SiC Wafer Mounting Structure for Epi-Crown Suppression
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Solution Overview
Problem
Existing wafer mounting apparatuses for SiC epitaxial growth suffer from non-uniformity in the in-plane thickness of the epitaxial layer due to the epi-crown phenomenon, which is exacerbated by the wafer susceptor top distance and counterbore design, leading to reduced yield and efficiency in semiconductor chip production.
Innovation Solution
A wafer mounting apparatus with a disk, ring, and lift-up members that support the semiconductor wafer from the back surface, featuring an annular groove and cutout-side protruding wall to create a space for gas release, thereby reducing the epi-crown phenomenon and enhancing in-plane uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the wafer susceptor top distance is set to be relatively large, then the epi thickness in the peripheral region is affected, but in-plane uniformity of the epi thickness is deteriorated
Solution Approach 1:
The susceptor surface is segmented into multiple functional zones: a central raised portion for uniform gas distribution, peripheral grooves for gas diversion, and elevated edges for containment. This segmentation allows different regions to perform specialized functions that collectively improve in-plane uniformity while maintaining an optimized wafer susceptor top distance
Solution Approach 2:
Different regions of the susceptor are given different local qualities through varying heights and surface features. The central region has a raised surface for direct gas exposure, while peripheral regions have grooves and elevated edges with different geometries. This local differentiation enables precise control of gas flow and epitaxial growth conditions across the wafer surface
2Device complexity
If a conventional susceptor design is used, then the structure is simple, but the epi-crown phenomenon occurs causing non-uniform epitaxial layer thickness
Solution Approach 1:
The susceptor design incorporates preliminary anti-action by pre-configuring gas flow control features (grooves, raised portions, elevated edges) that prevent the epi-crown phenomenon before it occurs. The peripheral grooves preemptively divert excess gas away from edge regions, while elevated edges contain and redirect gas flow, thereby preventing non-uniform deposition patterns from developing
Solution Approach 2:
The susceptor acts as an intermediary device between the gas source and the wafer surface. Through its specially designed surface features including grooves and raised portions, it mediates gas flow distribution to achieve uniform epitaxial growth. The elevated edges and peripheral grooves serve as intermediate structures that control and optimize the interaction between gas and wafer surface
Data Source
AI summary
A ring is mounted on a satellite disk in such a manner that a terrace portion is supported by a peripheral portion front surface of a peripheral portion of the satellite disk. A SiC wafer is mounted on three lift-up pins mounted on a front surface of the terrace portion. A disk upper space is formed between a front surface of an upper layer portion of the satellite disk and a back surface of the SiC wafer. A wall portion of the ring is disposed to face an orientation flat portion via a gap space. On the back surface side of the SiC wafer, an annular groove is formed along an outer periphery of an opening in plan view, and one side surface of the groove is a side surface of the upper layer portion.