MOCVD Reactor Gas Inlet Element with Annular Walls
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Solution Overview
Problem
Current MOCVD reactors face limitations in increasing growth rate and improving crystal quality of semiconductor layers due to temperature and speed gradients, leading to saturation effects and increased homogeneous gas-phase reactions, which hinder the efficiency of depositing buffer layers for light-emitting diodes.
Innovation Solution
The gas inlet element is modified with annular walls having gas-permeable openings that minimize speed gradients, featuring a circular cylinder shape with uniform diameter, optimized outlet openings, and a herringbone pattern to reduce turbulence, allowing for increased total pressure and TMGa concentration without clogging, thereby enhancing gas flow and reducing nucleations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the total pressure and TMGa concentration are increased to enhance growth rate, then productivity improves, but homogeneous gas-phase reactions increase leading to nucleations and reduced manufacturing precision
Solution Approach 1:
The gas inlet element is divided into multiple gas inlet chambers (first, second, third chambers) that are spatially separated and introduce gases at different locations and times. This segmentation prevents the premature mixing of hydride and organometallic compound gases, allowing higher concentrations to be used without causing homogeneous gas-phase reactions and nucleations, thus enabling increased growth rate while maintaining crystal quality.
Solution Approach 2:
The carrier gas is introduced first through the first gas inlet chamber to establish a stable flow pattern and prepare the reaction environment before the hydride and organometallic compound gases are introduced. This preliminary action ensures that the subsequent high-concentration gas introduction does not lead to uncontrolled homogeneous reactions, allowing higher productivity while preserving manufacturing precision.
2Manufacturing precision
If porous materials are used in the gas inlet element to control gas flow, then manufacturing precision improves, but the porous structure clogs over time reducing productivity
Solution Approach 1:
The porous material is completely removed from the gas inlet element structure. Instead of using porous walls, the patent employs discrete gas outlet openings in the annular wall of each gas inlet chamber. This extraction eliminates the clogging problem inherent in porous structures while maintaining precise gas flow control through the engineered openings, thus preserving manufacturing precision while enabling sustained high productivity.
Solution Approach 2:
The patent inverts the conventional approach by using non-porous materials with specifically designed openings. The annular walls contain gas outlet openings that provide controlled gas release without the clogging issues of porous structures. This allows the system to maintain precise gas flow control (manufacturing precision) while avoiding the productivity loss from clogging.
3Use of energy by moving object
If vertical temperature gradients are present in the process chamber, then heating efficiency improves, but speed gradients increase causing turbulence and reduced manufacturing precision
Solution Approach 1:
The gas inlet system is segmented into multiple chambers that introduce gases at different vertical positions. This segmentation allows the temperature gradient to be utilized for efficient heating while the distributed gas introduction points compensate for the resulting speed gradients, maintaining flow uniformity and manufacturing precision despite the temperature differential.
Solution Approach 2:
Different regions of the process chamber are provided with tailored gas introduction characteristics through the segmented chambers. The local gas flow conditions are optimized for each vertical position, allowing the temperature gradient to enhance heating efficiency while local flow control maintains manufacturing precision by compensating for temperature-induced speed variations.
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 achieves higher growth rates and improved crystal quality by minimizing temperature and speed gradients, allowing for increased total pressure and TMGa concentration, resulting in enhanced material efficiency and reduced nucleations, thus optimizing the deposition process for semiconductor layers.
Implementation Method 1
process gases are introduced into the process chamber through three gas inlet zones arranged vertically one above the other at different heights
Implementation Method 2
a heater arranged vertically below the susceptor for heating the susceptor
Implementation Method 3
The starting materials usually used, ie PH3, AsH3 and NH3 or TMGa, TMIn or TMAl decompose at different temperatures in the gas phase
Implementation Method 4
a device for depositing layers, in particular semiconductor layers
Data Source
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AI summary
The invention relates to a device for depositing semiconductor layers, comprising a process chamber (1) arranged substantially rotationally symmetrically about a center (11), a susceptor (2), a process chamber ceiling (3), a gas inlet element (4) having gas inlet chambers (8, 9, 10) that are arranged vertically on top of each other, and a heater (27) arranged below the susceptor (2), wherein the topmost (8) of the gas inlet chambers is directly adjacent to the process chamber ceiling (3) and is connected to a feed line (14) for feeding a hydride together with a carrier gas into the process chamber (1), wherein the lowest (10) of the gas inlet chambers is directly adjacent to the susceptor (2) and is connected to a feed line (16) for feeding a hydride together with a carrier gas into the process chamber (1), wherein at least one center gas inlet chamber (9) arranged between the lowest (10) and the topmost (8) gas inlet chamber is connected to a feed line (15) for feeding an organometallic compound into the process chamber (1). According to the invention, the gas inlet chambers (8, 9, 10) are closed off toward the process chamber (1) by annular walls (22, 23, 24), wherein the annular walls (22, 23, 24) comprise a plurality a gas outlet openings (25) arranged closely next to each other, have a uniform outside diameter, and an outer wall that is substantially without projections and directed toward the process chamber (1).