FinFET Carrier Mobility via Magnetic Lorentz Force

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Solution Overview

Problem

As semiconductor devices shrink, the shallower channel region in transistors leads to reduced carrier mobility due to carrier reflections at the interface between the dielectric layer and the channel, impairing transistor performance.

Innovation Solution

The method involves forming magnetic material layers on both sides of the channel region, magnetizing them to create a magnetic field that affects carrier trajectories, preventing reflections and enhancing mobility by applying a Lorentz force to carriers moving towards the interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the channel region size is reduced to shrink device critical dimension, then device integration density is improved, but carrier mobility deteriorates due to increased carrier reflection at the dielectric-channel interface

Engineering Contradiction:

Improvedevice integration densityVSAvoidcarrier mobility

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A magnetic field is introduced as an intermediary force between the carriers and the dielectric-channel interface. The magnetic field exerts a Lorentz force on the carriers, modifying their trajectories and preventing direct reflection at the interface, thus maintaining carrier mobility despite reduced channel dimensions

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical state of the channel environment by applying a magnetic field, which alters the carrier motion parameters. This parameter change (magnetic field application) enables carriers to navigate the shallower channel without suffering from interface reflection, thereby preserving mobility while allowing device scaling

Inventive Principle:

Principle #35Parameter changes

2Reliability

If stress memorization technology or embedded SiGe technology is used to improve carrier mobility, then transistor performance is enhanced, but device complexity increases

Engineering Contradiction:

Improvecarrier mobilityVSAvoidfabrication process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical/stress-based methods (stress memorization, embedded SiGe) with a magnetic field-based approach. Instead of physically modifying the crystal lattice through stress or material composition changes, a magnetic field is applied to control carrier trajectories, thereby reducing fabrication complexity while maintaining mobility enhancement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the control parameter from mechanical stress or material composition to magnetic field strength and direction. This parameter change enables a simpler fabrication process that does not require complex stress engineering or additional material layers, thus reducing device complexity while achieving the same mobility improvement

Inventive Principle:

Principle #35Parameter changes

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 approach significantly improves carrier mobility and transistor performance by ensuring carriers directly move from the source to the drain without reflection, thereby increasing driving current.

Implementation Method 1

magnetizing the magnetic material layers to form a magnetic field in the channel region between adjacent magnetic material layers

Methodology Applied

Scientific EffectLorentz force: Lorentz Force

Data Source

PatentUS8859358B2CMOS transistors, fin field-effect transistors and fabrication methods thereof

Publication Date: 2014.10.14 SEMICON MFG INT CORP

AI summary

A method is provided for fabricating a transistor. The method includes providing a semiconductor substrate; and configuring a channel region along a first direction. The method also includes forming trenches at both sides of the channel region along a second direction; and forming a magnetic material layer in each of the trenches. Further, the method includes magnetizing the magnetic material layers to form a magnetic field in the channel region between adjacent magnetic material layers; and forming source/drain regions at both ends of the channel region along the first direction.