SiC Seed Crystal Positioning Without Adhesive
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Solution Overview
Problem
Conventional methods for growing large-diameter single crystal ingots of silicon carbide face challenges such as warping, cracking due to residual stress, and quality deterioration caused by adhesives used in seed crystal attachment.
Innovation Solution
A process involving the preparation of a seed crystal with a protective layer, where a binder resin composition is molded into a sheet, cut to fit the seed crystal, and cured and carbonized to form a protective layer with a protrusion member, allowing the seed crystal to be grown without adhesion to a holder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a seed crystal is adhered to a holder using adhesive in the upper region of a reaction vessel, then the seed crystal can be securely positioned, but warping and cracking occur due to residual stress from CTE difference between seed crystal and holder
Solution Approach 1:
The invention removes the holder component entirely and extracts the adhesive from the system. The seed crystal is positioned directly in the reaction vessel without attachment to any holder, eliminating the source of CTE-induced stress and adhesive-related contamination that caused warping and cracking.
Solution Approach 2:
The invention introduces a protective layer as an intermediary between the seed crystal and the reaction environment. This protective layer prevents direct contact between the seed crystal and potential contaminants while allowing the seed crystal to be positioned without adhesive, solving both positioning and quality issues.
2Ease of operation
If adhesive is used to attach seed crystal to holder, then seed crystal can be fixed, but quality deteriorates due to adhesive contamination and detachment during growth
Solution Approach 1:
The invention completely removes the adhesive from the system. Instead of using adhesive to fix the seed crystal, the seed crystal is positioned directly in the reaction vessel, eliminating adhesive contamination and detachment problems that compromised ingot quality.
Solution Approach 2:
The protective layer serves as an intermediary that provides necessary protection and positioning functionality without requiring adhesive. This intermediary layer eliminates the harmful effects of adhesive while maintaining seed crystal stability during the growth process.
3Ease of operation
If adhesive is applied to seed crystal for attachment, then seed crystal can be secured, but surface contamination occurs on the seed crystal
Solution Approach 1:
The invention extracts the adhesive from the attachment system, eliminating the source of surface contamination. The seed crystal is positioned without adhesive application, preventing adhesive residues from contaminating the seed crystal surface and compromising ingot quality.
Solution Approach 2:
The protective layer acts as an intermediary that provides necessary protection and positioning without requiring adhesive. This intermediary prevents surface contamination while maintaining seed crystal security during the growth process.
4Area of stationary object
If the diameter of single crystal ingot is increased, then larger capacity devices can be produced, but warping and cracking are aggravated due to residual stress
Solution Approach 1:
The invention removes the holder and adhesive system that generates residual stress. By positioning the seed crystal directly in the reaction vessel without attachment, the invention eliminates the source of CTE-induced stress that causes warping and cracking, enabling the growth of larger diameter ingots with maintained quality.
Solution Approach 2:
The protective layer serves as an intermediary that protects the seed crystal during growth without contributing to residual stress. This intermediary enables the growth of larger diameter ingots by preventing surface contamination and mechanical stress while maintaining structural integrity.
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 method enables the growth of high-quality, large-diameter SiC single crystal ingots by preventing warping and cracking, and eliminating the adverse effects of adhesives, thus improving the overall quality and size of the ingot.
Implementation Method 1
curing and carbonizing the protective layer attached to the seed crystal
Implementation Method 2
curing and carbonizing the protective layer attached to the seed crystal
Implementation Method 3
a difference in the coefficient of thermal expansion (CTE) between the seed crystal and the holder causes a warp
Implementation Method 4
a raw material (300) is heated and sublimated in a reaction vessel (200), whereby a single crystal ingot is grown on the front side of the seed crystal (110)
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A method in which a carbonaceous protective film is formed on a rear surface of a single crystal SiC seed, the seed is placed in a reaction container without adhesion, and then single crystal SiC is grown from a SiC raw material on a front surface of the seed allows the seed to grow to a single crystal ingot having a large diameter since the absence of adhesion of the seed to a holder prevents the generation of warps or cracks attributed to a difference in thermal expansion coefficient between the seed and the holder during heating.