Bi-layered Free Layer Boron Gradients in Magnetic Memory
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Solution Overview
Problem
Current magnetic memory devices face challenges in enhancing tunneling magnetic resistance (TMR) and reliability, particularly in achieving stable coercivity and switching efficiency while maintaining resistance to high-temperature processes.
Innovation Solution
A magnetic memory device design featuring a bi-layered free layer with varying boron content, where the boron content of the first free magnetic pattern is higher than that of the second free magnetic pattern, and a thermal treatment process is used to crystallize these layers, improving TMR characteristics and switching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform boron content is used in the free layer, then the manufacturing process is simple, but the TMR characteristics and switching efficiency are insufficient
Solution Approach 1:
The free layer is divided into two distinct magnetic patterns with different boron contents: the first free magnetic pattern adjacent to the tunnel barrier layer has higher boron content (25-50 at %) to enhance TMR characteristics, while the second free magnetic pattern has lower boron content (20-35 at %) to maintain magnetic stability. This local differentiation of material composition resolves the contradiction between improving TMR and maintaining structural simplicity.
2Reliability
If high boron content is used in the free layer, then TMR characteristics improve, but thermal stability during high-temperature processes deteriorates
Solution Approach 1:
The patent applies different boron concentrations to different regions of the free layer. The first free magnetic pattern with higher boron content (25-50 at %) is positioned adjacent to the tunnel barrier layer where high TMR is critical, while the second free magnetic pattern with lower boron content (20-35 at %) is positioned farther away to provide thermal stability during high-temperature manufacturing processes.
Solution Approach 2:
The free layer is segmented into two distinct magnetic patterns with different compositions. This segmentation allows each region to be optimized for its specific function: the first pattern optimizes for TMR enhancement at the tunnel barrier interface, while the second pattern provides thermal stability, thereby resolving the contradiction between TMR improvement and thermal stability.
3Reliability
If the first free magnetic pattern has high boron content, then TMR characteristics improve, but the coercivity stability becomes difficult to maintain
Solution Approach 1:
The patent implements local quality differentiation by placing the high boron content first free magnetic pattern (25-50 at %) adjacent to the tunnel barrier layer to maximize TMR characteristics, while positioning the lower boron content second free magnetic pattern (20-35 at %) at a distance to maintain coercivity stability. The spatial separation allows each region to fulfill its specific magnetic function without compromising the other.
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 approach enhances TMR characteristics and switching efficiency, while also improving the device's thermal stability and resistance to high-temperature processes, thereby addressing the reliability and performance issues in magnetic memory devices.
Implementation Method 1
a thermal treatment process is used to crystallize these layers, improving TMR characteristics and switching efficiency
Implementation Method 2
enhancing tunneling magnetic resistance (TMR)
Data Source
AI summary
A memory device includes a magnetic tunnel junction comprising a first free layer, a pinned layer, and a tunnel barrier layer disposed between the first free layer and the pinned layer, wherein the first free layer comprises a first free magnetic pattern adjacent to the tunnel barrier layer, and a second free magnetic pattern spaced apart from the tunnel barrier layer with the first free magnetic pattern interposed therebetween, wherein the second free magnetic pattern contacts the first free magnetic pattern, wherein the first and second free magnetic patterns include boron (B), wherein a boron content of the first free magnetic pattern is higher than a boron content of the second free magnetic pattern, and wherein the boron content of the first free magnetic pattern is in a range of about 25 at % to about 50 at %.