Layered Nanosheet Source/Drain Structure for Leakage-Speed Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional nano-sheet-based transistors suffer from increased resistances and reduced performance due to conventional methods for mitigating leakage current, which adversely affect operational speeds.
Innovation Solution
Implement a multilayer source/drain feature structure with a first source/drain layer having low dopant concentration and a second layer with high dopant concentration, and laterally etch the higher channels to form concave sidewall surfaces with a convex profile towards the higher channels, reducing leakage current while maintaining operational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional methods are used to mitigate leakage current in nano-sheet-based transistors, then leakage current is reduced, but resistance increases and operational speed decreases
Solution Approach 1:
The patent applies local quality by creating different dopant concentrations in different regions of the source/drain structure. The first source/drain layer has a first dopant concentration while the second source/drain layer has a second dopant concentration, allowing localized optimization: the first layer reduces leakage current while the second layer maintains carrier mobility and operational speed.
Solution Approach 2:
The source/drain region is segmented into multiple layers with distinct dopant concentrations. The first source/drain layer and second source/drain layer are formed as separate structures, enabling independent optimization of leakage current reduction and operational performance without compromise.
2Object-affected harmful factors
If higher dopant concentration is used throughout the source/drain structure, then leakage current is reduced, but carrier migration speed decreases
Solution Approach 1:
Different regions of the source/drain structure are assigned different dopant concentrations tailored to their specific functions. The first source/drain layer uses a dopant concentration optimized for reducing leakage current, while the second source/drain layer uses a dopant concentration optimized for maintaining carrier migration speed, allowing each region to have the quality it needs.
Solution Approach 2:
The source/drain structure is divided into segmented layers with distinct dopant concentrations. This segmentation allows the first layer to focus on leakage reduction while the second layer focuses on maintaining high carrier mobility, preventing the uniform high dopant concentration from degrading overall device performance.
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 solution effectively reduces OFF-state leakage current while improving carrier migration speeds in higher channels, enhancing the overall performance of nano-sheet-based transistors without negating the benefits of reduced OFF-state leakage.
Implementation Method 1
a first source/drain layer with a first dopant concentration and a second source/drain layer with a second dopant concentration, the first dopant concentration being less than the second dopant concentration
Implementation Method 2
laterally etch the higher channels to form concave sidewall surfaces with a convex profile towards the higher channels, reducing leakage current while maintaining operational speed
Data Source
AI summary
A semiconductor device includes a source/drain feature over a semiconductor substrate, channel layers connected to the source/drain feature, a gate structure between adjacent channel layers and wrapping the channel layers, and an inner spacer between the source/drain feature and the gate structure and between adjacent channel layers. The source/drain feature has a first interface with a first channel layer of the channel layer. The first interface has a convex profile protruding towards the first channel layer.