Single-Crystal Semiconductor Stack for Thermal Strain Compensation
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Solution Overview
Problem
The cost and size limitations of single crystal substrates for epitaxial growth of Group III-V compound semiconductor layers, as well as the challenge of thermal expansion mismatch between amorphous substrates and single crystal semiconductor layers, hinder the efficient production of high-quality single crystal semiconductor structures.
Innovation Solution
A single crystal semiconductor structure is formed on an amorphous substrate using a strain compensation layer, a lattice matching layer with a direction control film and buffer layers, and a mask pattern, which includes a molybdenum alloy strain compensation layer and a lattice matching layer with a thin single crystal structure, to minimize thermal expansion differences and enhance crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single crystal substrate is used for epitaxial growth of single crystal Group III-V compound semiconductor layers, then the crystallinity and quality of the semiconductor layer are improved, but the cost increases and the size is limited
Solution Approach 1:
The patent introduces an amorphous substrate as an intermediary carrier that enables cost-effective production. A thin single crystal semiconductor layer is formed on this amorphous substrate through epitaxial growth, then transferred to a final single crystal substrate. This intermediary approach avoids the need for expensive large-area single crystal substrates while maintaining high crystallinity in the semiconductor layer.
Solution Approach 2:
The patent segments the manufacturing process into distinct stages: forming the single crystal semiconductor layer on an amorphous substrate, then transferring it to a final single crystal substrate. This segmentation allows the expensive single crystal substrate to be used only for the final high-quality layer, rather than requiring a large expensive substrate for the entire structure.
2Ease of manufacture
If an amorphous substrate is used to reduce cost, then the cost decreases and size flexibility increases, but thermal expansion mismatch causes strain and deformation
Solution Approach 1:
The patent controls the thickness of the single crystal semiconductor layer to be equal to or less than 10 times the critical thickness hc. By controlling this critical parameter (layer thickness), the strain caused by thermal expansion mismatch between the amorphous substrate and single crystal layer is managed, enabling cost-effective production without excessive deformation.
Solution Approach 2:
The patent applies different quality requirements to different parts of the structure: the thin single crystal semiconductor layer maintains high crystallinity where needed, while the amorphous substrate provides cost-effective support. The strain management is localized to the interface region through controlled layer thickness.
3Strength
If the thickness of the direction control film exceeds 10 times the critical thickness, then the film provides better structural support, but strain accumulation increases and crystallinity deteriorates
Solution Approach 1:
The patent establishes a critical thickness relationship where the direction control film thickness is controlled to be equal to or less than 10 times the critical thickness hc (calculated using the given equation involving Burgers vector, Poisson's ratio, and lattice misfit). This parameter control ensures the film provides sufficient structural support while preventing strain accumulation that would deteriorate crystallinity.
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 allows for the cost-effective growth of high-quality single crystal semiconductor layers on amorphous substrates, reducing deformation due to thermal expansion differences and improving crystallinity, while maintaining a stable and uniform temperature for epitaxial growth.
Implementation Method 1
capable of compensating for a strain due to a difference in a coefficient of thermal expansion between an amorphous substrate and a single crystal semiconductor layer
Implementation Method 2
A single crystal substrate is used for epitaxy growth of a single crystal Group III-V compound semiconductor layer
Data Source
AI summary
A single crystal semiconductor includes a strain compensation layer; an amorphous substrate disposed on the strain compensation layer; a lattice matching layer disposed on the amorphous substrate and including two or more single crystal layers; and a single crystal semiconductor layer disposed on the lattice matching layer, the lattice matching layer including a direction control film disposed on the amorphous substrate and including a single crystal structure, and a buffer layer including a material different from that of the direction control film, the buffer layer being disposed on the direction control film and including a single crystal structure.