TAS-MRAM Cell Structure Reducing Mask Adders
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Solution Overview
Problem
Current embedded non-volatile memory solutions, such as MRAM, are expensive due to the use of multiple mask adders and exhibit limited performance and cross-technology-node compatibility issues, requiring substantial redesign and optimization for each technology variant.
Innovation Solution
A thermally assisted magnetoresistive random access memory (TAS-MRAM) cell structure with a first and second metal layer, an interlayer, and magnetic stacks, where the metal lines and straps are not in direct contact, allowing for a reduced number of mask adders and improved compatibility across technology nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple mask adders are used to embed non-volatile memory, then the memory can tolerate high temperature operation, but the fabrication cost increases and chip density decreases
Solution Approach 1:
The patent combines the word line and bit line functions into a single metal layer structure where metal lines serve dual purposes as both word lines and bit lines depending on the operational mode. This merging eliminates the need for separate word line and bit line layers, reducing the total number of mask adders required for fabrication while maintaining high temperature operation tolerance through the MRAM cell structure itself
2Reliability
If multiple mask adders are used to embed non-volatile memory, then the memory can tolerate high temperature operation, but the chip density decreases
Solution Approach 1:
The patent merges word line and bit line functionality into a single metal layer, reducing the number of fabrication masks needed and allowing for more compact cell layouts. This enables higher chip density while maintaining the high temperature operation capability through the inherent properties of the MRAM cell structure
Solution Approach 2:
The patent utilizes vertical stacking of magnetic stacks and interlayer structures to achieve three-dimensional integration. By moving functionality into the vertical dimension rather than requiring additional lateral metal layers, the design achieves high temperature tolerance without sacrificing chip density
3Productivity
If existing MRAM cell structure is used, then high speed and endurance are achieved, but cross-technology-node compatibility requires substantial redesign
Solution Approach 1:
The patent designs a universal MRAM cell structure where the same basic architecture can be scaled across different technology nodes. The metal line configuration and magnetic stack arrangement maintain consistent functionality from 65nm to 180nm nodes, eliminating the need for substantial redesign while preserving high speed and endurance characteristics
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
The TAS-MRAM cell structure reduces fabrication costs, increases chip density, and enhances performance by minimizing the number of mask adders and ensuring compatibility across different technology nodes, while maintaining high speed and endurance.
Implementation Method 1
thermally assisted magnetoresistive random access memory (TAS-MRAM)
Implementation Method 2
magnetoresistive random access memory (MRAM)
Data Source
AI summary
A thermally assisted magnetoresistive random access memory cell, a corresponding array, and a method for fabricating the array. An example cell includes a first metal layer, a second metal layer, an interlayer, a first magnetic stack, and a first non-magnetic via. The first metal layer includes a pad and a first metal line, with the pad not in direct contact with the first metal line. The second metal layer includes a second metal line and a metal strap. The second metal line is perpendicular to the first metal line and not in contact with the metal strap. The interlayer is located between the first and second metal layers. The first metal line is not in direct contact with the interlayer. The first magnetic stack is in direct contact with the interlayer and the metal strap. The first non-magnetic via is in direct contact with the pad and the metal strap.