Dual-PEL Magnetic Memory Element for Stable Low-Power STT-MRAM
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Solution Overview
Problem
Spin transfer torque magnetic random access memory (STT-MRAM) devices face challenges in achieving thermal stability and scalability while maintaining low power consumption, particularly as the size of the perpendicular magnetic tunnel junction (MTJ) is miniaturized, leading to degradation in thermal stability and increased power consumption.
Innovation Solution
Incorporating a magnetic tunnel junction (MTJ) structure with a magnetic free layer and a magnetic reference layer separated by an insulating tunnel junction layer, along with a perpendicular enhancement layer (PEL) made of materials like cobalt, iron, and boron, and an anti-ferromagnetic coupling layer to enhance perpendicular anisotropy and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the size of the perpendicular magnetic tunnel junction is miniaturized, then the power consumption is reduced, but the thermal stability deteriorates
Solution Approach 1:
The patent employs composite material structures including perpendicular enhancement layers made of CoFeB, CoFe, or CoFeTa alloys combined with MgO tunnel barriers and capping layers. These composite structures provide both the miniaturization capability for low power consumption and the thermal stability through engineered material properties and interface effects that maintain magnetic anisotropy at reduced dimensions.
Solution Approach 2:
The patent utilizes parameter changes in the magnetic layer compositions, including varying the thickness, saturation magnetization, and perpendicular magnetic anisotropy of the enhancement layers and magnetic tunnel junction components. By adjusting these parameters, the device achieves optimal balance between reduced size for lower power consumption and sufficient thermal stability for data retention.
2Productivity
If the size of the perpendicular magnetic tunnel junction is miniaturized, then the device scalability is improved, but the thermal stability deteriorates
Solution Approach 1:
The patent transitions from in-plane magnetization to perpendicular magnetization, utilizing the out-of-plane dimension for magnetic moment orientation. This dimensional change enables better scaling behavior as device size reduces, because perpendicular magnetization provides stronger magnetic anisotropy energy that maintains thermal stability even at smaller dimensions, thereby improving device scalability without sacrificing stability.
Solution Approach 2:
The engineered composite structure with multiple functional layers (tunnel barrier, enhancement layers, capping layers) provides scalable thermal stability through interface-induced perpendicular magnetic anisotropy. This composite approach allows the device to maintain adequate thermal stability across a range of尺寸的, enabling better scalability compared to conventional in-plane magnetization structures.
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 solution improves the thermal stability and scalability of STT-MRAM devices, maintaining low power consumption by optimizing the magnetic layer structures and enhancing perpendicular anisotropy, thereby addressing the limitations of miniaturization.
Implementation Method 1
enhancing perpendicular anisotropy
Implementation Method 2
anti-ferromagnetic coupling layer
Implementation Method 3
spin transfer torque magnetic random access memory
Data Source
AI summary
The present invention is directed to a magnetic memory element including a magnetic free layer structure incorporating two magnetic free layers separated by a perpendicular enhancement layer (PEL) and having a variable magnetization direction substantially perpendicular to layer planes thereof; an insulating tunnel junction layer formed adjacent to the magnetic free layer structure; a magnetic reference layer structure formed adjacent to the insulating tunnel junction layer opposite the magnetic free layer structure; an anti-ferromagnetic coupling layer formed adjacent to the magnetic reference layer structure; and a magnetic fixed layer formed adjacent to the anti-ferromagnetic coupling layer. The magnetic reference layer structure includes first, second, and third magnetic reference layers separated by two PELs and having a first invariable magnetization direction substantially perpendicular to layer planes thereof. The magnetic fixed layer has a second invariable magnetization direction substantially opposite to the first invariable magnetization direction.