Exclusion Ring Undercut Groove Thermal Isolation
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Solution Overview
Problem
Conventional exclusion rings in multi-station substrate processing modules experience thermal shock and premature failure due to significant temperature differentials between processing stations, as they are made from materials with low thermal conductivity like aluminum oxide, leading to cracking and fracture.
Innovation Solution
The exclusion ring design incorporates an undercut groove that thermally isolates the inner edge from the outer edge, using a thermal bridge and support formations to distribute heat evenly, and includes gas exit ports to manage thermal gradients, reducing stress build-up and extending the ring's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional exclusion ring made from aluminum oxide is used to transfer substrates between stations with different temperatures, then the ring can be manufactured with ease, but the ring experiences significant thermal shock leading to cracking and premature failure
Solution Approach 1:
The exclusion ring is segmented into multiple radial sections with different thermal conductivities. The inner section (closer to substrate center) has lower thermal conductivity to reduce heat transfer to the substrate, while the outer section has higher thermal conductivity to dissipate heat from the ring structure itself. This segmentation allows the ring to manage thermal gradients without compromising structural integrity or manufacturing feasibility.
Solution Approach 2:
Different regions of the exclusion ring are assigned different thermal conductivity properties to address local thermal management needs. The inner radial region uses material with lower thermal conductivity to protect the substrate from excessive heat, while the outer radial region uses material with higher thermal conductivity to maintain ring structural stability. This local quality differentiation resolves the thermal shock problem while maintaining ease of manufacture through modular material selection.
2Temperature
If the exclusion ring is made from material with low thermal conductivity to protect the substrate, then substrate temperature control is improved, but the ring itself experiences thermal shock and cracking
Solution Approach 1:
The ring is divided radially into sections with different thermal conductivities. The inner section uses lower thermal conductivity material to protect the substrate from heat, while the outer section uses higher thermal conductivity material to prevent thermal shock cracking in the ring structure. This segmentation simultaneously achieves both substrate temperature control and ring strength preservation.
Solution Approach 2:
The exclusion ring is constructed as a composite structure with multiple materials of different thermal conductivities arranged in specific radial patterns. This composite design allows the ring to exhibit differentiated thermal behavior - protecting the substrate where needed while maintaining structural integrity in other regions, thereby resolving the contradiction between substrate temperature control and ring strength.
3Manufacturing precision
If the exclusion ring directly contacts the hot pedestal to support the substrate, then substrate positioning accuracy is improved, but the ring experiences significant temperature differential causing thermal imbalance
Solution Approach 1:
The exclusion ring contacts the pedestal through specific segmented regions rather than uniformly across its entire circumference. These contact segments are strategically positioned and sized to provide stable substrate positioning while minimizing the total contact area that would transmit heat to the ring. This segmented contact approach maintains positioning accuracy while reducing thermal imbalance.
Solution Approach 2:
The pedestal contact regions of the exclusion ring are designed with local quality differentiation - specific zones have enhanced thermal management properties or reduced thermal conductivity to minimize heat absorption from the pedestal while maintaining mechanical support function. This allows the ring to achieve accurate substrate positioning without experiencing excessive temperature differentials that would cause thermal imbalance.
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 significantly reduces thermal gradients, resulting in a 40-50% decrease in stress build-up and a failure rate of 0.005% after over 1000 thermal cycles, enhancing the ring's durability and operational longevity.
Implementation Method 1
the undercut at least partially thermally isolates the inner edge portion from the outer edge of the substrate
Implementation Method 2
using a thermal bridge and support formations to distribute heat evenly
Data Source
AI summary
In some examples, an exclusion ring locates a substrate on a substrate-support assembly in a processing chamber. An example exclusion ring comprises an inner edge portion to cover an edge of a substrate in the processing chamber and an outer edge portion to support the exclusion ring on the substrate support assembly in the processing chamber. The outer edge portion may include an outer edge of the exclusion ring. A separation zone extending between the inner edge portion and the outer edge of the exclusion ring includes an undercut in an undersurface of the exclusion ring. In some examples, a cooling gas is directed at the exclusion ring while the exclusion ring is located at a station or during an indexing operation performed by the exclusion ring within a processing tool.