Radial Thermal Chokes in High Temperature Electrostatic Chuck
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Solution Overview
Problem
Semiconductor wafer processing tools face challenges in maintaining thermal uniformity across the wafer support due to excessive heat flow, which requires larger heaters and can lead to logistical issues and thermal expansion problems.
Innovation Solution
The implementation of radial thermal chokes in the heat flow path from the wafer support to the pedestal, combined with high-temperature coolers, to manage heat flow effectively and maintain thermal uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the wafer support is heated to maintain process temperature, then the wafer can be processed, but excessive heat flow causes thermal expansion problems and requires larger heaters
Solution Approach 1:
The cooling plate is divided into multiple zones with different thermal conductivities: a first cooling zone with higher thermal conductivity and a second cooling zone with lower thermal conductivity. This segmentation allows different regions to handle heat flow differently, maintaining wafer support temperature while controlling thermal expansion through optimized heat distribution patterns.
Solution Approach 2:
Different regions of the cooling plate are assigned different thermal properties - the first cooling zone has higher thermal conductivity for efficient heat removal, while the second cooling zone has lower thermal conductivity for controlled heat management. This local quality variation enables precise thermal control to prevent excessive thermal expansion while maintaining processing temperature.
2Temperature
If larger heaters are used to compensate for heat loss, then temperature maintenance is improved, but device complexity and logistical issues increase
Solution Approach 1:
The cooling plate is segmented into zones with different thermal conductivities to optimize heat flow management. This segmentation creates more efficient thermal pathways that reduce overall heat loss, allowing smaller heaters to maintain temperature uniformity across the wafer support without increasing device complexity.
Solution Approach 2:
The cooling plate uses composite construction with regions of different thermal conductivities, combining materials or structures that provide both efficient heat removal and controlled thermal management. This composite approach improves temperature uniformity while avoiding the need for larger, more complex heater systems.
3Temperature
If thermal contact area between cooling plate and wafer support is increased, then cooling efficiency is improved, but thermal chokes become less effective
Solution Approach 1:
The thermal contact interface is segmented into different zones: a first thermal contact area with higher thermal conductivity for efficient cooling, and a second thermal contact area with lower thermal conductivity to maintain thermal choke effectiveness. This segmentation allows the system to achieve both improved cooling efficiency and maintained thermal choke reliability simultaneously.
Solution Approach 2:
Different regions of the thermal contact interface have different thermal properties - the first thermal contact area provides high thermal conductivity for efficient heat removal, while the second thermal contact area maintains lower thermal conductivity to preserve thermal choke functionality. This local quality variation resolves the contradiction between cooling efficiency and thermal choke effectiveness.
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 solution provides a wide range of cooling and heating performance, reducing the need for larger heaters and minimizing thermal expansion issues, while effectively managing heat flow during both heating and cooling processes.
Implementation Method 1
a first radial thermal choke in a region outside of the nominal outer diameter of the first thermal contact area
Implementation Method 2
radial thermal chokes in the heat flow path from the wafer support to the pedestal
Implementation Method 3
ESCs may incorporate electrodes used to generate electromagnetic fields via radio frequency (RF)
Implementation Method 4
An ESC may also include a heater to heat a wafer prior to or during processing
Data Source
AI summary
A wafer support assembly including a wafer support and cooling plate with radial thermal chokes is provided. The cooling plate and wafer support may have limited contact and may not contact each other outside of certain limited thermal contact patches. The thermal contact patches may generally define one or more radial thermal choke regions. In some implementations, high- and low-temperature cooling systems may be placed at one or more locations across the cooling plate to assist in temperature management.