Spin Hall Electrode Structure for Focused MTJ Current in MRAM
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Solution Overview
Problem
Current magneto-resistive random-access memory (MRAM) devices face challenges in optimizing the structure of spin Hall electrodes to enhance current flow and resistance differences, which affects the performance and efficiency of memory cells.
Innovation Solution
The proposed solution involves patterning spin Hall electrodes with varying thicknesses, where the central portion is thicker and the peripheral portions are thinner, with a global etching process to create a resistance gradient, allowing increased current flow from the periphery to the center and into the magnetic tunneling junction (MTJ) structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the spin Hall electrode has uniform thickness, then the manufacturing process is simple, but the current distribution and resistance variation are insufficient
Solution Approach 1:
The spin Hall electrode is designed with non-uniform thickness, featuring a thicker central portion and thinner peripheral portions. This local variation in geometry creates differential resistance across the electrode, directing current flow preferentially through the central region into the MTJ structure, thereby improving current distribution without requiring complex manufacturing processes
Solution Approach 2:
The electrode structure is modified by changing the thickness parameter across different regions. By varying the thickness of the spin Hall electrode from center to periphery, the resistance distribution is controlled to achieve optimal current flow characteristics, resolving the contradiction between simple manufacturing and improved current distribution
2Productivity
If the spin Hall electrode has varying thickness, then the current flow into MTJ is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
Instead of varying the electrode pattern in the planar dimensions, the invention utilizes the vertical dimension by controlling the thickness of the spin Hall electrode. This dimensional approach allows complex current distribution characteristics to be achieved through a relatively simple deposition process, maintaining ease of manufacture while enhancing device efficiency
3Manufacturing precision
If the spin Hall electrode is uniformly etched, then the manufacturing process is straightforward, but the resistance variation across the electrode is insufficient
Solution Approach 1:
The spin Hall electrode is deposited with predetermined non-uniform thickness before the etching process. This preliminary structural preparation ensures that subsequent uniform etching preserves the intended thickness variation, achieving the desired resistance variation without requiring complex selective etching processes
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 enhances the current flow and resistance differences within the spin Hall electrode, improving the performance and efficiency of MRAM memory cells by optimizing the structure and manufacturing process.
Implementation Method 1
A spin Hall electrode that extends underneath the MTJ pillar is provided. A spin current is generated through the spin Hall electrode to switch a magnetic moment of the free layer
Data Source
AI summary
A memory device and a method of manufacturing the same are provided. The memory device includes a semiconductor substrate, an interconnect structure and a memory cell. The interconnect structure is disposed over the semiconductor substrate, and the memory cell is disposed over the interconnect structure and electrically coupled with the semiconductor substrate and the interconnect structure. The memory cell includes a spin Hall electrode layer, an MTJ pillar, a hard mask, and a spacer. The MTJ pillar is disposed on the spin Hall electrode layer, the hard mask is disposed on the MTJ pillar, and the spacer is disposed on sidewalls of the MTJ pillar and the hard mask. Suitably, the spin Hall electrode layer at least comprises an inner portion and an outer portion surrounding the inner portion, and a top surface of the outer portion is lower than a top surface of the inner portion.