CVD Gas-Inlet Shield Plate Structure for Cold Spot Suppression
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Solution Overview
Problem
Existing gas-inlet elements for CVD reactors cause temperature inhomogeneities and cold spots on the shield plate arrangement facing the susceptor, affecting the uniform growth of layers on substrates.
Innovation Solution
The design incorporates through openings with varying diameters for pipes, where the first section has a larger diameter than the pipe's outer diameter and a second section with a smaller diameter, and a shield plate arrangement with sections of different thermal conductivities, allowing for controlled temperature distribution and reduced cooling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pipes are cooled by the cooling device to a temperature less than the shield plate arrangement temperature, then the pipes can effectively cool the gas-inlet element, but cold spots are created on the broadside surface of the shield plate arrangement facing the susceptor, causing temperature inhomogeneities that affect layer growth uniformity
Solution Approach 1:
The shield plate arrangement is designed with spatially varying thermal conductivity properties. The region near the pipe penetration points has lower thermal conductivity to prevent excessive heat loss to the cooled pipes, while other regions maintain higher thermal conductivity for overall heat distribution. This local differentiation of thermal properties prevents cold spot formation while maintaining effective pipe cooling.
Solution Approach 2:
The patent modifies the thermal conductivity parameter of the shield plate arrangement in specific regions to address the temperature uniformity issue. By changing the thermal conductivity parameter locally near the pipe penetration zones, the system prevents excessive heat transfer to the cooled pipes, thereby eliminating cold spots and ensuring uniform temperature distribution across the broadside surface.
2Temperature
If the shield plate arrangement is cooled to maintain low temperatures for process control, then temperature regulation is improved, but cold spots are created that locally influence layer growth and reduce manufacturing precision
Solution Approach 1:
The shield plate arrangement implements spatially differentiated thermal properties, with regions of varying thermal conductivity positioned strategically around the pipe penetration points. This local quality variation allows the system to maintain overall temperature control while preventing localized cold spots that would compromise layer growth uniformity and manufacturing precision.
Solution Approach 2:
The thermal conductivity parameter of the shield plate arrangement is modified in specific local regions to prevent excessive heat loss to the cooled pipes. This parameter change enables the system to maintain regulated temperatures overall while avoiding the formation of cold spots that would adversely affect layer deposition precision and uniformity.
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 solution minimizes temperature inhomogeneities and cold spots, enhancing the uniformity of layer growth on substrates by optimizing the thermal conductivity and geometry of the shield plate arrangement.
Implementation Method 1
The gas-inlet element is cooled, and to this end has a cooling volume through which a cooling liquid flows
Implementation Method 2
the first pipes having end portions exiting from the gas outlet plate spring from the front side, which protrude into first through openings of a shield plate arrangement
Data Source
AI summary
A gas-inlet element for a CVD reactor includes a gas distribution volume arranged rearward of a gas outlet plate, from which volume pipes having end portions protruding from the gas outlet plate on the front side emerge. The pipes extend into through openings in a shield plate assembly extending parallel to the gas outlet plate. The through openings have a first portion facing the gas outlet plate with a large diameter which is larger than the outer diameter of the respective end portions, and a second portion facing away from the gas outlet plate with a smaller diameter. In order to prevent temperature non-uniformities in the region of the through openings, the diameter of the second portion is smaller than the outer diameter of the respective end portions. The shield plate arrangement additionally consists of two shield plates with different thermal conductivities arranged one above another.