MRAM Structure With Conductive Shunting for High TMR and PMA
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Solution Overview
Problem
Magnetic tunnel junctions (MTJs) in electronic memory devices face challenges with high series resistance due to the capping metal oxide layer, which enhances perpendicular magnetic anisotropy but increases power consumption and set voltage.
Innovation Solution
Incorporating a shunting structure that electrically shorts the free layer to the conductive capping layer, mitigating the series resistance of the capping metal oxide layer while preserving high perpendicular magnetic anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a capping metal oxide layer is used to enhance perpendicular magnetic anisotropy, then magnetic anisotropy is improved, but series resistance increases
Solution Approach 1:
A conductive capping layer is introduced as an intermediary between the capping metal oxide layer and the free layer. This conductive layer serves as a mediator that provides a low-resistance electrical path while allowing the metal oxide layer to maintain its function of enhancing perpendicular magnetic anisotropy through spin-orbit coupling at the interface.
Solution Approach 2:
The capping structure is segmented into multiple functional layers: a capping metal oxide layer for enhancing magnetic anisotropy and a separate conductive capping layer for reducing series resistance. This segmentation allows each layer to optimize its specific function without compromising the other.
2Strength
If a capping metal oxide layer is used to enhance perpendicular magnetic anisotropy, then magnetic anisotropy is improved, but power consumption increases
Solution Approach 1:
The conductive capping layer acts as an intermediary that reduces the overall series resistance of the MTJ stack. By providing a low-resistance electrical path, it reduces the power consumption required to switch the magnetic states while preserving the high perpendicular magnetic anisotropy provided by the metal oxide layer.
3Strength
If a capping metal oxide layer is used to enhance perpendicular magnetic anisotropy, then magnetic anisotropy is improved, but set voltage increases
Solution Approach 1:
The conductive capping layer serves as a mediator that reduces the series resistance in the electrical path. This reduction in resistance directly lowers the set voltage required to switch the MTJ state, while the capping metal oxide layer continues to provide the necessary perpendicular magnetic anisotropy enhancement.
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
The shunting structure reduces power consumption and set voltage while maintaining high magnetic anisotropy, thereby enhancing the magnetoresistance ratio and improving the performance of MTJ memory elements.
Implementation Method 1
a shunting structure that electrically shorts the free layer to the conductive capping layer
Implementation Method 2
enhances perpendicular magnetic anisotropy
Implementation Method 3
Magnetic tunnel junctions (MTJs) can be used in hard disk drives and/or RAM
Data Source
AI summary
Various embodiments of the present disclosure are directed towards a method for forming an integrated chip, the method includes forming a memory cell stack over a substrate. The memory cell stack comprises a tunnel barrier layer, a free layer over the tunnel barrier layer, a capping dielectric layer over the free layer, and a conductive capping layer on the capping dielectric layer. A conductive shunting structure is formed along outer sidewalls of the free layer, outer sidewalls of the capping dielectric layer, and outer sidewalls of the conductive capping layer. A bottommost point of the conductive shunting structure in contact with the free layer is disposed above a bottom surface of the free layer.