Corundum Oxide Laminate Seed Layer for Low-Defect Epitaxy
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Solution Overview
Problem
The mist CVD method for producing gallium oxide (α-Ga2O3) with a corundum structure struggles to achieve high-quality crystals with suppressed crystal defects, and the conventional ELO method is costly and complex due to the need for a dedicated mask formation process.
Innovation Solution
A laminate structure comprising a crystal substrate, a middle layer with a mixture of amorphous and crystal regions, and a crystal layer, where the middle layer acts as a seed crystal to inhibit dislocation defects, allowing for the growth of a high-quality corundum-structured crystal layer without the need for a dedicated mask, using a mist CVD process that incorporates silicon to form the middle layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conventional ELO method with amorphous mask is used to suppress crystal defects, then crystal quality is improved, but device complexity and manufacturing cost increase due to dedicated mask formation process
Solution Approach 1:
The patent combines the mask layer and middle layer into a single integrated layer formed by one CVD process. This middle layer simultaneously provides the masking function for selective epitaxial growth and serves as the intermediate layer for crystal orientation control, eliminating the need for separate mask formation processes while maintaining crystal quality improvement
Solution Approach 2:
The middle layer performs multiple functions: it acts as a mask for selective epitaxial growth to suppress dislocation, serves as an intermediate layer for crystal orientation control, and provides a transition zone between substrate and epitaxial layer. This multi-functionality replaces the dedicated mask's single function while adding beneficial properties
2Manufacturing precision
If the conventional ELO method with amorphous mask is used to suppress crystal defects, then crystal quality is improved, but productivity decreases due to additional process steps
Solution Approach 1:
The patent combines the mask layer and middle layer into a single integrated layer formed by one CVD process. This middle layer simultaneously provides the masking function for selective epitaxial growth and serves as the intermediate layer for crystal orientation control, eliminating the need for separate mask formation processes while maintaining crystal quality improvement
Solution Approach 2:
The middle layer is formed in advance with the appropriate crystal orientation before the final epitaxial growth. This preliminary preparation of the intermediate layer with correct orientation ensures that subsequent epitaxial growth proceeds with proper crystal alignment, maintaining high crystal quality while streamlining the overall process
3Ease of manufacture
If mist CVD method is used to produce gallium oxide crystal, then production cost is reduced, but crystal defects are not sufficiently suppressed
Solution Approach 1:
The patent applies local quality by creating a middle layer with specific crystal orientation properties between the substrate and the epitaxial layer. This intermediate layer has different structural characteristics from both the substrate and the final epitaxial layer, providing local control over dislocation propagation and enabling high crystal quality while maintaining the cost-effective CVD process
Solution Approach 2:
The middle layer acts as an intermediary between the substrate and the epitaxial layer. It mediates the lattice mismatch and dislocation propagation by providing a transition zone with appropriate crystal orientation, thereby suppressing crystal defects without requiring the complex and expensive conventional ELO mask 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
This approach enables the production of high-quality corundum-structured crystal layers with reduced defects at a lower cost and increased throughput, suitable for semiconductor devices, by using a single apparatus and simplifying the manufacturing process.
Implementation Method 1
a crystal layer formed on the middle layer and having a corundum structure mainly made of a second metal oxide
Implementation Method 2
the middle layer comprising a mixture of an amorphous region in an amorphous phase and a crystal region in a crystal phase having a corundum structure
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 using a raw material atomized into a mist form
Data Source
AI summary
A laminate contains a crystal substrate; a middle layer formed on a main surface of the crystal substrate, the middle layer comprising 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, wherein the crystal region is an epitaxially grown layer from a crystal plane of the crystal substrate.