Power Converter Control for Uniform Multi-Zone Heater Startup
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Solution Overview
Problem
In semiconductor processing, pedestal heaters with resistive heating elements experience thermal stress and cracking due to non-uniform heating zones and manufacturing differences, leading to temperature discrepancies and thermal expansion issues.
Innovation Solution
A thermal system with a power converter and controller that adjusts voltage output based on current and voltage feedback, allowing for independent control of heating elements to maintain uniform temperature across zones, reducing thermal stress and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the same power is applied to all resistive heating elements during heater startup, then the heating process is simple to control, but temperature differences between heating zones cause thermal stress and cracking in the ceramic substrate
Solution Approach 1:
The heating system is divided into multiple independently controllable heating zones, each with its own power converter. This allows separate control of power delivery to each heating element, enabling temperature uniformity across zones while maintaining simple overall control through centralized management of individual zone controllers
Solution Approach 2:
The system dynamically adjusts power delivery to each heating zone based on real-time temperature feedback. Power converters modify their output dynamically during startup and operation to compensate for varying thermal characteristics of different zones, preventing thermal stress without requiring complex manual control
2Reliability
If power converters are added to enable independent control of heating zones, then temperature uniformity and thermal stress reduction are achieved, but device complexity increases
Solution Approach 1:
Each power converter is designed as a multi-functional module that performs voltage conversion, current regulation, and temperature compensation simultaneously. This universal design reduces overall system complexity by consolidating multiple functions into single integrated components rather than requiring separate devices for each function
Solution Approach 2:
The system implements feedback control where temperature sensors monitor each heating zone and automatically adjust power converter output accordingly. This closed-loop feedback eliminates the need for complex manual control systems while maintaining temperature uniformity, as the automatic adjustment compensates for thermal variations without additional 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
The system effectively reduces thermal stress and cracking by enabling precise control of heating zones, ensuring uniform temperature distribution and preventing substrate damage.
Implementation Method 1
The heating plate may include a ceramic substrate and a plurality of resistive heating elements embedded in the ceramic substrate
Implementation Method 2
The controller is in communication with the power switch to control the voltage output of the power converter based on at least one of a current and a voltage at the heater
Implementation Method 3
the temperature is determined based on a resistance of the heater, which is determined by the voltage and the current of the heater
Implementation Method 4
the temperature difference between the adjacent heating zones causes different thermal expansion and consequently thermal stress between the adjacent heating zones
Data Source
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AI summary
The invention relates to a control system for controlling a heater (102), the control system comprising: a power converter (116) including a power switch (206) and operable to generate an adjustable output voltage; a sensor circuit (208) configured to measure at least one of a voltage and an electric current of the heater (102); and a controller (104) connected to the power converter (116), wherein the controller (104) is configured to determine an input parameter based on the at least one of the voltage and the electric current, determine the output voltage applied for the heater (102) based on the input parameter and a desired setpoint, wherein the desired setpoint is based on an operational state of the heater (102), and operate the power switch (206) of the power converter (116) to generate the output voltage.