Superlattice Source/Drain Structure for Dopant Diffusion Control
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Solution Overview
Problem
Existing semiconductor devices face challenges in enhancing charge carrier mobility and reducing dopant diffusion, which affects device performance and efficiency.
Innovation Solution
Incorporation of a semiconductor superlattice structure with alternating semiconductor and non-semiconductor monolayers, arranged to form a constrained lattice, which acts as a barrier to dopant diffusion and improves the interface quality with insulators, thereby enhancing charge carrier mobility and providing piezoelectric, pyroelectric, and ferroelectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a superlattice structure with alternating semiconductor and non-semiconductor monolayers is used, then charge carrier mobility is enhanced and dopant diffusion is reduced, but device complexity increases
Solution Approach 1:
The source/drain region is segmented into multiple alternating monolayers of semiconductor and non-semiconductor materials, forming a superlattice structure. This segmentation creates distinct functional zones within the source/drain region that simultaneously achieve dopant confinement and carrier mobility enhancement without requiring separate discrete components
Solution Approach 2:
The superlattice structure combines semiconductor and non-semiconductor materials at the monolayer level to create a composite material with properties superior to either material alone. The composite structure provides both the dopant-blocking properties of non-semiconductor layers and the high-mobility channels of semiconductor layers in a unified integrated structure
2Reliability
If dopant concentration is increased to reduce resistance, then conductivity improves, but dopant diffusion increases causing performance degradation
Solution Approach 1:
Non-semiconductor monolayers are introduced as intermediary barrier layers between doped semiconductor regions. These intermediary layers physically block dopant atoms from diffusing into the channel while allowing high dopant concentrations to be maintained in the source/drain regions, thereby achieving both high conductivity and dopant concentration stability
Solution Approach 2:
The superlattice structure creates local quality variations where non-semiconductor monolayers provide dopant-blocking properties at specific locations within the source/drain region. This allows different zones to have different functional properties: high dopant concentration zones for conductivity and barrier zones for dopant confinement
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 enhances charge carrier mobility, reduces scattering effects, and improves device performance by confining carriers effectively, while also acting as a dopant trap to maintain high dopant concentrations without diffusion, thus increasing electron velocity and reducing resistance.
Implementation Method 1
a quantum well structure comprising two barrier regions and a thin epitaxially grown semiconductor layer sandwiched between the barriers
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
acts as a barrier to dopant diffusion and improves the interface quality with insulators
Data Source
AI summary
A semiconductor device may include a substrate, a stack of alternating gate and nanostructure layers above the substrate, and a first superlattice laterally adjacent the stack on a first side thereof and extending from the substrate to an upper surface of the stack to define a first source/drain region. The first superlattice may include a plurality of stacked groups of layers, with each group of layers including a plurality of 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. The non-semiconductor monolayers of the first superlattice may be arranged along growth rings extending outwardly from respective adjacent nanostructure layer portions.