Wafer Temperature Control Using Gas Pressure Predictive Modeling
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Solution Overview
Problem
Conventional wafer temperature control systems face challenges in accurately controlling the temperature of a wafer due to varying heat transfer coefficients influenced by gas pressure, leading to difficulties in maintaining a predetermined target temperature.
Innovation Solution
A wafer temperature control device that employs model predictive control (MPC) with a variable heat transfer coefficient model, using a pressure regulator and vicinity temperature sensor to adjust gas pressure, allowing for precise temperature control by calculating and updating the coefficient matrix based on real-time pressure and temperature data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant heat transfer coefficient is used in the model predictive control to simplify the model, then the numerical burden is reduced, but the temperature control accuracy deteriorates because the heat transfer coefficient varies with gas pressure
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant heat transfer coefficient to a dynamic variable heat transfer coefficient that changes with gas pressure. The heat transfer coefficient is now a function of pressure, allowing the model to adapt to varying operating conditions and maintain accuracy without excessive complexity
Solution Approach 2:
The patent changes the parameter representation by introducing gas pressure as a variable that directly influences the heat transfer coefficient. This parameter change allows the model to capture the physical relationship between pressure and heat transfer, improving temperature control accuracy while maintaining manageable model complexity through systematic formulation
2Loss of energy
If the pressure of the heat transfer gas is adjusted to control wafer temperature, then heat transfer efficiency is improved, but the temperature control accuracy deteriorates due to various technical limitations in conventional systems
Solution Approach 1:
The patent implements feedback by using the measured vicinity temperature and target temperature to dynamically adjust the pressure operation amount input to the pressure regulator. This closed-loop control system continuously monitors temperature and adjusts gas pressure accordingly, enabling accurate temperature control while maintaining efficient heat transfer
Solution Approach 2:
The patent replaces conventional mechanical temperature control systems with a model predictive control system that uses computational modeling and optimization. The MPC algorithm predicts future temperature based on the variable heat transfer coefficient model and determines optimal pressure adjustments, substituting traditional mechanical control mechanisms with intelligent algorithmic control
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 accurate prediction and control of wafer temperature by incorporating a variable heat transfer coefficient model in the MPC, ensuring the wafer reaches and maintains the target temperature effectively.
Implementation Method 1
a heat transfer gas such as a helium gas is considered to be supplied between the plate and the wafer in order to promote heat transfer from the temperature adjusted plate to the wafer
Implementation Method 2
The temperature of the plate such as the electrostatic chuck is adjusted to control the temperature of the wafer... a heat transfer gas such as a helium gas is considered to be supplied between the plate and the wafer
Data Source
AI summary
A wafer temperature control device controls a temperature of a wafer by adjusting pressure of a gas, predicts future a temperature, and controls the temperature to a target temperature. The wafer is placed on a temperature adjusted plate and the gas is supplied between the plate and the wafer to control the wafer temperature. The control device comprises a pressure regulator that adjusts the pressure of the gas, a sensor that measures the vicinity temperature of the wafer, and a pressure control unit that controls a pressure operation amount input to the pressure regulator by model predictive control based on the vicinity temperature and target temperature of the wafer, and the pressure control unit uses a model, in which a heat transfer coefficient between the plate and the wafer is a variable obtained from the pressure of the gas, as a predictive model for the model predictive control.