Semiconductor Fin Layout for Trapping Threading Dislocations
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Solution Overview
Problem
The integration of different semiconductor materials, particularly between group III/V and group IV materials, often results in defects such as threading dislocations due to lattice mismatch, which can render semiconductor devices unusable.
Innovation Solution
A method involving the formation of semiconductor fins using epitaxial growth within trenches, where the orientation and patterning of the epitaxial layers trap threading dislocations, ensuring a defect-free lattice structure through aspect-ratio-trapping and crystallographic direction alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different semiconductor materials (group III/V and group IV) are integrated in semiconductor structures, then performance benefits are achieved, but threading dislocations occur due to lattice mismatch
Solution Approach 1:
A buffer layer is introduced as an intermediary between the group III/V semiconductor layer and the group IV semiconductor substrate. This buffer layer has a lattice constant intermediate between the two materials, gradually transitioning the lattice structure and reducing the abrupt mismatch that causes threading dislocations. The buffer layer acts as a mediator that enables material integration while maintaining crystal structure integrity.
Solution Approach 2:
The lattice constant parameter is gradually changed through the buffer layer, which has a composition gradient or stepped structure. By changing the lattice constant parameter progressively rather than abruptly, the patent reduces the strain and dislocation formation that would occur with direct heteroepitaxial growth on highly mismatched substrates.
2Ease of manufacture
If epitaxial growth is performed on mismatched lattice structures, then semiconductor device fabrication is enabled, but threading dislocations are generated
Solution Approach 1:
The buffer layer serves as an intermediary structure that enables epitaxial growth on mismatched substrates while maintaining lattice structure quality. It provides a graded transition that allows continuous epitaxial growth without generating high densities of threading dislocations, thus preserving manufacturing precision while enabling fabrication.
Solution Approach 2:
The epitaxial growth process is segmented into multiple stages: first growing the buffer layer with graded composition, then growing the active semiconductor layer on top. This segmentation allows each layer to be optimized independently - the buffer for lattice matching and the active layer for device performance - thereby maintaining high manufacturing precision throughout the fabrication process.
3Adaptability or versatility
If high threading dislocation density occurs, then semiconductor device becomes unusable, but material integration is desired
Solution Approach 1:
The buffer layer acts as a mediator that decouples the lattice mismatch problem from the device structure. By placing the buffer layer between the mismatched materials, the patent enables material integration while protecting the device region from threading dislocations, thus maintaining both adaptability and reliability.
Solution Approach 2:
The threading dislocation problem is extracted and isolated into the buffer layer region, away from the active device structures. The buffer layer absorbs and contains the dislocation density, while the subsequent active layers grown on top maintain low dislocation density and high device functionality.
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 effectively confines and eliminates threading dislocations, enabling the fabrication of semiconductor devices with improved performance and reliability by ensuring a defect-free lattice structure.
Implementation Method 1
A method involving the formation of semiconductor fins using epitaxial growth within trenches, where the orientation and patterning of the epitaxial layers trap threading dislocations
Data Source
AI summary
A semiconductor device includes first to fourth semiconductor fins, a first gate structure, and a second gate structure. The first and second semiconductor fins are substantially aligned along a first direction. The third and fourth semiconductor fins are substantially aligned along the first direction. The third and fourth semiconductor fins have a conductivity type different from that of the first and second semiconductor fins. The first gate structure extends across the first and third semiconductor fins substantially along a second direction. The second gate structure extends across the second and fourth semiconductor fins substantially along the second direction. The first and fourth semiconductor fins are substantially aligned along a third direction crossing the first and second directions, and the third direction is substantially parallel with a <100> crystallographic direction.