VGAA Gate Structure With Layered Dielectrics for Leakage Control
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Solution Overview
Problem
The leakage current in vertical gate-all-around (VGAA) transistors is high, negatively impacting the performance of semiconductor structures.
Innovation Solution
A semiconductor structure is fabricated by forming a first trench in a substrate, followed by a protective material layer and a first dielectric layer, with a second dielectric layer on the trench side wall, and filling the trench to create a work function structure with multiple layers of varying work functions to reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a vertical gate-all-around (VGAA) transistor structure is used to increase area utilization and reduce feature size, then area utilization is improved, but leakage current increases
Solution Approach 1:
The patent applies local quality by creating different dielectric layers with different properties at different locations within the trench structure. Specifically, a first dielectric layer is formed at the bottom of the trench and a second dielectric layer is formed on the side walls, with each layer having optimized properties for its specific location to control leakage current while maintaining the VGAA transistor's area utilization benefits
Solution Approach 2:
The patent uses composite materials by combining multiple dielectric layers (first dielectric layer and second dielectric layer) with different material properties within the same trench structure. This composite approach allows optimization of electrical properties at different locations, reducing leakage current while preserving the vertical gate-all-around structure's space efficiency
Data Source
AI summary
Embodiments relate to a semiconductor structure and a fabrication method. The method includes: providing a substrate, where a first trench is formed in the substrate; forming a first dielectric layer and a protective material layer in the first trench, where the first dielectric layer is positioned between the protective material layer and the substrate, and an upper surface of the first dielectric layer is lower than an upper surface of the substrate, to expose a portion of a side wall of the first trench; forming a second dielectric layer on the exposed side wall of the first trench; and filling the second trench to form a work function structure, where the work function structure includes a first work function layer and a second work function layer, where the second work function layer is positioned on an upper surface of the first work function layer.