SiC Epitaxial Wafer Notch Layout for Thickness Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variations in thickness or shape near the notch of a SiC epitaxial wafer can cause failure in accurately reading the notch position during the fabrication of SiC devices, leading to misalignment and defects.
Innovation Solution
A SiC epitaxial wafer design with a notch that has specific side orientations and measurement points, ensuring a film thickness variation of less than 10% between designated measurement points, and a susceptor with a slit to supply purge gas evenly on both sides of the notch, reducing thickness variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a notch is formed in the SiC epitaxial wafer to determine crystal axis orientation, then the orientation control is improved, but film thickness variation near the notch increases
Solution Approach 1:
The patent applies local quality by specifying different film thickness requirements for different regions of the wafer. The claim establishes that while overall film thickness uniformity is important, the critical region is near the notch where thickness variation between specific measurement points must be controlled within 10%. This localized quality control ensures laser reading accuracy in the notch region without requiring perfect uniformity across the entire wafer surface.
2Object-generated harmful factors
If gas is supplied to the back surface of the SiC substrate to prevent deposits, then deposit adhesion is reduced, but film thickness uniformity near the notch deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the gas supply conditions during epitaxial growth. Specifically, it controls the gas flow rate, temperature distribution, and pressure parameters to achieve a balance where sufficient gas reaches the back surface to prevent deposit adhesion, while the overall film thickness uniformity including the notch region is maintained within acceptable limits. This involves adjusting multiple process parameters simultaneously to resolve the contradiction.
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
The design achieves high uniformity in the SiC epitaxial layer thickness near the notch, enabling precise control of position and orientation, reducing defects in SiC device fabrication.
Implementation Method 1
The SiC epitaxial wafer is obtained by laminating the SiC epitaxial layer on a surface of a SiC substrate
Implementation Method 2
supplying gas to a back surface of the SiC substrate in order to prevent deposits from adhering to the back surface of the SiC substrate
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The SiC epitaxial wafer has a notch. The notch has a first side and a second side that connect the innermost point of the notch and an outer circumference of the wafer. The first side is in a [-1-120] direction from the innermost point, and the second side is in a [11-20] direction from the innermost point. A position of 0.5 mm from a middle point of the first side in a [-1100] direction is set as a first measurement point, and a position of 0.5 mm from a middle point of the second side in the [-1100] direction is set as a second measurement point. A film thickness variation at the first measurement point and the second measurement point of the SiC epitaxial layer of the SiC epitaxial wafer is less than 10%.