3D Ferroelectric Memory with Epitaxial Templates

Solution Overview

Problem

Prior art ferroelectric hafnia-based compounds grown using atomic layer deposition result in polycrystalline films with reduced total polarization and limited domain switching speed due to random grain orientations, limiting the effectiveness and efficiency of ferroelectric memory devices.

Innovation Solution

The development of a three-dimensional ferroelectric memory device employing epitaxial ferroelectric memory elements with single crystalline or highly textured polycrystalline crystallization templates, where a doped non-centrosymmetric orthorhombic hafnium oxide ferroelectric material is used with a textured crystallographic orientation to enhance remanent polarization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If polycrystalline films are grown using atomic layer deposition, then manufacturing simplicity is maintained, but remanent polarization and domain switching speed are reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidremanent polarization

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the crystallographic orientation parameter of the ferroelectric film from random polycrystalline orientation to highly textured (001) orientation through controlled epitaxial growth on lattice-matched templates, thereby increasing remanent polarization while maintaining manufacturing feasibility through standardized semiconductor processing techniques

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces lattice-matched templates as an intermediary layer between the substrate and the ferroelectric film. These templates provide a crystalline structure that mediates the growth of highly textured ferroelectric films, enabling controlled orientation without requiring complex direct epitaxial growth equipment

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If polycrystalline films are grown using atomic layer deposition, then manufacturing simplicity is maintained, but domain switching speed is limited

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiddomain switching speed

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The patent changes the crystallographic orientation parameter of the ferroelectric film from random polycrystalline orientation to highly textured (001) orientation through controlled epitaxial growth on lattice-matched templates, thereby increasing remanent polarization while maintaining manufacturing feasibility through standardized semiconductor processing techniques

Inventive Principle:

Principle #35Parameter changes

3Reliability

If epitaxial ferroelectric memory elements with single crystalline templates are used, then remanent polarization and switching speed are improved, but device complexity increases

Engineering Contradiction:

Improveremanent polarizationVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the crystallographic orientation parameter of the ferroelectric film from random polycrystalline orientation to highly textured (001) orientation through controlled epitaxial growth on lattice-matched templates, thereby increasing remanent polarization while maintaining manufacturing feasibility through standardized semiconductor processing techniques

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces lattice-matched templates as an intermediary layer between the substrate and the ferroelectric film. These templates provide a crystalline structure that mediates the growth of highly textured ferroelectric films, enabling controlled orientation without requiring complex direct epitaxial growth equipment

Inventive Principle:

Principle #24Intermediary (Mediator)

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 increases the effective dipole moment and remanent polarization of the ferroelectric memory devices, improving their storage capabilities and switching speed compared to polycrystalline films with random orientations.

Implementation Method 1

each of the crystalline ferroelectric memory material portions is epitaxially aligned to a respective one of the epitaxial template portions

Methodology Applied

Scientific EffectEpitaxy: Epitaxy

Data Source

PatentUS11594553B2Three-dimensional ferroelectric memory device containing lattice-matched templates and methods of making the same

Publication Date: 2023.02.28 SANDISK TECHNOLOGIES LLC

AI summary

A ferroelectric memory device includes an alternating stack of insulating layers and electrically conductive layers, a memory opening vertically extending through the alternating stack, and a memory opening fill structure located in the memory opening and containing a vertical stack of memory elements and a vertical semiconductor channel. Each memory element within the vertical stack of memory elements includes a crystalline ferroelectric memory material portion and an epitaxial template portion.