Vertical III-V Nanowire Transistor Defect Mitigation
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Solution Overview
Problem
Integrating free-standing III-V and Ge nanostructures on silicon substrates is challenging due to defect formation and chemistry incompatibilities, which hinders the development of high-performance vertical field effect transistors.
Innovation Solution
A method for forming semiconductor structures involving epitaxial growth of gallium arsenide fin structures on a silicon substrate, followed by the formation of indium gallium arsenide or germanium channel layers, and subsequent source/drain and gate structures, allowing for position-controlled growth of vertical III-V/Ge nanowires without buffering layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If free-standing III-V and Ge nanostructures are integrated on silicon substrates, then high-performance vertical field effect transistors can be achieved, but defect formation and chemistry incompatibilities occur
Solution Approach 1:
The patent introduces buffer layers (e.g., AlAs, InAlAs) and transition layers (e.g., InGaAs) as intermediaries between the silicon substrate and the III-V/Ge channel layers. These intermediary layers serve as defect sinks and lattice mismatch buffers, preventing harmful dislocations from propagating into the active channel regions while enabling high-performance transistor operation.
Solution Approach 2:
The patent employs composite material structures combining multiple semiconductor materials with different properties - silicon substrate, AlAs buffer layers, InAlAs transition layers, InGaAs channel layers, and Ge layers. This composite approach leverages the advantageous properties of each material: silicon for substrate stability, AlAs for defect filtering, InAlAs for lattice matching, and InGaAs/Ge for high mobility channels.
2Reliability
If free-standing III-V and Ge nanostructures are integrated on silicon substrates, then high-performance vertical field effect transistors can be achieved, but chemistry incompatibilities occur
Solution Approach 1:
The patent systematically varies material composition parameters (indium content, aluminum content, germanium content) and layer thickness parameters to optimize lattice matching and chemical compatibility. By adjusting these parameters, the patent achieves progressive transition from silicon chemistry to III-V chemistry, enabling successful integration despite fundamental chemistry incompatibilities between the substrate and channel materials.
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
Enables the integration of free-standing III-V/Ge nanowires on silicon substrates, reducing defect-related leakage and facilitating the creation of high-performance vertical field effect transistors with improved scalability and efficiency.
Implementation Method 1
One or more fin structures comprising gallium arsenide are epitaxially grown in contact with a portion of a substrate
Data Source
AI summary
A semiconductor structure and a method for fabricating the same. The semiconductor structure includes a substrate and a first source/drain layer in contact with at least the substrate. A vertical channel including indium gallium arsenide or germanium contacts at least the first/source drain layer. A gate structure contacts at least the vertical channel. A second source/drain layer contacts at least inner sidewalls of the vertical channel. The method includes epitaxially growing one or more fin structures comprising gallium arsenide in contact with a portion of a substrate. A separate channel layer comprising indium gallium arsenide or germanium is formed in contact with a respective one of the one or more fin structures.