Nanostructure Transistors With Dopant-Blocking Superlattice Channels
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Solution Overview
Problem
Current semiconductor devices face limitations in enhancing charge carrier mobility and reducing defects, leading to suboptimal performance in advanced semiconductor materials and processing techniques.
Innovation Solution
The semiconductor device incorporates a superlattice structure with alternating layers of semiconductor materials, including dopant blocking superlattices and buffer layers, which reduce charged impurity concentration and improve interface quality, thereby enhancing charge carrier mobility and providing piezoelectric, pyroelectric, and ferroelectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional semiconductor structures are used, then manufacturing simplicity is maintained, but charge carrier mobility is limited due to scattering effects and interface defects
Solution Approach 1:
The semiconductor structure is divided into multiple functional layers including a superlattice structure with alternating high-bandgap and low-bandgap material layers. This segmentation creates distinct regions for carrier confinement, scattering reduction, and dopant blocking, thereby enhancing charge carrier mobility through reduced scattering effects while maintaining manageable manufacturing complexity through systematic layering
Solution Approach 2:
The invention employs composite material structures including superlattices formed by alternating layers of different semiconductor materials with varying bandgaps. These composite structures create beneficial effects such as carrier confinement in low-bandgap regions, reduced scattering at interfaces, and improved mobility through the combined properties of constituent materials, directly addressing the mobility limitation without excessive complexity
2Reliability
If dopant diffusion is allowed for device fabrication, then manufacturing process simplicity is maintained, but charged impurity concentration increases causing performance degradation
Solution Approach 1:
The superlattice structure acts as an intermediary barrier between source/drain regions and the channel region. The alternating high-bandgap and low-bandgap layers create a dopant blocking effect that prevents charged impurity diffusion into the channel, thereby maintaining device performance and reducing scattered carriers without requiring complex fabrication processes
Solution Approach 2:
The invention utilizes changes in material parameters such as bandgap energy across the superlattice layers to create regions with different dopant diffusion characteristics. The high-bandgap layers serve as diffusion barriers while low-bandgap layers allow controlled carrier transport, enabling performance improvement through parameter variation rather than process complexity
3Speed
If interface quality is improved to reduce defects, then charge carrier mobility increases, but manufacturing precision requirements increase
Solution Approach 1:
The superlattice structure provides locally optimized interfaces between high-bandgap and low-bandgap materials. Each interface is designed with specific quality characteristics tailored to its function: some interfaces are optimized for carrier confinement while others are optimized for reduced scattering. This local quality optimization enhances overall mobility without requiring uniform high precision across the entire structure
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 superlattice structure achieves higher charge carrier mobility, reduces scattering effects, and enhances device performance by confining carriers effectively, making it suitable for advanced semiconductor applications, including opto-electronic devices.
Implementation Method 1
respective dopant blocking superlattices adjacent lateral ends of the nanostructures and offset outwardly from adjacent surfaces of the insulating regions
Implementation Method 2
The resulting biaxial strain in the upper silicon layer alters the carrier mobilities enabling higher speed and/or lower power devices
Implementation Method 3
providing piezoelectric, pyroelectric, and ferroelectric properties
Implementation Method 4
The resulting biaxial strain in the upper silicon layer alters the carrier mobilities
Data Source
AI summary
A semiconductor device may include a substrate and spaced apart gate stacks on the substrate defining respective trenches therebetween. Each gate stack may include alternating layers of first and second semiconductor materials, with the layers of the second semiconductor material defining nanostructures. The semiconductor device may further include respective source/drain regions within the trenches, respective insulating regions adjacent lateral ends of the layers of the first semiconductor material, and respective dopant blocking superlattices adjacent lateral ends of the nanostructures and offset outwardly from adjacent surfaces of the insulating regions. Each dopant blocking superlattice may include a plurality of stacked groups of layers, with each group of layers comprising stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions.