Dog Bone Nanosheet FET Channels Without Inner Spacers
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Solution Overview
Problem
Existing semiconductor technologies face challenges in achieving balanced electron and hole mobility, particularly in nanosheet FET devices, leading to disparities between P-type and N-type metal oxide semiconductor devices, exacerbated by the transition to thinner channel structures.
Innovation Solution
The introduction of dog bone channels in nanosheet FETs without inner spacers, featuring thicker end portions and a narrower central portion, allows for enhanced compressive strain and improved hole mobility, aligning it with electron mobility, and provides better short channel control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inner spacers are used in nanosheet FET channels, then manufacturing precision is improved, but device complexity increases and hole mobility is reduced
Solution Approach 1:
The patent removes the inner spacer component from the nanosheet FET channel structure. By extracting this element, the device complexity is reduced while maintaining manufacturing precision through alternative design features such as the dog bone channel geometry that provides structural definition without requiring additional spacer components.
Solution Approach 2:
The patent employs asymmetric dog bone channel geometry where the channel width varies along its length, being narrower at the center and wider at the ends. This asymmetric design provides structural precision and control without requiring symmetric inner spacers, thereby reducing device complexity while maintaining manufacturing precision.
2Shape
If inner spacers are used in nanosheet FET channels, then channel structure is defined, but hole mobility is reduced due to decreased compressive strain
Solution Approach 1:
The patent applies local quality by creating regions of different channel width along the channel length. The narrower central portion provides strong electrostatic control, while the wider end portions allow for enhanced compressive strain and improved hole mobility. This local variation in geometry optimizes both structure definition and carrier transport properties.
Solution Approach 2:
The dog bone channel features curved transitions between the narrow central region and wider end regions. These curved geometries facilitate strain distribution and improve hole mobility by reducing stress concentration points while maintaining well-defined channel boundaries without requiring inner spacers.
3Length of moving object
If channel thickness is reduced to nanosheet dimensions, then device scaling is achieved, but disparity between electron and hole mobility is exacerbated
Solution Approach 1:
The patent uses local quality by creating regions of different channel widths along the channel length. The narrower central portion provides strong electrostatic control for scaling, while the wider end portions allow for enhanced compressive strain and improved hole mobility, thereby balancing electron and hole mobility in thin nanosheet channels.
Solution Approach 2:
The patent changes the geometric parameters of the channel by introducing variable width along the channel length. This parameter variation allows optimization of both electrostatic control and strain effects in the nanosheet channel, addressing the mobility disparity that arises from channel thinning while maintaining device scaling benefits.
Data Source
AI summary
A semiconductor device includes source/drain regions having a main portion and a buffer layer partially encapsulating the main portion. Dog bone channels extend across a gate conductor and connect between the buffer layer at end portions of the dog bone channels. The end portions are thicker than a central portion of the dog bone channels.