GAA Nanostructure Inner Spacer Layout for Short-Channel Control
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Solution Overview
Problem
The integration of gate-all-around (GAA) transistor features around nanowires in semiconductor manufacturing is challenging due to high complexity and the need for continued miniaturization while maintaining gate control and mitigating short-channel effects.
Innovation Solution
A semiconductor structure is developed with a gate stack wrapping around nanostructures, including a semiconductor inner spacer layer between the gate stack and source/drain features, which reduces crystalline defects and allows for further miniaturization by configuring the inner spacer layer as a channel portion, enabling improved gate control and reduced short-channel effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate-all-around transistor features are integrated around nanowires using conventional methods, then gate control is improved and short-channel effects are reduced, but manufacturing complexity increases significantly
Solution Approach 1:
The method performs preliminary actions by forming the gate stack around the nanowire channel before forming the source/drain features. This sequence reversal allows the gate to be established first, enabling better gate control over the channel while simplifying subsequent source/drain formation processes
Solution Approach 2:
The invention segments the transistor formation process into distinct stages: first forming the gate stack around the nanowire, then separately forming source/drain features in recesses. This segmentation allows independent optimization of gate control and source/drain integration, reducing overall manufacturing complexity
2Productivity
If semiconductor device dimensions are scaled down continuously, then production efficiency improves and costs decrease, but manufacturing process complexity increases
Solution Approach 1:
The invention transitions to three-dimensional gate-all-around structures that wrap around nanowire channels, utilizing vertical and lateral dimensions simultaneously. This dimensional change enables continued scaling while maintaining effective gate control through enhanced gate-channel coupling in multiple directions
Solution Approach 2:
The gate stack is nested around the nanowire channel in a concentric arrangement, with the gate completely surrounding the channel region. This nested configuration maximizes gate control efficiency while minimizing the device footprint, enabling further miniaturization
3Length of moving object
If inner spacer layer is configured as channel portion, then further miniaturization is enabled and short-channel effects are reduced, but crystalline defects in source/drain features increase
Solution Approach 1:
The inner spacer layer is selectively configured as channel portion only in specific regions where it provides beneficial strain effects, while maintaining distinct source/drain regions with different material properties. This local quality differentiation allows miniaturization with controlled crystalline quality
Solution Approach 2:
The channel region utilizes composite material structure combining the inner spacer layer material with adjacent semiconductor materials, creating a heterostructure that provides both strain enhancement for carrier mobility and controlled crystalline properties for device reliability
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a plurality of nanostructures vertically stacked and separated from one another, a source/drain feature adjacent to the plurality of nanostructures, and an inner spacer layer. The inner spacer layer includes a vertical portion interposing between the plurality of nanostructures and the source/drain feature and a plurality of horizontal portions interposing between the nanostructures. A source/drain junction is located in the vertical portion of the inner spacer layer and is spaced apart from the plurality of nanostructures by a distance.