Dual Zone Pedestal Temperature Control via Heater Resistance
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Solution Overview
Problem
In substrate processing systems, particularly in atomic layer deposition (ALD), the limited accurate control of temperature across different zones of a pedestal leads to non-uniformities, potentially causing damage to substrates and components due to uncertainty in temperature measurements, especially in outer zones without separate temperature sensors.
Innovation Solution
A controller system calculates the resistance of heater elements with high thermal coefficients, allowing independent temperature control of different zones by measuring current and voltage, using a thermal coefficient of resistance to correlate resistance with temperature, and applying correction factors for precise temperature control without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate temperature sensors are installed in each zone of the pedestal, then temperature measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The heater elements serve dual functions: heating the substrate and sensing their own temperature through resistance measurements. The controller measures the resistance of each heater element to determine its temperature, eliminating the need for separate temperature sensors in each zone. This self-service approach reduces device complexity while maintaining temperature measurement capability.
Solution Approach 2:
The heater elements are designed to perform multiple functions: they provide thermal energy to heat the substrate and simultaneously serve as temperature sensors through their resistance-temperature relationship. This multi-functionality allows the system to obtain temperature information from existing components without adding separate sensing elements, thereby reducing overall system complexity.
2Manufacturing precision
If multiple separate temperature sensors are used for different zones, then temperature control accuracy is improved, but manufacturing cost increases
Solution Approach 1:
Each heater element monitors its own temperature through resistance measurements, providing self-service temperature sensing without requiring additional sensor components. This approach eliminates the cost of purchasing and installing multiple separate temperature sensors while maintaining the ability to control temperature accurately across different zones.
Solution Approach 2:
The temperature sensing function is merged with the existing heater elements by utilizing their electrical resistance properties. Instead of adding separate sensing components, the system combines the heating and sensing functions into a single element, reducing manufacturing costs associated with additional parts and assembly.
3Device complexity
If a single temperature sensor is used for the entire pedestal, then device complexity is reduced, but temperature uniformity control deteriorates
Solution Approach 1:
The pedestal heating system is divided into multiple independent heater elements, each controlling a specific zone. The controller independently measures the resistance of each heater element to determine the temperature of its respective zone, enabling zone-specific temperature control. This segmentation allows for maintaining temperature uniformity across different zones while managing complexity through modular control of individual heater elements.
4Measurement precision
If high thermal coefficient materials are used for heater elements, then temperature sensing precision is improved, but sensitivity to temperature changes increases which may cause instability
Solution Approach 1:
The controller continuously measures the resistance of each heater element to monitor temperature changes and adjusts the power supplied to maintain the desired temperature setpoint. This feedback mechanism compensates for the high sensitivity of materials with high thermal coefficients, ensuring temperature stability despite rapid resistance changes. The system uses the resistance measurements to dynamically adjust heating power, preventing temperature overshoot or oscillation.
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 method enables accurate and independent temperature control of multiple zones, reducing non-uniformities and preventing damage by calculating and adjusting power to heater elements based on resistance and thermal load, ensuring uniform or non-uniform temperature settings as needed during ALD processes.
Implementation Method 1
a thermal coefficient of resistance to correlate resistance with temperature
Implementation Method 2
calculates a first power associated with the first heater element based on the first voltage and the first current and calculate a second power associated with the second heater element based on the second voltage and the second current
Data Source
AI summary
A method for controlling temperature of a substrate support includes receiving first and second currents corresponding to first and second heater elements, respectively, of a substrate support, receiving first and second voltages corresponding to the first and second heater elements, respectively, calculating a first resistance of the first heater element based on the first voltage and the first current, calculating a second resistance of the second heater element based on the second voltage and the second current, calculating a first temperature of a first zone of the substrate support based on the first resistance and stored data correlating resistances to temperatures, calculating a second temperature of a second zone of the substrate support based on the second resistance and the stored data, and selectively adjusting the stored data based on a comparison between a sensed temperature and at least one of the calculated first temperature and second temperature.