CVD Reactor Shield Plate Geometry for Uniform Gas Outlet Temperature
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Solution Overview
Problem
In CVD reactors, non-homogeneous lateral temperature profiles on the shield plate's gas outlet surface lead to local temperature variations, which can disrupt the uniformity and stability of thin semiconductor layer deposition processes.
Innovation Solution
The shield plate's rear face features structures such as elevations and depressions that influence thermal coupling and heat flow, allowing for localized control of the surface temperature of the process chamber ceiling, minimizing temperature gradients by varying material thickness and thermal emissivity across different zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the shield plate has a uniform thickness, then the manufacturing is simple, but the temperature profile on the gas outlet surface becomes non-homogeneous
Solution Approach 1:
The shield plate incorporates local variations in thickness (elevations and depressions) to create different thermal characteristics in specific zones. The central zone has different thickness than the annular zone, allowing each region to be optimized for its specific thermal requirements while maintaining a relatively simple overall plate structure.
Solution Approach 2:
The patent changes the physical parameter of thickness locally across the shield plate. By varying the thickness parameter from the central zone to the annular zone, the thermal conductivity and heat capacity are modified to compensate for non-uniform heat flow from the susceptor, thereby achieving a more uniform temperature distribution on the gas outlet surface.
2Temperature
If the shield plate is actively cooled to maintain temperature, then the temperature control is improved, but the energy consumption increases
Solution Approach 1:
The shield plate uses its own thermal mass and conductive properties to regulate temperature. The varying thickness creates zones with different thermal inertias that passively respond to heat input from the susceptor, reducing the need for active cooling intervention while maintaining temperature uniformity.
Solution Approach 2:
By modifying the thickness parameter across different zones, the patent changes the thermal response characteristics of the shield plate itself, allowing it to self-regulate temperature distribution without requiring additional active cooling energy.
3Stability of the object's composition
If the shield plate thickness is increased, then the thermal stability is improved, but the response time to temperature changes decreases
Solution Approach 1:
The shield plate is segmented into zones with different thicknesses - a central zone and an annular zone. This segmentation allows different parts of the plate to have different thermal responses, with thicker regions providing stability and thinner regions allowing faster response, thereby resolving the contradiction between overall thermal stability and response speed.
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 design ensures a more uniform temperature profile on the shield plate's surface, enhancing the stability and consistency of thin semiconductor layer deposition processes by managing heat flow and thermal radiation variations.
Implementation Method 1
a cooled ceiling panel facing towards a process chamber
Implementation Method 2
a heat flow forms from the susceptor, through the process chamber, and through the shield plate, to the cooled ceiling panel
Implementation Method 3
a susceptor that can be heated by a heating device
Implementation Method 4
The temperature of the gas outlet surface of the shield plate facing towards the process chamber is essentially influenced by the local thermal radiation output of the susceptor surface
Implementation Method 5
the thermal coupling of the shield plate to the ceiling panel, and/or the heat flow through the shield plate, is influenced by means of structures arranged on the rear face of the shield plate
Data Source
AI summary
A CVD reactor includes a gas inlet member having a circular outline, and a susceptor that can be heated by a heating device. The gas inlet member has a cooled ceiling panel with outlet openings. The CVD reactor further comprises a shield plate, which adjoins the ceiling panel and has a circular outline. The shield plate has a central zone, an annular zone surrounding the central zone, having a rear side that points toward the ceiling panel, and a flat gas outlet surface pointing toward the process chamber, in which gas outlet openings terminate. The rear side in the central zone defines a rear plane running parallel to the gas outlet surface. The shield plate has a material thickness between 3 to 12 mm, and that the shield plate is spaced apart from the ceiling plate by a gap having a height between 0.3 to 1 mm.