Wafer Guide Chamfers to Prevent Cracking During Regeneration
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Solution Overview
Problem
In wafer support devices for SiC epitaxial growth apparatuses, the accumulation of reaction products on the wafer guide leads to damage during the removal process, particularly at right-angle intersections, which can cause cracks and hinder efficient regeneration.
Innovation Solution
The wafer support device incorporates first and second chamfered portions on the wafer guide, forming obtuse angles at intersections to alleviate stress concentration and prevent cracking, while maintaining optimal gas flow and reducing the need for extensive regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wafer guide is subjected to removal process at the intersection between upper surface and circumferential surface, then reaction products are removed to regenerate the wafer guide, but damage may occur due to stress concentration at right-angle intersections
Solution Approach 1:
The patent applies curvature by replacing the right-angle intersection with a chamfered portion that has a curved transition surface. This curved geometry eliminates stress concentration points that would otherwise form at sharp corners, allowing the wafer guide to withstand the mechanical stress of the removal process without cracking or damaging its structural integrity.
Solution Approach 2:
The chamfered portion is applied locally at the intersection between the upper surface and circumferential surface of the wafer guide. This localized modification specifically addresses the stress concentration issue at the critical intersection point while leaving the rest of the wafer guide structure unchanged, thereby maintaining overall structural integrity while improving local resistance to damage during regeneration.
2Ease of manufacture
If right-angle intersections are used in the wafer guide structure, then manufacturing is simpler, but cracks occur during regeneration and gas flow is hindered
Solution Approach 1:
The curved chamfered portion replaces the sharp right-angle intersection, creating a smooth transition that prevents crack initiation and propagation. This curved geometry ensures uniform gas flow distribution across the wafer guide surface, eliminating the gas flow irregularities that would otherwise occur at angular intersections.
3Productivity
If reaction products accumulate on the wafer guide, then the epitaxial growth process can proceed, but the accumulated products must be removed by polishing which causes damage at intersections
Solution Approach 1:
The chamfered portion with its curved geometry facilitates smoother removal of accumulated reaction products during the regeneration process. The curved surface allows polishing tools to work more effectively and uniformly, reducing the complexity and potential damage associated with removing deposits from angular intersections.
Data Source
AI summary
A wafer support device according to an embodiment provides a wafer support device. The wafer support device has a support table and a wafer guide portion. The wafer guide portion includes a first chamfered portion and a second chamfered portion. The support table has a support surface that supports the wafer. The wafer guide portion has an annular shape that surrounds the circumference of the wafer supported on the support surface with the central axis extending in a normal direction of the support surface as a center. The first chamfered portion connects an inner circumferential surface and an upper surface of the wafer guide portion, and extends upward from the inner circumferential surface toward the outer circumferential side. The second chamfered portion connects an outer circumferential surface and the upper surface of the wafer guide portion, and extends upward from the outer circumferential surface toward the inner circumferential side.