Phase Change Memory Block Layer for Heat Confinement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing electrically rewritable non-volatile memory elements using phase change material face challenges in heating efficiency due to heat diffusion issues, particularly with titanium nitride intermediate layers having low electrical resistivity, which reduces the effectiveness of write currents and increases power consumption.

Innovation Solution

Incorporating a block layer with higher electrical resistance than the recording layer, composed of phase change material with a different composition and higher crystallization temperature, to suppress heat flow and confine the phase change region, thereby enhancing heating efficiency and reducing write current requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If titanium nitride (TiN) is used as an intermediate layer between recording layers, then the structure allows efficient heat generation from write current, but the low electrical resistivity of TiN causes heat to diffuse along the plane of the intermediate layer, reducing heating efficiency

Engineering Contradiction:

Improveheat generation efficiencyVSAvoidheat diffusion loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent changes the electrical resistivity parameter of the intermediate layer by replacing TiN with tungsten (W), which has significantly higher electrical resistivity. This parameter change prevents heat diffusion along the intermediate layer plane, confining heat to the vertical direction and improving heating efficiency of the phase change material.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure with multiple intermediate layers having different materials and properties. The first intermediate layer uses tungsten with high electrical resistivity to block lateral heat diffusion, while the second intermediate layer provides additional thermal management, creating a composite solution that addresses both heat confinement and thermal control requirements.

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If a block layer with higher electrical resistance is introduced to block heat flow, then heating efficiency is enhanced and phase change region is confined, but the device structure becomes more complex

Engineering Contradiction:

Improveheating efficiencyVSAvoidlayer structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent segments the intermediate region into multiple functional layers: a first intermediate layer with high electrical resistivity material (tungsten) for blocking lateral heat diffusion, and a second intermediate layer for additional thermal management. This segmentation allows each layer to perform its specific function optimally while collectively solving the heat diffusion problem.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces tungsten as an intermediary material between the phase change material layers. This intermediary layer with high electrical resistivity acts as a thermal barrier that prevents heat from diffusing laterally, thereby confining the phase change region and improving heating efficiency without requiring direct modification of the phase change material itself.

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

The solution achieves high heating efficiency, allowing for faster writing speeds and reduced power consumption by limiting the phase change region and preventing intermixing between the recording and block layers, while maintaining the amorphous state of the block layer.

Implementation Method 1

the joule heat generated by the current flowing through the upper and lower recording layers spreads out along the plane of the intermediate layer

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

the structure used should be one that does not readily allow the heat generated by the write current to diffuse

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

the storage of data is based on the phase state of phase change material contained in the recording layer. Specifically, there is a big difference between the electrical resistivity of the material in the crystalline state and the electrical resistivity in the amorphous state

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentUS7692272B2Electrically rewritable non-volatile memory element and method of manufacturing the same

Publication Date: 2010.04.06 MICRON TECHNOLOGY INC

AI summary

A non-volatile memory element comprises a bottom electrode 12; a top electrode 15; and a recording layer 13 containing phase change material and a block layer 14 that can block phase change of the recording layer 13, provided between the bottom electrode 12 and the top electrode 15. The block layer 14 is constituted of material having an electrical resistance that is higher than that of material constituting the recording layer 13. The block layer 14 suppresses the radiation of heat towards the top electrode 15 and greatly limits the phase change region when a write current is applied. The result is a high heating efficiency. The top electrode 15 itself can be used to constitute a bit line, or a separate bit line can be provided.