Asymmetric Rectify Layer for 1TnR Memory Current Limiting

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Solution Overview

Problem

One-transistor and multi-resistance (1TnR) non-volatile memory devices face issues such as sneak current and SET disturb due to high density, which affect their performance and reliability.

Innovation Solution

Incorporating a selector with a metal filling layer, a barrier layer, and a rectify layer, where the rectify layer has different diffusion paths for metal ions on its bottom and sidewall portions, acting as a current limiting device to mitigate sneak current and SET disturb.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a one-transistor and multi-resistance (1TnR) configuration is used to achieve high density, then storage density is improved, but sneak current and SET disturb occur

Engineering Contradiction:

Improvestorage densityVSAvoidsneak current and SET disturb

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

A selector device is introduced as an intermediary component between the memory device and the conductor layer. The selector includes a rectify layer with asymmetric diffusion paths that limits current flow, preventing sneak current and SET disturb while maintaining high storage density through the 1TnR configuration.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the first portion of the rectify layer has more diffusion paths for metal ions, then current limiting capability is improved, but metal ion migration increases

Engineering Contradiction:

Improvecurrent limiting capabilityVSAvoidmetal ion migration

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The rectify layer is designed with spatially varying properties: the first portion (between barrier layer and conductor layer) has more diffusion paths for superior current limiting, while the second portion (sandwiching the barrier layer) has fewer diffusion paths to reduce metal ion migration. This local differentiation resolves the contradiction between current limiting capability and ion migration control.

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 proposed solution effectively reduces sneak current and SET disturb in 1TnR devices, improving their operational characteristics and reliability by acting as a current limiting device, thereby enhancing the overall performance of non-volatile memory devices.

Implementation Method 1

The first portion has more diffusion paths of metal ions than the second portion

Methodology Applied

Scientific EffectIon diffusion: Diffusion

Data Source

PatentUS11189660B2Non-volatile memory and method of fabricating the same

Publication Date: 2021.11.30 WINBOND ELECTRONICS CORP

AI summary

Provided is a non-volatile memory including a conductor layer, a memory device, and a selector. The selector is located between and electrically connected to the memory device and the conductive layer. The selector includes a metal filling layer, a barrier layer, and a rectify layer. The metal filling layer is electrically connected to the memory device. The barrier layer is located on the sidewall and the bottom surface of the metal filling layer. The rectify layer is wrapped around the barrier layer. The rectify layer includes a first portion and a second portion. The first portion is located between the barrier layer on the bottom surface of the metal filling layer and the conductive layer. The second portion and the metal filling layer sandwich the barrier layer on the sidewall of the metal filling layer. The first portion has more diffusion paths of metal ions than the second portion.