Nanosheet Substrate Isolation via Lattice-Matched Wide Bandgap Semiconductor
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Solution Overview
Problem
Current nanosheet-based semiconductor devices face parasitic leakage issues due to the gate contacting the substrate, leading to off-state leakage current, which needs to be controlled without interfering with the device operation.
Innovation Solution
A lattice-matched wide bandgap semiconductor material with semi-insulating properties is used as an isolation layer between the substrate and the suspended semiconductor channel material nanosheets, eliminating parasitic leakage paths while maintaining device functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate contacts the substrate directly, then the device structure is simple and easy to manufacture, but parasitic leakage current occurs between source and drain regions
Solution Approach 1:
An isolation layer composed of semi-insulating wide bandgap semiconductor material is introduced between the substrate and the gate contact, serving as an intermediary that blocks parasitic leakage current paths while maintaining the electrical functionality of the device
2Reliability
If an isolation layer is added to eliminate parasitic leakage, then off-state leakage control improves, but the device structure becomes more complex
Solution Approach 1:
The isolation layer utilizes wide bandgap semiconductor material with specific doping concentrations to achieve semi-insulating properties, changing the electrical parameters of the substrate interface to block leakage currents while maintaining compatibility with existing fabrication processes
3Reliability
If a wide bandgap semiconductor material is used for the isolation layer, then parasitic leakage paths are eliminated, but material selection and lattice matching requirements increase complexity
Solution Approach 1:
The isolation layer is applied locally at the substrate interface where leakage occurs, using wide bandgap semiconductor material with specific crystalline orientation and lattice matching to the substrate, ensuring high precision only where needed rather than throughout the entire device 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 isolation layer effectively reduces parasitic leakage current between the source and drain regions, enhancing the off-state leakage control without disrupting the operation of the nanosheet CMOS devices.
Implementation Method 1
a thin layer of lattice matched wide bandgap semiconductor material having semi-insulating properties is employed as an isolation layer between the substrate and a vertical stack of suspended semiconductor channel material nanosheets
Data Source
AI summary
A thin layer of lattice matched wide bandgap semiconductor material having semi-insulating properties is employed as an isolation layer between the substrate and a vertical stack of suspended semiconductor channel material nanosheets. The presence of such an isolation layer eliminates the parasitic leakage path between the source region and the drain region that typically occurs through the substrate, while not interfering with the CMOS device that is formed around the semiconductor channel material nanosheets.