Shaped Semiconductor Fin Structure for Strain Retention and Low Capacitance
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to maintain mechanical stability and strain retention in fin transistors while scaling down, as thicker fins can degrade performance due to increased source-to-drain coupling and energy loss, and existing optimization solutions lead to capacitance loss and decreased yield.
Innovation Solution
The active channel region of the fin is selectively shaped after channel exposure, achieving zero capacitance penalty with a wider fin base outside the gate and a thin fin under the gate, ensuring strain retention without buckling or strain loss, and allowing for maximized channel strain with reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the fin thickness is increased to maintain mechanical stability and prevent buckling, then the fin structure becomes more stable, but source-to-drain coupling increases and energy loss increases
Solution Approach 1:
The fin structure implements different thicknesses at different locations: a first thickness in the channel region and a second thickness in the source/drain regions. This local variation allows the fin to maintain mechanical stability where needed while minimizing source-to-drain coupling and energy loss in other regions.
Solution Approach 2:
The fin is segmented into distinct regions with different thickness characteristics - a thinner channel region and thicker source/drain regions. This segmentation enables independent optimization of each region's properties to resolve the contradiction between mechanical stability and energy efficiency.
2Productivity
If the fin dimensions are scaled down to increase device density, then more devices can be fabricated per chip, but manufacturing constraints and process complexity become overwhelming
Solution Approach 1:
The method performs preliminary patterning actions using mandrel structures and spacer formations before final fin definition. This staged approach allows complex multi-thickness fin structures to be created through sequential, manageable process steps rather than attempting to define all features simultaneously, thereby reducing overall process complexity.
Solution Approach 2:
Mandrel structures and spacer layers are introduced as intermediary elements that facilitate the creation of complex fin geometries. These intermediaries enable precise control over fin thickness variations without requiring direct patterning of the final fin structure, simplifying the manufacturing process.
3Ease of manufacture
If a uniform fin thickness is used throughout the fin structure, then the manufacturing process is simpler, but the fin cannot maintain mechanical stability at scaled dimensions
Solution Approach 1:
Rather than using a uniform thickness, the fin structure implements locally optimized thickness variations - thinner in the channel for performance and thicker in source/drain regions for mechanical stability. This local differentiation maintains stability while remaining manufacturable through the staged patterning process.
4Loss of energy
If the fin is made thinner to reduce source-to-drain coupling, then energy loss is reduced, but the fin becomes mechanically unstable and prone to buckling
Solution Approach 1:
The fin structure uses different thicknesses in different regions: a first thickness in the channel region optimized for electrical performance and a second thickness in the source/drain regions optimized for mechanical stability. This local differentiation resolves the contradiction by allowing thin dimensions where energy loss matters while maintaining thickness for stability where mechanical support is critical.
Solution Approach 2:
The fin is segmented into functionally distinct regions with different thickness profiles. This segmentation enables the structure to simultaneously achieve low energy loss in the channel through thinner dimensions while maintaining mechanical stability in source/drain regions through thicker dimensions.
Data Source
AI summary
Fin shaping, and integrated circuit structures resulting therefrom, are described. For example, an integrated circuit structure includes a semiconductor fin having a protruding fin portion above an isolation structure above a substrate. The protruding fin portion has substantially vertical upper sidewalls and outwardly tapered lower sidewalls. A gate stack is over and conformal with the protruding fin portion of the semiconductor fin. A first source or drain region is at a first side of the gate stack, and a second source or drain region is at a second side of the gate stack opposite the first side of the gate stack.