Movable Preheating Ring Alignment for Uniform Epitaxial Wafers
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Solution Overview
Problem
In single-wafer vapor phase growth systems, the thickness distribution of semiconductor single-crystal layers is affected by temperature and gas flow variations, leading to uneven thickness and turbulence issues due to fixed preheating ring positions and susceptor height adjustments, which complicates achieving uniform epitaxial wafer quality.
Innovation Solution
A vapor phase growth system with a susceptor position changing mechanism and a preheating ring position changing mechanism that allows adjustable height settings to align the preheating ring with the substrate, reducing misalignment and turbulence, thereby controlling the source gas flow rate and ensuring uniform heating and growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the susceptor height is adjusted to reduce the source gas distribution space height, then the source gas flow rate on the substrate main surface increases and growth rate improves, but the preheating ring may become misaligned with the substrate causing turbulence and thickness variation
Solution Approach 1:
The preheating ring is designed to move vertically along with the susceptor, changing from a fixed position to a dynamic position that adapts to susceptor height adjustments. This ensures the preheating ring remains properly aligned with the substrate throughout the growth process, eliminating turbulence caused by misalignment while maintaining the benefits of reduced source gas distribution space height for improved growth rate.
2Productivity
If the source gas flow rate is increased to enhance growth rate, then the chemical reaction efficiency improves, but the temperature of the substrate main surface decreases due to enhanced heat transfer
Solution Approach 1:
The preheating ring provides preliminary heating to the substrate main surface before the source gas arrives. By preheating the substrate surface, the system compensates for the cooling effect caused by high-velocity source gas flow, maintaining optimal reaction temperature while achieving high growth rates through increased source gas flow rate.
3Device complexity
If the preheating ring position is fixed, then the system structure is simple, but adjusting susceptor height causes misalignment between the preheating ring and substrate leading to turbulence
Solution Approach 1:
The preheating ring movement mechanism is merged with the susceptor positioning system. Both components share the same vertical movement mechanism, so that when the susceptor is raised or lowered, the preheating ring automatically follows the same movement. This integration ensures continuous alignment between the preheating ring and substrate without requiring separate control systems, maintaining relatively simple system structure while achieving precise alignment.
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 configuration reduces thickness variations and improves the uniformity of semiconductor single-crystal layers by aligning the preheating ring with the substrate, enhancing heat distribution and gas flow, resulting in more consistent epitaxial wafer production.
Implementation Method 1
a preheating ring position changing mechanism, which changes a height position of holding the preheating ring in the reaction vessel body on the basis of raising and lowering of the preheating ring
Implementation Method 2
a susceptor position changing mechanism, which changes a height position of holding the susceptor in the reaction vessel body on the basis of raising and lowering of the susceptor
Implementation Method 3
a source gas for forming a semiconductor single-crystal thin film is introduced through the gas inlet port into the main body of the reaction vessel, and the source gas flows along the main surface of the single-crystal substrate
Implementation Method 4
Vapor phase growth system and method of producing epitaxial wafer... forming a semiconductor single-crystal thin film on a main surface of a single-crystal substrate
Data Source
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. A preheating ring position changing mechanism changes the height position of holding the preheating ring in the reaction vessel body based on 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.