FinFET Fin Collapse Prevention via Temporary Bracing
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Solution Overview
Problem
Vertical fin structures in FinFET devices are prone to collapse during wet cleaning and drying processes due to surface tension forces, which can render devices unusable.
Innovation Solution
A bracing structure is formed on the hardmask stacks to resist bending forces, comprising a cover layer and a bracing layer that spans adjacent hardmasks, allowing for cleaning while preventing fin collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wet cleaning and drying processes are performed on vertical fin structures, then cleaning effectiveness is improved, but surface tension forces cause fin collapse
Solution Approach 1:
A bracing layer is introduced as an intermediary structure between the substrate and the fin structures. This bracing layer provides mechanical support during wet cleaning and drying processes, counteracting surface tension forces that would otherwise cause fin collapse. The bracing layer is temporarily present during critical processes and is subsequently removed, serving its protective function only when needed.
Solution Approach 2:
The bracing layer is formed in advance before the wet cleaning and drying processes. This preliminary structural reinforcement cushions the fin structures against the harmful surface tension forces that will be encountered during subsequent processing steps, preventing collapse before it can occur.
2Reliability
If a bracing structure is formed on hardmask stacks, then fin collapse is prevented, but device complexity increases
Solution Approach 1:
The bracing layer is a temporary structure that is formed to provide necessary support during critical processing steps, then deliberately removed after it has served its protective function. This approach allows the benefit of structural reinforcement without the permanent complexity of leaving the bracing structure in place. The bracing layer is discarded after completing its protective mission.
Solution Approach 2:
The bracing structure is segmented into discrete bracing segments that are positioned between adjacent hardmask stacks. This segmentation allows for targeted support where needed while minimizing overall process complexity. The segmented approach also facilitates easier removal and reduces interference with subsequent processing steps.
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
The bracing structure effectively counteracts surface tension forces, preventing fin collapse and ensuring device integrity during downstream processing.
Implementation Method 1
exposing the plurality of vertical fins to a wet cleaning solution, and removing the bracing segment
Data Source
AI summary
A method of preventing the collapse of fin structures is provided. The method includes forming a plurality of vertical fins on a substrate, and a hard mask stack on each of the vertical fins. The method further includes forming a cover layer on the plurality of vertical fins and hard mask stacks, and reducing the height of the cover layer to expose an upper portion of each of the hard mask stacks. The method further includes forming a bracing layer on the reduced height cover layer and exposed portion of each of the hard mask stacks, and removing a portion of the bracing layer to expose a portion of the reduced height cover layer and form a bracing segment on the exposed portion of each of the hard mask stacks. The method further includes removing the reduced height cover layer.