MRAM MTJ Cover Layers for Oxidation-Stable High-Temperature Processing
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Solution Overview
Problem
The existing magnetic random access memory (MRAM) devices face challenges in maintaining the integrity of the magnetic tunnel junction (MTJ) film stack during manufacturing processes, particularly due to oxidation issues which affect the resistance ratio and thermal stability, leading to potential damage and reduced performance.
Innovation Solution
The use of a zirconium-based oxygen getter layer and a silicon carbide (SiC) layer as insulating cover layers helps prevent oxygen diffusion into the MTJ film stack, thereby protecting it from high-temperature processes and maintaining the desired resistance ratio of the MRAM cell stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the MTJ film stack is exposed to high-temperature manufacturing processes, then the manufacturing process can be completed, but oxygen diffusion damages the MTJ film stack and reduces resistance ratio
Solution Approach 1:
An oxygen barrier layer is introduced as an intermediary component between the MTJ film stack and the external environment. This barrier layer acts as a mediator that blocks oxygen diffusion pathways, allowing the MTJ stack to withstand high-temperature manufacturing processes without oxidation damage, thus enabling both process completion and device reliability
Solution Approach 2:
The oxygen barrier layer is formed prior to subsequent high-temperature manufacturing steps. This preliminary protective action prevents oxygen exposure before damage can occur, allowing the MTJ film stack to maintain its integrity throughout the manufacturing process while enabling complete fabrication
2Reliability
If the resistance ratio is increased to improve memory performance, then the thermal stability improves, but the manufacturing precision requirements increase due to sensitivity to oxidation
Solution Approach 1:
The oxygen barrier layer serves as a protective intermediary that decouples the relationship between resistance ratio and oxidation sensitivity. By providing this physical barrier, the system can achieve high resistance ratios and thermal stability without requiring extremely precise oxidation control during manufacturing, as the barrier layer prevents oxygen exposure regardless of minor process variations
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 effectively prevents damage to the MTJ film stack, ensuring a high resistance ratio of over 80% and enhancing the thermal stability and performance of the MRAM device.
Implementation Method 1
The use of a zirconium-based oxygen getter layer helps prevent oxygen diffusion into the MTJ film stack
Implementation Method 2
a silicon carbide (SiC) layer as insulating cover layers helps prevent oxygen diffusion into the MTJ film stack
Data Source
AI summary
In a method of manufacturing a semiconductor device, a magnetic random access memory (MRAM) cell structure is formed. The MRAM cell structure includes a bottom electrode, a magnetic tunnel junction (MTJ) stack and a top electrode. A first insulating cover layer is formed over the MRAM cell structure. A second insulating cover layer is formed over the first insulating cover layer. An interlayer dielectric (ILD) layer is formed. A contact opening in the ILD layer is formed, thereby exposing the second insulating cover layer. A part of the second insulating cover layer and a part of the first insulating cover layer are removed, thereby exposing the top electrode. A conductive layer is formed in the opening contacting the top electrode. The second insulating cover layer has an oxygen getter property.