MRAM MTJ Stack Patterning for Controlled Bottom-Electrode Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing magnetic random access memory (MRAM) technologies face challenges in achieving high performance, low power consumption, and non-volatile data storage with minimal degradation over time, while also requiring efficient manufacturing processes.
Innovation Solution
The development of a magnetic tunnel junction (MTJ) cell structure with specific ferromagnetic layers and tunneling barrier materials, coupled with a semiconductor device, allows for efficient data storage and retrieval based on resistance differences, utilizing a 1T1R architecture and advanced manufacturing methods like PVD, MBE, and ALD for layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic tunnel junction cell structure is used for data storage, then non-volatile data storage with minimal degradation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the magnetic tunnel junction into distinct functional layers: pinned ferromagnetic layer, free ferromagnetic layer, and tunnel barrier layer. Each layer is deposited using specialized techniques (PVD for ferromagnetic layers, ALD for tunnel barrier), allowing independent optimization of each component's properties while maintaining overall device functionality and reducing manufacturing complexity through modular fabrication.
Solution Approach 2:
The patent utilizes parameter changes in material properties during deposition processes. By controlling deposition parameters (temperature, pressure, material composition ratios) during PVD and ALD processes, the tunnel barrier layer's resistance and thickness are precisely controlled to achieve optimal tunneling characteristics while maintaining manufacturing feasibility.
2Manufacturing precision
If advanced layer deposition techniques (PVD, MBE, ALD) are used for MTJ manufacturing, then manufacturing precision is improved, but production time increases
Solution Approach 1:
The patent merges multiple deposition techniques into a unified fabrication process flow. PVD is used for ferromagnetic layers, ALD for tunnel barrier layers, and MBE for specific interface layers, combining these methods in a sequential process that achieves precise thickness control (at atomic level for tunnel barriers) while optimizing overall manufacturing efficiency through integrated process planning.
Solution Approach 2:
The patent employs preliminary actions by depositing seed layers and buffer layers before the main MTJ structure. These preliminary layers prepare the substrate surface and establish controlled interfaces, enabling subsequent layers to be deposited with precise thickness and composition control, thereby improving manufacturing precision without requiring excessive deposition time for each individual layer.
3Speed
If MTJ cell structure with specific ferromagnetic layers is implemented, then fast access times are achieved, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning specific material compositions and magnetic properties to different layers. The pinned ferromagnetic layer uses CoFeB with specific thickness (2-4 nm) for stable magnetization, while the free layer uses CoFe with different composition (3-5 nm) for fast switching. The tunnel barrier layer (MgO, 1-2 nm) is optimized locally for high tunneling resistance. This localized optimization achieves fast access times while managing overall device complexity through purposeful material selection.
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 fast access times, low power consumption, and non-volatile data storage with minimal degradation, while enabling efficient manufacturing through optimized layer deposition techniques.
Implementation Method 1
An MRAM cell is formed by a magnetic tunneling junction (MTJ) comprising two ferromagnetic layers which are separated by a thin insulating barrier, and operates by tunneling of electrons between the two ferromagnetic layers through the insulating barrier.
Implementation Method 2
The MTJ cell structure allows for efficient data storage and retrieval based on resistance differences
Data Source
AI summary
In a method of manufacturing a semiconductor device including a magnetic random access memory (MRAM) cell, a first layer made of a conductive material is formed over a substrate. A second layer for a magnetic tunnel junction (MTJ) stack is formed over the first conductive layer. A third layer is formed over the second layer. A first hard mask pattern is formed by patterning the third layer. The MTJ stack is formed by patterning the second layer by an etching operation using the first hard mask pattern as an etching mask. The etching operation stops at the first layer. A sidewall insulating layer is formed over the MTJ stack. After the sidewall insulating layer is formed, a bottom electrode is formed by patterning the first layer to form the MRAM cell including the bottom electrode, the MTj stack and the first hard mask pattern as an upper electrode.