CPP GMR Device Plasma Nitridation Insulator Formation
Solution Overview
Problem
Current CPP GMR devices face issues with copper purity degradation and low MR ratio due to oxidation during insulator formation in CCP-CPP schemes, leading to compromised Cu purity and magnetic layer contamination.
Innovation Solution
Plasma nitridation is used instead of plasma oxidation to form the CCP layer, utilizing insulating metallic nitrides, maintaining the structure at temperatures above 150°C to prevent copper nitride formation and minimize oxygen contamination in magnetic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma oxidation is used to form the CCP layer, then the insulator formation is achieved, but copper purity is degraded and magnetic layers are contaminated
Solution Approach 1:
The patent changes the chemical parameter of the plasma process from oxidation to nitridation. By using plasma nitridation instead of plasma oxidation, the process forms aluminum nitride insulator rather than aluminum oxide, which prevents copper oxidation and maintains copper purity while still achieving the required insulating properties.
Solution Approach 2:
The patent creates an inert nitrogen-based plasma environment during the insulator formation process. This nitrogen atmosphere prevents oxygen from contacting and oxidizing the copper layers, effectively protecting copper purity while allowing the aluminum-based insulator to form through nitridation rather than oxidation.
2Reliability
If plasma oxidation is used for insulator formation, then the CCP layer is formed, but magnetic layers are oxidized and performance deteriorates
Solution Approach 1:
The patent uses nitrogen-based plasma to create an inert atmosphere during insulator formation. This prevents oxygen from reaching and oxidizing the magnetic layers (CoFeB, CoFe), maintaining their integrity and magnetic properties while still enabling the aluminum-based insulator to form through nitridation.
Solution Approach 2:
The patent changes the chemical environment parameter from oxygen-rich (oxidation) to nitrogen-rich (nitridation). This parameter change protects magnetic layers from oxidation while maintaining the insulating functionality of the CCP layer through aluminum nitride formation.
3Reliability
If conventional oxidation process is used, then insulator is formed, but copper filaments are oxidized and MR ratio decreases
Solution Approach 1:
The patent employs nitrogen-based plasma to create an oxygen-free inert environment during insulator formation. This protects the copper filaments from oxidation, maintaining their high conductivity and ensuring high MR ratio performance, while the aluminum-based insulator forms through nitridation.
Solution Approach 2:
The patent changes the chemical composition parameter of the plasma process from oxygen to nitrogen. This parameter change prevents copper oxidation and maintains the high MR ratio by preserving copper filament purity, while still achieving insulator formation through aluminum nitride creation.
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 enhances copper purity, prevents magnetic layer oxidation, and improves the GMR ratio by maintaining the integrity of the copper filaments and magnetic layers, resulting in better overall device performance.
Implementation Method 1
Plasma nitridation is used instead of plasma oxidation to form the CCP layer, utilizing insulating metallic nitrides
Implementation Method 2
maintaining the structure at temperatures above 150°C to prevent copper nitride formation and minimize oxygen contamination in magnetic layers
Data Source
AI summary
Plasma nitridation, in place of plasma oxidation, is used for the formation of a CCP layer. Al, Mg, Hf, etc. all form insulating nitrides under these conditions. Maintaining the structure at a temperature of at least 150° C. during plasma nitridation and/or performing post annealing at a temperature of 220° C. or higher, ensures that no copper nitride can form. Additionally, unintended oxidation by molecular oxygen of the exposed magnetic layers (mainly the pinned and free layers) is also avoided.