Group III Nitride Crystal Growth Temperature Gradient Control
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Solution Overview
Problem
Existing methods for producing group III nitride crystals, such as oxide vapor phase epitaxy, face challenges in controlling the temperature gradient, leading to the generation of polycrystals and deterioration of crystal quality due to exothermic reactions and Mullins-Sekerka instability.
Innovation Solution
A device and method that include a raw material chamber generating a group III element oxide gas and a growth chamber with a heat release promoting structure, featuring a substrate tray, susceptor, and rotary shaft, which creates a temperature gradient with a positive difference between the front and back surface temperatures of the seed substrate, suppressing polycrystal formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxide vapor phase epitaxy is used to produce group III nitride crystal, then crystal growth can be achieved, but temperature gradient control is difficult leading to polycrystal generation and crystal quality deterioration
Solution Approach 1:
The heating system is segmented into multiple independent heating units (first heating unit and second heating unit) that can control temperature independently at different locations. This allows precise control of temperature gradients across the substrate, preventing polycrystal formation while maintaining crystal growth quality.
Solution Approach 2:
Different regions of the substrate are given different temperature characteristics through localized heating. The first heating unit provides heating from the front surface while the second heating unit provides heating from the back surface, creating controlled temperature gradients in specific regions to suppress Mullins-Sekerka instability and ensure single crystal growth.
2Productivity
If exothermic reaction occurs during crystal growth, then crystal formation is promoted, but temperature gradient becomes negative causing Mullins-Sekerka instability and polycrystal generation
Solution Approach 1:
The exothermic reaction heat, which originally causes harmful temperature gradients and polycrystal formation, is converted into a beneficial controlled heating mechanism. By introducing heating units that actively control temperature distribution, the system transforms the harmful thermal effect into a controllable parameter that promotes stable single crystal growth.
Solution Approach 2:
The temperature parameters are dynamically adjusted through multiple heating units to maintain optimal conditions. By changing the temperature distribution pattern and controlling the temperature gradient to be positive or zero, the system prevents Mullins-Sekerka instability while maintaining high crystal growth rates.
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 solution effectively reduces polycrystal generation and enhances the quality of group III nitride crystals by stabilizing single crystal growth through controlled heat release, improving the crystal quality and yield in device production.
Implementation Method 1
a structure of promoting heat release from the back surface side of the seed substrate, the structure including a substrate tray on which the seed substrate is placed, a substrate susceptor on which the substrate tray is placed, and a rotary shaft on which the substrate susceptor is placed
Implementation Method 2
an NH3 gas is introduced, and the NH3 gas is caused to react with the generated Ga2O gas to generate a GaN crystal on a seed substrate
Implementation Method 3
The introduced H2O gas reacts with Ga to generate Ga2O gas... the NH3 gas is caused to react with the generated Ga2O gas to generate a GaN crystal
Data Source
AI summary
A device for producing a group III nitride crystal includes a raw material chamber that generates a group III element oxide gas, and a growth chamber that causes the group III element oxide gas supplied from the raw material chamber to react with a nitrogen element-containing gas to generate a group III nitride crystal on a seed substrate, wherein the growth chamber includes, on a back surface side of the seed substrate, a structure of promoting heat release from the back surface side of the seed substrate, the structure including a substrate tray on which the seed substrate is placed, a substrate susceptor on which the substrate tray is placed, and a rotary shaft on which the substrate susceptor is placed.