xMR Sensor Reference Layer Programming With Masked Laser Heating
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Solution Overview
Problem
Existing methods for producing xMR magnetic field sensors face challenges in achieving economical and high-quality manufacturing, particularly in setting the spatial orientation of the reference magnetization direction with precision.
Innovation Solution
A method and system for producing xMR magnetic field sensors involve a programming operation where the reference magnetization direction is set by heating the reference layer with laser radiation beyond a threshold temperature, exposing it to an external magnetic field, and then cooling it. This process includes a mask projection operation for precise localization and homogenization of the laser radiation to ensure uniform heating and magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the reference layer is heated locally by laser radiation to set the magnetization direction, then the spatial orientation precision is improved, but the manufacturing complexity increases due to the need for mask projection and precise laser control
Solution Approach 1:
A mask is introduced as an intermediary component between the laser source and the reference layer. The mask with precisely positioned apertures defines the heating regions, simplifying the complexity of direct laser control while maintaining high spatial orientation precision. The mask acts as a template that guides the laser radiation to specific sensor regions without requiring complex real-time positioning systems.
Solution Approach 2:
The mask is prepared in advance with predetermined aperture patterns that correspond to the desired sensor element layout. This preliminary preparation of the heating pattern eliminates the need for complex real-time control during the laser processing operation, reducing device complexity while maintaining manufacturing precision.
2Productivity
If multiple sensor elements are produced from a single workpiece, then the productivity is improved, but the manufacturing precision decreases due to the need for selective localization of magnetization directions
Solution Approach 1:
The workpiece is divided into multiple sensor elements, each with its own designated heating region defined by mask apertures. This segmentation allows simultaneous or sequential processing of multiple elements while maintaining precise localization of magnetization directions through the mask-guided laser radiation.
Solution Approach 2:
Different regions of the workpiece receive localized laser heating through selectively positioned mask apertures, enabling each sensor element to have its magnetization direction precisely controlled independently. This local quality approach maintains manufacturing precision across multiple elements produced from a single workpiece.
3Stability of the object's composition
If the laser radiation is homogenized before masking, then the heating uniformity is improved, but the device complexity increases due to additional optical components
Solution Approach 1:
Laser beam homogenization is performed in advance before the light reaches the mask. This preliminary preparation of the laser radiation ensures uniform energy distribution across the beam, which then passes through the mask apertures to create uniformly heated regions. This approach improves heating uniformity while keeping the overall system relatively simple.
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 method enables the production of xMR magnetic field sensors with high sensitivity and stable output signals, allowing for economical and precise manufacturing of components with high quality.
Implementation Method 1
heating the reference layer in a laser processing operation in the sensor region in a locally delimited manner beyond a threshold temperature by laser radiation
Implementation Method 2
the heated sensor region of the reference layer is exposed to an external magnetic field with a specifiable field direction to set the reference magnetization direction
Implementation Method 3
a region of the mask aperture that is fully illuminated with laser radiation is imaged into the processing plane with the aid of an imaging lens arranged between the mask plane and the processing plane
Implementation Method 4
Highly sensitive magnetic field sensors can be constructed by using GMR or TMR sensor elements
Implementation Method 5
giant magnetoresistance (also referred to as GMR effect), tunnel magnetoresistance (TMR) or TMR effect
Data Source
AI summary
A method for fabricating an xMR magnetic field sensor with at least one xMR sensor element from a workpiece containing an xMR multilayer system, including a magnetically hard reference layer with a reference magnetization direction. The method involves a programming operation to set or modify the reference magnetization direction in a sensor region by locally heating the reference layer beyond a threshold temperature using laser radiation, exposing the heated region to an external magnetic field to set the reference magnetization direction, and subsequently cooling the region. The laser processing operation employs a mask projection technique, where a mask with at least one aperture is irradiated with laser pulses, and the fully illuminated aperture region is imaged onto the processing plane using an imaging lens.