MgO Barrier Layer Reactive Oxidation for TMR Sensors
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Solution Overview
Problem
Increasing the tunneling magnetoresistive (TMR) value of reader sensors while maintaining low area resistance (RA) has been a challenge, particularly with magnesium oxide (MgO) barrier layers, as RF-deposition processes lead to ion damage, poor textural structure, and increased exchange coupling.
Innovation Solution
Employing a reactive oxidation (R-ox) MgO deposition process with low power deposition of Mg metal films in the presence of oxygen to form a more uniform and smooth MgO barrier layer, reducing ion damage and exchange coupling, and increasing TMR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RF-deposition process is used to form MgO barrier layer, then deposition is achieved, but ion damage occurs and textural structure deteriorates
Solution Approach 1:
The patent changes the deposition parameters by switching from RF-deposition to reactive oxidation deposition. This parameter change eliminates ion damage while achieving uniform and smooth MgO barrier layer formation, directly resolving the contradiction between manufacturing precision and harmful factors.
Solution Approach 2:
The patent replaces the RF-deposition mechanical process with a chemical oxidation process. Instead of using radio frequency energy to deposit MgO, the invention uses reactive oxidation of Mg metal in the presence of oxygen, substituting a chemical mechanism for a physical one, thereby eliminating ion damage.
2Reliability
If RF-deposition process is used to form MgO barrier layer, then deposition is achieved, but exchange coupling increases
Solution Approach 1:
By changing the deposition method from RF-deposition to reactive oxidation, the patent alters the structural parameters of the MgO barrier layer. This results in reduced exchange coupling between magnetic layers while maintaining reliable TMR sensor performance.
3Reliability
If TMR value is increased, then sensor sensitivity improves, but area resistance increases
Solution Approach 1:
The patent changes the deposition parameters to create an optimized MgO barrier layer structure through reactive oxidation. This produces a layer with uniform thickness and smooth texture that achieves high TMR value while maintaining low area resistance, resolving the contradiction between sensitivity and resistance.
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 R-ox MgO process enhances the quality of the MgO barrier layer, resulting in higher TMR values and lower exchange coupling, maintaining low RA and improving the overall performance of TMR sensors.
Implementation Method 1
depositing a second MgO-source layer on the first layer using a reactive oxide deposition process in the presence of oxygen from an Mg target
Implementation Method 2
depositing a first MgO-source layer from an Mg target, depositing a second MgO-source layer on the first layer using a reactive oxide deposition process
Implementation Method 3
annealing the first MgO-source layer, the second MgO-source layer, and the third MgO-source layer to form an MgO barrier layer
Data Source
AI summary
A method of making an MgO barrier layer for a TMR sensor, the method including depositing a first Mg layer in a first chamber, depositing a second Mg layer on the first Mg layer using a reactive oxide deposition process in the presence of oxygen in the first chamber or in a second chamber different than the first chamber, depositing a third Mg layer on the second MgO layer in either the first chamber, the second chamber, or a third chamber, and annealing the first layer, the second layer, and the third layer to form an MgO barrier layer.