MRAM Memory Device Shared Layer Etching Process
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Solution Overview
Problem
The manufacturing process of magnetoresistive random access memory (MRAM) devices is complex due to the requirement for precise control of magnetic tunnel junction elements, which complicates the integration of memory and conductive regions in a memory device.
Innovation Solution
A memory device design that includes a first magnetic tunnel junction element with a specific threshold current for magnetization inversion and a second magnetic tunnel junction element that maintains its magnetization direction, allowing for simplified manufacturing by using a shared layer structure for both elements, reducing the need for separate conductive parts and exposure processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate conductive parts and exposure processes are used for memory and conductive regions, then manufacturing precision can be maintained, but device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent merges the formation of memory regions and conductive regions into a single etching process. The stacked film containing lower and upper ferromagnetic material layers, tunnel barrier layer, and capping layer is etched simultaneously to form both memory regions (with MTJ elements) and conductive regions (with magnetic conductors), eliminating the need for separate exposure and etching processes while maintaining manufacturing precision
Solution Approach 2:
The stacked film structure serves multiple functions: it provides the magnetic tunnel junction elements for memory regions, provides magnetic conductors for conductive regions, and enables both regions to be formed through a single etching process. This multi-functionality reduces the number of manufacturing steps while maintaining the required precision for both memory and conductive region formation
2Device complexity
If simplified manufacturing process is used with shared layer structure, then device complexity is reduced, but manufacturing precision may be compromised
Solution Approach 1:
The patent applies local quality by providing different magnetization directions in different regions through a single etching process. Memory regions have magnetization directions inverted relative to conductive regions, achieved by selective etching that leaves different portions of the stacked film. This local differentiation maintains manufacturing precision while using a simplified unified process
Solution Approach 2:
The stacked film is prepared in advance with lower and upper ferromagnetic material layers having opposite magnetization directions before etching. This preliminary preparation of the magnetic layer structure with built-in magnetization direction control enables the simplified etching process to achieve precise magnetization orientation in both memory and conductive regions without requiring additional post-processing steps
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 design simplifies the manufacturing process by allowing for the simultaneous formation of memory and conductive regions with reduced exposure processes, enhancing precision and stability in the device's operation while maintaining low resistance states for efficient data storage and retrieval.
Implementation Method 1
The MTJ element includes a pair of ferromagnetic layers and a tunnel barrier layer provided between the pair of ferromagnetic layers. The MTJ element is an element which, according to a parallel or antiparallel state in a magnetization direction of the ferromagnetic layer, changes the resistance value with respect to a tunnel current flowing through the tunnel barrier layer.
Implementation Method 2
The transistor controls a conduction of each of a current in a first direction flowing between the first signal line and the second signal line and a current in a second direction opposite to the first direction
Data Source
AI summary
According to one embodiment, a memory device includes: a first signal line; a second signal line; a transistor; a memory region; and a conductive region. The transistor controls a conduction of each of a current in a first direction flowing between the first line and the second line and a current in a second direction opposite to the first direction. The memory region has a first magnetic tunnel junction element which is connected between the first line and one end of the transistor, a magnetization direction of which becomes parallel when a current not less than a first parallel threshold value flows in the first direction, and the magnetization direction of which becomes antiparallel when a current not less than a first antiparallel threshold value flows in the second direction. The conductive region is connected between the second line and the other end of the transistor.