Magnetizing System for Magnetic Annealing Throughput
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Solution Overview
Problem
Magnetic annealing systems have long temperature ramp-up and ramp-down cycle times, leading to reduced throughput in MRAM device manufacturing, which is critical due to limited manufacturing facility floor-space and the need for high productivity.
Innovation Solution
A magnetizing system and method that includes a workpiece holder and a magnet assembly with a first and second magnet, arranged to generate a magnetic field substantially perpendicular to the workpiece, achieving uniformity less than 10% variation across the workpiece diameter and supporting thermal processing up to 600 degrees Centigrade, enabling throughput of over 10 workpieces per hour.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional magnetic annealing systems are used, then magnetic domains can be properly oriented, but the temperature ramp-up and ramp-down cycle times are long, reducing throughput
Solution Approach 1:
The patent changes the magnetic field generation method from conventional slow-ramping electromagnetic systems to fast-acting permanent magnets or electromagnets that can rapidly establish the required magnetic field strength (0.02-7 T) without long ramp-up times. This parameter change in field generation speed enables both proper magnetic domain orientation and high throughput exceeding 10 workpieces per hour
2Quantity of substance
If batch-mode magnetic annealing is used, then multiple workpieces can be processed simultaneously, but the overall cycle time remains long due to thermal processing requirements
Solution Approach 1:
The patent segments the magnetic field application from the thermal processing steps, allowing the magnetic field to be rapidly applied and removed independently of the thermal cycle. This enables batch processing of multiple workpieces while minimizing the time each workpiece spends in the magnetic field, reducing overall cycle time while maintaining quantity processing capability
Solution Approach 2:
The patent applies the magnetic field during the soak phase when workpieces are already at target temperature, rather than ramping the field during temperature changes. This preliminary positioning of the magnetic field application timing eliminates unnecessary field ramp time and reduces overall cycle time for batch processing
3Manufacturing precision
If magnetic field uniformity is improved, then consistent magnetization across the workpiece is achieved, but the magnet assembly complexity increases
Solution Approach 1:
The patent uses permanent magnets with specifically engineered local geometries and magnetic properties to create a uniform magnetic field distribution across the workpiece surface. By optimizing the local characteristics of each magnet in the assembly, consistent magnetization is achieved without requiring complex control systems or additional components
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 system enhances workpiece throughput and field uniformity, addressing the inefficiencies of conventional magnetic annealing by allowing for faster processing and increased productivity in MRAM device manufacturing.
Implementation Method 1
a magnet assembly having a first magnet and a second magnet, the first and second magnets defining a gap between opposing poles of each magnet, wherein the magnet assembly is arranged to generate a magnetic field substantially perpendicular to the planar surface of the one or more workpieces
Implementation Method 2
the magnetic domains of the workpiece, e.g., magnetic layer(s), must be held at a predetermined temperature in a pre-determined magnetic field for a period of time long enough for the crystals to orient themselves in a common direction upon cooling
Data Source
AI summary
An apparatus for magnetic annealing one or more workpieces, and a method of operating the apparatus, are described. The apparatus includes: a workpiece holder configured to support one or more workpieces, wherein the one or more workpieces having at least one substantially planar surface; an optional workpiece heating system configured to elevate the one or more workpieces to an anneal temperature; and a magnet assembly having a first magnet and a second magnet, the first and second magnets defining a gap between opposing poles of each magnet, wherein the magnet assembly is arranged to generate a magnetic field substantially perpendicular to the planar surface of the one or more workpieces.