Iridium Conductive Layer for pMTJ Perpendicular Magnetic Anisotropy
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Solution Overview
Problem
The commercialization of perpendicular magnetic tunnel junction (pMTJ) devices is hindered by challenges in enhancing perpendicular magnetic anisotropy in pinning magnetic layers, which affects the stability and efficiency of memory devices, particularly due to diffusion issues during high-temperature annealing.
Innovation Solution
Implementing a single layer of conductive material like platinum or tungsten between magnetic layers in the pinning structure, and using iridium as a conductive layer with a FCC crystal texture to reduce diffusion and enhance perpendicular magnetic anisotropy, thereby stabilizing the magnetic layers and improving the tunnel magneto-resistance ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional conductive layers are used in pinning magnetic layers, then device fabrication can proceed, but iron and platinum diffusion occurs during high-temperature annealing which degrades perpendicular magnetic anisotropy and reduces device reliability
Solution Approach 1:
The patent introduces an iridium conductive layer as an intermediary between magnetic layers in the pinning structure. This iridium layer acts as a diffusion barrier that prevents iron and platinum diffusion during high-temperature annealing, thereby maintaining perpendicular magnetic anisotropy and improving device reliability without compromising electrical conductivity
Solution Approach 2:
The patent changes the material parameter of the conductive layer from traditional materials (platinum, tungsten) to iridium with specific properties (FCC crystal texture, low diffusion coefficient). This parameter change enables the layer to simultaneously provide electrical conductivity and prevent diffusion during annealing, resolving the contradiction between device reliability and diffusion prevention
2Manufacturing precision
If high-temperature annealing is performed to improve device properties, then crystal texture and electrical conductivity improve, but diffusion of magnetic layer materials increases which degrades perpendicular magnetic anisotropy
Solution Approach 1:
The iridium conductive layer serves as a protective intermediary that enables high-temperature annealing to proceed while preventing the degradation of perpendicular magnetic anisotropy. The layer allows beneficial diffusion (improving crystal texture) while blocking harmful diffusion (maintaining magnetic layer composition stability)
Solution Approach 2:
By changing the conductive layer material to iridium with appropriate thickness and FCC crystal structure, the patent enables the system to withstand higher annealing temperatures without composition degradation, thus allowing crystal texture improvement while maintaining magnetic anisotropy stability
3Reliability
If conventional pinning magnetic layer structures are used, then device assembly can be simplified, but tunnel magneto-resistance ratio remains insufficient for high-performance memory applications
Solution Approach 1:
The patent optimizes parameters of the pinning structure by using iridium with FCC crystal texture and specific thickness ranges. These parameter changes enhance the tunnel magneto-resistance ratio to exceed 100% while maintaining a relatively simple layered structure that can be integrated into existing memory device architectures
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 reduces iron and platinum diffusion, enhances perpendicular magnetic anisotropy, and increases the tunnel magneto-resistance ratio, leading to improved switching efficiency and data retention in pMTJ devices even at higher anneal temperatures.
Implementation Method 1
reduces iron and platinum diffusion
Implementation Method 2
tunnel magneto-resistance ratio
Data Source
AI summary
A memory device includes a first electrode, a conductive layer including iridium above the first electrode, a magnetic junction on the conductive layer and a second electrode above the magnetic junction. The magnetic junction includes a magnetic structure including a first magnetic layer including cobalt, a non-magnetic layer including platinum or tungsten on the first magnetic layer and a second magnetic layer including cobalt on the non-magnetic layer. The magnetic junction further includes an anti-ferromagnetic layer on the magnet structure, a fixed magnet above the anti-ferromagnetic layer, a free magnet above the fixed magnet and a tunnel barrier between the fixed magnet and the free magnet.