GAA Source/Drain Dielectric Isolation for Leakage and DIBL
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Solution Overview
Problem
Current semiconductor technologies face challenges in managing current leakage and drain-induced barrier lowering (DIBL) issues in nanostructure transistors, particularly in gate-all-around (GAA) devices, due to the design limitations of source/drain epitaxial structures.
Innovation Solution
The integration of dielectric structures under the source/drain epitaxial structures in GAA devices, which include bottom dielectric structures to isolate the source/drain epitaxial structures from the substrate, reducing current leakage and enhancing device performance by improving carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If source/drain epitaxial structures are used in GAA devices, then device performance and carrier mobility are improved, but current leakage and DIBL issues occur
Solution Approach 1:
A dielectric structure is introduced as an intermediary layer between the source/drain epitaxial structure and the substrate. This dielectric structure acts as a mediator that blocks the harmful current leakage path while allowing the beneficial carrier mobility enhancement from the epitaxial structure to be maintained. The dielectric material serves as a physical barrier that prevents direct electrical contact between the epitaxial structure and substrate, thereby eliminating the leakage issue without compromising device performance.
2Reliability
If source/drain epitaxial structures are used in GAA devices, then carrier mobility is enhanced, but DIBL problems occur
Solution Approach 1:
The dielectric structure serves as a mediator that decouples the source/drain epitaxial structure from the substrate, preventing the DIBL effect while preserving carrier mobility enhancement. By inserting this dielectric layer, the electric field distribution is modified to reduce the drain-induced barrier lowering effect, allowing high carrier mobility in the epitaxial structure without suffering from DIBL degradation.
3Object-generated harmful factors
If dielectric structures are added under source/drain epitaxial structures, then current leakage is reduced, but device complexity increases
Solution Approach 1:
The device structure is segmented by introducing a distinct dielectric layer that separates the source/drain epitaxial structure from the substrate. This segmentation approach allows the current leakage path to be blocked at a specific interface without requiring complex modifications to the entire device architecture. The dielectric structure creates a clear division between functional regions, simplifying the overall design compared to more complex alternative solutions.
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 dielectric structures effectively mitigate current leakage and DIBL problems, while allowing for reduced parasitic capacitance and improved device performance through strained epitaxial structures.
Implementation Method 1
bottom dielectric structures to isolate the source/drain epitaxial structures from the substrate, reducing current leakage
Implementation Method 2
improved device performance through strained epitaxial structures
Data Source
AI summary
A device includes a channel structure, a gate structure, a first source/drain epitaxial structure, and a second source/drain epitaxial structure. The channel layer is over a substrate and extends in a first direction. The gate structure covers the channel structure and extends in a second direction different from the first direction. The first source/drain structure and the second source/drain structure are on opposite sides of the channel structure. A void is contained in between the first source/drain structure and the substrate.