Semiconductor Substrate with Segmented Sacrificial Layer for Epitaxial Growth
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Solution Overview
Problem
Existing semiconductor substrates face challenges with lattice mismatch and poor heat conductivity, leading to inefficiencies in epitaxial layer growth and removal processes, such as poor etching efficiency due to dense film structures and side etching issues.
Innovation Solution
A semiconductor substrate design featuring a base layer with a sacrificial layer comprising spaced-apart sacrificial film regions and passages, including nanostructures, which allows for efficient etching and separation of epitaxial layers using selective etching agents, enhancing etching rates and reducing dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sacrificial layer with dense film structure is used, then the epitaxial layer quality is maintained, but the etching efficiency is poor
Solution Approach 1:
The sacrificial layer is designed with a porous structure containing multiple passages (first passages extending through the thickness, and second passages within the film plane) that enable etching agents to penetrate and remove the sacrificial layer efficiently through the dense film structure without compromising the quality of the epitaxial layer grown on top
2Ease of operation
If the substrate is removed by wet etching the sacrificial layer, then the epitaxial layers are separated from the substrate, but side etching occurs reducing etching efficiency
Solution Approach 1:
The sacrificial layer is segmented into spaced-apart sacrificial film regions separated by first passages that extend through the thickness of the sacrificial layer. This segmentation allows etching agents to access and remove the sacrificial layer through multiple pathways (both vertically through first passages and laterally through second passages), preventing side etching and significantly improving etching efficiency
3Reliability
If a substrate with preferable lattice mismatch is used for epitaxial growth, then the epitaxial layer quality is improved, but the heat conductivity is poor
Solution Approach 1:
The substrate (sapphire) is completely removed from the epitaxial structure by etching away the sacrificial layer through the passages. This extraction eliminates the poor heat conductivity of the sapphire substrate while maintaining the high-quality epitaxial layers that were grown on the substrate, as the epitaxial layers are transferred to a new support structure or standalone
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 substrate design improves etching efficiency, reduces dislocation density in epitaxial layers, and allows for the reuse of the base layer, while maintaining the quality of epitaxial layers and enhancing heat conduction.
Implementation Method 1
wet etching the sacrificial layer so as to remove the substrate from the semiconductor epitaxial structure
Implementation Method 2
allows for efficient etching and separation of epitaxial layers using selective etching agents
Data Source
AI summary
A semiconductor substrate includes: a base layer; a sacrificial layer that is formed on a base layer and that includes a plurality of spaced apart sacrificial film regions and a plurality of first passages each of which is defined between two adjacent ones of the sacrificial film regions. Each sacrificial film region has a plurality of nanostructures and a plurality of second passages defined among the nanostructures. The second passages communicate spatially with the first passages and have a width less than that of the first passages. An epitaxial layer is disposed on the sacrificial layer.