Multi-Zone Ceramic Heater With Hermetic Thermocouple Routing
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Solution Overview
Problem
Current multi-zone heaters in semiconductor processing face limitations due to the inability to install multiple control thermocouples within the heater zones while maintaining isolation from the processing environment, leading to variations in resistance and inconsistent watt-density maps across units.
Innovation Solution
A multi-zone heater design featuring a multi-layer ceramic structure with hermetic joints and thermocouples mounted between plate layers, allowing for independent temperature monitoring and control of each zone, with thermocouple leads routed through a ceramic hollow shaft to maintain isolation and hermetic seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple thermocouples are installed within heater zones to enable independent temperature monitoring and control of each zone, then temperature control precision and watt-density map consistency are improved, but the complexity of maintaining thermocouple isolation from the processing environment increases
Solution Approach 1:
The heater plate is divided into multiple independent heater zones, each with its own thermocouple for temperature monitoring. This segmentation allows independent control of each zone to achieve precise temperature profiles and consistent watt-density maps across multiple units.
Solution Approach 2:
Thermocouples are nested within the heater plate structure, with their leads routed through the hollow shaft. This nesting approach protects thermocouples from the processing environment while enabling multiple thermocouples to be installed within the heater zones for precise temperature monitoring.
2Reliability
If thermocouple leads are routed through the hollow shaft to maintain isolation from the processing environment, then thermocouple protection and hermetic seal integrity are improved, but the ease of installation and maintenance decreases
Solution Approach 1:
The hollow shaft is designed with pre-formed channels or pathways that guide thermocouple leads from the heater zones to the exterior. This preliminary structural preparation simplifies the installation process while maintaining hermetic seal integrity, as thermocouple leads can be routed through these pre-designed pathways without compromising the seal.
3Adaptability or versatility
If multiple independent heater circuits are used to change watt-density maps on-the-fly, then adaptability and versatility are improved, but the device complexity and control difficulty increase
Solution Approach 1:
The heater system uses multiple independent heater circuits that can be dynamically controlled to change the watt-density map on-the-fly. Each zone's power level can be adjusted independently by varying the voltage and current applied to that zone, enabling flexible adaptation to different process requirements while maintaining a manageable control structure through modular zone independence.
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 precise temperature control and repeatable watt-density maps across multiple units, enhancing the consistency and efficiency of semiconductor processing by allowing direct feedback from multiple thermocouples within each zone.
Implementation Method 1
A first thermocouple is mounted between the top plate layer and the intermediate plate layer and a second thermocouple is mounted between the intermediate plate layer and the bottom plate layer
Implementation Method 2
By varying the voltages and currents applied to the different circuits, you can change the power levels in the locations of the individual circuits. The locations of these specific circuits are called 'zones'. By increasing the voltage (and thereby the current as these heater elements are all resistance heaters) to a given zone, you increase the temperature in that zone
Data Source
AI summary
A multi-zone heater with a plurality of thermocouples such that different heater zones can be monitored for temperature independently. The independent thermocouples may have their leads routed out from the shaft of the heater in a channel that is closed with a joining process that results in hermetic seal adapted to withstand both the interior atmosphere of the shaft and the process chemicals in the process chamber. The thermocouple and its leads may be enclosed with a joining process in which a channel cover is brazed to the heater plate with aluminum.