Hyper-abrupt Varactor With Superlattice Junctions
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Solution Overview
Problem
Current semiconductor devices face limitations in enhancing charge carrier mobility and performance due to issues like alloy scattering and diffusion in thin layers, which affect device efficiency and mobility.
Innovation Solution
The development of a hyper-abrupt junction semiconductor device with a superlattice structure, comprising stacked semiconductor and non-semiconductor monolayers, which reduces effective mass and enhances mobility by blocking 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 alloy scattering and diffusion in thin layers cause performance degradation
Solution Approach 1:
The patent divides the semiconductor layer into a superlattice structure consisting of multiple alternating thin layers of different semiconductor materials (e.g., SiGe and Si). This segmentation into periodic layers reduces alloy scattering by confining carriers to narrower regions and providing periodic potential landscapes that enhance mobility while minimizing the harmful effects of alloy disorder.
Solution Approach 2:
The patent employs composite semiconductor structures combining different materials (Si, SiGe, and other group IV or III-V semiconductors) in a superlattice configuration. This composite approach allows optimization of carrier mobility through material composition control while managing alloy scattering effects by carefully designing layer thicknesses and material combinations.
2Speed
If thin semiconductor layers are used to reduce alloy scattering, then mobility is enhanced, but diffusion and performance degradation occur
Solution Approach 1:
The patent incorporates barrier layers or interface engineering at the boundaries of thin semiconductor layers before diffusion can significantly occur. This preliminary structural preparation prevents unwanted interdiffusion between adjacent layers, maintaining sharp interfaces and stable composition profiles even in ultra-thin layers where mobility enhancement is critical.
3Speed
If superlattice structures are implemented to reduce effective mass, then mobility increases, but device complexity increases
Solution Approach 1:
The patent optimizes superlattice parameters such as layer thickness, periodicity, and material composition to achieve the desired mobility enhancement with minimal structural complexity. By carefully selecting parameters like layer thickness in the range of a few nanometers and using standard semiconductor materials, the design achieves high mobility while remaining compatible with existing manufacturing processes.
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 ionized impurity scattering, and provides improved conductive properties, making it suitable for advanced semiconductor devices with enhanced performance and potential for opto-electronic applications.
Implementation Method 1
The resulting biaxial strain in the upper silicon layer alters the carrier mobilities enabling higher speed and/or lower power devices
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
The development of a hyper-abrupt junction semiconductor device with a superlattice structure, comprising stacked semiconductor and non-semiconductor monolayers, which reduces effective mass and enhances mobility by blocking diffusion and scattering
Data Source
AI summary
A method for making a semiconductor device may include forming a hyper-abrupt junction region above a substrate and including a first semiconductor layer having a first conductivity type, a first superlattice layer on the first semiconductor layer, a second semiconductor layer on the first superlattice layer and having a second conductivity type different than the first conductivity type, and a second superlattice layer on the second semiconductor layer. The method may further include forming a first contact coupled to the hyper-abrupt junction region and a second contact coupled to the substrate to define a varactor. The first and second superlattices may each include 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.