Tapered FinFET Gate Profile for Residue-Free HKMG Transition
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Solution Overview
Problem
Conventional methods for forming gate structures in semiconductor devices face challenges with residue and byproduct formation during the scaling down process, leading to electrical shorting issues and reduced device performance due to incomplete removal of particles trapped between fin structures.
Innovation Solution
Optimizing the shape and profile of dummy gate structures by making end segments inwardly tapered or elongated, which facilitates easier removal of etching byproducts and reduces the likelihood of electrical shorting during the transition to high-k metal gate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gate structure formation methods are used, then manufacturing simplicity is maintained, but residue and byproduct accumulate leading to electrical shorting
Solution Approach 1:
The gate structure is divided into multiple segments including a main gate body and extended end segments. This segmentation allows the end segments to serve as dedicated zones for residue collection, separating the functional gate region from the residue accumulation zones, thereby preventing electrical shorting while maintaining manufacturing feasibility
Solution Approach 2:
The harmful residue and byproducts are extracted from the critical gate region and relocated to the extended end segments. By designing the gate structure to extend beyond the active channel region, residues are naturally directed to these extended portions during fabrication, removing them from positions where they could cause electrical shorting
2Productivity
If device geometry is scaled down, then production efficiency increases, but residue removal becomes more difficult
Solution Approach 1:
The gate structure extends in the lateral dimension beyond the active channel region, creating extended end segments. This dimensional extension provides additional space for residue accumulation away from the critical vertical channel region, enabling better residue removal even as device sizes scale down and maintaining production efficiency
3Reliability
If gate structure is optimized with extended end segments, then residue removal is improved, but device area increases
Solution Approach 1:
The gate structure implements local quality by having different functional regions: the main gate body optimized for electrical function and the extended end segments optimized for residue management. This localized differentiation improves residue removal effectiveness in specific areas without requiring uniform expansion of the entire gate structure, thus minimizing overall area increase
Data Source
AI summary
A device includes a plurality of fin structures that each protrude vertically upwards out of a substrate and each extend in a first direction in a top view. A gate structure is disposed over the fin structures. The gate structure extends in a second direction in the top view. The second direction is different from the first direction. The fin structures have a fin pitch equal to a sum of: a dimension of one of the fin structures in the second direction and a distance between an adjacent pair of the fin structures in the second direction. An end segment of the gate structure extends beyond an edge of a closest one of the fin structures in the second direction. The end segment has a tapered profile in the top view or is at least 4 times as long as the fin pitch in the second direction.