Magnetoresistive Memory Device Etching Rate Control

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Solution Overview

Problem

Magnetoresistive memory devices face challenges in achieving high-density and reliable data storage due to issues with the etching process, which can lead to redeposition of materials and unintended electrical conduction between ferromagnetic layers, disrupting the magnetoresistive effect.

Innovation Solution

Incorporating a nonmagnet layer with a specific etching rate lower than the cap layer, using a high-angle ion beam for initial etching and a low-angle ion beam for subsequent etching to control the etching process and prevent redeposition, ensuring the integrity of the magnetic tunnel junction structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional etching process is used without specific rate control, then the etching process is simple and fast, but material redeposition occurs and unintended electrical conduction between ferromagnetic layers is caused

Engineering Contradiction:

Improveetching precisionVSAvoidetching process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by controlling the etching rate of the nonmagnet layer to be lower than that of the cap layer. This specific parameter relationship prevents the etching plasma from exposing the ferromagnetic layer directly, thereby avoiding unintended electrical conduction while maintaining manufacturing precision through controlled material removal rates.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The nonmagnet layer serves as an intermediary between the cap layer and the ferromagnetic layer. By positioning this intermediate layer with a specific etching rate characteristic, it acts as a protective barrier during the etching process, preventing direct exposure of the ferromagnetic layer to the etching plasma and thus preventing harmful electrical conduction.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the etching rate of the nonmagnet layer is made lower than the cap layer, then material redeposition is suppressed and magnetoresistive effect is maintained, but the etching process becomes more complex and time-consuming

Engineering Contradiction:

Improvemagnetoresistive effect integrityVSAvoidetching process time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent utilizes parameter changes by establishing a specific etching rate relationship where the nonmagnet layer etches slower than the cap layer. This parameter control ensures that the nonmagnet layer protects the ferromagnetic layer during etching, preventing plasma exposure and maintaining the integrity of the magnetoresistive effect, though it does increase etching time.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If high-density storage is achieved through precise etching control, then data storage density increases, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvedata storage densityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by controlling the etching rate of the nonmagnet layer to be lower than the cap layer. This specific parameter control enables precise definition of the magnetic tunnel junction structure, achieving high-density storage by preventing plasma exposure of the ferromagnetic layer while maintaining manageable manufacturing complexity through a systematic approach to etching rate management.

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 approach enables the realization of high-performance variable resistance elements with controlled etching, suppressing redeposition and maintaining the intended magnetoresistive effect, thus enhancing data storage reliability and density.

Implementation Method 1

The nonmagnet includes a material that is removed at a first etching rate against a first ion beam. The first conductor includes a material that is removed at a second etching rate against the first ion beam.

Methodology Applied

Scientific EffectIon beam etching: Ion Beam

Data Source

PatentUS11682441B2Magnetoresistive memory device and method of manufacturing magnetoresistive memory device

Publication Date: 2023.06.20 KIOXIA CORP

AI summary

According to an embodiment, a magnetoresistive memory device includes a layer stack. The layer stack includes a first ferromagnet, an insulator on the first ferromagnet, and a second ferromagnet on the insulator. A nonmagnet is provided above the layer stack. A first conductor is provided on the nonmagnet. A hard mask is provided above the first conductor. The nonmagnet includes a material that is removed at a first etching rate against a first ion beam. The first conductor includes a material that is removed at a second etching rate against the first ion beam. The first etching rate is lower than the second etching rate.