Susceptor Contact Structure for Wafer Temperature Uniformity
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Solution Overview
Problem
Existing susceptors for thermal processing of semiconductor substrates suffer from temperature non-uniformities across the substrate surface, particularly near the edges and center, which affect the quality of deposited layers.
Innovation Solution
The susceptor design includes structures such as wedges, bumps, and insulating separators to reduce the contacting surface area between the substrate and the susceptor, primarily by using elevated features and thermal breaks to minimize conductive heat transfer and enhance radiant heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate contacts the susceptor over a large surface area, then mechanical support is improved, but temperature uniformity deteriorates due to conductive heating and hotspots
Solution Approach 1:
The susceptor surface is segmented into multiple discrete contact points (elevated structures such as bumps, ridges, or posts) rather than a continuous contact surface. This segmentation reduces the total contact area between substrate and susceptor, minimizing conductive heat transfer while maintaining mechanical support through distributed point contacts.
Solution Approach 2:
An intermediate layer or gap is introduced between the substrate and susceptor at contact points. This intermediary reduces direct thermal conduction while allowing mechanical support, effectively decoupling the thermal and mechanical functions. The elevated structures create controlled thermal barriers while maintaining structural integrity.
2Use of energy by moving object
If heating lamps are positioned close to the substrate, then heating efficiency is improved, but temperature non-uniformity worsens near substrate edges
Solution Approach 1:
The susceptor design incorporates localized elevated structures at specific positions (e.g., near substrate edges) to create non-uniform contact patterns. This local modification of contact characteristics compensates for the non-uniform heating distribution, reducing edge hotspots while maintaining overall heating efficiency through the close positioning of lamps.
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 design improves thermal uniformity by reducing conductive heating, preventing hotspots, and ensuring more uniform temperature control across the substrate surface, leading to higher quality deposition processes.
Implementation Method 1
The heated susceptor can then transfer heat to the substrate, primarily by radiation emitted by the susceptor
Implementation Method 2
one or more structures for reducing a contacting surface area between a substrate and the susceptor when the substrate is supported by the susceptor
Data Source
AI summary
In one embodiment, a susceptor for thermal processing is provided. The susceptor includes an outer rim surrounding and coupled to an inner dish, the outer rim having an inner edge and an outer edge. The susceptor further includes one or more structures for reducing a contacting surface area between a substrate and the susceptor when the substrate is supported by the susceptor. At least one of the one or more structures is coupled to the inner dish proximate the inner edge of the outer rim.