Silicon Carbide Growth Lid Pattern for Thermal-Stress Relief
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Solution Overview
Problem
Conventional methods for growing silicon carbide single crystals result in the generation of threading screw dislocations, basal plane dislocations, and threading edge dislocations due to thermal stress between the seed crystal substrate and the growth container, leading to degraded device performance.
Innovation Solution
A silicon carbide single crystal growth apparatus with a growth container lid featuring a pattern that penetrates the adhesion region of the seed crystal substrate, formed either radially or concentrically, to allow for elastic deformation and reduce thermal stress, thereby suppressing dislocation generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a seed crystal substrate is adhered to a growth container lid made from carbon material, then the substrate can be held in place for crystal growth, but thermal stress occurs due to the difference in coefficient of thermal expansion between the substrate and the container, causing warp and dislocation
Solution Approach 1:
The growth container lid is segmented into multiple regions: a first region with the adhesion pattern for substrate attachment, and a second region without the pattern. This segmentation allows the lid to provide both strong adhesion in the first region and reduced thermal stress in the second region, resolving the contradiction between adhesion strength and crystal quality.
Solution Approach 2:
The adhesion pattern is applied locally only in the first region of the growth container lid where substrate attachment is needed, rather than uniformly across the entire lid. This local application of the adhesion pattern ensures strong bonding where required while minimizing thermal stress in other areas, thereby improving crystal quality.
2Ease of manufacture
If the growth container lid has a uniform structure, then manufacturing is simple, but thermal stress causes warp that leads to basal plane dislocation and threading screw dislocation
Solution Approach 1:
The lid structure is segmented into a first region with adhesion pattern and a second region without the pattern. This segmentation allows the manufacturing process to remain relatively simple while achieving the precision needed to prevent dislocation, as the pattern can be applied only where necessary for attachment.
Solution Approach 2:
The adhesion pattern is pre-formed on the growth container lid before the crystal growth process. This preliminary action ensures that the thermal stress management feature is already in place, allowing the lid to maintain its structural integrity and prevent warp during the heating and cooling cycles of crystal growth.
3Strength
If the entire growth container lid is covered with adhesion pattern, then the seed crystal substrate adheres strongly, but thermal stress is increased leading to more dislocation
Solution Approach 1:
The adhesion pattern is applied locally only in the first region of the growth container lid where substrate attachment is needed, rather than uniformly across the entire lid. This local application ensures strong bonding where required while minimizing thermal stress in other areas, thereby improving crystal quality and reducing dislocation density.
Solution Approach 2:
The lid is divided into functional zones: a first region with adhesion pattern for strong substrate attachment and a second region without the pattern to reduce thermal stress. This segmentation allows the system to achieve strong adhesion without the penalty of increased dislocation density that would result from full-coverage patterning.
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 apparatus effectively suppresses the formation of threading screw and basal plane dislocations, enabling the production of silicon carbide single crystals with low dislocation densities.
Implementation Method 1
heating with a heater (high frequency heating coil) 203
Implementation Method 2
The silicon carbide raw material 206 is solid, and is sublimed under high temperature and reduced pressure
Implementation Method 3
On the outside of the growth container 201, a heat-insulating container 202 is disposed
Data Source
Figure 1~2(f)
Figure 3~5(b)
Figure 6(a)~7(f)
AI summary
The present invention is a silicon carbide single crystal growth apparatus including: a growth container including a growth container lid to which a seed crystal substrate is adhered and a growth container body for containing the seed crystal substrate and a silicon carbide raw material; a heat-insulating container surrounding the growth container; a temperature measuring equipment for measuring a temperature inside the growth container through a hole for temperature measurement provided in the heat-insulating container; and a heater for heating the silicon carbide raw material, where a silicon carbide single crystal is grown on the seed crystal substrate by heating and subliming the silicon carbide raw material by a sublimation method, where the growth container lid has a pattern that penetrates the growth container lid formed only within an adhesion region of the seed crystal substrate on the growth container lid. This provides a silicon carbide single crystal growth apparatus and manufacturing method that can suppress the generation of threading screw dislocation, basal plane dislocation, and threading edge dislocation.