Gate-All-Around Low-Dimensional Transistor for Uniform CNT Fabrication
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Solution Overview
Problem
Transistors with carbon nanotube channels face performance issues such as poor operation performance, fabrication process incompatibility, and device uniformity, which hinder their widespread adoption and integration.
Innovation Solution
A transistor design featuring a gate-all-around structure with spacers, sources, and drains, utilizing low-dimensional materials like carbon nanotubes, nanowires, or two-dimensional materials, and a self-aligned fabrication process that includes specific deposition and etching techniques to ensure uniformity and compatibility, with spacers acting as masks to control position and morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional transistor fabrication processes are used with carbon nanotube channels, then the process is simple, but the device uniformity and operation performance are poor
Solution Approach 1:
The fabrication process is divided into distinct stages: forming insulating layers, creating spacer structures, defining source/drain regions, and forming gate structures. Each stage uses specific deposition and etching techniques to achieve precise control over device geometry and material properties, thereby improving device uniformity while maintaining process manageability
Solution Approach 2:
Insulating layers are formed on the substrate before carbon nanotube placement, and spacer structures are created before source/drain formation. These preliminary actions establish precise geometric constraints and protective structures that ensure uniform device characteristics throughout the fabrication process
2Reliability
If carbon nanotubes are used as channel material, then mobility and thermal conductivity are high, but contact resistance and thermal stability are problematic
Solution Approach 1:
Spacer structures made of conductive material are introduced as intermediary elements between the carbon nanotube channel and the source/drain electrodes. These spacers reduce contact resistance by providing a conductive pathway while maintaining thermal stability through their engineered material composition and geometric configuration
Solution Approach 2:
The transistor structure employs composite material systems combining carbon nanotubes with metal spacers, dielectric layers, and conductive source/drain materials. This composite approach optimizes both electrical contact properties and thermal stability by leveraging the complementary characteristics of different materials
3Reliability
If gate-all-around structure is implemented, then electrostatic control is improved, but fabrication complexity increases
Solution Approach 1:
The gate structure is formed by nesting multiple layers: a first gate electrode is positioned within a cavity formed in the insulating layers, surrounded by spacer structures, with a second gate electrode formed above. This nested configuration achieves gate-all-around control of the carbon nanotube channel while organizing complex fabrication steps into sequential, manageable processes
Data Source
AI summary
A transistor and a method for fabricating the transistor are provided. The semiconductor structure transistor includes a base, a low-dimensional material layer, a plurality of spacers, a source, a drain, and a gate stack. The low-dimensional material layer is provided above the base. The plurality of spacers is provided on a surface of the low-dimensional material layer away from the base and spaced apart from each other. The source and the drain are provided on the surface of the low-dimensional material layer away from the base, respectively. The gate stack is provided on the surface of the low-dimensional material layer away from the base and between the source and the drain, in which the gate stack, the source and the drain are separated by the spacers, and in contact with the spacers, respectively. Therefore, the transistor has advantages of excellent comprehensive performance, high process compatibility, and good device uniformity.