FinFET Gate Isolation Structure for Larger End Cap Windows
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Solution Overview
Problem
As semiconductor devices continue to scale down, the complexity of IC structures and processing challenges, such as device performance degradation and increased fabrication costs, are not adequately addressed by existing methods, particularly in non-planar transistor architectures like FinFETs and GAAFETs.
Innovation Solution
A semiconductor device fabrication method involving the formation of a cut poly (CPO) structure between a dummy fin and an inactive fin, which provides a larger processing window by disconnecting CPO process variations from end cap windows, achieved through the formation of a gate isolation structure between the dummy fin and the inactive fin, allowing for reduced device size and improved yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device size is reduced to increase functional density, then productivity and cost efficiency are improved, but device performance degradation and manufacturing precision challenges worsen
Solution Approach 1:
The patent divides the gate structure into multiple segments: a first gate structure over active fins, a second gate structure over inactive fins, and a gate isolation structure between them. This segmentation allows independent optimization of each gate region, enabling the active region to achieve high performance while the inactive region can be designed for process stability and yield, thus resolving the contradiction between device size reduction and manufacturing precision.
Solution Approach 2:
The patent applies different gate structures and materials to different regions: the first gate structure uses a first material (e.g., polysilicon) optimized for active transistor performance, while the second gate structure uses a second material (e.g., dielectric) optimized for process stability. This local differentiation allows each region to be optimized for its specific function, maintaining high manufacturing precision even as overall device size decreases.
2Productivity
If complex three-dimensional transistor structures are used to continue scaling, then functional density is improved, but device performance degradation and fabrication complexity worsen
Solution Approach 1:
The patent segments the transistor structure into active fins with gate structures and inactive fins without gate structures, allowing simplified processing in inactive regions while maintaining advanced 3D structures in active regions. This reduces overall fabrication complexity by eliminating the need to process gates over entire fin arrays, thereby enabling continued scaling without proportionally increasing fabrication difficulty.
Solution Approach 2:
The patent extracts the gate structure from inactive fin regions, removing unnecessary complexity from areas that do not require active transistor functionality. This extraction simplifies the fabrication process by reducing the number of patterning and deposition steps required, while preserving the complex 3D gate-all-around structures in active regions where high functional density is needed.
3Ease of manufacture
If gate structures are formed over inactive fins, then manufacturing process is simplified, but end cap window processing and device yield worsen
Solution Approach 1:
The patent segments the gate formation process into two distinct stages: forming a first gate structure over active fins, then forming a second gate structure over inactive fins. This segmentation allows the end cap window to be defined and processed independently between these structures, improving access for subsequent processing steps and enhancing device yield without significantly complicating the overall manufacturing process.
Solution Approach 2:
The gate isolation structure acts as an intermediary element between the first and second gate structures. It provides a physical and electrical barrier that enables independent processing of the end cap window region, allowing manufacturing to proceed efficiently while improving yield by preventing process variations from affecting both gate regions simultaneously.
Data Source
AI summary
A method of fabricating a semiconductor device is described. A substrate is provided. A plurality of fins is formed extending from the substrate, the fins including a first group of active fins arranged in an active region, and including an inactive fin having at least a portion in an inactive region, the active fins separated by first trench regions between adjacent of the active regions, the inactive fin separated from its closest active fin by a second trench region, the second trench region having a greater width than that of a trench region of the first trench regions. A dummy fin is formed on the isolation dielectric in the second trench region, the dummy fin disposed between the first group of active fins and the inactive fin. A dummy gate is formed over the fins. The gate isolation structure is disposed between the dummy fin and the inactive fin and separates regions of the dummy gate.