Ion Conductive Layer Resistance Control in Non-Volatile Memory

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Solution Overview

Problem

Conventional non-volatile semiconductor memory devices face challenges in providing a sufficient margin for read and write operations due to rapid resistance changes with applied voltage, making it difficult to maintain reliable data storage.

Innovation Solution

A non-volatile memory device with a storage node structure that includes a lower electrode, a data storage layer formed with a compound layer of transition metals and Group V elements, and noble metal electrodes, along with insulating layers, which controls ion concentration to manage resistance changes, ensuring sufficient voltage margins for read and write operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional copper sulfide layer is used as an ion conductive layer, then the device achieves non-volatile memory functionality, but the resistance changes rapidly with applied voltage making it difficult to provide sufficient margin for read and write operations

Engineering Contradiction:

Improvemargin for read and write operationsVSAvoidresistance change control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the ion conductive layer by replacing conventional copper sulfide with a compound layer containing transition metal atoms and Group V element atoms (such as MoSx, WSx, MoSex, WSex). This compositional parameter change results in reduced resistance change with applied voltage, providing sufficient margin for reliable read and write operations while maintaining non-volatile memory functionality.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material strategy by creating a compound layer with specific combinations of transition metal atoms (Mo, W) and Group V element atoms (S, Se). This composite approach leverages the favorable properties of both element groups to achieve stable resistance characteristics that are neither too sensitive nor too insensitive to voltage changes, enabling reliable memory operation margins.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the ion concentration in the copper sulfide layer is increased to improve data storage capability, then the resistance varies significantly with voltage, but this makes it difficult to maintain stable resistance for reliable data retention

Engineering Contradiction:

Improveion concentrationVSAvoidresistance stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent changes the fundamental material parameter from copper sulfide to transition metal-Group V element compounds. This parameter change allows the device to maintain stable resistance characteristics even with optimized ion concentration, as the compound structure inherently provides better resistance stability compared to conventional copper sulfide.

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

The proposed solution effectively reduces resistance changes with applied voltage, ensuring stable data storage and maintaining sufficient margins for read and write operations, enabling reliable multi-bit data recording and retention.

Implementation Method 1

a non-volatile semiconductor memory device having an ion conductive layer illustrating different resistant characteristics in accordance with percolation diffusion

Methodology Applied

Scientific EffectPercolation diffusion: Diffusion

Implementation Method 2

a lower electrode used as an ion source; a data storage layer formed on the lower electrode, a portion thereof being spaced from the lower electrode

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS8193569B2Non-volatile semiconductor memory device having ion conductive layer and methods of fabricating and operating the same

Publication Date: 2012.06.05 SAMSUNG ELECTRONICS CO LTD

AI summary

A non-volatile semiconductor memory device having an ion conductive layer, and methods of fabricating and operating the same are disclosed. The non-volatile memory device may include a substrate, a switching element formed in the substrate, and a storage node connected to the switching element, the storage node may include a lower electrode connected to the switching element, and used as an ion source; a data storage layer formed on the lower electrode, a portion thereof being spaced from the lower electrode; a side electrode spaced from the lower electrode, a side surface thereof being connected to a portion of the data storage layer spaced from the lower electrode; and an upper electrode formed on the data storage layer, or may include a lower electrode connected to the switching element, and used as an ion source; and a data storage layer formed on the lower electrode; an upper electrode formed on the data storage layer.