Anomaly Detection Controller for Substrate Processing Liquid Level
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Solution Overview
Problem
Existing substrate processing apparatuses face challenges in detecting level sensor failures, leading to potential overconsumption of processing liquid and increased operating costs due to the rapid corrosion of low-level sensors.
Innovation Solution
A substrate processing apparatus equipped with a level sensor, a high-level sensor, and an anomaly detection controller that calculates processing liquid consumption based on valve opening and closing events, generating a failure alarm if consumption exceeds a predetermined amount without a state transition, thereby detecting sensor failures and reducing maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low level sensor is added to detect level sensor failure, then the reliability of level detection is improved, but the operating cost increases due to rapid corrosion and frequent replacement
Solution Approach 1:
The patent replaces the mechanical/physical low level sensor with a software-based anomaly detection system. The anomaly detection controller calculates expected liquid consumption based on valve operation history and compares it with actual consumption patterns to detect level sensor failures, eliminating the need for physical contact with corrosive processing liquid.
Solution Approach 2:
The patent introduces an intermediary calculation process that uses valve opening/closing history as a mediator to indirectly detect liquid level changes. Instead of directly measuring liquid level with a sensor in contact with the liquid, the system uses the intermediary relationship between valve operations and liquid consumption to infer level changes.
2Reliability
If the level sensor is continuously monitored, then the reliability of detection is improved, but the device complexity increases due to additional sensors and control logic
Solution Approach 1:
The anomaly detection controller performs multiple functions: it monitors valve operations, calculates liquid consumption, detects level sensor failures, and generates alerts. By making the controller multi-functional, the patent avoids adding separate dedicated monitoring hardware, thus reducing overall system complexity while maintaining high reliability.
Solution Approach 2:
The patent merges the level detection function with the existing valve control and consumption calculation functions in a single anomaly detection controller. This consolidation eliminates the need for separate monitoring systems and reduces the overall complexity of the detection infrastructure.
Data Source
AI summary
The amount of processing liquid consumed from the processing liquid in the tank is calculated based on the history of opening and closing events of one or more of the valves, and that the anomaly detection controller of the substrate processing apparatus generates a level sensor failure alarm if the calculated amount of consumed processing liquid has increased beyond a state transition liquid consumption amount and yet the level sensor has not switched from the first state to the second state. The substrate processing apparatus and the level sensor are designed so that the level sensor switches from the first state to the second state when the calculated amount of consumed processing liquid has increased beyond the state transition liquid consumption amount.