Magnetic Tunnel Junction Patterning via Oxidation-Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for patterning nonvolatile memory devices, such as MTJ and resistance change memory devices, face challenges with short circuits, current leaks, and damage due to etching and oxidation processes, particularly with thin tunnel insulator films and resistance change layers, leading to reliability issues and variations in properties.

Innovation Solution

A method involving sequential lamination of magnetic material layers and tunnel insulator films, followed by oxidation and reduction of uncovered parts using mask layers to control oxidation depth and prevent damage, thereby maintaining functional integrity and reducing oxygen-related damage during the manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional etching methods are used for patterning magnetic material layers, then material removal is achieved, but short circuits and current leaks occur due to damage to the tunnel insulator film

Engineering Contradiction:

Improvepatterning capabilityVSAvoidshort circuit and current leak prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A protective film is introduced as an intermediary layer between the tunnel insulator film and the etching process. This protective film prevents direct contact between the etching plasma and the tunnel insulator film, thereby preventing damage that would cause short circuits and current leaks while still allowing the magnetic material layer to be properly patterned

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective film is formed in advance before the etching process begins. This preliminary action ensures that the tunnel insulator film is already protected when the etching plasma is introduced, preventing damage before it can occur

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If oxidation process is used to remove uncovered magnetic material, then material removal is achieved, but excessive oxygen causes damage to the magnetic material layer

Engineering Contradiction:

Improvematerial removal capabilityVSAvoidoxygen-induced damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

Excessive oxygen is extracted or removed from the system by introducing a reducing atmosphere in a subsequent processing step. This prevents the accumulation of harmful oxygen concentrations that would damage the magnetic material layer while still achieving the desired material removal through the controlled oxidation step

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The oxidation-reduction process controls the concentration parameter of oxygen in the magnetic material layer. By first introducing oxygen for controlled oxidation and then removing excessive oxygen through reduction, the process maintains oxygen concentration within safe limits that prevent material damage

Inventive Principle:

Principle #35Parameter changes

3Length of moving object

If tunnel insulator film thickness is reduced to 1 nm for device miniaturization, then device scaling is achieved, but the film becomes more susceptible to etching damage and short circuits

Engineering Contradiction:

Improvetunnel insulator film thicknessVSAvoidshort circuit and current leak resistance

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The protective film serves as a cushioning layer that absorbs the mechanical and chemical stress of the etching process before it can reach the thin tunnel insulator film. This beforehand protection is crucial for preventing damage to the vulnerable 1 nm thick film that would otherwise be directly exposed to harsh etching conditions

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 approach prevents short circuits, current leaks, and damage, ensuring high reliability and long-term stability of nonvolatile memory devices by controlling oxidation and reducing unnecessary material removal, thus enhancing the separation of readout resistance values and minimizing the incidence of shorted devices.

Implementation Method 1

oxidizing a part uncovered by the mask layer of the second magnetic material layer

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

reducing the oxidized part of the second magnetic material layer

Methodology Applied

Scientific EffectReduction: Reduction

Data Source

PatentUS8268713B2Method of manufacturing nonvolatile memory device

Publication Date: 2012.09.18 SONY GROUP CORP

AI summary

A method of manufacturing a nonvolatile memory device having a laminated structure in which a first magnetic material layer, a tunnel insulator film, and a second magnetic material layer are sequentially laminated, in which information is stored when an electric resistance value changes depending on a magnetization reversal state is disclosed. The method includes the steps of: sequentially forming the first magnetic material layer, the tunnel insulator film, and the second magnetic material layer; forming a mask layer on the second magnetic material layer; oxidizing a part uncovered by the mask layer of the second magnetic material layer; and reducing the oxidized part of the second magnetic material layer.