In-Situ Flow Controller Calibration for Substrate Processing
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Solution Overview
Problem
Flow controllers in substrate processing systems often fail to maintain accurate flow rates over their full range due to calibration inaccuracies, leading to inefficiencies and potential equipment downtime.
Innovation Solution
An in-situ calibration method for flow controllers, which determines the actual relationship between flow rate and setpoint by measuring flow rates at multiple setpoints using a standard gas, allowing for precise adjustment and wider flow rate accuracy, and includes health monitoring features to prevent equipment failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow controller is calibrated using standard gas by manufacturer prior to installation, then initial calibration is achieved, but flow rate accuracy deteriorates over time and across full range
Solution Approach 1:
The system performs preliminary calibration actions by establishing a baseline relationship between setpoint and actual flow rate using standard gas during manufacturing. This preliminary calibration stored in memory allows the flow controller to operate initially without immediate site calibration, preventing downtime while maintaining acceptable accuracy for standard gases.
Solution Approach 2:
The system implements feedback by measuring actual flow rates at multiple setpoints using a flow verification device, comparing these measurements to the stored baseline relationship, and generating correction factors. This feedback loop continuously refines the setpoint-to-flow-rate relationship, maintaining accuracy over time and across different gases without requiring frequent manual recalibration.
2Ease of manufacture
If flow controller uses calculated relationship from standard gas, then setup is simplified, but flow rate accuracy for process gas deteriorates
Solution Approach 1:
The system changes parameters by measuring actual flow rates at multiple different setpoints (e.g., 10, 20, 30, 40, 50 sccm) rather than relying on a single calculated relationship. By collecting data across multiple parameter values and fitting a curve to this data, the system adapts the calibration to match the specific process gas characteristics, improving accuracy while maintaining ease of manufacture through automated measurement and curve fitting.
3Productivity
If flow controller operates without in-situ calibration, then operational time is reduced, but flow rate accuracy deteriorates
Solution Approach 1:
The system enables self-service calibration by allowing operators to perform in-situ calibration at the substrate processing system using the actual process gas. The flow controller automatically measures its own performance at multiple setpoints, compares results to the stored baseline, and self-corrects by storing new relationship data. This self-calibration capability maintains high flow rate accuracy while minimizing operational time loss, as the calibration process is streamlined and requires minimal intervention.
Data Source
AI summary
Methods and apparatus for in-situ calibration of a flow controller are provided herein. In some embodiments, a method of flowing a gas includes providing a flow controller configured to provide a first gas at a first value of a flow rate based on a calculated first relationship determined by using a standard gas; determining an actual first relationship between the flow rate and the setpoint for the first gas from a plurality of values of the flow rate of the first gas determined at a corresponding plurality of values of the setpoint of the flow controller, wherein each of the plurality of values of the flow rate is determined from flowing the first gas through the flow controller at corresponding ones of the plurality of values for the setpoint; and flowing the first gas at the first value of the flow rate based on the actual first relationship.