Core-Shell Hybrid Fin Structure for Low-Capacitance Nanosheet Gates
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Solution Overview
Problem
As semiconductor devices scale down, it becomes challenging to fabricate hybrid fin structures without defects, and high cell capacitance associated with high-k dielectric materials in existing hybrid fin structures limits device performance.
Innovation Solution
Implementing a core-shell structured top portion with a low-k dielectric material core and a high-k dielectric material shell, which provides improved etch resistance and reduced cell capacitance, allowing for continued scaling with enhanced device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-k dielectric material is used in the bulk top portion of hybrid fin structures, then etching resistance is improved, but cell capacitance increases and defect rates increase
Solution Approach 1:
The top portion of the hybrid fin structure is segmented into a core region and a shell region. The core region contains low-k dielectric material that reduces cell capacitance, while the shell region contains high-k dielectric material that provides etching resistance. This segmentation allows both contradictory requirements to be satisfied in different spatial zones of the same structure.
Solution Approach 2:
Different regions of the hybrid fin structure are assigned different dielectric properties: the core region uses low-k dielectric material optimized for reducing capacitance, while the shell region uses high-k dielectric material optimized for providing etching resistance. This local differentiation of material properties resolves the contradiction between minimizing capacitance and maximizing etching resistance.
2Strength
If high-k dielectric material is used in the bulk top portion of hybrid fin structures, then etching resistance is improved, but defect rates increase
Solution Approach 1:
The top portion is divided into core and shell regions with different dielectric materials. The low-k dielectric core reduces stress and improves fabrication reliability, while the high-k dielectric shell maintains etching resistance. This segmentation allows the structure to achieve both high reliability and high etching resistance.
Solution Approach 2:
The hybrid fin structure uses a composite material system combining low-k dielectric material and high-k dielectric material in a core-shell configuration. This composite structure integrates the beneficial properties of both materials: low defect rates from the low-k core and high etching resistance from the high-k shell.
3Productivity
If device geometry is scaled down, then production efficiency is improved and costs are lowered, but manufacturing complexity increases
Solution Approach 1:
The core-shell structure embeds the low-k dielectric core within the high-k dielectric shell, creating a nested configuration. This nested design allows both material systems to be integrated in a compact manner that is compatible with scaled-down device geometries, maintaining manufacturing efficiency while managing the complexity of multiple materials.
Solution Approach 2:
The use of composite core-shell structures enables scaled-down devices to maintain necessary functional properties. The composite design allows optimization of etching resistance and capacitance characteristics even at reduced dimensions, managing manufacturing complexity while preserving production efficiency.
Data Source
AI summary
A semiconductor device includes a pair of fin structures on a semiconductor substrate, each including a vertically stacked plurality of channel layers, a dielectric fin extending in parallel to and between the fin structures, and a gate structure on and extending perpendicularly to the fin structures, the gate structure engaging with the plurality of channel layers. The dielectric fin includes a fin bottom and a fin top over the fin bottom. The fin bottom has a top surface extending above a bottom surface of a topmost channel layer. The fin top includes a core and a shell, the core having a first dielectric material, the shell surrounding the core and having a second dielectric material different from the first dielectric material.