Low Thermal Mass Wafer Support With Recessed Surface
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Solution Overview
Problem
Existing semiconductor wafer supports for high-temperature heat treatment in vertical furnaces often cause contamination and slip due to contact with hole edges and inadequate stress relief, leading to production issues like photolithography overlay failures and yield losses.
Innovation Solution
A wafer support system featuring plates with a recessed surface and no holes on the support surface, combined with vertically extending fingers and platforms, reduces thermal mass and minimizes contact risks, preventing contamination and slip by distributing stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If holes are present on the support surface to reduce thermal mass, then thermal mass is reduced, but contamination occurs due to contact with hole edges
Solution Approach 1:
The patent extracts the holes from the support surface where they would contact the wafer, relocating them to the recessed surface instead. This separation maintains the thermal mass reduction benefit while eliminating the contamination source, as the recessed surface is spaced away from the wafer contact area.
Solution Approach 2:
The patent applies different structural qualities to different regions: the support surface remains solid and hole-free to prevent contamination, while the recessed surface contains holes for thermal mass reduction. This localized differentiation allows each surface to optimize its specific function without compromising the other.
2Strength
If conventional support structures are used to provide adequate support, then mechanical support is sufficient, but slip occurs due to local gravitational and thermal stresses
Solution Approach 1:
The support structure is segmented into multiple functional zones: the support surface for stable wafer contact, the recessed surface for stress relief, and holes in the recessed surface for thermal management. This segmentation allows each zone to address specific aspects of wafer stability without interfering with others.
Solution Approach 2:
The recessed surface acts as a pre-positioned stress-relief zone that cushioning thermal and gravitational stresses before they can cause slip. By providing this intermediate recessed area with holes, the structure preemptively manages stress distribution to prevent wafer instability.
3Area of stationary object
If wafer holder platforms are used to increase supported area, then support area is increased, but device complexity increases
Solution Approach 1:
The plate structure serves multiple functions simultaneously: the support surface provides stable contact, the recessed surface offers stress relief, and the holes in the recessed surface reduce thermal mass. This multi-functionality eliminates the need for separate wafer holder platforms, reducing overall structural complexity while maintaining adequate support area.
Data Source
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AI summary
A support for a semiconductor wafer includes a plate having a support surface for supporting the wafer and a recessed surface spaced from the support surface and spaced from the wafer. A plurality of holes extends from the recessed surface, and the support surface is free of holes to inhibit contamination of the wafer.