MGO Deposition on CoFeB Using Reducing Agent to Prevent Interface Oxidation

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Solution Overview

Problem

Conventional semiconductor fabrication techniques face challenges in depositing metal oxide layers for magnetic tunnel junctions, particularly in preventing oxidation of underlying metal layers, which affects the efficiency and reliability of magnetic devices.

Innovation Solution

A method involving the deposition of a metal oxide film on a magnetic film using chemical vapor deposition, with exposure to a reducing agent during deposition to reduce oxide formation at the interface, and alternating cycles of metal precursors and oxidants to control the thickness and properties of the metal oxide layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional deposition techniques are used to deposit metal oxide layers, then the deposition process can be completed, but oxidation of underlying metal layers occurs and interface integrity deteriorates

Engineering Contradiction:

Improveinterface integrityVSAvoidoxidation of metal layers

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A reducing agent is introduced during the metal oxide deposition process to preemptively counteract oxidation of the underlying magnetic metal layer. This preliminary anti-action prevents the formation of unwanted oxide at the interface before it can compromise the interface integrity and device performance.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The reducing agent acts as an intermediary substance during the deposition process, mediating between the oxidizing environment (necessary for metal oxide formation) and the magnetic metal layer (which must remain reduced). This intermediary protects the metal layer while allowing the dielectric layer to form.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If metal oxide film is deposited to form magnetic tunnel junction, then the device structure is created, but oxidation during deposition compromises the magnetic film and reduces device performance

Engineering Contradiction:

Improvedevice fabricationVSAvoiddevice performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The reducing agent is applied during the deposition process to prevent oxidation of the magnetic film, ensuring that the device can be manufactured without compromising performance. This allows standard deposition techniques to be used while protecting against harmful oxidation effects.

Inventive Principle:

Principle #9Preliminary anti-action

3Manufacturing precision

If alternating cycles of metal precursor and oxidant are used for deposition, then controlled metal oxide film formation is achieved, but interface oxidation may still occur between cycles

Engineering Contradiction:

Improvefilm thickness controlVSAvoidinterface oxidation

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The deposition process uses alternating cycles of metal precursor exposure and oxidant exposure to build the metal oxide film layer by layer. By introducing reducing agent pulses between these cycles, the process maintains precise thickness control while preventing interface oxidation that would occur during the oxidant exposure phases.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The reducing agent is applied continuously or periodically throughout the deposition process, ensuring that protection against oxidation is maintained without interruption. This continuous protective action occurs alongside the periodic deposition cycles, ensuring no gaps in protection while maintaining precise film formation.

Inventive Principle:

Principle #20Continuity of useful action

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 formation of magnetic tunnel junctions with high tunnel magnetoresistance, maintaining the integrity of the metal oxide interface and preventing oxidation, thus enhancing the performance and reliability of magnetic devices.

Implementation Method 1

exposing the magnetic film to a reducing agent during the deposition of the metal oxide film to reduce oxide at an interface between the metal oxide film and the magnetic film

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 2

The metal oxide film may be deposited by chemical vapor deposition

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 3

The metal oxide film is deposited by exposing the magnetic film to alternating cycles of a metal precursor and an oxidant

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS9988715B2Interface engineering during MGO deposition for magnetic tunnel junctions

Publication Date: 2018.06.05 LAM RES CORP

AI summary

Methods of fabricating magnetic devices are described herein. Methods involve exposing a magnetic film, such as a CoFeB film, to a reducing agent before, during, or after depositing a metal oxide film using atomic layer deposition or chemical vapor deposition. Some methods include exposing the magnetic film in cycles involving exposure to a reducing agent, exposure to a magnesium-containing precursor, and exposure to an oxidant. Methods are suitable for depositing a magnesium oxide layer on a CoFeB layer to form part of a magnetic tunnel junction.