MTJ Sidewall Slope Fabrication for Compact, Stable MRAM
Find Innovative SolutionsGenerate Solutions
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 sensing applications.
Innovation Solution
A semiconductor device is fabricated using a method that includes forming an inter-metal dielectric layer, a metal interconnection, and a magnetic tunneling junction (MTJ) with specifically designed slopes on its sidewalls, achieved through a series of etching and trimming processes, including inductively coupled plasma reactive ion etching (ICP-RIE) and ion beam etching (IBE), to optimize the device's structure and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional MRAM fabrication methods are used, then the device can be manufactured, but the chip area is large and manufacturing precision is insufficient
Solution Approach 1:
The patent divides the MTJ sidewall shaping into multiple sequential etching steps: first ICP-RIE etching to create initial sidewalls, then IBE etching to refine and angle the sidewalls. This segmentation allows precise control over the final sidewall geometry without requiring a single complex etching process, thereby improving manufacturing precision while maintaining compact device dimensions.
Solution Approach 2:
The patent introduces a new dimensional aspect by creating sloped sidewalls at specific angles (e.g., 45 degrees) through the combination of ICP-RIE and IBE etching. This angular dimensionality change in the sidewall geometry allows for more efficient space utilization and compact device footprint, directly addressing the chip area issue while achieving high manufacturing precision.
2Measurement precision
If existing MRAM structures are used, then the device functions, but power consumption is high and sensitivity is limited
Solution Approach 1:
The patent optimizes the MTJ structure by changing critical parameters including sidewall angle (e.g., 45 degrees), layer thicknesses, and material compositions. These parameter changes enhance the magnetic tunneling junction's performance, improving sensitivity to magnetic field changes while reducing the current required for operation, thus lowering power consumption.
Solution Approach 2:
The patent employs composite material structures in the MTJ, combining multiple ferromagnetic layers (e.g., CoFeB, CoFe), tunnel barriers (MgO), and exchange springs (Ni80Fe20B20). This composite approach enables enhanced magnetic coupling and tunneling characteristics, achieving high sensitivity with reduced power consumption by optimizing the magnetic and electrical properties of each material layer.
3Reliability
If standard fabrication processes are used, then manufacturing is straightforward, but temperature sensitivity is high and reliability is reduced
Solution Approach 1:
The patent performs preliminary actions by forming sacrificial layers and protective structures before the final MTJ etching. The ICP-RIE etching is performed as a preliminary step to create initial sidewalls, followed by IBE etching to refine the geometry. This preliminary action approach allows for better control of thermal processes and reduces temperature sensitivity during fabrication, improving reliability without excessive manufacturing complexity.
Solution Approach 2:
The patent replaces conventional single-step mechanical etching with a combination of plasma-based ICP-RIE and ion beam IBE etching processes. This substitution provides more precise control over sidewall formation with reduced thermal impact, improving temperature stability and reliability while maintaining ease of manufacture through established semiconductor fabrication techniques.
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 approach results in a more compact, cost-effective, and temperature-stable MRAM device with improved sensitivity, addressing the limitations 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. 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 magnetic tunneling junction (MTJ) on the metal interconnection
Implementation Method 3
utilizing multiple etching processes including inductively coupled plasma reactive ion etching (ICP-RIE)
Implementation Method 4
utilizing multiple etching processes including inductively coupled plasma reactive ion etching (ICP-RIE) and ion beam etching (IBE) to shape the MTJ sidewalls
Data Source
AI summary
A method for fabricating semiconductor device includes the steps of forming an inter-metal dielectric (IMD) layer on a substrate, forming a metal interconnection in the IMD layer, forming a magnetic tunneling junction (MTJ) on the metal interconnection, and performing a trimming process to shape the MTJ. Preferably, the MTJ includes a first slope and a second slope and the first slope is less than the second slope.