Nonvolatile Ternary Memory Using 2D Ferroelectric Polarization

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Solution Overview

Problem

Conventional ternary memory devices are complex and volatile, limiting their effectiveness and requiring further research to address these issues.

Innovation Solution

A nonvolatile ternary memory device is developed using a two-dimensional ferroelectric material, such as SnTe or GeSnTe2, which allows for a simple structure and stable ferroelectric properties by representing ternary states through different polarization directions, enabling efficient writing and reading processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional ternary logic memory structure is used, then ternary data representation is achieved, but the device structure becomes complicated and volatile

Engineering Contradiction:

Improveternary data representationVSAvoiddevice structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameter of data representation from voltage levels (conventional ternary) to polarization directions of two-dimensional ferroelectric material. By utilizing the intrinsic ferroelectric properties and multiple stable polarization states of materials like SnTe and GeSnTe2, the device achieves ternary and quaternary data representation with a simple capacitor-like structure, eliminating the need for complex transistor arrays required by conventional approaches

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional voltage-based electrical system with a polarization-based ferroelectric system. Instead of using complex voltage level control and multiple transistor configurations, the invention uses the spontaneous polarization directions of two-dimensional ferroelectric materials to encode ternary and quaternary data, significantly simplifying the device structure while maintaining nonvolatile operation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If conventional ternary memory is used, then ternary logic is implemented, but the memory becomes volatile and requires continuous power

Engineering Contradiction:

Improveternary logic implementationVSAvoiddata retention

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The two-dimensional ferroelectric material inherently maintains its polarization state through its own crystal structure stability, requiring no external power for data retention. The material's spontaneous polarization and high coercive field enable it to self-preserve the stored ternary or quaternary information without continuous power supply, achieving nonvolatile operation

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent employs composite structures combining two-dimensional ferroelectric materials (SnTe, GeSnTe2) with conventional semiconductor components. The unique properties of these two-dimensional materials, including their stable polarization states and interface characteristics, provide nonvolatile data retention while maintaining compatibility with existing semiconductor fabrication processes

Inventive Principle:

Principle #40Composite materials

3Device complexity

If two-dimensional ferroelectric material is used, then structure is simplified and nonvolatile operation is achieved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvedevice structureVSAvoidmaterial deposition control

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent focuses on achieving high-quality two-dimensional ferroelectric material deposition in the critical local region where the material interfaces with electrodes. By optimizing the deposition process specifically for this interface region and using appropriate thickness ranges (1-10 nm), the invention maintains manufacturing feasibility while achieving the desired ferroelectric properties and data retention characteristics

Inventive Principle:

Principle #3Local quality

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 device achieves stable ternary or quaternary data representation with low power consumption and thermal stability, simplifying the structure and enhancing energy efficiency.

Implementation Method 1

a two-dimensional ferroelectric material formed on the lower electrode... representing a ternary state according to a polarization direction of a two-dimensional ferroelectric material

Methodology Applied

Scientific EffectFerroelectricity:

Implementation Method 2

A magnitude of a tunneling current between the first upper electrode and the lower electrode may be used to represent a ternary state according to a polarization direction of the two-dimensional ferroelectric material

Methodology Applied

Scientific EffectTunneling current:

Data Source

PatentUS11296098B2Nonvolatile ternary memory device using two-dimensional ferroelectric material and method of manufacturing the same

Publication Date: 2022.04.05 UNIST (ULSAN NAT INST OF SCI & TECH)

AI summary

The present disclosure relates to a nonvolatile ternary memory device using a two-dimensional ferroelectric material and a method of manufacturing the same. The method of manufacturing the nonvolatile ternary memory device according to an embodiment of the present disclosure includes (a) forming a lower electrode on a substrate, (b) forming a two-dimensional ferroelectric material on the lower electrode, (c) forming a semiconductor on the two-dimensional ferroelectric material, and (d) forming an upper electrode on the semiconductor.