Variable Resistance Memory Device Trench Sidewall Formation

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Solution Overview

Problem

Conventional variable resistance memory devices face challenges in achieving uniform switching characteristics and high integration density due to sidewall deformation during etching, leading to leakage currents and limitations in reducing the width of the variable resistance material layer.

Innovation Solution

A variable resistance memory device is fabricated with a trench structure in an insulating layer, where the variable resistance material layer is formed on the sidewalls and bottom surface of the trench, allowing for a larger contact area and eliminating the need for etching the material layer, thereby preventing sidewall damage and simplifying the process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the variable resistance material layer is patterned through an etch process, then the switching characteristic can be secured, but the width of the variable resistance material layer cannot be reduced sufficiently

Engineering Contradiction:

Improvewidth of variable resistance material layerVSAvoidsidewall deformation

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

Instead of etching the variable resistance material layer to form the memory element, the patent inverts the approach by forming a trench in the insulating layer and depositing the variable resistance material conformally on the trench sidewalls. This inversion allows the material to be placed precisely where needed without the damage caused by etching, enabling reduced width while maintaining manufacturing precision.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent replaces the mechanical etching process with a deposition process. By using physical vapor deposition or chemical vapor deposition to form the variable resistance material layer conformally on the trench sidewalls, the harmful mechanical impact of etching is substituted with a gentile deposition mechanism that preserves sidewall integrity and enables precise width control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Area of stationary object

If the width of the variable resistance material layer is reduced to increase integration density, then the integration degree increases, but leakage current occurs through the sidewalls

Engineering Contradiction:

Improveintegration densityVSAvoidleakage current

Core Design Contradiction:

Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent inverts the conventional structure by placing the variable resistance material on the sidewalls of a trench rather than forming a wide planar layer. This sidewall placement reduces the horizontal footprint (increasing integration density) while the trench structure provides vertical confinement that prevents leakage current, solving both problems simultaneously.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent transitions from a two-dimensional planar structure to a three-dimensional vertical structure by forming the variable resistance material layer on the sidewalls of a trench. This dimensional change allows the material to occupy less horizontal space (increasing integration density) while the trench provides vertical isolation that prevents leakage current.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If the etch process is used to form the variable resistance material layer, then the fabrication process can be completed, but the sidewalls are deformed and leakage current occurs

Engineering Contradiction:

Improvefabrication processVSAvoidswitching characteristic

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent inverts the conventional fabrication sequence by depositing the variable resistance material before forming the final trench structure, or by depositing conformally on pre-formed trench sidewalls. This inversion eliminates the need to etch the material layer itself, avoiding sidewall deformation while maintaining fabrication feasibility through standard deposition and etching processes applied to different layers.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent substitutes the mechanical etching of the variable resistance material with a deposition-based formation method. By depositing the material conformally on trench sidewalls and using insulation or removal processes instead of etching the material itself, the harmful mechanical impact is replaced, preserving sidewall integrity and ensuring reliable switching characteristics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8916847B2Variable resistance memory device and method for fabricating the same

Publication Date: 2014.12.23 MIMIRIP LLC

AI summary

A variable resistance memory device includes a plurality of first conductive lines extended in a first direction, a plurality of second conductive lines arranged over or under the first conductive lines and extended in a second direction crossing the first direction, an insulating layer disposed between the first conductive lines and the second conductive lines and having a trench extended in the second direction and defined by a first side wall and a second sidewall facing each other and a bottom surface connecting the first sidewall and the second sidewall, and a variable resistance material layer formed on the first and second sidewalls and the bottom surface of the trench, wherein the first and second sidewalls of the trench overlap two adjacent second conductive lines, respectively.