Trench-Structured Seed Layer for Threading Dislocation Suppression
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Solution Overview
Problem
The challenge is to minimize the density of threading dislocations in a seed layer and prevent their propagation to the upper channel layer in semiconductor devices, particularly when growing high-crystalline channel layers.
Innovation Solution
A semiconductor device with a trench structure is designed, where the seed layer is disposed within the trench. The trench has specific aspect ratios and configurations to terminate threading dislocations at its sidewalls, thereby reducing their propagation to the upper channel layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seed layer is grown with a material having a different lattice constant than Si substrate, then the upper channel layer can be grown on an insulating layer, but threading dislocations are formed and propagate to the channel layer
Solution Approach 1:
The patent divides the continuous seed layer into multiple segments by forming trenches that penetrate through the seed layer. These trenches segment the dislocation propagation paths, forcing threading dislocations to terminate at the trench sidewalls rather than propagating continuously to the upper channel layer. This segmentation approach maintains the lattice-mismatched material benefit while blocking harmful dislocation propagation.
Solution Approach 2:
The patent extracts or removes portions of the seed layer by forming trenches that extend through it. By taking out these trench regions, the patent creates physical barriers that prevent threading dislocations from propagating upward. The trenches effectively remove the continuous path that would otherwise allow dislocations to reach the channel layer.
2Reliability
If the trench aspect ratio is increased to terminate threading dislocations, then dislocation propagation is suppressed, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the trench aspect ratio parameter to a specific range (1.37 or higher) that provides effective dislocation termination while avoiding excessive manufacturing complexity. By carefully selecting this parameter within an optimal range, the patent achieves the desired dislocation suppression effect without requiring excessively deep or narrow trenches that would be difficult to manufacture.
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 trench structure effectively suppresses the extension of threading dislocations to the upper channel layer, reducing dislocation density and enhancing the crystallinity of the channel layer, which improves device performance and fabrication reliability.
Implementation Method 1
The seed layer includes a threading dislocation extending at least partially in a first direction non-parallel to the upper surface of the substrate and parallel to a direction of a (111) plane and a threading dislocation extending at least partially in a second direction, and the extension of the threading dislocation is terminated at a sidewall of the trench.
Implementation Method 2
The seed layer is made of a second material, the second material lattice-mismatches with respect to the first material, the seed layer includes a threading dislocation extending at least partially in a first direction non-parallel to the upper surface of the substrate
Data Source
AI summary
Embodiments relate to a semiconductor device, which includes: a substrate made of a first material; an insulating layer formed on an upper surface of the substrate; a trench formed at the insulating layer to penetrate the insulating layer toward the substrate; and a seed layer disposed in the trench. The seed layer is made of a second material, the second material lattice-mismatches with respect to the first material, the seed layer includes a threading dislocation extending at least partially in a first direction non-parallel to the upper surface of the substrate and parallel to a <110> direction of a (111) plane and a threading dislocation extending at least partially in a second direction, and the extension of the threading dislocation is terminated at a sidewall of the trench.