Step-Down Power Converter for Multi-Zone Heater Temperature Uniformity
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Solution Overview
Problem
In semiconductor processing tools, uneven heating due to non-uniform application of power to resistive heating elements causes thermal stress and potential thermal cracks in the ceramic substrate, resulting from differences in heating zone positions and manufacturing characteristics.
Innovation Solution
A control system with a power converter and sensor circuit measures voltage and current to determine temperature and resistance, adjusting output voltage based on desired setpoints to manage thermal expansion and reduce temperature differences between heating zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same power is applied to all resistive heating elements during heater startup, then the heater structure is simple and easy to manufacture, but temperature uniformity deteriorates and thermal stress causes ceramic substrate cracks
Solution Approach 1:
The patent divides the heating system into multiple independently controllable heating zones, each with its own power control circuit. This allows separate power adjustment for each heating element based on real-time temperature feedback, enabling precise temperature uniformity control across different zones while maintaining a modular heater structure that is relatively easy to manufacture.
Solution Approach 2:
The patent dynamically changes the power parameter applied to each heating element based on real-time temperature measurements. By continuously adjusting the power input to individual heating zones according to their specific thermal characteristics and position, the system achieves uniform temperature distribution across the ceramic substrate, preventing thermal stress and cracks.
2Device complexity
If the same power is applied to all resistive heating elements, then the control system is simple, but temperature difference between heating zones increases causing thermal stress
Solution Approach 1:
The patent implements a feedback control system where temperature sensors continuously monitor the temperature of each heating zone and feed this information back to the control circuit. The control circuit then adjusts the power input to each heating element based on the temperature feedback, maintaining minimal temperature differences between zones and preventing thermal stress, all while using a relatively simple control architecture.
3Manufacturing precision
If position-dependent power adjustment is implemented to compensate for heating zone characteristics, then temperature uniformity is improved, but device complexity increases due to multiple sensors and control circuits
Solution Approach 1:
The patent employs a universal control architecture where a single microcontroller or control circuit board manages multiple heating zones through standardized control interfaces. Temperature sensors from different zones feed into a unified control system that applies position-dependent power adjustment algorithms, achieving precise temperature uniformity control without requiring separate dedicated control circuits for each zone, thus limiting the increase in device 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 controls temperature uniformity across heating zones, reducing thermal stress and preventing cracks by dynamically adjusting power supply to individual elements, ensuring consistent heating.
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 configured to determine an input parameter based on the at least one of the voltage and the electric current. The input parameter is indicative of a temperature of the heater
Data Source
AI summary
A control system includes a power converter being a step-down voltage converter and including a power switch. The power converter is operable to generate an adjustable output voltage and includes a sensor circuit configured to measure at least one of a voltage and an electric current of the heater. The control system includes a controller connected to the power converter and the sensor circuit. The controller is configured to determine an input parameter based on the at least one of the voltage and the electric current. The input parameter is indicative of a temperature of the heater. The controller is configured to set the output voltage applied for the heater based on the input parameter and a desired setpoint. The desired setpoint is based on an operational state of the heater. The controller is configured to operate the power switch of the power converter to generate the output voltage.