Preheating Ring Alignment for Uniform Epitaxial Wafer Thickness
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Solution Overview
Problem
Existing single-wafer vapor phase growth systems face challenges in controlling the thickness distribution of semiconductor single-crystal layers due to variations in temperature and gas flow, particularly at the substrate's peripheral edge, leading to uneven thickness and turbulence, which is exacerbated by changes in susceptor position and the absence of effective preheating rings.
Innovation Solution
A vapor phase growth system with a susceptor position changing mechanism and a preheating ring position changing mechanism that adjusts the height of the susceptor and preheating ring relative to the reaction vessel, allowing precise control of the source gas flow rate and distribution, thereby reducing thickness variations and turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the susceptor position is changed to adjust source gas flow rate, then the growth rate of semiconductor single-crystal layer is improved, but thickness distribution uniformity deteriorates
Solution Approach 1:
The preheating ring provides localized heating to the peripheral edge region of the substrate, creating a non-uniform temperature distribution that compensates for the non-uniform gas flow distribution caused by susceptor position changes. This local quality adjustment ensures uniform thickness distribution across the entire substrate surface.
2Productivity
If the source gas flow rate is increased to enhance growth rate, then productivity is improved, but turbulence and thickness variation increase
Solution Approach 1:
The preheating ring changes the temperature parameter in the peripheral edge region, creating a temperature gradient that stabilizes the gas flow and reduces turbulence. This parameter change allows high gas flow rates to be maintained while minimizing thickness variations and turbulence effects.
3Manufacturing precision
If the preheating ring is added to improve thickness distribution, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The preheating ring is integrated with the susceptor assembly, merging the preheating function with the existing substrate holding mechanism. This combination reduces device complexity by eliminating separate preheating components and simplifying the overall system structure.
4Productivity
If the susceptor is positioned closer to the reaction vessel wall to increase gas flow velocity, then growth rate is improved, but temperature distribution uniformity deteriorates
Solution Approach 1:
The preheating ring applies localized heating to the peripheral edge region where temperature drops occur due to proximity to reaction vessel walls. This local quality compensation ensures uniform temperature distribution across the substrate surface while maintaining high gas flow velocity for improved growth rate.
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 system effectively reduces thickness variations and turbulence in semiconductor single-crystal layers by aligning the preheating ring with the substrate surface, ensuring uniform heat distribution and stable gas flow, enhancing the quality and efficiency of epitaxial wafer production.
Implementation Method 1
a preheating ring arranged to surround a susceptor
Implementation Method 2
growing vapor phase of a semiconductor single-crystal thin film on a main surface of a single-crystal substrate
Implementation Method 3
source gas is introduced through a gas inlet port formed on one end side into a main body of the reaction vessel
Implementation Method 4
the single-crystal substrate mounted on a disk-shaped susceptor, which is rotationally driven
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
In a vapor phase growth system in which a preheating ring is provided around a susceptor, the flow rate of source gas can be adjusted by changing the position of the susceptor, and the effect on the film thickness variation of a semiconductor single-crystal layer due to the changes of the position of the susceptor is caused to be less likely to occur. The susceptor is raised/lowered by a susceptor position changing mechanism, and the height position of holding the susceptor in a reaction vessel body can be changed. Moreover, a preheating ring position changing mechanism is provided that changes the height position of holding the preheating ring in the reaction vessel body on the basis of raising/lowering of the preheating ring in accordance with the changes of the height position of holding the susceptor. The misalignment between the preheating ring and the substrate in the height direction may be reduced even if the susceptor holding position is changed, advantageously reducing the effects of insufficient heat equalization effect on the outer circumference of the substrate due to the preheating ring and the effect of turbulence in the source gas flow due to a step between the substrate main surface and the preheating ring, and thereby reducing the effects on the thickness variation of the resulting semiconductor single-crystal layer.