Dummy Fin Structures for Fine-Pitch Dummy Gate Stack Stability
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Solution Overview
Problem
In the semiconductor industry, the reduction in minimum feature size leads to issues with fine-pitched dummy gate stacks collapsing during manufacturing due to their high aspect ratio and lack of structural support, resulting in manufacturing defects and source/drain bridging during epitaxial growth processes.
Innovation Solution
The formation of dummy fins, comprising one or more insulating layers, is used to anchor dummy gate stacks not formed on semiconductor fins, providing structural support and reducing defects by acting as placeholders during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dummy gate stacks are formed with fine pitch to increase integration density, then manufacturing precision deteriorates due to collapse of high aspect ratio structures
Solution Approach 1:
The patent introduces dummy fins as intermediary structures that provide physical support to unanchored dummy gate stacks. These dummy fins act as mediators between the substrate and the dummy gate stacks, preventing collapse during manufacturing processes while enabling fine-pitch configurations that increase integration density.
Solution Approach 2:
The patent segments the support structure into two types: anchored dummy gate stacks that rely on substrate support and unanchored dummy gate stacks that require additional dummy fin support. This segmentation allows different regions of the semiconductor device to be optimized independently, maintaining manufacturing precision across the entire chip.
2Productivity
If minimum feature size is reduced to increase integration density, then reliability deteriorates due to source/drain bridging during epitaxial growth
Solution Approach 1:
The dummy fins serve as intermediary physical barriers between source and drain regions during epitaxial growth. By introducing these intermediate structures, the patent prevents direct contact between source and drain materials that would otherwise bridge at reduced feature sizes, thereby maintaining reliability while enabling higher integration density.
Solution Approach 2:
The patent performs preliminary formation of dummy fins and anchored dummy gate stacks before the critical epitaxial growth step. This preliminary structuring creates physical barriers in advance that prevent source/drain bridging during subsequent processing, ensuring reliability is maintained throughout manufacturing.
Data Source
AI summary
An embodiment method includes depositing a first dielectric film over and along sidewalls of a semiconductor fin, the semiconductor fin extending upwards from a semiconductor substrate. The method further includes depositing a dielectric material over the first dielectric film; recessing the first dielectric film below a top surface of the semiconductor fin to define a dummy fin, the dummy fin comprising an upper portion of the dielectric material; and forming a gate stack over and along sidewalls of the semiconductor fin and the dummy fin.