Support Cylinder Thermal Expansion Mismatch
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Solution Overview
Problem
The mismatch in thermal expansion coefficients between the polysilicon layer and opaque quartz in traditional support cylinders for thermal processing chambers leads to cracking and contamination issues during high-temperature processing.
Innovation Solution
A support cylinder made of synthetic black quartz with a clear fused quartz coating, which has a similar thermal expansion coefficient, is used to prevent cracking and contamination, and is designed with beveled and rounded surfaces to minimize mechanical stress and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polysilicon layer is coated on opaque quartz to provide light shielding, then light shielding properties are improved, but thermal expansion mismatch causes cracking and contamination under high temperature
Solution Approach 1:
The patent changes the material parameter (thermal expansion coefficient) by selecting fused quartz instead of opaque quartz. Fused quartz has a thermal expansion coefficient that matches polysilicon, eliminating the thermal expansion mismatch that causes cracking during thermal cycling while maintaining light shielding properties.
Solution Approach 2:
The patent uses a composite structure of polysilicon layer on fused quartz substrate. This composite material combination provides both light shielding from the polysilicon and thermal stability from the fused quartz, preventing the cracking and contamination issues that occur with opaque quartz.
2Illumination intensity
If opaque quartz is used for the support cylinder, then light shielding is provided, but thermal expansion mismatch with polysilicon layer causes peeling and particle contamination
Solution Approach 1:
The patent changes the thermal expansion parameter of the quartz material from opaque quartz to fused quartz. This parameter change ensures thermal compatibility with the polysilicon coating, preventing peeling and particle contamination during high-temperature processing while maintaining light shielding.
3Stability of the object's composition
If a rotatable tubular support cylinder is used to rotate the substrate, then temperature uniformity is improved, but thermal expansion mismatch causes structural failure
Solution Approach 1:
The patent changes the material composition from opaque quartz to fused quartz, altering the thermal expansion parameter to match polysilicon. This enables the support cylinder to maintain structural integrity during rotation and thermal cycling while preserving the temperature uniformity benefit.
4Illumination intensity
If polysilicon layer is applied to opaque quartz, then opacity is maintained, but cracking occurs under thermal stress compromising opacity and causing contamination
Solution Approach 1:
The patent changes the substrate material from opaque quartz to fused quartz, modifying the thermal expansion parameter to match polysilicon. This enables the polysilicon coating to remain intact without cracking during thermal processing, maintaining both opacity and manufacturing precision.
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 solution ensures thermal stability and prevents particle contamination by matching thermal expansion coefficients and reducing mechanical stress, maintaining the opacity and light shielding properties of the support cylinder during thermal processing.
Implementation Method 1
The mismatch in thermal expansion coefficients of polysilicon layer and opaque quartz under high temperatures can cause cracking in the polysilicon layer and/or in the vicinity of the interface between the polysilicon layer and the opaque quartz
Implementation Method 2
a first end having a first beveled portion, a first rounded portion, and a first planar portion connecting the first beveled portion and the first rounded portion
Implementation Method 3
The support cylinder is made of opaque quartz to provide light shielding properties and low thermal conductivity such that heat from the processing area and/or the heating source is substantially attenuated near the support cylinder
Implementation Method 4
The support cylinder is made of opaque quartz to provide light shielding properties
Data Source
AI summary
Embodiments of the disclosure generally relate to a support cylinder used in a thermal process chamber. In one embodiment, the support cylinder includes a hollow cylindrical body comprising an inner peripheral surface, an outer peripheral surface parallel to the inner peripheral surface, wherein the inner peripheral surface and the outer peripheral surface extend along a direction parallel to a longitudinal axis of the support cylinder, and a lateral portion extending radially from the outer peripheral surface to the inner peripheral surface, wherein the lateral portion comprises a first end having a first beveled portion, a first rounded portion, and a first planar portion connecting the first beveled portion and the first rounded portion, and a second end opposing the first end, the second end having a second beveled portion, a second rounded portion, and a second planar portion connecting the second beveled portion and the second rounded portion.