Co-Ir Synthetic Antiferromagnetic Reference Layer for MRAM
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing magnetic random access memory (MRAM) devices with cobalt (Co)/platinum (Pt) reference layers face issues with thermal stability and perpendicular magnetic anisotropy due to diffusion of Pt, leading to a large dipole field on the free layer, which compromises data reading and writing reliability.
Innovation Solution
A magnetic memory device with an antiferromagnetic reference layer based on cobalt (Co) and iridium (Ir), where Co-containing layers are anti-parallel coupled by Ir-containing layers, minimizing the net dipole field and enhancing perpendicular magnetic anisotropy, thereby improving thermal stability and data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Co/Pt multilayer reference layer is used, then the device can operate, but thermal stability deteriorates due to Pt diffusion during high temperature annealing
Solution Approach 1:
The patent replaces the thermally unstable Pt layers with Ir layers that form a stable Co-Ir multilayer reference layer. The Ir layers act as a thermally stable alternative that prevents diffusion issues during high temperature annealing, maintaining compositional integrity throughout the device lifetime.
Solution Approach 2:
The patent creates a composite Co-Ir multilayer structure where alternating layers of Co and Ir are deposited to form a synthetic antiferromagnetic reference layer. This composite structure provides both the desired magnetic properties and thermal stability, as the Ir layers prevent interdiffusion and maintain structural integrity during annealing processes.
2Device complexity
If Co/Pt reference layer is used, then the device structure is simple, but perpendicular magnetic anisotropy deteriorates due to Pt diffusion
Solution Approach 1:
The patent substitutes Pt with Ir in the reference layer structure. While Ir is a different material, it maintains the multilayer structure simplicity while providing superior thermal stability and preserving perpendicular magnetic anisotropy that would otherwise be compromised by Pt diffusion during fabrication and operation.
Solution Approach 2:
The Co-Ir composite multilayer structure provides perpendicular magnetic anisotropy through the interface between Co and Ir layers. The alternating layer structure creates the necessary magnetic anisotropy while the Ir layers prevent diffusion that would degrade this property, maintaining strong perpendicular magnetic anisotropy throughout device operation.
3Ease of manufacture
If Co/Pt reference layer is used, then the manufacturing process is straightforward, but the dipole field on free layer increases compromising data reliability
Solution Approach 1:
The patent replaces Pt with Ir in the reference layer, maintaining ease of manufacture through similar deposition techniques while fundamentally improving data reliability. The Ir-based structure minimizes dipole field generation, ensuring stable magnetic states for reliable data storage and retrieval operations.
Solution Approach 2:
The Co-Ir composite multilayer structure creates a reference layer with minimized net magnetic moment through antiparallel coupling of adjacent Co layers separated by Ir. This composite structure reduces the dipole field acting on the free layer, enabling reliable magnetic tunnel junction operation for data reading and writing without compromising manufacturing simplicity.
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 Co-Ir multilayer structure provides a stable and low dipole field, enhancing the thermal stability and perpendicular magnetic anisotropy of MRAM devices, ensuring reliable data reading and writing even under high temperature annealing.
Implementation Method 1
adjacent Co-containing layers in the stack are separated by an Ir-containing layer such that the adjacent Co-containing layers in the stack are anti-parallel coupled by the Ir-containing layer therebetween
Implementation Method 2
enhancing perpendicular magnetic anisotropy, thereby improving thermal stability and data integrity
Data Source
AI summary
Magnetic memory devices having an antiferromagnetic reference layer based on Co and Ir are provided. In one aspect, a magnetic memory device includes a reference magnetic layer having multiple Co-containing layers oriented in a stack, wherein adjacent Co-containing layers in the stack are separated by an Ir-containing layer such that the adjacent Co-containing layers in the stack are anti-parallel coupled by the Ir-containing layer therebetween; and a free magnetic layer separated from the reference magnetic layer by a barrier layer. A method of writing data to a magnetic random access memory device having at least one of the present magnetic memory cells is also provided.