Ferroelectric Gate Stack With Oxygen Barrier for Thin Interfacial Layers

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Solution Overview

Problem

Existing semiconductor devices face limitations in achieving subthreshold swing below 60 mV/dec due to the theoretical constraints of field-effect transistors, which can be overcome by incorporating a ferroelectric layer with a specific crystal structure and stabilization layer to enhance ferroelectric properties.

Innovation Solution

A semiconductor device design featuring a ferroelectric layer stabilized by a stabilization layer, an oxygen diffusion barrier layer, and a threshold voltage control layer, along with an interfacial layer, to improve ferroelectric properties and control threshold voltage, thereby reducing subthreshold swing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a ferroelectric layer is formed and annealed to achieve the desired crystal structure, then the ferroelectric property is improved, but the interfacial layer thickness increases which degrades device performance

Engineering Contradiction:

Improveferroelectric propertyVSAvoidinterfacial layer thickness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

An oxygen diffusion barrier layer is introduced as an intermediary between the interfacial layer and the ferroelectric layer. This barrier layer prevents oxygen from the ferroelectric layer from diffusing into the interfacial layer during annealing, thus maintaining the interfacial layer thickness while still allowing the ferroelectric layer to achieve its desired crystal structure through annealing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The gate insulating layer is segmented into multiple distinct layers: an interfacial layer, an oxygen diffusion barrier layer, and a ferroelectric layer. This segmentation allows each layer to perform its specific function independently - the interfacial layer provides interface quality, the barrier layer prevents oxygen diffusion, and the ferroelectric layer provides the desired ferroelectric properties.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If the interfacial layer thickness is reduced to improve device performance, then the subthreshold swing improves, but the ferroelectric layer cannot be properly stabilized during annealing

Engineering Contradiction:

Improveinterfacial layer thicknessVSAvoidferroelectric phase stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The oxygen diffusion barrier layer serves as a protective intermediary that allows the interfacial layer to remain thin for improved device performance while preventing oxygen loss from the ferroelectric layer during annealing, thus maintaining ferroelectric phase stability despite the thin interfacial layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The oxygen diffusion barrier layer is placed beforehand between the interfacial layer and ferroelectric layer to cushion against oxygen diffusion during subsequent annealing processes. This pre-positioned barrier ensures that even with a thin interfacial layer, the ferroelectric layer remains stable throughout the annealing process.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If conventional field-effect transistor design is used, then the device structure is simple, but the subthreshold swing cannot go below 60 mV/dec due to theoretical limitations

Engineering Contradiction:

Improvegate structureVSAvoidsubthreshold swing

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The gate insulating layer uses a composite structure combining an interfacial layer, an oxygen diffusion barrier layer, and a ferroelectric layer. This composite material approach enables the device to achieve subthreshold swing below the conventional 60 mV/dec limit by utilizing the negative capacitance effect of the ferroelectric layer, while the barrier layer ensures structural stability.

Inventive Principle:

Principle #40Composite materials

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 proposed design achieves a subthreshold swing below 60 mV/dec, enhancing device performance by stabilizing the ferroelectric phase and preventing interfacial layer thickness increase during annealing.

Implementation Method 1

a process of annealing the ferroelectric layer may be performed to form the desired phase having a certain crystal structure therein

Methodology Applied

Scientific EffectAnnealing: Annealing

Implementation Method 2

a ferroelectric layer capable of providing a negative capacitance characteristic when used as a gate insulating layer, has been considered. In order for a ferroelectric material to have a ferroelectric property, the ferroelectric material should have a phase with a certain crystal structure

Methodology Applied

Scientific EffectPhase transition: Phase Change

Implementation Method 3

preventing oxygen from being diffused into the interfacial layer

Methodology Applied

Scientific EffectOxygen diffusion: Diffusion

Data Source

PatentUS12550333B2Semiconductor switching devices having ferroelectric layers therein and methods of fabricating same

Publication Date: 2026.02.10 SAMSUNG ELECTRONICS CO LTD

AI summary

A semiconductor device includes a substrate, a channel on or in the substrate, a source/drain pair respectively on opposite ends of the channel, and a gate structure on the channel between the source/drain pair, wherein the gate structure includes an interfacial layer, a ferroelectric layer, a stabilization layer, an oxygen diffusion barrier layer, and a threshold voltage control layer that are sequentially stacked on the channel.