MRAM Etch-Stop Layer Protects MTJ Structures

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Solution Overview

Problem

Existing semiconductor memory devices, particularly magnetoresistive random access memory (MRAM) devices, face challenges in forming magnetic tunnel junction (MTJ) structures and bit lines without damage during fabrication, leading to contact failures and resistance variations.

Innovation Solution

The MRAM device incorporates a specific structure with a first insulating interlayer, a pattern of pillar-shaped MTJ structures, a capping layer, a filling layer, bit lines, and an etch-stop layer, where the etch-stop layer is formed on the filling layer pattern between the bit lines and the insulating interlayer, reducing damage and contact failures by controlling the etching process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional fabrication methods are used to form MTJ structures and bit lines, then manufacturing process is simple, but damage to MTJ structures and contact failures occur

Engineering Contradiction:

Improvecontact reliabilityVSAvoidfabrication process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The etch-stop layer is formed on the filling layer pattern before the bit line formation process. This preliminary action protects the MTJ structures from damage during subsequent etching and fabrication steps, preventing contact failures without requiring complex process changes

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The etch-stop layer acts as an intermediary protective layer between the filling layer pattern and the bit lines. It mediates the interaction during fabrication, preventing direct damage to the MTJ structures while allowing the bit lines to be properly formed and connected

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If etching process is performed to form bit lines, then bit line formation is achieved, but damage to MTJ structures occurs

Engineering Contradiction:

Improvebit line formationVSAvoidMTJ structure integrity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The etch-stop layer is deposited beforehand on the filling layer pattern to cushion and absorb the mechanical and chemical stress during the bit line etching process. This prevents damage to the underlying MTJ structures while allowing complete bit line formation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The etch-stop layer serves as a mediator during the etching process, allowing the etchant to remove unwanted material for bit line formation while stopping before damaging the MTJ structures. It enables the etching process to proceed without compromising manufacturing precision

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If bit lines directly contact MTJ structures, then electrical connection is established, but contact failures and resistance variations occur

Engineering Contradiction:

Improvecontact stabilityVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The etch-stop layer is preliminarily formed on the filling layer pattern before bit line deposition. This creates a protected interface that ensures stable electrical contact between bit lines and MTJ structures, reducing contact failures and resistance variations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The etch-stop layer acts as an intermediary at the contact interface between bit lines and MTJ structures. It provides a stable, damage-free surface for electrical connection, eliminating direct exposure of MTJ structures to fabrication stresses that cause contact failures

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces damage to the MTJ structures during fabrication, minimizes contact failures between MTJ structures and bit lines, and decreases resistance variations, resulting in improved operational characteristics of the MRAM device.

Implementation Method 1

an etch-stop layer, wherein the etch-stop layer is formed on the filling layer pattern between the bit lines and the insulating interlayer

Methodology Applied

Scientific EffectEtching:

Implementation Method 2

magnetoresistive random access memory (MRAM) devices... magnetic tunnel junction (MTJ) structures

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS9543357B2Magnetoresistive random access memory devices and methods of manufacturing the same

Publication Date: 2017.01.10 SAMSUNG ELECTRONICS CO LTD

AI summary

An MRAM device comprises an insulating interlayer comprising a flat first upper surface on a first region and a second region of a substrate. A pattern structure comprising pillar-shaped magnetic tunnel junction (MTJ) structures and a filling layer pattern between the MTJ structures is formed on the insulating interlayer of the first region. The pattern structure comprises a flat second upper surface that is higher than the first upper surface. Bit lines are formed on the pattern structure that contact top surfaces of the MTJ structures. An etch-stop layer is formed on the pattern structure between the bit lines of the first region and the first upper surface of the first insulating interlayer of the second region. A first portion of an upper surface of the etch-stop layer on the first region is higher than a second portion of the upper surface of the etch-stop layer on the second region.