MTJ Stack Etching with Protective Overhangs for Dense Device Spacing
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Solution Overview
Problem
Current magnetic tunneling junction (MTJ) devices face issues such as larger wafer area occupation, expensive manufacturing processes, high power consumption, insufficient sensitivity, and susceptibility to temperature changes, necessitating improvements in their fabrication methods.
Innovation Solution
A method involving two ion beam etching processes and a protective layer with overhangs is used to fabricate MTJ devices, ensuring precise profile and size, avoiding abnormal connections, and reducing wafer area occupation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional fabrication methods are used for MTJ devices, then the manufacturing process is simpler, but the wafer area occupied by MTJ device units is larger
Solution Approach 1:
The fabrication process is divided into multiple sequential ion beam etching steps (first, second, and third ion beam etching processes) with intermediate protective layer formations. This segmentation allows precise control of the MTJ device profile and spacing, achieving smaller device footprint while maintaining manufacturing feasibility through systematic process breakdown
Solution Approach 2:
A protective layer is formed in advance between the first and second ion beam etching processes to prevent abnormal connections. This preliminary protective action ensures that subsequent etching steps can proceed with precise spacing control, enabling reduced wafer area occupation without compromising device reliability
2Reliability
If conventional fabrication methods are used for MTJ devices, then the manufacturing process is less complex, but abnormal connections between MTJ device units occur
Solution Approach 1:
A protective layer is deposited in advance between the first and second ion beam etching processes to prevent abnormal connections between adjacent MTJ device units. This preliminary protective measure ensures reliable device isolation while the multi-step etching process achieves the required precise profiles and spacing
Solution Approach 2:
The protective layer acts as an intermediary element between adjacent MTJ device units during the fabrication process. It temporarily prevents unwanted material transfer or connection between units during etching, ensuring device reliability while allowing the use of aggressive etching parameters for precise profile control
3Area of stationary object
If MTJ device spacing is reduced, then wafer area occupation decreases, but abnormal connections between units increase
Solution Approach 1:
The etching process is segmented into multiple steps with intermediate protective layer formation. This allows the use of smaller device spacing while the protective layer prevents abnormal connections during processing, enabling both reduced wafer area occupation and maintained device reliability
Solution Approach 2:
The protective layer is formed in advance before the second ion beam etching process, establishing a barrier that prevents abnormal connections even when devices are closely spaced. This preliminary protective action enables aggressive spacing reduction while maintaining device isolation integrity
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 reliability and accuracy of MTJ devices, reduces spacing between units, and minimizes wafer area usage while preventing abnormal connections, thereby improving reading and writing accuracy.
Implementation Method 1
a first ion beam etching process is performed to etch the patterned second electrode layer and pattern the MTJ stack layer and the first electrode layer
Implementation Method 2
A first protective layer is formed to cover a top surface and a sidewall of the second electrode and a sidewall of the MTJ stack structure. Using the protective layer as a mask, a second ion beam etching process is performed
Implementation Method 3
The magnetoresistance (MR) effect is the effect that the resistance of the material changes with the change of the external magnetic field
Data Source
AI summary
A method of fabricating an MTJ device is provided including the following process. A first via is formed in the first dielectric layer. A first electrode layer is formed on the first dielectric layer and the first via. An MTJ stack layer is formed on the first electrode layer. A patterned second electrode layer is formed on the MTJ stack layer and used as a mask. A first ion beam etching process is performed to etch the patterned second electrode layer and pattern the MTJ stack layer and the first electrode layer to form a second electrode, an MTJ stack structure, and a first electrode. A first protective layer is formed to cover the second electrode and the MTJ stack structure. A second ion beam etching process is performed to remove a portion of the MTJ stack structure and a portion of the first electrode.