Semiconductor Superlattice With Oxygen and Carbon Monolayers for Mobility
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Solution Overview
Problem
Despite existing advancements, further enhancements are desired to achieve improved performance in semiconductor devices using advanced semiconductor materials and processing techniques.
Innovation Solution
A method for making semiconductor devices involves forming a superlattice adjacent a semiconductor layer, with the superlattice comprising stacked groups of layers including base semiconductor monolayers and non-semiconductor monolayers, such as oxygen and carbon, to reduce effective mass and enhance charge carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional semiconductor materials and structures are used, then manufacturing processes are simpler, but charge carrier mobility is limited
Solution Approach 1:
The semiconductor layer is segmented into a superlattice structure with alternating monolayers of different materials (e.g., Si/SiGe, Si/SiC) to create periodic potential barriers that enhance charge carrier mobility through quantum confinement effects and reduced scattering
Solution Approach 2:
Composite semiconductor materials are used in the superlattice structure, combining different semiconductor compounds (silicon, silicon-germanium, silicon-carbide) to achieve superior electrical properties that cannot be obtained with single materials
2Speed
If strained material layers are introduced to enhance mobility, then charge carrier mobility improves, but manufacturing precision requirements increase
Solution Approach 1:
The lattice constant and strain state are controlled by adjusting the composition ratio of alloy materials (e.g., Ge content in SiGe, C content in SiC) and layer thickness, allowing optimization of strain-induced mobility enhancement while maintaining manufacturability
Solution Approach 2:
Strain is localized to specific thin layers within the superlattice structure, with buffer layers and relaxation layers strategically placed to manage stress distribution and prevent defect propagation
3Reliability
If impurity-free zones are created to improve performance, then device performance improves, but manufacturing complexity increases
Solution Approach 1:
The superlattice structure is formed with inherently low-defect regions during the epitaxial growth process itself, creating impurity-free zones before subsequent processing steps, thereby reducing the need for additional complex processing to achieve clean regions
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 and provides improved energy band structures, acting as a barrier to dopant diffusion and reducing scattering effects, which is advantageous for both electronic and opto-electronic devices.
Implementation Method 1
Electrons having a smaller effective mass, and which have been induced by an electric field applied to the gate electrode, are confined in the second silicon layer
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
a Si—Ge short period superlattice with higher mobility achieved by reducing alloy scattering in the superlattice
Data Source
AI summary
A method for making a semiconductor device may include forming a superlattice adjacent a semiconductor layer. The 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 at least one non-semiconductor monolayer in a first group of layers of the superlattice may comprise oxygen and be devoid of carbon, and the at least one non-semiconductor monolayer in a second group of layers of the superlattice may comprise carbon.