Edge Ring Lip Substrate Support for Thermal Uniformity
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Solution Overview
Problem
Existing support rings fail to provide adequate temperature uniformity across substrates during rapid thermal processing due to high temperature gradients and azimuthal variations caused by non-uniform convection and conduction heat losses, especially when heating rates exceed 200°C/second.
Innovation Solution
A substrate support ring with a ring body, an edge lip extending radially inwardly, and three or more substrate supports spaced equally around the circumference, which make discrete point contacts with the substrate to reduce thermal conduction and minimize light leakage, thereby minimizing temperature gradients and achieving uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the substrate is supported by an annular lip contacting the edge of the substrate, then temperature gradients are reduced and radiant energy leakage is prevented, but temperature uniformity deteriorates during rapid heating processes due to high heating rates generating excessive temperature gradients along the substrate periphery
Solution Approach 1:
The continuous annular lip is segmented into discrete contact points by forming protrusions that extend from the lip. This segmentation reduces the contact area between the support ring and substrate, minimizing thermal conduction heat loss while still providing adequate mechanical support and maintaining temperature uniformity during rapid heating processes.
2Temperature
If the substrate and support ring overlap near the edge of the substrate, then radiant energy leakage is prevented, but azimuthal temperature variations are caused by variable solid-solid thermal contact
Solution Approach 1:
The continuous contact surface is segmented into discrete protrusion contact points, which reduces azimuthal variations in thermal contact. This segmentation ensures more uniform heat distribution around the substrate periphery while maintaining adequate support.
Solution Approach 2:
The support ring features localized protrusions with specific geometric properties (height, spacing, contact area) that are optimized to provide consistent thermal contact characteristics around the entire substrate periphery, reducing azimuthal temperature variations.
3Strength
If the annular lip contacts the substrate edge, then mechanical support is provided, but excessive temperature gradients are generated during rapid thermal processing due to non-uniform convection and conduction heat losses
Solution Approach 1:
The continuous annular lip is divided into discrete protrusions that provide mechanical support at specific contact points. This segmentation reduces the thermal conduction path while maintaining adequate mechanical support, thereby minimizing temperature gradients during rapid thermal processing.
Solution Approach 2:
The protrusions are designed with dimensions and spacing that allow dynamic thermal management during rapid heating, balancing mechanical support requirements with thermal isolation to prevent excessive temperature gradients.
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 solution effectively reduces temperature gradients and azimuthal variations, enabling more uniform thermal processing across the substrate with reduced heat loss and improved pyrometry accuracy, even at high heating rates.
Implementation Method 1
make discrete point contacts with the substrate to reduce thermal conduction and minimize light leakage
Implementation Method 2
minimized enough to prevent significant light passage
Implementation Method 3
heating the substrate by directing radiant energy towards the substrate
Data Source
AI summary
Embodiments of the invention generally relate to a support ring to support a substrate in a process chamber. In one embodiment, the support ring comprises an inner ring, an outer ring connecting to an outer perimeter of the inner ring through a flat portion, an edge lip extending radially inwardly from an inner perimeter of the inner ring to form a supporting ledge to support the substrate, and a substrate support formed on a top surface of the edge lip. The substrate support may include multiple projections extending upwardly and perpendicularly from a top surface of the edge lip, or multiple U-shaped clips securable to an edge portion of the edge lip. The substrate support thermally disconnects the substrate from the edge lip to prevent heat loss through the edge lip, resulting in an improved temperature profile across the substrate with a minimum edge temperature gradient.