Oxidizing Apparition Partition Voltage Control TMR Film
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Solution Overview
Problem
Existing methods for forming thin oxide layers, such as tunnel barrier films for TMR elements, face challenges in achieving low junction resistance and high resistance change rates due to plasma damage and inefficient oxidation processes, including high oxidation rates and unoxidized portions, which affect the stability and productivity of TMR multilayered films.
Innovation Solution
An oxidizing method and apparatus using a thick partition with through holes to isolate plasma and control the ratio of active species, allowing for radical and ion beam oxidation processes, enabling the formation of oxide films with desired quality and thickness by adjusting the voltage applied to the partition, thereby reducing plasma damage and optimizing film characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma oxidation is used to form a thin metal film barrier layer, then the oxidation rate is very high and productivity increases, but the ferromagnetic layer below the barrier layer suffers oxidation damage and junction resistance increases
Solution Approach 1:
The invention divides the oxidation process into two distinct stages: first forming a thin barrier layer using plasma oxidation, then forming a thicker protective layer using natural oxidation. This segmentation allows each oxidation method to perform its optimal function without causing harm to underlying layers.
Solution Approach 2:
The thin barrier layer is formed first as a preliminary protective structure before the thicker protective layer is formed. This preliminary action creates a controlled interface that prevents excessive oxidation of the ferromagnetic layer while maintaining the desired barrier properties.
2Reliability
If natural oxidation is used to form a barrier layer, then junction resistance decreases significantly, but the oxidation time required is 60 minutes or more which decreases productivity
Solution Approach 1:
The oxidation process is segmented into two phases: a brief plasma oxidation phase that creates a thin barrier layer quickly, followed by a natural oxidation phase that develops the thicker protective layer. This segmentation achieves low junction resistance without requiring the full 60+ minutes of pure natural oxidation.
Solution Approach 2:
The invention changes the oxidation parameters by switching from high-energy plasma oxidation to low-energy natural oxidation at different stages. This parameter change allows the process to achieve the desired electrical properties while controlling the total oxidation time and improving productivity.
3Productivity
If radical oxidation is used instead of natural oxidation, then productivity increases and oxidation time decreases, but junction resistance increases two orders of magnitude or more
Solution Approach 1:
The invention segments the oxidation process to use radical-based plasma oxidation only for the initial thin barrier layer formation, then transitions to natural oxidation for the thicker protective layer. This segmentation prevents the junction resistance increase that would result from using radical oxidation throughout the entire process.
Solution Approach 2:
Different oxidation methods are applied to different regions of the oxidation process: plasma oxidation is used locally for the initial barrier layer where high oxidation rate is needed, while natural oxidation is used for the thicker protective layer where low junction resistance is critical. This local quality approach optimizes both productivity and electrical properties.
4Productivity
If ion beam oxidation is used by applying voltage to a mesh-like extracting electrode, then oxidation can be performed, but the plasma cannot be sufficiently isolated and the oxide film suffers damage similar to plasma oxidation
Solution Approach 1:
The invention extracts only the beneficial oxidation capability from plasma oxidation by using natural oxidation in a controlled environment, while taking out the harmful plasma damage effects. This is achieved by eliminating the plasma phase after the initial barrier layer formation and allowing only neutral oxygen molecules to continue the oxidation process.
Solution Approach 2:
The thin barrier layer formed by plasma oxidation acts as an intermediary structure that protects the ferromagnetic layer from direct plasma exposure during subsequent processing. This intermediary structure allows the system to benefit from plasma oxidation's speed while avoiding its damaging effects on the underlying functional layers.
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 allows for the stable production of high-performance TMR multilayered films with low junction resistance and high resistance change rates, improving film quality and productivity by selectively using radical and ion beam oxidation processes, preventing overoxidation, and enhancing the magnetoresistance change rate.
Implementation Method 1
a plasma generating chamber for generating a plasma
Implementation Method 2
the substrate surface is oxidized by this ion beam
Implementation Method 3
an ion beam is extracted from the plasma by applying a voltage to the extracting electrode
Implementation Method 4
a thick partition having a number of through holes to isolate the plasma
Data Source
AI summary
An oxidizing method and oxidizing apparatus in which a plasma generating chamber having an oxidizing gas supply port and a substrate processing chamber having an exhaust port and internally having a substrate susceptor are connected via a partition having a number of through holes, a plasma of an oxidizing gas supplied into the plasma generating chamber is generated, and an oxide layer is formed on a substrate surface by supplying the generated active species onto a substrate are characterized in that the partition is connected to a power supply via a switching mechanism such that a positive, negative, or zero voltage is applied to the partition, and an oxidation process is performed by changing the ratio of radicals, positive ions, and negative ions in the active species supplied onto the substrate by switching the voltages at least once during the oxidation process.