Electrostatic Chuck Support Assembly Thermal Tuning
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Solution Overview
Problem
The thermal conductivity variations in electrostatic chuck support assemblies lead to undesirable process variations during semiconductor wafer processing, requiring improved temperature uniformity and repeatability.
Innovation Solution
A method to tune the thermal conductivity of the electrostatic chuck support assembly by measuring temperature at multiple sites, determining fractional reductions in area, and removing material from the surface to create a cell structure with specific hole patterns, thereby adjusting the thermal conductivity to achieve a target equilibrium temperature profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If material is removed from the support assembly surface to decrease thermal conductivity, then temperature uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
The support assembly surface is divided into multiple cells, with material removal patterns (holes, grooves, or recesses) applied selectively to specific cells based on local temperature measurements. This segmentation allows precise control of thermal conductivity in different regions to achieve overall temperature uniformity while maintaining manufacturability through standardized cell-based processing.
Solution Approach 2:
Material removal is applied non-uniformly across the support assembly surface, with different cell configurations (number, size, and distribution of holes or grooves) in different regions. This local quality approach addresses specific hot or cold spots by modifying thermal conductivity only where needed, rather than applying uniform changes across the entire surface.
2Reliability
If material is removed from the support assembly surface, then thermal conductivity is decreased, but structural strength is reduced
Solution Approach 1:
The support assembly incorporates controlled porosity through holes, grooves, or recesses in the removed material cells. This porous structure decreases thermal conductivity in specific regions while maintaining sufficient structural strength through the remaining material framework. The porous design allows thermal management without completely compromising mechanical integrity.
Solution Approach 2:
Material removal is applied partially rather than completely across the support assembly. Only specific cells have material removed, and the extent of removal is controlled to achieve the desired thermal conductivity reduction while preserving sufficient material to maintain structural strength. This partial action approach balances thermal performance with mechanical requirements.
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 approach enhances the equilibrium temperature uniformity of the electrostatic chuck support assembly, ensuring that the temperature profile meets specifications, which is crucial for precise semiconductor processing.
Implementation Method 1
the electrostatic chuck, provides more uniform clamping than chucks employing mechanical clamping, and can operate in vacuum chambers where a vacuum chuck cannot be used
Implementation Method 2
variations in aspects of the thermal conductivity of the assembly can cause undesirable process variations within a wafer
Data Source
AI summary
A method of tuning the thermal conductivity of an electrostatic chuck (ESC) support assembly comprises measuring the temperature at a plurality of sites on a support assembly surface in which each site is associated with a given cell, determining from the measurements any fractional reduction in area suggested for each cell, and removing material from the support assembly surface within each cell in accordance with the suggested fractional reduction in order to decrease thermal conductivity in that cell. The material removal can result in an improvement to the equilibrium temperature uniformity of the electrostatic chuck support assembly at the chuck surface of an electrostatic chuck bonded to the support assembly surface, or can result in an equilibrium temperature profile of the ESC support assembly which approaches or achieves a target equilibrium temperature profile. Thermal conductivity tuning can thus take place by a method comprising defining a cell structure, determining the target areal density of each cell and removing a fractional area of material to achieve the target areal density for that cell. Material removal can be effected by drilling, routing, laser machining or grit blast machining on an X-Y table.