Backside Contact Gate Isolation for Nanosheet Leakage Control
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Solution Overview
Problem
The challenge in semiconductor device fabrication is achieving effective gate isolation in nanosheet transistors to prevent leakage current and signal interference, while also addressing issues related to work function metallization patterning undercut.
Innovation Solution
The semiconductor device incorporates self-aligned gate isolation using dielectric bars and nanosheet gates, along with airgaps and shallow trench isolation, to achieve precise isolation and minimize leakage. Additionally, the use of placeholders and optimized etching processes helps prevent work function metallization patterning undercut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate isolation structures are introduced to prevent leakage current and signal interference, then device reliability is improved, but device complexity increases
Solution Approach 1:
The gate isolation structure is merged with the gate electrode itself, where the gate isolation layer is positioned between the gate electrode and the channel region. This integration allows the gate structure to simultaneously perform switching and isolation functions, preventing leakage current and signal interference while avoiding the need for separate isolation components, thus improving reliability without proportionally increasing device complexity.
Solution Approach 2:
The gate isolation structure is segmented into distinct layers including the gate isolation layer, gate electrode, and channel region. This segmentation allows each component to be optimized independently for its specific function while maintaining overall system reliability. The gate isolation layer specifically addresses leakage prevention, while the gate electrode handles signal switching, creating a modular approach to solving multiple problems simultaneously.
2Reliability
If self-aligned gate isolation is implemented to minimize leakage current, then electrical performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The gate isolation structure utilizes self-aligned fabrication where the gate isolation layer is automatically positioned relative to the gate electrode and channel region through the fabrication process itself. This self-alignment mechanism ensures precise positioning without requiring additional alignment steps or higher precision equipment, thereby achieving improved electrical performance through minimized leakage current while maintaining feasible manufacturing precision requirements.
3Reliability
If dielectric bars and airgaps are used to achieve precise isolation, then signal integrity is improved, but device complexity increases
Solution Approach 1:
The gate isolation layer acts as an intermediary structure between the gate electrode and the channel region, providing electrical isolation while maintaining the necessary spatial relationships for proper device operation. This intermediary layer prevents direct electrical contact that would cause leakage and signal interference, thereby improving signal integrity. The dielectric bars and airgaps further serve as intermediary elements to isolate adjacent structures, achieving precise isolation without requiring complex multi-component assemblies.
Data Source
AI summary
A semiconductor device includes source and drain regions above a substrate layer and a dielectric bar between each of the source and drain regions. Each of the source and drain regions has a filleted shape, with a bottom portion of the filleted shape including a horizontal bottom surface connecting two sloped surfaces. Two sloped surfaces on a backside of the semiconductor device are surrounded by a metal contact.