Gate Isolation Structure With Dummy Fins for Dense GAA Layouts
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Solution Overview
Problem
Existing semiconductor fabrication methods face challenges in designing patterns for cut gate structures, particularly in terms of spacing and alignment constraints, which affect the efficiency and complexity of forming gate-all-around (GAA) transistors.
Innovation Solution
The method involves forming dielectric dummy fin structures between functional fin structures, depositing a gate layer, etching it to expose dummy fin structures, and then using a conductive layer to connect gate segments, followed by forming cut features over the dummy fin structures to electrically isolate adjacent gate segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication methods are used for cut gate structures, then manufacturing process is simpler, but spacing and alignment constraints increase
Solution Approach 1:
The gate structure is divided into multiple gate segments separated by dummy fin structures. Each gate segment can be independently formed and positioned, allowing relaxed spacing and alignment constraints compared to a continuous gate structure. The dummy fin structures act as physical separators that define the boundaries between gate segments.
Solution Approach 2:
Dummy fin structures are introduced as intermediary elements between functional fin structures. These dummy fins serve as mediators that enable the formation of cut gate structures by providing separation and alignment references, thereby reducing the direct spacing and alignment constraints between adjacent gate segments.
2Productivity
If fin structures are placed closer together to increase pattern density, then circuit design efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
By segmenting the gate structure into discrete gate segments separated by dummy fin structures, the patent enables closer placement of functional fin structures without compromising manufacturing precision. The segmentation allows each gate segment to be independently formed with relaxed spacing requirements.
Solution Approach 2:
The patent introduces an additional dimensional element by placing dummy fin structures between functional fins in the lateral dimension. This dimensional addition provides physical separation and alignment references that enable closer spacing of functional fins while maintaining manufacturability.
3Ease of manufacture
If dummy fin structures are used to separate gate segments, then spacing constraints are reduced, but device structure complexity increases
Solution Approach 1:
The dummy fin structures serve multiple functions: they act as physical separators between gate segments, provide alignment references during fabrication, and define the boundaries of cut gate structures. This multi-functionality reduces the need for additional separate structures, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The dummy fin structures are formed using the same fabrication processes as the functional fin structures, utilizing self-aligned deposition and etching techniques. This self-service approach minimizes additional process steps and reduces the complexity increase associated with adding dummy structures.
Data Source
AI summary
A semiconductor structure includes a plurality of active regions extending along a first direction, a plurality of gate structure segments positioned along a line extending in a second direction, the second direction being orthogonal to the first direction, wherein the gate structure segments are separated by dummy structures. The semiconductor structure further includes a conductive layer disposed over both the gate structure segments and the dummy structures to electrically connect at least some of the gate structure segments, and a cut feature aligned with one of the dummy structures and positioned to electrically isolate gate structure segments on both sides of the one of the dummy structures.