Hyper-abrupt Varactor Superlattice for Carrier Mobility
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Solution Overview
Problem
Current semiconductor devices face limitations in enhancing charge carrier mobility and performance due to issues such as alloy scattering and inter-diffusion in thin layers, which affect device efficiency and mobility.
Innovation Solution
The implementation of a hyper-abrupt junction semiconductor device with a superlattice structure, comprising stacked semiconductor monolayers and non-semiconductor monolayers within the crystal lattice, which reduces effective mass and enhances mobility by blocking inter-diffusion and scattering, and providing a common energy band structure and insulating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If strained material layers are used to enhance carrier mobility, then device speed and performance are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the semiconductor layer into multiple thin monolayer segments stacked in a superlattice structure. This segmentation allows each layer to be thin enough to maintain crystal integrity while collectively providing the desired strain effect for enhanced carrier mobility without excessive complexity
Solution Approach 2:
The patent employs composite material structures combining different semiconductor materials (e.g., SiGe/Si superlattice) to achieve both the strain necessary for high carrier mobility and compatibility with existing CMOS manufacturing processes, thereby improving performance without proportionally increasing complexity
2Speed
If thin layers are used to reduce scattering, then carrier mobility is enhanced, but inter-diffusion between layers increases
Solution Approach 1:
The patent introduces intermediate barrier layers or interface structures between adjacent semiconductor layers in the superlattice. These intermediaries prevent direct inter-diffusion while maintaining the thin-layer configuration necessary for high carrier mobility, effectively decoupling the two competing requirements
3Speed
If alloy scattering is reduced to improve mobility, then carrier speed increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent systematically varies parameters such as layer thickness, composition ratios, and stacking sequences in the superlattice structure to optimize carrier mobility while maintaining manufacturability. By carefully controlling these parameters within specific ranges, the patent achieves high mobility without requiring extreme manufacturing precision that would be difficult to implement
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 configuration results in higher charge carrier mobility, reduced scattering effects, and improved device performance, including enhanced conductivity and potential for direct energy bandgap structures suitable for opto-electronic devices.
Implementation Method 1
Si—Ge short period superlattice with higher mobility achieved by reducing alloy scattering in the superlattice
Implementation Method 2
hyper-abrupt junction region including a superlattice... blocking inter-diffusion and scattering
Implementation Method 3
The resulting biaxial strain in the upper silicon layer alters the carrier mobilities enabling higher speed and/or lower power devices
Implementation Method 4
alters the carrier mobilities enabling higher speed
Implementation Method 5
a silicon and carbon layer sandwiched between silicon layers so that the conduction band and valence band of the second silicon layer receive a tensile strain
Implementation Method 6
a quantum well structure comprising two barrier regions and a thin epitaxially grown semiconductor layer sandwiched between the barriers
Implementation Method 7
a plurality of layers, less than eight monolayers, and containing a fractional or binary or a binary compound semiconductor layer, are alternately and epitaxially grown
Data Source
AI summary
A semiconductor device may include a substrate and a hyper-abrupt junction region carried by the substrate. The hyper-abrupt junction region may include a first semiconductor layer having a first conductivity type, a superlattice layer on the first semiconductor layer, and a second semiconductor layer on the superlattice layer and having a second conductivity type different than the first conductivity type. The superlattice may include stacked groups of layers, with each group of layers including 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 semiconductor device may further include a first contact coupled to the hyper-abrupt junction region, and a second contact coupled to the substrate to define a varactor.