GAA FET Fin Layout With Dielectric Passivation for Iso-Dense Loading
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Solution Overview
Problem
The semiconductor industry faces challenges in forming gate-all-around (GAA) FET devices due to the iso-dense loading effect, which causes imbalanced processing conditions and poorly formed metal gate structures, especially at the edges of fin groups, leading to performance issues.
Innovation Solution
Incorporating inactive fins on the edges of adjacent fin groups, coupled with dielectric trenches, to mitigate the iso-dense loading effect by protecting active fins and delaying the formation of inactive fins until after the dummy gate structure is defined, allowing for a well-defined metal gate profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inactive fins are formed early in the process, then the iso-dense loading effect is reduced, but the active fin profiles become poorly formed and device performance deteriorates
Solution Approach 1:
The patent applies preliminary action by forming inactive fins at a delayed stage in the fabrication process, specifically after the dummy gate structure is defined. This timing ensures that the inactive fins do not interfere with the formation of active fin profiles while still providing the beneficial iso-dense loading effect mitigation during subsequent processing steps.
Solution Approach 2:
The patent implements local quality by creating spatial differentiation between active fins and inactive fins. The inactive fins are positioned specifically at the edges of fin groups where the iso-dense loading effect occurs, while the central active fins maintain their integrity. This localized approach allows different regions to have different functional properties.
2Productivity
If continuous processing is maintained without delays, then productivity is high, but processing conditions become imbalanced leading to poorly formed metal gate structures
Solution Approach 1:
The patent uses preliminary action by preparing the fin structure with inactive fins in place before the metal gate formation stage. This advance preparation ensures that when the metal gate structure is formed, the processing conditions are balanced across all fins, preventing deformation while maintaining overall process efficiency.
Solution Approach 2:
The patent applies preliminary anti-action by introducing inactive fins that counterbalance the iso-dense loading effect before the metal gate formation process. This preemptive measure prevents the imbalanced processing conditions that would otherwise cause poor metal gate structure formation, thereby maintaining both productivity and precision.
3Productivity
If fin group density is increased to improve integration, then more devices fit in given area, but edge effects cause imbalanced processing conditions
Solution Approach 1:
The patent applies segmentation by dividing the fin structure into active fins in the center and inactive fins at the edges. This segmentation allows the edge fins to be treated differently from the active fins, with the inactive fins serving as placeholders that balance the processing conditions without requiring the same quality standards as active fins.
Solution Approach 2:
The patent implements local quality by applying different functional requirements to different regions of the fin structure. The inactive fins at the edges provide structural balance and process uniformity, while the active fins in the center maintain high-quality profiles for device operation. This localized differentiation enables high integration density while maintaining processing uniformity.
Data Source
AI summary
A semiconductor device includes a first stack structure, a second stack structure, and a third stack structure. Each of the stack structure includes semiconductor layers vertically spaced from one another. The first, second, and third stack structures all extend along a first lateral direction. The second stack structure is disposed between the first and third stack structures. The semiconductor device includes a first gate structure that extends along a second lateral direction and wraps around each of the semiconductor layers. The semiconductor layers of the first stack structure are coupled with respective source/drain structures. The semiconductor layers of the second stack structure are coupled with respective source/drain structures. The semiconductor layers of the third stack structure are coupled with a dielectric passivation layer.