Corundum Crystal Laminate with Mixed Middle Layer for Defect Suppression
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Solution Overview
Problem
Conventional methods for producing high-quality corundum-structured crystals, such as mist CVD and ELO, face challenges with crystal defects and high production costs due to complex processes and the need for dedicated mask formation.
Innovation Solution
A laminate structure with a middle layer containing a mixture of crystal and amorphous regions, formed using a mist CVD process that includes silicon, effectively reduces dislocation defects and allows for epitaxial growth of a high-quality corundum-structured crystal layer without the need for a dedicated mask, enabling low-cost production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ELO method with amorphous mask is used, then crystal defects are suppressed, but process complexity and production cost increase
Solution Approach 1:
The invention extracts and eliminates the dedicated mask layer from the ELO process. Instead of using a separate amorphous mask material (such as SiO2) that requires additional formation and removal steps, the method uses the substrate surface itself with selective exposure to define growth regions, thereby simplifying the overall process while maintaining defect suppression
Solution Approach 2:
The substrate surface serves multiple functions: it acts as both the growth substrate and the selective mask definition layer. By using the same substrate for both purposes, the invention eliminates the need for dedicated mask materials and processes, reducing complexity while maintaining the ability to suppress crystal defects through selective epitaxial growth
2Manufacturing precision
If conventional ELO method with dedicated mask is used, then crystal defects are suppressed, but production cost increases
Solution Approach 1:
The invention removes the dedicated mask layer component from the process, eliminating material costs and additional processing steps associated with mask formation, patterning, and removal, thereby reducing production cost while maintaining crystal quality through selective growth
Solution Approach 2:
The substrate surface itself provides the masking function through selective exposure regions, eliminating the need for external mask materials and processes. This self-service approach reduces both material and processing costs while achieving the same defect suppression effect
3Device complexity
If mist CVD method is used, then production process is simplified, but crystal defects are not sufficiently suppressed
Solution Approach 1:
The invention applies local quality by creating regions of different growth conditions on the substrate surface. By selectively exposing certain areas while protecting others, the method achieves lateral overgrowth in specific regions that suppresses dislocation propagation, thereby improving crystal quality without complicating the overall mist CVD process
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 laminate achieves a high-quality corundum-structured crystal layer with reduced defects and lower production costs, suitable for semiconductor devices, by using a silicon-containing middle layer to inhibit dislocation defects and facilitate epitaxial growth.
Implementation Method 1
the amorphous region in the middle layer stops extension of dislocation defect attributable to the substrate
Implementation Method 2
the crystal region of the middle layer serves as a seed crystal, resulting in a high-quality crystal layer according to the crystal orientation of the crystal substrate
Implementation Method 3
Mist Chemical Vapor Deposition (Mist CVD. Hereinafter, this method may also be referred to as 'mist CVD method') has been developed by which crystal is grown on a substrate
Data Source
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AI summary
The present invention is a laminate including: a crystal substrate; a middle layer formed on a main surface of the crystal substrate, the middle layer containing a mixture of an amorphous region in an amorphous phase and a crystal region in a crystal phase having a corundum structure mainly made of a first metal oxide; and a crystal layer formed on the middle layer and having a corundum structure mainly made of a second metal oxide. Thus, provided is a laminate having high-quality corundum-structured crystal with sufficiently suppressed crystal defects.