Gas Flow Rate Inspection Using Pressure Differential Monitoring
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Solution Overview
Problem
The gas supply system in substrate processing apparatuses experiences changes over time, leading to variations in gas flow rates, which can result in different substrate states, necessitating a method to inspect and ensure consistent gas supply.
Innovation Solution
A method involving flow rate controllers with pressure gauges and control valves, where pressure differences and steady-state measurements are used to determine if the gas flow rate has changed, allowing for real-time inspection and potential alarm or process interruption if thresholds are exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gas supply system operates continuously over time, then productivity is improved, but the gas flow rate stability deteriorates due to system state changes
Solution Approach 1:
The inspection method performs measurements and calculations in advance to detect flow rate changes before they affect substrate processing. By continuously monitoring pressure values and calculating flow rates proactively, the system can identify deviations from the reference flow rate before they cause substrate state variations, allowing preventive maintenance or adjustment.
Solution Approach 2:
The system establishes a feedback loop by comparing the calculated flow rate against the reference flow rate obtained during normal operation. When the flow rate falls outside the predetermined range, the system generates an alarm signal, creating a closed-loop control mechanism that continuously monitors and responds to flow rate variations, thereby maintaining stability over extended operation periods.
2Measurement precision
If pressure gauges and flow rate controllers are used to monitor gas flow, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The flow rate controller utilizes its own built-in pressure gauges to perform self-inspection and self-monitoring functions. Instead of requiring separate external measurement devices, the system leverages the pressure measurement capabilities already integrated into the flow rate controller to calculate and monitor gas flow rates, thereby achieving precise measurement without adding external complexity.
Solution Approach 2:
The pressure gauges within the flow rate controller serve multiple functions: they are used for normal flow rate control operations and simultaneously for inspection and monitoring purposes. This multi-functionality allows the same components to fulfill both operational and diagnostic roles, avoiding the need for additional dedicated inspection equipment and reducing overall system complexity.
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
Enables precise detection of changes in gas flow rates, ensuring consistent substrate processing by identifying deviations and preventing process disruptions through real-time monitoring and control.
Implementation Method 1
a first pressure gauge configured to measure an internal pressure of the fourth line between the control valve and the orifice
Implementation Method 2
a second pressure gauge configured to measure an internal pressure of the fifth line
Implementation Method 3
The flow rate controller of this type includes an orifice, a control valve, a first pressure gauge and a second pressure gauge
Data Source
AI summary
A flow rate of a gas supplied into a processing vessel of a substrate processing apparatus is controlled according to a set flow rate of a first flow rate controller. The gas is also supplied into a second flow rate controller. When an output flow rate of the first flow rate controller is in a steady state, a first pressure measurement value of a first pressure gauge and a second pressure measurement value of a second pressure gauge of the second flow rate controller are obtained. A difference absolute value between the first pressure measurement value and a reference pressure value and a difference absolute value between the second pressure measurement value and a reference pressure value are calculated, and then, an average value of the difference absolute values is calculated. The difference absolute values and the average value are respectively compared with a first to third threshold value.