MRAM MTJ Structure Asymmetric Width Etching

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Solution Overview

Problem

Magnetic random access memory (MRAM) devices with magnetic tunnel junction (MTJ) structures face challenges in securing the reliability of the MTJ structure due to the difficulty in etching materials and maintaining the gap between memory cells, which affects the electrical and mechanical reliability.

Innovation Solution

The MRAM device is designed with a specific structure including a first magnetic material pattern, a tunnel barrier layer pattern, and a second magnetic material pattern, where the width of the tunnel barrier layer pattern increases from the bottom to the top, and the first and second magnetic material patterns have widths that decrease from the bottom to the top, preventing re-deposition phenomena during ion beam etching and ensuring structural reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the gap between memory cells is reduced to achieve high integration degree, then the storage capacity increases, but the reliability of the MTJ structure deteriorates due to difficulty in etching and maintaining the gap

Engineering Contradiction:

Improveintegration degreeVSAvoidMTJ structure reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent divides the MTJ structure into multiple patterns (first magnetic material pattern, tunnel barrier layer pattern, second magnetic material pattern) with different width characteristics. Each pattern is segmented to have specific width variations that prevent re-deposition during etching, thereby maintaining structural reliability while achieving high integration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces asymmetric width designs where the tunnel barrier layer pattern has increasing width from bottom to top, while magnetic material patterns have decreasing width. This asymmetric configuration prevents re-deposition phenomena during ion beam etching, resolving the reliability issue while maintaining small cell gaps for high integration.

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If conventional etching processes are used on MTJ materials, then the manufacturing process is simpler, but the structural integrity deteriorates due to re-deposition phenomena

Engineering Contradiction:

Improveetching process simplicityVSAvoidMTJ structure integrity

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent performs preliminary patterning to create specific width profiles in the tunnel barrier layer and magnetic material patterns before the main etching process. The tunnel barrier layer is patterned to have increasing width from bottom to top, while magnetic material patterns have decreasing width, which preliminarily prevents re-deposition during subsequent etching operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies different width characteristics to different parts of the MTJ structure. The tunnel barrier layer has increasing width locally, while magnetic material patterns have decreasing width locally. This local quality differentiation ensures that each region has optimal dimensions for preventing re-deposition during etching, maintaining structural integrity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10164173B2Magnetic random access memory devices and methods of manufacturing the same

Publication Date: 2018.12.25 SAMSUNG ELECTRONICS CO LTD

AI summary

Magnetic random access memory (MRAM) devices, and methods of manufacturing the same, include at least one first magnetic material pattern on a substrate, at least one second magnetic material pattern on the at least one first magnetic material pattern, and at least one tunnel barrier layer pattern between the at least one first magnetic material pattern and the at least one second magnetic material pattern. A width of a top surface of the at least one first magnetic material pattern may be less than a width of a bottom surface of the at least one second magnetic material pattern.