flowmeters) to concentration (measured by reliable optical concentration meter). By shifting the controlled parameter from flow rate to concentration, the system maintains ease of operation while eliminating information loss due to flowmeter inaccuracies.
3Manufacturing precision
If the concentration of the mixed liquid is not accurately controlled, then processing performance is affected, but continuous monitoring and adjustment increase system complexity
Solution Approach 1:
The patent makes the controller multi-functional by integrating both flow rate control and concentration control functions into a single device. The controller not only regulates flow rates based on set values but also performs real-time concentration measurement, comparison, and automatic adjustment, thereby achieving high manufacturing precision without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the flow rate control system and concentration control system into a unified integrated control system. By combining the concentration meter, controller, and flow rate regulators into one coordinated system, the patent achieves precise concentration control while minimizing the increase in overall system complexity through functional integration.
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 continuous and accurate supply of a mixed liquid with the correct concentration and flow rate to the substrate, mitigating the impact of zero-point deviation and maintaining processing performance.
Implementation Method 1
a first flow rate measurement unit (11) configured to measure a flow rate of the first liquid C by a differential pressure
Implementation Method 2
a concentration meter (51) configured to measure a concentration of the first liquid C in the mixed liquid M
Data Source
AI summary
A substrate processing apparatus 1 includes a substrate processing unit 40 configured to process a substrate W by supplying a mixed liquid M of a first liquid C and a second liquid D to the substrate W, a first flow rate regulator 10 disposed in a first supply pipe 31 configured to allow the first liquid C to flow therethrough, and the first flow rate regulator 10 configured to measure a flow rate by a differential pressure and to regulate the flow rate, a second flow rate regulator 20 disposed in a second supply pipe 32 configured to allow the second liquid D to flow therethrough, and the second flow rate regulator 20 configured to measure a flow rate by a differential pressure and to regulate the flow rate, a concentration meter 51 disposed in a mixed liquid pipe 33 configured to guide the mixed liquid M with a mixture of the first liquid C having passed through the first flow rate regulator 10 and the second liquid D having passed through the second flow rate regulator 20 to the substrate processing unit 40, and a controller 60 configured to take difference elimination measures when the difference between a conforming concentration as the concentration of the mixed liquid M suitable for processing the substrate W in the substrate processing unit 40 and the concentration measured with the concentration meter 51 exceeds a predetermined value. With this, even if zero-point deviation of a differential pressure flowmeter occurs, it is possible to eliminate the difference in concentration.