MTJ Layer Composition for Dense MRAM Shunt Failure Suppression
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Solution Overview
Problem
Magnetic memory devices face challenges in maintaining high-density memory cell arrangements without increasing shunt failure rates, as high-density packing leads to increased shunt failure rates due to processing influences, and existing structures struggle to balance storage capacity with reliable magnetic tunnel junction characteristics.
Innovation Solution
The magnetic memory device incorporates a specific layered structure with a nonmagnetic layer containing cobalt iron boron (CoFeB) and molybdenum (Mo) or tungsten (W) impurities, which enhances the hardness of the top layer, reducing etching rates and improving magnetic characteristics, thereby suppressing shunt failures and maintaining MTJ element performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are arranged in high density, then storage capacity is improved, but shunt failure rate increases
Solution Approach 1:
The patent applies local quality by modifying only the top layer composition locally (adding Mo or W impurities to the CoFeB top layer) rather than changing the entire MTJ structure. This localized modification improves etching selectivity and reduces shunt failures in high-density regions without affecting the overall memory cell functionality or requiring changes to other layers.
Solution Approach 2:
The patent changes the chemical composition parameter of the top layer by introducing Mo or W impurities at controlled concentrations (0.1-10 at%). This parameter change modifies the etching characteristics of the top layer, creating better etching selectivity that prevents shunt failures during fabrication of high-density memory arrays.
2Reliability
If top layer hardness is increased to reduce shunt failure, then etching rate decreases, but manufacturing complexity increases
Solution Approach 1:
The patent changes the etching rate parameter by controlling the concentration of Mo or W impurities in the CoFeB top layer. By optimizing the impurity content (0.1-10 at%), the patent achieves a balance where the top layer has sufficient hardness to prevent shunt failures during high-density fabrication while maintaining an acceptable etching rate for manufacturing.
Solution Approach 2:
The patent creates a composite top layer structure by combining CoFeB with Mo or W impurities. This composite material exhibits both the magnetic properties needed for MTJ functionality and the enhanced hardness/modified etching characteristics needed to reduce shunt failures in high-density memory devices.
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 configuration effectively reduces shunt failure rates while preserving the magnetic tunnel junction characteristics, allowing for high-density memory cell arrangements with improved storage capacity and reliability.
Implementation Method 1
a nonmagnetic layer containing cobalt iron boron (CoFeB) and molybdenum (Mo) or tungsten (W) impurities, which enhances the hardness of the top layer
Implementation Method 2
A memory device (magnetoresistive random access memory (MRAM)), which adopts a magnetoresistive effect element as a memory element
Data Source
AI summary
A magnetic memory device according to an embodiment includes a first ferromagnetic layer, a first nonmagnetic layer on the first ferromagnetic layer, a second ferromagnetic layer on the first nonmagnetic layer, an oxide layer on the second ferromagnetic layer, and a second nonmagnetic layer on the oxide layer. The oxide layer contains an oxide of a rare-earth element. The second nonmagnetic layer contains cobalt (Co), iron (Fe), boron (B), and molybdenum (Mo).