SiC Epitaxial Wafer Support Geometry for Epi Crown Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
SiC epitaxial wafers face challenges with the growth of an epi crown on the outer circumferential portion, leading to triangular defects and increased risk of cracking during processing. Additionally, the existing methods for removing the epi crown through polishing can result in reduced yield and damaged surfaces.
Innovation Solution
The solution involves using a wafer support base with an annular wall surface that surrounds the SiC single crystal substrate, where the substrate is placed with its main surface inclined and partially disposed outward of the annular wall. This configuration suppresses the growth of the epi crown by hindering gas supply to the outer circumferential portion and reduces triangular defects by minimizing dust generation from substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If gas supply is increased to promote epitaxial growth, then film thickness is improved, but epi crown growth on outer circumferential portion increases
Solution Approach 1:
The patent applies local quality by creating different gas supply conditions in different regions of the substrate. The gas supply amount is specifically controlled to be smaller in the outer circumferential region compared to the central region, resulting in different epitaxial growth rates that suppress epi crown formation while maintaining adequate film thickness.
Solution Approach 2:
The patent implements dynamics by making the gas supply amount variable across the substrate surface. By adjusting the gas supply distribution dynamically (with higher supply at the center and lower supply at the periphery), the system achieves uniform film thickness without excessive epi crown growth.
2Shape
If polishing is used to remove epi crown, then surface flatness is improved, but yield decreases due to cracking and surface damage
Solution Approach 1:
The patent applies preliminary anti-action by suppressing epi crown formation during the epitaxial growth process itself, rather than attempting to remove it afterward. By controlling gas supply to prevent excessive growth at the outer circumferential portion, the need for aggressive polishing is eliminated, thereby avoiding yield loss from cracking and surface damage.
Solution Approach 2:
The patent converts the potential harm of reduced gas supply at the periphery (which could lead to thin film formation) into a benefit by precisely controlling the gas distribution. This creates a natural suppression of epi crown growth that maintains surface flatness without requiring damaging mechanical removal processes.
3Volume of moving object
If substrate temperature is increased to accelerate epitaxial growth, then film thickness is improved, but triangular defects increase due to substrate deformation
Solution Approach 1:
The patent applies local quality by creating different gas supply conditions in different regions of the substrate. The gas supply amount is specifically controlled to be smaller in the outer circumferential region compared to the central region, resulting in different epitaxial growth rates that suppress epi crown formation while maintaining adequate film thickness.
Solution Approach 2:
The patent implements dynamics by making the gas supply amount variable across the substrate surface. By adjusting the gas supply distribution dynamically (with higher supply at the center and lower supply at the periphery), the system achieves uniform film thickness without excessive epi crown growth.
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 results in a SiC epitaxial wafer with a suppressed epi crown growth, no triangular defects within 1 mm from the edge, and a reduced likelihood of cracking during processing, thereby enhancing the yield and quality of the wafer.
Implementation Method 1
when a main surface of a SiC single crystal substrate is heated to a high temperature, the main surface deforms in a direction in which the main surface becomes non-planar with respect to a wafer support base
Implementation Method 2
a SiC epitaxial film is grown on a main surface of a SiC single crystal substrate
Data Source
AI summary
A SiC epitaxial wafer (1) of the present invention is a SiC epitaxial wafer having a SiC epitaxial film (E) on a main surface of a SiC single crystal substrate (W), in which an orientation flat or a notch is provided thereon, a height (h) of an epi crown (Ec), which is present on an outer circumferential portion of the SiC epitaxial film, with respect to a level surface of the SiC epitaxial film (E) at a position on a wafer diameter intersecting a longitudinal center of the orientation flat or a groove bottom of the notch is 30% or less of a thickness (Et) of the SiC epitaxial film (E) at a wafer center (C), and the SiC epitaxial film (E) does not have triangular defects in a region less than 1 mm from an edge in a direction toward the wafer center.