MRAM MTJ Dielectric Stack Layout for Void-Free Compact Sensing
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Solution Overview
Problem
Current magnetoresistive random access memory (MRAM) devices face issues such as high chip area, high cost, high power consumption, and sensitivity to temperature variations, limiting their effectiveness in magnetic field sensor applications.
Innovation Solution
The method involves forming a semiconductor device with a first and second magnetic tunneling junction (MTJ) on a substrate, topped with electrodes and ultra low-k (ULK) dielectric layers, and a passivation layer, where the bottom surface of the passivation layer between the MTJs is lower than the top surface of the MTJs, creating a tri-layered structure to minimize voids and enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional MRAM device structures are used, then magnetic field sensing functionality is achieved, but chip area is large and cost is high
Solution Approach 1:
The device is segmented into multiple functional layers including first and second MTJ structures with distinct magnetic tunneling junctions, allowing independent optimization of sensing elements and reducing overall chip area while maintaining sensing performance
Solution Approach 2:
The patent transitions from planar sensor arrangements to a vertical stacked configuration with multiple ULK dielectric layers and passivation layers, utilizing the third dimension to reduce chip footprint while preserving magnetic field sensing capability
2Ease of manufacture
If conventional dielectric layer structures are used, then manufacturing is simplified, but voids form between MTJs reducing device performance
Solution Approach 1:
The dielectric structure exhibits local quality variations with different ULK dielectric layers having distinct properties - the first ULK layer provides void prevention between MTJs while the second ULK layer offers planarization, optimizing both manufacturing and performance locally
Solution Approach 2:
The patent employs a composite dielectric structure combining multiple ULK dielectric layers with a passivation layer, where each material layer contributes specific functions to prevent void formation while maintaining manufacturing feasibility
3Device complexity
If standard passivation layer configurations are used, then device fabrication is straightforward, but temperature stability is poor
Solution Approach 1:
The passivation layer is positioned at a specific height parameter (bottom surface lower than MTJ top surface) to create optimal thermal isolation, changing the geometric parameter to improve temperature stability while maintaining reasonable fabrication 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 reduces chip area, lowers power consumption, and improves temperature stability, resulting in a more efficient and cost-effective MRAM device with enhanced sensitivity.
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.
Implementation Method 2
forming a first ultra low-k (ULK) dielectric layer on the first MTJ and the second MTJ; forming a passivation layer on the first ULK dielectric layer
Data Source
AI summary
A semiconductor device includes a first magnetic tunneling junction (MTJ) and a second MTJ on a substrate, a first ultra low-k (ULK) dielectric layer on the first MTJ and the second MTJ, a passivation layer on the first ULK dielectric layer, and a second ULK dielectric layer on the passivation layer. Preferably, the first ULK dielectric layer includes a first thickness, the passivation layer between the first MTJ and the second MTJ includes a second thickness, the passivation layer on top of the first MTJ includes a third thickness, and the first thickness is greater than the second thickness