MTJ Interconnect and Spacer Layout for Compact MRAM Cells
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Solution Overview
Problem
Current magnetoresistive random access memory (MRAM) devices face challenges such as high chip area, high cost, high power consumption, and sensitivity to temperature variations, which limit their performance and practicality.
Innovation Solution
The development of a semiconductor device with a magnetic tunneling junction (MTJ) on a substrate, featuring specific spacer and liner configurations, and metal interconnections that include protrusions and different material layers to optimize the device's structure and functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional MRAM device structures are used, then data storage capability is achieved, but chip area is large
Solution Approach 1:
The patent transitions from planar 2D MTJ structures to three-dimensional stacked configurations, placing multiple MTJ cells vertically on top of each other. This vertical stacking enables multiple storage elements to occupy the same footprint area, dramatically reducing chip area while maintaining data storage capability through layered architecture.
Solution Approach 2:
The patent implements nested structures where spacers are formed around MTJ pillars, and additional spacers are formed around the first spacers. This nested arrangement maximizes space utilization within the chip area, allowing multiple functional layers to be contained within compact boundaries while preserving storage functionality.
2Use of energy by moving object
If conventional magnetic field sensor technologies are used, then sensing capability is achieved, but power consumption is high
Solution Approach 1:
The patent modifies the magnetic anisotropy parameters of the MTJ free layer through precise control of layer composition and thickness. By adjusting the perpendicular magnetic anisotropy (PMA) parameters, the device achieves high sensitivity to magnetic field changes while requiring lower switching currents, thereby reducing power consumption compared to conventional sensors.
Solution Approach 2:
The patent employs composite magnetic tunneling junction structures with multiple functional layers including CoFeB, MgO, CoFe, and Ru. This composite material architecture combines the advantages of different materials to achieve both high sensitivity through enhanced magnetoresistance ratio and low power consumption through optimized magnetic properties.
3Measurement precision
If conventional MTJ structures are used, then magnetic field sensing is achieved, but sensitivity is limited
Solution Approach 1:
The patent divides the sensing function into multiple segmented MTJ cells arranged in arrays, where each cell contributes to the overall sensitivity. The segmentation allows parallel processing of magnetic field measurements and enables differential sensing configurations that enhance sensitivity while managing structural complexity through modular design.
Solution Approach 2:
The patent designs the MTJ structure to serve multiple functions simultaneously: data storage, magnetic field sensing, and non-volatile memory. This multi-functionality is achieved through the same perpendicular magnetization MTJ cell, eliminating the need for separate dedicated sensing structures and thereby improving sensitivity without proportionally increasing device complexity.
4Stability of the object's composition
If conventional MRAM devices are used, then data storage is achieved, but temperature stability is poor
Solution Approach 1:
The patent optimizes the magnetic anisotropy parameters and coercivity of the MTJ free layer to achieve thermal stability. By carefully selecting layer thicknesses and compositions to achieve specific perpendicular magnetic anisotropy values, the device maintains stable magnetic states across a wide temperature range, preventing thermal fluctuations from causing unwanted state transitions.
Solution Approach 2:
The patent incorporates sacrificial spacer materials that are intentionally designed to be removed after serving their temporary purpose during fabrication. These disposable spacer structures enable precise alignment and spacing during manufacturing but are eliminated in the final device to reduce parasitic effects and improve temperature stability.
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 configuration enhances the performance of MRAM devices by reducing chip area, lowering costs, improving sensitivity, and minimizing temperature effects, resulting in a more efficient and reliable memory solution.
Implementation Method 1
Magnetoresistance (MR) effect has been known as a kind of effect caused by altering the resistance of a material through variation of outside magnetic field. The physical definition of such effect is defined as a variation in resistance obtained by dividing a difference in resistance under no magnetic interference by the original resistance.
Data Source
AI summary
A semiconductor device includes a magnetic tunneling junction (MTJ) on a substrate, a first spacer on one side of the of the MTJ, a second spacer on another side of the MTJ, a first metal interconnection on the MTJ, and a liner adjacent to the first spacer, the second spacer, and the first metal interconnection. Preferably, each of a top surface of the MTJ and a bottom surface of the first metal interconnection includes a planar surface and two sidewalls of the first metal interconnection are aligned with two sidewalls of the MTJ.