Magnetic Memory Stack Etching via Ion Beam Segmentation
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Solution Overview
Problem
The miniaturization of magnetic memory devices poses challenges in forming accurate stack structures due to the shadow effect in ion beam etching, leading to difficulties in processing thin films with high aspect ratios and requiring the combination of ion beam etching and reactive ion etching, which complicates precise etching control.
Innovation Solution
A method for manufacturing magnetic memory devices using ion beam etching (IBE) to form both the lower and upper structures of the stack, with overetching to self-align the structures and reduce the impact of positional gaps, and optionally using ion implantation to prevent magnetic field concentration, allowing for precise control and minimization of sidewall damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion beam etching is used to process stack film with high aspect ratio, then etching capability is improved, but shadow effect prevents accurate formation of stack structure
Solution Approach 1:
The patent divides the continuous ion beam etching process into multiple discrete etching steps with different ion beam conditions. Each step targets specific portions of the stack structure, allowing precise control over etching depth and profile while avoiding shadow effect accumulation. This segmented approach enables accurate formation of high aspect ratio structures.
Solution Approach 2:
The patent dynamically adjusts ion beam parameters (energy, angle, flux) between different etching steps. By varying these parameters adaptively across multiple steps, the process compensates for shadow effects and achieves uniform etching throughout the high aspect ratio stack structure, improving manufacturing precision.
2Volume of moving object
If miniaturization is pursued to reduce device size, then device dimensions are reduced, but stack structure formation becomes more difficult due to increased aspect ratio
Solution Approach 1:
The patent applies segmentation by dividing the etching of miniaturized stack structures into multiple controlled steps. This allows each step to be optimized for specific dimensional requirements, maintaining precision even as overall device size decreases and aspect ratios increase.
Solution Approach 2:
The patent changes multiple process parameters (ion beam energy, incidence angle, gas composition, temperature) across different etching steps to adapt to miniaturized dimensions. This parameter optimization enables accurate stack structure formation in smaller devices where traditional single-step etching fails.
3Manufacturing precision
If multiple etching methods (IBE and RIE) are combined to form stack structure, then etching capability is improved, but process complexity increases and precise control becomes difficult
Solution Approach 1:
The patent merges multiple etching methodologies into a unified multi-step ion beam etching process. By integrating the advantages of different etching approaches within a single IBE framework, it achieves the precision benefits of combined methods while maintaining process simplicity and controllability.
Solution Approach 2:
The patent makes the ion beam etching process multi-functional by adjusting parameters to achieve different etching objectives in sequential steps. A single IBE system performs multiple functions (selective etching, profile control, depth regulation) that would otherwise require multiple different etching tools, reducing overall process complexity.
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 enables the accurate formation of stack structures with reduced variations in magnetic field intensity distribution, improving the characteristics of magnetoresistive effect elements and facilitating the miniaturization of magnetic memory devices without damaging the sidewalls.
Implementation Method 1
The stack film is processed by applying an ion beam in an oblique direction
Implementation Method 2
the stack film is processed by applying an ion beam in an oblique direction. Therefore, when the ratio of the height of the stack structure to the width of the space between the stack structures adjacent to each other is high, it is difficult to process the stack film by IBE due to a shadow effect
Implementation Method 3
optionally using ion implantation to prevent magnetic field concentration
Data Source
AI summary
According to one embodiment, a method of manufacturing a magnetic memory device includes a stack structure formed of a plurality of layers including a magnetic layer, the method includes forming a lower structure film including at least one layer, etching the lower structure film to form a lower structure of the stack structure, forming an upper structure film including at least one layer on a region including the lower structure, and etching the upper structure film to form an upper structure of the stack structure on the lower structure.