Magnetic Memory Device Oxidation Etch Selectivity

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Solution Overview

Problem

Conventional magnetic memory device fabrication methods often result in etch byproducts that can cause short-circuits between magnetic layers, leading to malfunction due to conductive etch byproducts on the sidewalls of magnetic tunnel junctions.

Innovation Solution

A method involving the sequential formation of magnetic layers with fixed and changeable magnetization orientations, where the top magnetic layer is oxidized using a conductive capping pattern as a mask, and the oxidized portion is removed using an etch process with argon, chlorine, and oxygen gases, ensuring the tunnel barrier layer acts as an etch-stop to prevent short-circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional etch process is used to form the MTJ pattern, then the magnetic layers can be patterned, but etch byproducts are produced on the sidewalls that can become conductive and cause short-circuits

Engineering Contradiction:

Improveetch processVSAvoidshort-circuit prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

An oxidation step is performed before the etch process to convert the top magnetic layer into an oxidized form. This preliminary oxidation action ensures that when the etch process occurs, the oxidized material is less likely to produce conductive byproducts, thereby preventing short-circuits while still allowing successful patterning.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The chemical state of the top magnetic layer is changed from metallic to oxidized form. This parameter change in the material's chemical composition fundamentally alters its etching behavior, reducing the production of conductive etch byproducts and preventing short-circuits between the bottom and top magnetic patterns.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the top magnetic layer is oxidized to prevent conductive byproducts, then short-circuit risk is reduced, but the etch process becomes more complex

Engineering Contradiction:

Improveshort-circuit preventionVSAvoidetch process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The top magnetic layer undergoes a phase transition from metallic state to oxidized state through controlled oxidation. This phase transition simplifies the overall process by creating a material that is inherently less prone to producing conductive byproducts during etching, thereby reducing the need for complex process controls and additional protective steps.

Inventive Principle:

Principle #36Phase transitions

3Manufacturing precision

If the oxidized portion of the second magnetic layer is removed to expose the tunnel barrier layer, then the MTJ structure is properly formed, but etch damage to the tunnel barrier layer may occur

Engineering Contradiction:

Improvetunnel barrier layer exposureVSAvoidetch damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The etch process parameters are optimized to exploit the difference between oxidized and unoxidized magnetic materials. By controlling etch selectivity through parameter adjustment, the oxidized top magnetic layer is removed with minimal damage to the tunnel barrier layer, achieving precise exposure while reducing harmful etch effects.

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 effectively prevents short-circuits and maintains the resistance variation property of magnetic tunnel junctions, ensuring the magnetic memory device functions correctly by enhancing etch selectivity and reducing etch damage to the tunnel barrier layer.

Implementation Method 1

portions of the second magnetic layer are oxidized using the conductive capping pattern as a mask

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

The oxidized portion of the second magnetic layer is removed to expose the tunnel barrier layer and opposite sidewalls of the second magnetic pattern

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS7541199B2Methods of forming magnetic memory devices including oxidizing and etching magnetic layers

Publication Date: 2009.06.02 SAMSUNG ELECTRONICS CO LTD

AI summary

Methods of forming a magnetic memory device include oxidizing a top magnetic layer using a conductive capping pattern as a mask. An etch selectivity between an oxidized portion of the top magnetic layer and a tunnel barrier layer may be relatively high. Using the tunnel barrier layer as an etch-stop layer, the oxidized portion of the top magnetic layer is selectively removed to form a top magnetic pattern, and to expose at least a portion of opposite sidewalls of the top magnetic pattern and the tunnel barrier layer. The unoxidized portion of the top magnetic layer forms a top magnetic pattern.