Self-centering wafer carrier with asymmetric edge geometry
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Solution Overview
Problem
Chemical vapor deposition (CVD) processes face challenges in achieving uniform thermal profiles across substrates due to non-uniform temperature distributions caused by wafer carrier rotation eccentricity, leading to asymmetric temperature profiles and non-uniform film deposition.
Innovation Solution
A self-centering wafer carrier system is designed with a wafer carrier and rotating tube having specific edge geometries and materials with different coefficients of thermal expansion, ensuring coincident alignment of the wafer carrier's central axis and the rotating tube's axis at process temperature, thereby reducing rotation eccentricity and creating an axially symmetric temperature profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional wafer carrier systems are used, then wafer processing is enabled, but rotation eccentricity causes non-uniform temperature distribution across the substrate
Solution Approach 1:
The wafer carrier edge is designed with an asymmetric geometry featuring a flat portion and a rounded portion, which asymmetrically engages with the rotating tube to generate a centering moment that counteracts rotation eccentricity, thereby achieving uniform temperature distribution and film deposition
Solution Approach 2:
The system exploits changes in thermal expansion parameters of the wafer carrier and rotating tube materials at processing temperatures to enable self-centering, where the differential expansion creates geometric conditions that align the wafer carrier center with the rotation axis
2Productivity
If wafer carrier rotation eccentricity is present, then wafer processing can proceed, but asymmetric temperature profiles result leading to non-uniform film deposition
Solution Approach 1:
The asymmetric edge geometry (flat portion at 0-45 degrees and rounded portion at 45-90 degrees) creates a centering moment during rotation that actively compensates for eccentricity, maintaining both processing capability and film uniformity simultaneously
3Ease of manufacture
If standard wafer carrier geometries are used, then manufacturing is simplified, but thermal expansion differences cause misalignment between wafer carrier central axis and rotating tube axis
Solution Approach 1:
The asymmetric edge geometry with specific angular divisions (flat portion 0-45 degrees, rounded portion 45-90 degrees) provides thermal expansion compensation while maintaining manufacturability through defined geometric features rather than complex adaptive mechanisms
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 self-centering wafer carrier system achieves a uniform temperature distribution across the substrate, improving film deposition uniformity and compensating for thermal non-uniformities using multi-zone heating elements.
Implementation Method 1
A self-centering wafer carrier system is designed with a wafer carrier and rotating tube having specific edge geometries and materials with different coefficients of thermal expansion, ensuring coincident alignment of the wafer carrier's central axis and the rotating tube's axis at process temperature
Data Source
AI summary
A self-centering wafer carrier system for a chemical vapor deposition (CVD) reactor includes a wafer carrier comprising an edge. The wafer carrier at least partially supports a wafer for CVD processing. A rotating tube comprises an edge that supports the wafer carrier during processing. An edge geometry of the wafer carrier and an edge geometry of the rotating tube being chosen to provide a coincident alignment of a central axis of the wafer carrier and a rotation axis of the rotating tube during process at a desired process temperature.