Magnetic Memory Device Tunnel Barrier Layer Fabrication
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Solution Overview
Problem
Current magnetic memory devices face challenges in achieving a high magnetoresistance ratio necessary for improved performance, particularly in mass production, due to issues with the resistance variation in magnetic tunnel junctions based on magnetization direction.
Innovation Solution
A method of fabricating a magnetic memory device with an improved magnetoresistance ratio is achieved by forming a tunnel barrier layer comprising multiple metal oxide layers and a metal layer, where a first thermal treatment process oxidizes the metal layer to reduce remnant ion sources, preventing excessive accumulation and enhancing spin-dependent tunneling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional tunnel barrier layer is formed using a single metal oxide layer, then the fabrication process is simple, but the magnetoresistance ratio is insufficient for improved performance
Solution Approach 1:
The tunnel barrier layer is segmented into multiple sub-layers including a first metal oxide layer, a metal layer, and a second metal oxide layer. This segmentation allows each sub-layer to contribute differently to the overall magnetoresistance ratio, with the first metal oxide layer providing a baseline barrier, the metal layer enhancing spin-dependent tunneling, and the second metal oxide layer completing the barrier structure, thereby achieving higher magnetoresistance ratio than a single-layer structure
Solution Approach 2:
The tunnel barrier layer employs a composite structure combining different materials (metal oxides and metal) in a layered configuration. This composite approach leverages the complementary properties of each material to achieve superior magnetoresistance ratio, where the metal layer provides enhanced spin polarization while the metal oxide layers provide appropriate barrier heights and tunneling characteristics
2Reliability
If remnant ion sources are not controlled during fabrication, then the manufacturing process is simpler, but excessive ion source accumulation degrades device performance
Solution Approach 1:
A thermal treatment process is performed preliminarily during the fabrication sequence to oxidize the metal layer and remove remnant ion sources before subsequent device formation steps. This preliminary action prevents excessive ion source accumulation that would otherwise degrade device performance, addressing the contradiction by proactively managing ion source removal rather than dealing with it later
Solution Approach 2:
The thermal treatment process employs accelerated oxidation to efficiently convert and remove remnant ion sources from the metal layer. By using thermal energy to drive the oxidation reaction, the process effectively eliminates harmful ion sources without requiring additional chemical treatments or complex fabrication steps, thus maintaining ease of manufacture while improving device performance
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 results in a magnetic memory device with an increased magnetoresistance ratio without increasing the resistive area, thereby improving the device's performance and manufacturability.
Implementation Method 1
performing a first thermal treatment process to oxidize at least a portion of the first metal layer
Implementation Method 2
Resistance of the MTJ may vary depending on magnetization directions of the magnetic layers
Implementation Method 3
enhancing spin-dependent tunneling
Data Source
AI summary
A magnetic memory device and a method of fabricating the same are provided. The method includes forming a first magnetic layer on a substrate, forming a tunnel barrier layer on the first magnetic layer, and forming a second magnetic layer on the tunnel barrier layer. The forming of the tunnel barrier layer includes forming a first metal oxide layer on the first magnetic layer, forming a first metal layer on the first metal oxide layer, forming a second metal oxide layer on the first metal layer, and performing a first thermal treatment process to oxidize at least a portion of the first metal layer.