Stacked GAA Gate Structure for Dense 3D Semiconductor Layouts
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving reliable three-dimensional designs with high device density and performance while maintaining cost-effectiveness, particularly in the fabrication and design stages as they progress into 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 over an isolation structure to create a barrier for gate structures, allowing for the formation of vertically stacked semiconductor layers and reducing parasitic capacitance through the use of inner spacer layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If three-dimensional designs are implemented to increase device density, then device density and performance are improved, but fabrication complexity and reliability challenges increase
Solution Approach 1:
The device structure is segmented into distinct functional regions including channel regions, source/drain regions, and barrier structures. The barrier structure itself is segmented into multiple layers including dummy fin structures and capping layers, allowing complex three-dimensional functionality to be achieved through systematic division of the device architecture.
Solution Approach 2:
The patent implements vertical stacking of semiconductor layers and barrier structures to transition from two-dimensional planar devices to three-dimensional vertically-integrated devices. This dimensional transition increases device density by utilizing the vertical dimension for multiple channel regions and functional elements stacked above the substrate.
2Productivity
If gate structures are positioned closer together to increase device density, then device density is improved, but parasitic capacitance between gates increases
Solution Approach 1:
Barrier structures comprising dummy fin structures and capping layers are introduced as intermediary elements positioned between adjacent gate structures. These barrier structures electrically isolate neighboring gates, preventing parasitic capacitance formation while allowing the gates to be positioned closely together to achieve high device density.
Solution Approach 2:
The barrier structures are formed in advance during the fabrication process to preemptively prevent parasitic capacitance between gates. By establishing these isolating structures before final gate positioning, the design proactively counteracts the harmful capacitive coupling that would otherwise occur in densely-packed three-dimensional devices.
3Productivity
If advanced nanometer process nodes are used to improve performance, then device performance is improved, but fabrication reliability and time-dependent dielectric breakdown resistance deteriorate
Solution Approach 1:
The barrier structure employs composite material architecture combining different semiconductor layers and dielectric materials. The dummy fin structures and capping layers utilize materials with complementary properties that provide both the electrical isolation needed for reliability and the dimensional precision required for advanced nanometer process nodes.
Solution Approach 2:
The barrier structures serve as protective cushioning elements formed beforehand to shield critical dielectric regions from stress and electrical breakdown. This preliminary protection mechanism compensates for the reduced dielectric strength inherent in scaled nanometer devices, maintaining reliability despite operating at advanced process nodes.
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes first nanostructures and second nanostructures stacked in a vertical direction over a substrate, and a first dielectric structure between the first nanostructures and the second nanostructures. The semiconductor device structure includes a first gate structure formed over the first nanostructures. The first gate structure comprises a gate dielectric layer, and a topmost surface of the gate dielectric layer is higher than a top surface of the first dielectric structure.