GAA FET Isolation Structure for Source/Drain Leakage Control
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in preventing current leakage between adjacent source/drain regions in gate-all-around FETs due to the complexity of scaling down semiconductor devices, which affects device performance and manufacturing costs.
Innovation Solution
The introduction of isolation structures comprising an undoped semiconductor layer, a dielectric layer, and an air spacer to electrically isolate epitaxial S/D regions from the fin base, preventing current leakage and minimizing diffusion of dopants, using silicon-rich dielectric materials to enhance etch resistance and control epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scaling down semiconductor device dimensions is pursued to increase storage capacity and processing performance, then device performance is improved, but manufacturing complexity increases
Solution Approach 1:
The isolation structure is divided into multiple functional layers: an undoped semiconductor layer for physical isolation, a dielectric layer for electrical insulation, and an air spacer for additional isolation. This segmentation allows each layer to perform its specific function independently, simplifying the overall manufacturing process while achieving effective isolation in scaled-down devices
Solution Approach 2:
The undoped semiconductor layer acts as an intermediary between the fin base and the source/drain regions, creating a transition zone that prevents direct interaction and potential current leakage. This intermediary layer simplifies the isolation requirement by providing a dedicated buffer zone that is easier to manufacture than perfect isolation boundaries
2Reliability
If isolation structures are introduced to prevent current leakage between adjacent source/drain regions, then device reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The isolation structure is segmented into three distinct layers with specific functions: the undoped semiconductor layer provides physical separation, the dielectric layer provides electrical insulation, and the air spacer provides additional isolation. This segmentation simplifies manufacturing by allowing each layer to be deposited using standard semiconductor fabrication processes
Solution Approach 2:
The isolation structure applies different material properties to different regions: the undoped semiconductor layer provides mechanical isolation, the dielectric layer provides electrical insulation, and the air spacer provides volumetric isolation. This local differentiation of material properties achieves comprehensive isolation without requiring a single complex structure
3Reliability
If undoped semiconductor layers are used for isolation, then current leakage is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The undoped semiconductor layer is grown epitaxially on the fin base before forming the source/drain regions. This preliminary action establishes the isolation structure early in the manufacturing process, allowing subsequent doping and patterning steps to proceed without requiring precise control of the isolation layer itself
Solution Approach 2:
The undoped semiconductor layer serves as an intermediary that simplifies subsequent manufacturing steps. By establishing this layer first, the source/drain regions can be formed without direct contact with the fin base, and doping processes can be controlled more easily since the isolation layer is already in place
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
This solution effectively prevents current leakage and dopant diffusion, maintaining device performance while reducing manufacturing costs by optimizing the isolation structure's dimensions and materials.
Implementation Method 1
an undoped semiconductor layer disposed on the second portion of the fin base
Implementation Method 2
preventing current leakage and minimizing diffusion of dopants
Implementation Method 3
an air spacer disposed on the dielectric layer
Implementation Method 4
using silicon-rich dielectric materials to enhance etch resistance
Data Source
AI summary
A semiconductor device and a method of fabricating the semiconductor device are disclosed. The semiconductor device includes a substrate, a fin base disposed on the substrate, nanostructured channel regions disposed on a first portion of the fin base, a gate structure surrounding the nanostructured channel regions, a source/drain (S/D) region disposed on a second portion of the fin base, and an isolation structure disposed between the S/D region and the second portion of the fin base. The isolation structure includes an undoped semiconductor layer disposed on the second portion of the fin base, a silicon-rich dielectric layer disposed on the undoped semiconductor layer, and an air spacer disposed on the silicon-rich dielectric layer.