Variable Resistance Layer Oxygen Deficiency Segmentation

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Solution Overview

Problem

Conventional variable resistance nonvolatile memory elements with metal oxide layers face challenges in sequentially and successively manufacturing multiple memory elements with stable variable resistance characteristics due to variations in oxygen flow rates and target surface oxidation during the reactive sputtering process.

Innovation Solution

A nonvolatile memory element design featuring a variable resistance layer with a first oxygen-deficient metal oxide layer and a second metal oxide layer, including host layers and inserted layers with controlled oxygen deficiency, where the inserted layer has a higher oxygen deficiency than the host layer, to stabilize resistance values across multiple manufacturing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If reactive sputtering is used to form metal oxide layers with nonstoichiometric composition, then fast operation speed and high rewrite capability are achieved, but stable variable resistance characteristics cannot be maintained in successive manufacturing

Engineering Contradiction:

Improveoperation speedVSAvoidstability of variable resistance characteristics

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The variable resistance layer is segmented into multiple sub-layers with different oxygen deficiencies. The first sub-layer has higher oxygen deficiency for fast operation, while the second sub-layer has lower oxygen deficiency for stability. This segmentation allows each sub-layer to fulfill different functional requirements simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the variable resistance layer are assigned different oxygen deficiencies to optimize local properties. The first sub-layer near the first electrode has higher oxygen deficiency for speed, while the second sub-layer has lower oxygen deficiency for stability, creating local quality variations that resolve the contradiction.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If oxygen flow rate is increased during sputtering to reduce target surface oxidation, then more stable resistance characteristics are achieved, but manufacturing precision decreases due to oxygen incorporation

Engineering Contradiction:

Improveconsistency of resistance valuesVSAvoidoxygen deficiency composition

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The variable resistance layer is divided into sub-layers with different oxygen contents. The first sub-layer accepts higher oxygen flow rates during sputtering to achieve fast operation, while the second sub-layer uses lower oxygen flow rates to maintain stability, thus segmenting the oxygen incorporation process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different oxygen flow rates are applied during the formation of different sub-layers. By changing the oxygen flow rate parameter between sub-layer formation processes, the patent achieves both fast operation (higher oxygen) and stability (lower oxygen) in different regions.

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

This configuration allows for the stabilization of variable resistance characteristics in nonvolatile memory elements by maintaining a consistent oxygen deficiency in the host layer, reducing the impact of target surface oxidation and environmental factors, thereby ensuring consistent performance across multiple memory element production.

Implementation Method 1

Methodology Applied

Scientific EffectVariable resistance effect: Electrical Resistance

Implementation Method 2

a variable resistance layer which is provided between the first electrode layer and the second electrode layer and has a resistance value which reversibly changes according to application of an electrical pulse, wherein the variable resistance layer includes a first variable resistance layer which is in contact with the first electrode layer and comprises an oxygen-deficient first metal oxide

Methodology Applied

Scientific EffectReactive sputtering: Sputtering

Data Source

PatentUS8999808B2Nonvolatile memory element and method for manufacturing the same

Publication Date: 2015.04.07 PANASONIC SEMICON SOLUTIONS CO LTD

AI summary

A nonvolatile memory element includes a first and a second electrode layers, and a variable resistance layer provided between the first and the second electrode layers and having a resistance value reversibly changing according to application of an electrical pulse, wherein the variable resistance layer includes a first variable resistance layer contacting the first electrode layer and comprising an oxygen-deficient first metal oxide, and a second variable resistance layer contacting the first variable resistance layer and comprising a second metal oxide having a smaller oxygen deficiency than the first metal oxide, and including host layers and an inserted layer between each of adjacent pairs of the host layers, wherein the second metal oxide of the inserted layer has a larger oxygen deficiency than the second metal oxide of the host layer, and the first metal oxide has a larger oxygen deficiency than the second metal oxide of the host layer.