Gate-All-Around Transistor Structure for Leakage Control
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Solution Overview
Problem
The challenge in integrated circuit manufacturing is the difficulty in fabricating gate-all-around transistors with contact-shaped or bar-shaped gate electrodes, which leads to insufficient overlap margin during photolithography and increased leakage current between the substrate and source/drain regions, particularly as design rules are scaled down.
Innovation Solution
The solution involves creating gate-all-around integrated circuit devices with a gate electrode that surrounds the channel region, using a linearly shaped active region and source/drain regions separated by a partial insulating layer, and employing a polysilicon or composite gate electrode with a thermal silicon oxide insulating layer, allowing for improved fabrication and reduced leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contact-shaped or bar-shaped gate electrodes are used in gate-all-around transistors, then the transistor structure can be formed, but the overlap margin is insufficient during photolithography operations
Solution Approach 1:
The gate electrode is changed from a planar contact-shaped or bar-shaped pattern to a three-dimensional surrounding structure that encircles the channel region. This dimensional transition allows the gate to wrap around the channel from multiple directions, providing sufficient overlap margin in photolithography while maintaining manufacturability through the gate-all-around configuration.
Solution Approach 2:
The gate electrode is positioned to surround the channel region in a nested configuration, with the gate structure enclosing the channel from multiple sides. This nesting arrangement ensures adequate overlap margin during photolithography operations while maintaining the compact structure needed for high integration density.
2Reliability
If contact-shaped or bar-shaped gate electrodes are used, then the transistor can be fabricated, but leakage current between substrate and source/drain regions is not sufficiently limited
Solution Approach 1:
The gate electrode surrounds the channel region in a nested configuration, with the gate structure encircling the channel from multiple sides including the bottom. This complete surrounding structure effectively isolates the channel from the substrate, preventing leakage current paths between the substrate and source/drain regions while maintaining fabrication feasibility.
Solution Approach 2:
The gate-all-around structure provides enhanced local isolation at the channel-substrate interface by surrounding the channel region completely. This localized quality improvement at critical interfaces effectively limits leakage current without requiring complex fabrication processes across the entire device.
3Productivity
If design rules are scaled down to increase integration density, then more devices can be packed, but the short channel effect becomes more pronounced
Solution Approach 1:
The gate electrode is configured to surround the channel region completely, with the gate structure nesting around the channel from all directions including the bottom. This complete surrounding provides strong electrostatic control over the channel, effectively suppressing the short channel effect even when design rules are scaled down to achieve high integration density.
Solution Approach 2:
The transition from planar gate structures to three-dimensional gate-all-around structures adds vertical control dimensions. This dimensional enhancement provides superior electrostatic control over the channel region, counteracting the short channel effects that arise from scaled-down design rules and enabling high integration density with maintained reliability.
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
This approach enables more precise control over the gate electrode formation, enhances integration density, and effectively limits the short channel effect and leakage current, ensuring reliable operation of the transistors even at smaller scales.
Implementation Method 1
A thermal silicon oxide gate insulating layer may be provided between the gate electrode and the channel region and between the gate electrode and the active area of the integrated circuit substrate
Implementation Method 2
The first and second source/drain regions form p-n rectifying junctions with the active area
Data Source
AI summary
Gate-all-around integrated circuit devices include first and second source/drain regions on an active area of an integrated circuit substrate. The first and second source/drain regions form p-n rectifying junctions with the active area. A channel region extends between the first and second source/drain regions. An insulated gate electrode surrounds the channel region.