GAA Gate Structure with Dummy Fin for Self-Aligned Gate Spacing
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving precise three-dimensional designs and high device density while maintaining low costs and performance, particularly in the fabrication and design stages as the industry transitions to nanometer technology process nodes.
Innovation Solution
The development of a gate all around (GAA) transistor structure using a self-aligned cut metal gate process, which involves forming a dummy fin structure and capping layer to separate gate structures, allowing for reduced pitch between gate structures and improved alignment without alignment issues, thereby enhancing device density and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional lithography alignment processes are used for gate structures, then manufacturing process is simpler, but alignment precision deteriorates at nanometer technology process nodes
Solution Approach 1:
The dummy fin structure serves as a self-aligned reference that automatically defines the position of subsequent gate structures. The cut metal gate process uses the dummy fin as a physical barrier and alignment reference, eliminating the need for complex lithography alignment steps. The structure itself provides the alignment function, achieving self-service alignment that ensures precise positioning at nanometer process nodes without increasing overall process complexity
Solution Approach 2:
The dummy fin structure acts as an intermediary element between the isolation structure and the gate structures. It provides a physical reference plane and spacing mechanism that mediates the positioning of adjacent gate structures, ensuring precise pitch control and alignment. This intermediary structure translates the design intent into physical alignment without requiring complex lithography processes
2Quantity of substance
If pitch between gate structures is reduced to increase device density, then device density improves, but parasitic capacitance increases
Solution Approach 1:
The dummy fin structure is segmented into discrete elements that are positioned between gate structures. These segmented dummy fins create electrical isolation zones that break up continuous parasitic capacitance paths. By segmenting the structure into alternating active gate regions and dummy fin regions, the parasitic capacitance between adjacent gates is reduced while maintaining high device density in the active regions
Solution Approach 2:
The dummy fin structure serves as an intermediary barrier between adjacent gate structures. This intermediary element provides electrical isolation that reduces parasitic capacitance coupling between gates while maintaining the reduced pitch configuration. The dummy fin acts as a mediator that allows close spacing for density while preventing harmful capacitive coupling
3Quantity of substance
If three-dimensional designs are implemented to achieve higher device density, then device density improves, but manufacturing precision requirements increase
Solution Approach 1:
The dummy fin structure is formed in advance before the gate structures are created. This preliminary action establishes the precise pitch and alignment references that will guide subsequent gate formation steps. By pre-defining the spatial framework with dummy fins, the manufacturing process achieves high precision in three-dimensional configurations without requiring equally high precision in all subsequent steps
Solution Approach 2:
The three-dimensional structure utilizes the dummy fin elements as self-aligning references that automatically define the positioning of gate structures in multiple dimensions. The vertical and horizontal spacing is self-determined by the dummy fin geometry, eliminating the need for complex multi-dimensional lithography alignment and reducing manufacturing precision requirements while achieving high device density
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes a first stacked nanostructure and a second stacked nanostructure formed over a substrate, and a dummy fin structure between the first stacked nanostructure and the second stacked nanostructure. The semiconductor device structure includes a gate structure formed over the first stacked nanostructure and the second stacked nanostructure, and a conductive layer formed over the gate structure. The semiconductor device structure includes a capping layer formed over the dummy fin structure, and each of the gate structure and the conductive layer is divided into two portions by the capping layer.