TiN (111) MRAM Top Electrode for Oxygen-Resistant MTJ Patterning
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Solution Overview
Problem
Oxidation of the top electrode and underlying layers during patterning in MRAM devices can inhibit electron spin and magnetic reversibility of the magneto tunnel junction (MTJ), leading to operational issues.
Innovation Solution
The use of a titanium nitride top electrode with a (111) crystal orientation to reduce oxygen contamination, combined with controlled deposition techniques to achieve a strong crystalline film that inhibits oxygen infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a top electrode is used in MRAM devices, then the device structure is completed and electrical connections are established, but oxidation of the top electrode and underlying layers during patterning occurs which inhibits electron spin and magnetic reversibility
Solution Approach 1:
The patent employs a composite material structure consisting of a titanium nitride top electrode layer combined with a magnesium oxide barrier layer. The titanium nitride provides electrical conductivity and magnetic field generation capabilities, while the magnesium oxide layer acts as an oxidation barrier. This composite structure resolves the contradiction by maintaining the necessary electrical and magnetic functions while preventing oxygen contamination that would otherwise harm magnetic reversibility.
Solution Approach 2:
The patent creates an inert environment by depositing a magnesium oxide barrier layer between the titanium nitride top electrode and the underlying magnetic layers. This barrier layer establishes an oxygen-free zone that protects the sensitive magnetic layers from oxidation during subsequent patterning processes, thereby preserving electron spin and magnetic reversibility while allowing the top electrode to function.
2Manufacturing precision
If subsequent patterning steps are performed after top electrode formation, then device patterning is completed, but oxygen infiltration occurs which damages the MTJ structure
Solution Approach 1:
The patent applies preliminary action by depositing the magnesium oxide barrier layer immediately after forming the titanium nitride top electrode and before performing any patterning steps. This preliminary protective layer is in place before oxygen exposure can occur during subsequent processing, preventing oxygen infiltration that would damage the MTJ structure while allowing precise patterning to proceed.
Solution Approach 2:
The magnesium oxide barrier layer serves as an intermediary between the top electrode assembly and the underlying MTJ structure. During patterning steps, this intermediary layer blocks oxygen from reaching the sensitive MTJ components, thereby protecting structure integrity while permitting the necessary patterning operations to define device geometry with high precision.
3Use of energy by moving object
If titanium nitride is used as top electrode material, then electrical conductivity and magnetic field generation are achieved, but oxidation resistance during processing is insufficient without additional barrier layers
Solution Approach 1:
The patent combines titanium nitride material with magnesium oxide barrier layer to create a composite top electrode structure. The titanium nitride component provides the necessary electrical conductivity and magnetic field generation efficiency, while the integrated magnesium oxide layer supplies oxidation resistance during processing. This composite approach resolves the contradiction by maintaining energy efficiency for magnetic operations while adding protective functionality.
Solution Approach 2:
The patent modifies the material parameter composition of the top electrode assembly by adding a magnesium oxide layer with specific barrier properties. This parameter change transforms the top electrode from a single-material structure vulnerable to oxidation into a multi-layer structure with enhanced oxidation resistance, while preserving the titanium nitride's electrical and magnetic field generation parameters.
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 reduces oxygen contamination, maintaining the integrity of the MTJ structure and enhancing the operational reliability of MRAM devices by preventing oxygen infiltration during subsequent processing steps.
Implementation Method 1
a titanium nitride top electrode with a (111) crystal orientation to reduce oxygen contamination, combined with controlled deposition techniques to achieve a strong crystalline film that inhibits oxygen infiltration
Data Source
AI summary
A top electrode of a magnetoresistive random access memory (MRAM) device over a magnetic tunnel junction (MTJ) is formed using a film of titanium nitride oriented in a (111) crystal structure rather than a top electrode which uses tantalum, tantalum nitride, and/or a multilayer including tantalum and tantalum nitride.