MRAM MTJ Fabrication Using a Sacrificial Layer for Smaller Chips
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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, limited sensibility, and susceptibility to temperature variations.
Innovation Solution
A method for fabricating a semiconductor device, specifically a MRAM device, involving the formation of a first inter-metal dielectric (IMD) layer, a metal interconnection, a bottom electrode layer, a pinned layer, a sacrificial layer, and a magnetic tunneling junction (MTJ), followed by the removal of the sacrificial layer and additional processing steps to create a functional MRAM device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional MRAM fabrication methods are used, then magnetic field sensor functionality is achieved, but chip area is large and cost is high
Solution Approach 1:
The patent segments the magnetic field sensor into distinct functional layers including pinned layer, free layer, barrier layer, and electrode layers. Each layer performs a specific function, allowing optimization of individual components while reducing overall chip area through integrated multi-layer structure
Solution Approach 2:
The patent implements a nested multi-layer structure where the barrier layer is positioned between the pinned and free layers, and electrode layers are integrated within the magnetic layer stack. This nesting approach reduces the horizontal footprint of the sensor while maintaining all necessary functional elements
2Use of energy by moving object
If conventional magnetic field sensor technologies are used, then sensing capability is provided, but power consumption is high
Solution Approach 1:
The patent utilizes magnetoresistance effect where the resistance of the magnetic tunnel junction changes in response to magnetic field variations. By detecting resistance changes rather than requiring continuous power for active sensing, the device achieves low power consumption while maintaining sensing capability
Solution Approach 2:
The magnetic field sensor operates passively by utilizing the inherent magnetoresistance effect of the MTJ structure. The magnetic field directly modulates the resistance without requiring external power activation, enabling the sensor to 'sense' fields through its passive electrical properties
3Measurement precision
If conventional MRAM devices are fabricated, then data storage is achieved, but sensitivity is limited and temperature susceptibility is high
Solution Approach 1:
The patent employs composite magnetic layer structures including pinned layer, free layer, and barrier layer with specific material compositions. This composite structure enhances the magnetoresistance effect and improves sensitivity while the engineered layer configuration provides thermal stability to reduce temperature susceptibility
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 proposed method enables the fabrication of MRAM devices with improved performance, reduced chip area, lower power consumption, enhanced sensibility, and increased resistance to temperature variations, addressing the shortcomings of existing MRAM technologies.
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
Implementation Method 2
removing the sacrificial layer
Data Source
AI summary
A method for fabricating semiconductor device includes the steps of: forming a first inter-metal dielectric (IMD) layer on a substrate; forming a metal interconnection in the first IMD layer; forming a bottom electrode layer and a pinned layer on the first IMD layer; forming a sacrificial layer on the pinned layer; patterning the sacrificial layer, the pinned layer, and the bottom electrode layer to form a first magnetic tunneling junction (MTJ); forming a second IMD layer around the first MTJ; and removing the sacrificial layer.