GAA Fin Structure Isolation Using Self-Aligned Dummy Gate Patterning
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Solution Overview
Problem
The integration of gate-all-around (GAA) transistor features around nanowires is challenging due to limitations in current fabrication methods, necessitating improved techniques to enhance gate control and reduce short-channel effects.
Innovation Solution
The method involves using a capping layer over fin isolation structures to isolate adjacent gate structures, with the dummy gate structures patterning the capping layer to create a self-aligned isolation structure between gate structures, allowing for more flexible gate contact placement and reduced device area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication methods are used for GAA features, then manufacturing process simplicity is maintained, but gate control is insufficient and short-channel effects increase
Solution Approach 1:
The method performs preliminary patterning of the capping layer using dummy gate structures before forming the actual gate-all-around features. This preliminary action establishes precise alignment references that enable subsequent self-aligned fabrication steps, improving gate control while managing process complexity through staged execution
Solution Approach 2:
Dummy gate structures serve as intermediary elements that facilitate the patterning process. These temporary structures act as masks and alignment references during capping layer patterning, enabling precise feature definition without requiring direct patterning of the final gate structures, thus improving reliability while keeping the overall process manageable
2Reliability
If gate structures are formed with larger dimensions, then manufacturing is easier, but device area increases and performance is reduced
Solution Approach 1:
The capping layer is self-aligned to the fin isolation structures through the patterning process, eliminating the need for additional alignment margins. This self-service approach allows gate structures to be formed with minimal spacing, reducing device area while maintaining manufacturing feasibility through the self-aligned fabrication sequence
3Manufacturing precision
If gate contact placement is constrained by alignment requirements, then manufacturing precision is maintained, but placement flexibility is reduced
Solution Approach 1:
The dummy gate structures serve as intermediary masks that define the capping layer pattern independently of the final gate contact positions. This intermediary approach decouples the alignment precision requirement from the gate contact placement, allowing flexible positioning of gate contacts while maintaining precise feature alignment through the self-aligned patterning process
Data Source
AI summary
A method for forming a semiconductor device structure includes forming a fin structure with alternating stacked first semiconductor layers and second semiconductor layers over a substrate. The method also includes forming a cladding layer over the fin structure. The method also includes forming a fin isolation structure beside the cladding layer. The method also includes forming a capping layer over the fin isolation structure. The method also includes forming a dummy gate structure across the capping layer. The method also includes patterning the dummy gate structure. The method also includes patterning the capping layer by using the dummy gate structure as a mask layer. The method also includes removing the dummy gate structure.