Closed-Loop Seal Ring Structure for Stable GAA Transistors
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Solution Overview
Problem
Existing seal ring structures in semiconductor wafers, particularly for gate-all-around devices like nanosheet devices, lack stability and reliability, necessitating improved fabrication methods to enhance compatibility and protection against moisture and mechanical stress.
Innovation Solution
The formation of a seal ring region with stacked semiconductor layers and dummy gate structures, followed by processes such as fin formation, isolation, epitaxial features, and metal gate replacement, results in a closed ring configuration that includes fin rings, isolation rings, epitaxial rings, and metal gate rings, providing enhanced stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing seal ring structures are used in gate-all-around devices, then fabrication simplicity is maintained, but seal ring stability and reliability deteriorate
Solution Approach 1:
The seal ring is divided into multiple distinct components including fin rings, isolation rings, epitaxial rings, and metal gate rings. Each component performs a specific function and is formed through targeted fabrication steps, allowing the complex seal ring structure to be built from manageable segments that collectively enhance stability without requiring complete redesign of the entire fabrication process
Solution Approach 2:
Dummy gate structures are formed in advance during FEOL processing before the actual metal gate replacement occurs. These preliminary structures serve as placeholders and structural foundations that guide subsequent fabrication steps, ensuring that the final seal ring configuration achieves the desired stability while following a systematic fabrication sequence
2Object-affected harmful factors
If traditional seal ring configurations are used, then manufacturing simplicity is maintained, but protection against moisture and mechanical stress deteriorates
Solution Approach 1:
The seal ring incorporates multiple materials with complementary properties: silicon-based fin rings provide structural foundation, isolation rings offer dielectric protection, epitaxial rings contribute to mechanical strength, and metal gate rings provide conductivity and additional structural support. This composite structure enhances protection against moisture ingress and mechanical stress while maintaining compatibility with existing semiconductor manufacturing processes
Solution Approach 2:
The seal ring components are arranged in a nested configuration where fin rings form the outer structure, isolation rings are positioned within, epitaxial rings are embedded, and metal gate rings are integrated in the innermost positions. This nested arrangement maximizes space utilization and creates multiple concentric barriers against harmful factors while following a logical fabrication sequence
Data Source
AI summary
The present disclosure provides a semiconductor structure. The semiconductor structure includes a substrate; and a seal ring region enclosing a circuit region disposed over the substrate. The seal ring region further includes a fin ring protruding from the substrate having a first width; an isolation ring disposed over the substrate and adjacent to the fin ring; a gate ring disposed over the fin ring having a second width, wherein the second width is less than the first width; an epitaxial ring disposed between the fin ring and the isolation ring; and a contact ring lands on the epitaxial ring and the isolation ring. Each of the fin ring, the isolation ring, the epitaxial ring, and the contact ring extends parallel to each other and fully surrounds the circuit region to form a closed loop.