GAA Nanostructure Gate Electrode Layout for Lower Gate Resistance
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Solution Overview
Problem
The integration of gate-all-around (GAA) transistor features around nanowires is challenging due to limitations in current fabrication methods, necessitating improved techniques to enhance gate control and reduce OFF-state current and short-channel effects.
Innovation Solution
A method for forming a semiconductor device structure that includes a cladding gate electrode layer formed over and beside nanostructures, which reduces gate resistance and provides channel strain for mobility enhancement, using techniques such as epitaxial growth and multi-patterning processes to create a GAA transistor structure with a low resistance cladding gate electrode layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication methods are used to form GAA features around nanowires, then manufacturing simplicity is maintained, but gate control and device performance are insufficient
Solution Approach 1:
The fabrication process is divided into multiple patterning steps (first pattern, second pattern, third pattern) to achieve complex GAA structures. Each patterning step creates specific features that are combined to form the complete gate-all-around structure, enabling precise gate control through systematic decomposition of the manufacturing process
Solution Approach 2:
The gate structure is formed to completely surround the nanowire channel, with the gate electrode wrapping around the channel region. This nested configuration provides gate control from multiple directions (top, bottom, and sidewalls), significantly enhancing the gate's ability to control carrier flow compared to conventional planar structures
2Reliability
If conventional gate structures are used, then device simplicity is maintained, but OFF-state current and short-channel effects are not sufficiently reduced
Solution Approach 1:
The gate structure exhibits asymmetric configuration relative to the nanowire channel, with the gate electrode positioned to provide enhanced control at critical regions. The gate-all-around structure creates asymmetric electric field distribution that effectively suppresses short-channel effects and reduces OFF-state current leakage paths
Solution Approach 2:
The gate control is extended from conventional two-dimensional planar control to three-dimensional gate-all-around control. The gate electrode wraps around the nanowire channel in multiple dimensions, providing electrostatic control from top, bottom, and sidewall directions simultaneously, which dramatically improves OFF-state current suppression and short-channel effect mitigation
3Speed
If standard electrode layers are formed, then manufacturing simplicity is maintained, but gate resistance is high and device speed is limited
Solution Approach 1:
The gate electrode structure employs local quality variation by forming different electrode regions with optimized properties. The cladding gate electrode layer is positioned specifically around the nanowire to provide low-resistance pathways where needed, while maintaining appropriate thickness and material composition in different regions to balance conductivity with manufacturing feasibility
Solution Approach 2:
The gate electrode is formed using composite material structures, combining multiple materials with complementary properties. The cladding gate electrode layer uses materials selected for their low resistance characteristics, while the overall gate structure integrates different material layers that provide both electrical conductivity and compatibility with the nanowire channel, achieving high device speed through optimized material composition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach reduces gate resistance and improves device speed while enhancing mobility by providing a low resistance cladding gate electrode layer that surrounds the nanostructures, thus addressing the challenges in integrating GAA transistor features.
Implementation Method 1
forming a cladding gate electrode layer with an extending portion protruding beside the nanostructures... reduces gate resistance
Implementation Method 2
provides channel strain for mobility enhancement
Data Source
AI summary
A semiconductor device structure includes nanostructures formed over a substrate. The structure also includes a fin isolation structure formed beside the nanostructures. The structure also includes a work function layer surrounding the nanostructures and covering a sidewall of the fin isolation structure. The structure also includes a gate electrode layer covering the work function layer. The gate electrode layer has an extending portion surrounded by the work function layer.