Bar-Type Magnetoresistive Device Thermal Stability
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Solution Overview
Problem
Current integrated circuit manufacturing processes for magnetoresistive random access memory (MRAM) cells face challenges in achieving long data retention times and reliable operation due to thermal instability and the complexity of patterning masks required for pillar-type or column-type magnetic tunnel junctions.
Innovation Solution
The use of bar-type magnetic tunnel junctions with a larger free layer volume and a larger-area barrier layer, along with a single etch process to form the antiferromagnetic, free, and reference layers, reduces thermal instability and simplifies the manufacturing process by using the same patterning mask for all layers, thereby increasing data retention and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If pillar-type or column-type magnetic tunnel junctions are used, then the device structure is compact, but thermal instability occurs leading to short data retention times
Solution Approach 1:
The patent transitions from a pillar-type magnetic tunnel junction with vertical magnetization to a bar-type structure with in-plane magnetization. This dimensional change in magnetization orientation allows for a larger free layer volume while maintaining thermal stability and extending data retention times, resolving the contradiction between device compactness and data retention reliability
2Manufacturing precision
If multiple patterning masks are used for different layers, then precise layer alignment is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent combines the patterning of the antiferromagnetic layer, free layer, and reference layer into a single patterning mask process. This merging of multiple patterning steps into one operation maintains precise layer alignment while significantly reducing manufacturing complexity and the number of processing steps required
3Device complexity
If a single patterning mask is used for all layers, then manufacturing complexity is reduced, but alignment precision may be compromised
Solution Approach 1:
The patent successfully merges the patterning of multiple layers (antiferromagnetic, free, and reference layers) into a single patterning mask operation. The bar-type geometric configuration and in-plane magnetization approach inherently maintain alignment precision across layers, eliminating the need for multiple separate patterning steps while preserving manufacturing accuracy
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 longer data retention times and improved reliability of MRAM cells by enhancing thermal stability and simplifying the manufacturing process, leading to increased efficiency and cost-effectiveness in producing MRAM cells with extended data retention.
Implementation Method 1
Magnetoresistive random access memory (MRAM) is a type of data storage element in which information is stored based on the orientation of a magnetic field in a circuit element
Implementation Method 2
a second ferromagnetic material to act as a free layer
Implementation Method 3
Magnetoresistive random access memory (MRAM) is a type of data storage element
Data Source
AI summary
A method of making an integrated circuit includes depositing a first ferromagnetic material over a substrate. The method further includes setting a magnetic field orientation of the first ferromagnetic material. The method further includes depositing barrier material over the first ferromagnetic layer. The method further includes depositing a second ferromagnetic material over the barrier material. The method further includes depositing an antiferromagnetic material over the second ferromagnetic material. The method further includes etching the first ferromagnetic material, the barrier material, the second ferromagnetic material, and the antiferromagnetic material, wherein the etching comprises defining a sidewall of the antiferromagnetic material, and the antiferromagnetic material comprises a first surface in contact with the second ferromagnetic material, and the sidewall is perpendicular to the first surface.