Magnetic Tunnel Junction Cell Structure for MRAM Storage Density
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Solution Overview
Problem
Magnetic random access memory (MRAM) technologies face challenges in achieving high storage density and low power consumption while maintaining fast access times and minimal degradation over time, particularly compared to flash memory which has limited rewrite cycles.
Innovation Solution
The development of a magnetic tunnel junction (MTJ) cell structure within a semiconductor device, comprising ferromagnetic layers separated by a thin insulating barrier, utilizing specific layer configurations and deposition methods to enhance electron tunneling and reduce resistance, allowing for efficient data storage and retrieval without the need for a storage energy source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If magnetic tunnel junction cell structure is used, then storage density and access speed are improved, but manufacturing precision requirements increase due to thin insulating barrier formation
Solution Approach 1:
The patent changes the material parameters and deposition conditions of the insulating barrier layer, using specific materials (such as oxide barriers) and controlling thickness parameters at the nanometer scale to achieve both high storage density and manufacturability. The MTJ cell structure utilizes precise control of barrier thickness and material composition to enable efficient electron tunneling while maintaining manufacturing feasibility.
Solution Approach 2:
The patent employs composite material structures in the MTJ cell, combining ferromagnetic layers with non-magnetic spacer layers and insulating barriers. This composite approach allows optimization of each layer's properties independently, achieving high storage density through material composition rather than solely relying on extreme dimensional precision.
2Reliability
If ferromagnetic layers with thin insulating barrier are used, then electron tunneling efficiency is improved, but resistance control becomes more difficult
Solution Approach 1:
The patent optimizes the resistance characteristics by changing parameters such as barrier thickness, material composition, and layer structure. By precisely controlling these parameters, the patent achieves efficient electron tunneling while maintaining controllable resistance levels suitable for memory operation.
Solution Approach 2:
The patent applies different material properties and structures to different regions of the MTJ cell. The insulating barrier has specific local properties optimized for tunneling, while ferromagnetic layers have properties optimized for magnetic stability. This local quality differentiation enables simultaneous optimization of tunneling efficiency and resistance control.
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 MTJ cell structure in MRAM offers faster access times, higher storage density, and lower power consumption compared to traditional memory technologies, with improved resistance characteristics for binary logic data storage and retrieval, ensuring non-volatile data retention.
Implementation Method 1
operates by tunneling of electrons between the two ferromagnetic layers through the insulating barrier
Implementation Method 2
An MRAM cell is formed by a magnetic tunneling junction (MTJ) comprising two ferromagnetic layers
Data Source
AI summary
In a method of manufacturing a semiconductor device, a cell structure is formed. The cell structure includes a bottom electrode, a magnetic tunnel junction (MTJ) stack disposed on the bottom electrode and a hard mask layer disposed on the MTJ stack. A first insulating cover layer is formed over sidewall of the MTJ stack. A second insulating cover layer is formed over the first insulating cover layer and the hard mask layer. A first interlayer dielectric (ILD) layer is formed. The hard mask layer is exposed by etching the first ILD layer and the second insulating cover layer. A second ILD layer is formed. A contact opening is formed in the second ILD layer by patterning the second ILD layer and removing the hard mask layer. A conductive layer is formed in the contact opening so that the conductive layer contacts the MTJ stack.