Wafer Edge Temperature Control Using Smith Predictor and ESO
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Solution Overview
Problem
Existing temperature control methods in semiconductor processing apparatuses, such as PID and model-based control, face challenges in achieving optimal temperature control performance due to trade-offs between transient response and convergence time, and inaccuracies in system modeling can degrade control performance.
Innovation Solution
A substrate processing apparatus with a controller that includes a Smith predictor and an extended state observer to estimate state variables and disturbances, and a compensation controller to generate control inputs, thereby improving temperature control without relying on specific system models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PID control method is used to control heater temperature, then temperature control can be achieved without requiring expert knowledge, but there is a trade-off between transient response and convergence time
Solution Approach 1:
The Smith predictor performs preliminary action by estimating the future temperature based on the current state and control input, effectively predicting where the system will be in the future. This allows the controller to act proactively rather than reactively, reducing convergence time while maintaining ease of operation through automated prediction algorithms
2Manufacturing precision
If model-based control method is used to design controller, then higher temperature control performance can be obtained, but it is difficult to obtain accurate mathematical model of the system
Solution Approach 1:
The extended state observer implements continuous feedback by constantly monitoring the actual temperature and comparing it with the predicted temperature from the model. This feedback mechanism allows the system to self-correct and maintain high temperature control performance without requiring a perfectly accurate mathematical model, thereby reducing the complexity of system modeling while preserving control precision
3Extent of automation
If conventional control methods are used, then temperature control can be implemented, but overshoot and undershoot occur during temperature transitions
Solution Approach 1:
The Smith predictor performs preliminary action by predicting future temperature based on current state and control input, allowing the controller to anticipate and compensate for temperature transitions before they fully occur. This proactive approach prevents overshoot and undershoot by adjusting the control input in advance, thereby improving temperature stability while maintaining full automation capability
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
The solution enhances temperature control performance, reduces overshoot and undershoot, stabilizes the processing environment, and shortens the time to reach target temperatures, improving the stability and efficiency of semiconductor processing.
Implementation Method 1
a heater configured to heat at least one from among the electro static chuck and the wafer substrate
Implementation Method 2
an electro static chuck configured to support a wafer substrate
Data Source
AI summary
A substrate processing apparatus may be provided and include: a heater configured to adjust a temperature of a periphery of a wafer substrate; a temperature sensor configured to measure the temperature of the periphery of the wafer substrate; and a controller configured to generate a control input based on a target temperature and based on a measured temperature obtained from the temperature sensor, and transmit the control input to the heater. The controller may be further configured to: calculate a first temperature based on the control input and the measured temperature by removing a time delay of the heater from the measured temperature; estimate a state variable and a disturbance of the heater based on the first temperature and the control input; and generate the control input to be transmitted to the heater based on the target temperature, the state variable, and the disturbance.