Curved Inner Spacer Profile for Nanosheet Gate Isolation
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Solution Overview
Problem
Existing integrated circuit (IC) fabrication methods struggle to achieve robust gate-to-source/drain isolation in gate-all-around devices due to limitations in spacer profiles.
Innovation Solution
The method involves forming nanosheets separated by inner spacers with a curved portion, followed by the formation of source/drain regions and gate material around the nanosheets to enhance spacer profiles and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planar FET structures are used, then manufacturing simplicity is maintained, but gate-to-source/drain isolation is insufficient
Solution Approach 1:
The inner spacer is formed with a curved portion at its end adjacent to the gate material, replacing conventional straight spacer structures. This curvature enables the spacer to conformally contact the gate material and nanosheet interface, achieving robust gate-to-source/drain isolation while maintaining manufacturing feasibility through standard deposition and etching processes.
2Reliability
If gate-all-around structure is implemented, then electrostatic control is improved, but spacer profile formation becomes difficult
Solution Approach 1:
The curved portion of the inner spacer is specifically designed to match the geometry of the gate-all-around structure. This curvature allows the spacer to form a precise conformal interface with both the gate material and nanosheet, enabling accurate spacer profile formation that supports the three-dimensional gate structure while maintaining manufacturing precision.
Solution Approach 2:
The inner spacer exhibits different geometries at different locations: a curved portion at the end adjacent to the gate material for precise interface contact, and a substantially straight portion extending toward the source/drain regions for stable structural support. This local variation in geometry optimizes both electrostatic control and manufacturing precision in different functional regions.
3Reliability
If inner spacers with curved portions are formed, then gate-to-source/drain isolation is enhanced, but manufacturing complexity increases
Solution Approach 1:
The curved portion of the inner spacer is formed during the spacer deposition process itself, before subsequent gate material deposition. This preliminary formation of the curved geometry allows the spacer to serve as a template that guides subsequent processing steps, simplifying overall manufacturing by integrating the complex geometry creation into an early process step rather than requiring additional post-processing operations.
Data Source
AI summary
Embodiments of the invention include a semiconductor structure having nanosheets separated by inner spacers, the inner spacers having a curved portion in a dimension. The semiconductor structure includes source/drain regions formed adjacent to the nanosheets and gate material formed on the nanosheets.