Piezo Valve Position Control for Sensorless Flow Ratio Accuracy
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Solution Overview
Problem
Conventional flow ratio control systems in substrate processing face limitations due to passive control's inability to adjust fluid flow ratios and active control's reliance on sensors in the wetted flow path, which suffer from hysteresis, low reproducibility, and sensor degradation, leading to ratio errors and substrate defects.
Innovation Solution
The system employs piezo position control with a processing device that generates a fluid conductance map based on valve positions and pressure values to proactively set valve positions, using a displacement device and sensor outside the wetted flow path to control fluid flow ratios, thereby avoiding sensor-related issues and improving throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sensors are placed in the wetted flow path for active control, then flow ratio control is enabled, but sensor hysteresis and degradation cause ratio errors and reduced reliability
Solution Approach 1:
The patent extracts the sensor from the wetted flow path environment. Instead of placing sensors directly in the fluid stream where they experience hysteresis and degradation, the system uses a model-based approach where sensors monitor conditions upstream and a pre-generated fluid conductance map predicts downstream flow ratios, eliminating sensor exposure to harmful flow conditions.
Solution Approach 2:
The patent creates a fluid conductance map that serves as a digital model or copy of the flow system's behavior. This map, generated through computational fluid dynamics (CFD) simulations, replicates the complex flow characteristics and allows the control system to predict flow ratios without requiring direct physical measurement in the flow path, thereby avoiding sensor degradation.
2Device complexity
If passive control is used for flow distribution, then system simplicity is maintained, but inability to adjust fluid flow ratios reduces adaptability
Solution Approach 1:
The patent performs preliminary computational work by generating a fluid conductance map through CFD simulations before the actual process runs. This pre-computed model captures the flow characteristics under various valve positions and conditions, allowing the simple control system to achieve complex adaptive flow ratio control by simply querying the pre-generated map during operation.
Solution Approach 2:
The patent introduces a fluid conductance map as an intermediary between the simple valve control system and the complex flow distribution requirements. This computational model acts as a mediator that translates simple valve position inputs into accurate flow ratio predictions, enabling adaptability without increasing physical system complexity.
3Ease of operation
If active control with wetted sensors is implemented, then flow ratio control is achieved, but maintenance frequency increases due to sensor degradation
Solution Approach 1:
The patent extracts sensors from the maintenance-prone wetted environment. By using a model-based control approach with sensors positioned upstream and a pre-generated fluid conductance map, the system eliminates the need for sensors to be continuously exposed to flowing fluids, dramatically reducing maintenance requirements and extending sensor life.
4Measurement precision
If conventional active control is used, then real-time flow measurement is possible, but hysteresis and low reproducibility lead to substrate defects
Solution Approach 1:
The patent replaces physical sensor measurement with a computational model (fluid conductance map) that copies the flow system's behavior. This digital twin approach eliminates sensor hysteresis and reproducibility issues by using pre-computed CFD data that accurately predicts flow ratios based on valve positions, ensuring consistent substrate quality without measurement errors.
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 approach enhances flow ratio control accuracy, reduces maintenance needs, and increases throughput by anticipating process requirements, minimizing hysteresis and substrate defects.
Implementation Method 1
Piezo position control
Implementation Method 2
a displacement sensor coupled to the displacement device
Data Source
AI summary
A method includes receiving, for a first pipe, first pressure values corresponding to first valve positions of a first valve coupled to the first pipe. The method further includes receiving, for a second pipe routed in parallel with the first pipe, second pressure values corresponding to second valve positions of a second valve coupled to the second pipe. The method further includes generating a fluid conductance map based on the first valve positions, the first pressure values, the second valve positions, and the second pressure values. The method further includes causing, by a processing device based on a recipe and the fluid conductance map, the first valve to be in a first valve position and the second valve to be in a second valve position for a process of the recipe.