SiC Single Crystal Surface Processing to Flatten Atomic Arrangement Plane
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Solution Overview
Problem
It is challenging to sufficiently suppress basal plane dislocation (BPD) in SiC wafers during crystal growth, as existing methods struggle to control stress and curvature of the atomic arrangement plane, leading to defects that affect the quality of SiC epitaxial wafers.
Innovation Solution
A method involving surface processing of the SiC single crystal attachment plane, where the shape of the atomic arrangement plane is measured and processed to introduce a processing distortion opposite to its curvature, using grinding techniques to adjust the surface state and warp amount, thereby flattening the atomic arrangement plane during crystal growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If stress applied to SiC single crystal during crystal growth is controlled by adjusting thermal expansion coefficients, then outer shape warp and undulation are reduced, but basal plane dislocation (BPD) density cannot be sufficiently suppressed
Solution Approach 1:
The attachment plane of the SiC single crystal is subjected to surface processing (grinding) before crystal growth to flatten the atomic arrangement plane. This preliminary action prevents BPD formation during subsequent crystal growth, addressing the limitation of controlling only outer shape warp.
Solution Approach 2:
Surface processing is applied specifically to the attachment plane (first plane) rather than the entire crystal. This localized processing flattens the atomic arrangement plane at the attachment interface where BPDs originate, without affecting other regions of the crystal.
2Reliability
If surface processing is applied to flatten atomic arrangement plane, then BPD density is reduced, but manufacturing process complexity increases
Solution Approach 1:
The surface state parameters of the attachment plane are changed through controlled grinding to create a flattened atomic arrangement. By adjusting grinding conditions (grit size, pressure, duration), the atomic arrangement plane curvature is optimized to minimize BPD formation without requiring complex multi-step processing.
3Manufacturing precision
If grinding is performed on attachment plane, then atomic arrangement plane is flattened, but manufacturing time increases
Solution Approach 1:
Grinding is applied to the attachment plane to a degree that flattens the atomic arrangement plane, but not necessarily to achieve complete surface flatness. This partial action is sufficient to prevent BPD formation while minimizing processing time compared to exhaustive surface preparation.
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 approach effectively reduces BPD density in SiC wafers, enhancing the quality of SiC epitaxial wafers by minimizing curvature and stress, resulting in improved forward characteristics and reduced cracking during crystal growth.
Implementation Method 1
a difference is given to a surface state between the first plane and the second plane facing the first plane, and the atomic arrangement plane is flattened by Twyman's effect
Data Source
AI summary
A method of processing a SiC single crystal includes a measuring step of measuring a shape of an atomic arrangement plane of the SiC single crystal along at least a first direction passing through a center in plan view and a second direction orthogonal to the first direction; and a surface processing step of processing a first plane serving as an attachment plane of the SiC single crystal, in which the surface processing step includes a grinding step of grinding the first plane, and in the grinding step, a difference is given to a surface state between the first plane and a second plane facing the first plane, and the atomic arrangement plane is flattened by Twyman's effect.