Multi-Layer MgO Capping for Low-RA Perpendicular MTJ Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic random access memory (MRAM) devices face challenges in maintaining data retention and reducing area resistance, which affects the reliability and performance of magnetoresistive tunnel junction (MTJ) elements due to limitations in interfacial perpendicular magnetic anisotropy and unwanted electrical resistance contributions from capping layers.
Innovation Solution
A multi-layer MgO structure is deposited using a sputtering process with DC power and controlled oxygen flow to create a capping layer with high interfacial perpendicular magnetic anisotropy while minimizing area resistance, achieved by adjusting deposition time, oxygen flow rate, and Mg thickness to maintain a resistance area (RA) of no greater than 1.5 Ωμm².
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capping layer is added to improve interfacial perpendicular magnetic anisotropy, then data retention is improved, but area resistance increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the MgO capping layer (optimizing at approximately 2-3 nm) and adjusting sputtering parameters (power, oxygen flow rate, pressure) to achieve the optimal balance between perpendicular magnetic anisotropy and electrical resistance. By tuning these parameters, the invention achieves high data retention while minimizing the resistance penalty associated with the capping layer.
Solution Approach 2:
The patent employs composite material structures by combining MgO capping layers with specific magnetic layer compositions (CoFeB, CoFe) and interface engineering. This composite approach allows the MgO layer to provide necessary perpendicular magnetic anisotropy for data retention while the overall composite structure manages electrical resistance through optimized material combinations and interface properties.
2Loss of energy
If MgO layer thickness is increased to reduce area resistance, then electrical performance is improved, but perpendicular magnetic anisotropy decreases
Solution Approach 1:
The patent applies parameter changes by identifying and optimizing the critical thickness range for MgO capping layers. Through systematic variation of layer thickness during development, the invention determined that approximately 2-3 nm provides the optimal balance point where perpendicular magnetic anisotropy remains sufficiently high while area resistance is adequately reduced. This precise thickness control resolves the trade-off between the two competing requirements.
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 enhances data retention and reduces area resistance, ensuring stable magnetization states and reliable data reading in MRAM devices by providing exceptional interfacial perpendicular magnetic anisotropy with negligible additional resistance, thus improving the overall performance of MTJ elements.
Implementation Method 1
The MgO layer is deposited in a sputtering deposition chamber with a Mg target using DC power
Implementation Method 2
The deposition can be performed in a series of steps of depositing Mg layers and introducing oxygen into the chamber to oxidize the deposited Mg
Implementation Method 3
The switching of the MTJ element between high and low resistance states results from electron spin transfer
Data Source
AI summary
The disclosure provides a magnetic random access memory element. The magnetic random access memory element includes a magnetic reference layer, a magnetic free layer, and a non-magnetic barrier layer between the magnetic free layer and the magnetic reference layer. The magnetic random access memory element further includes a MgO layer contacting the magnetic free layer. The MgO layer includes multiple homogeneous layers of MgO that provide excellent interfacial perpendicular magnetic anisotropy to the magnetic free layer while also having a low RA.