Magnetoresistive Sensor Electrode Layout for Higher Element Density
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Solution Overview
Problem
Existing magnetoresistive sensors face challenges in increasing the number of magnetoresistive elements per unit area due to limitations in aligning and connecting upper electrodes with magnetoresistive elements, leading to increased resistance and noise in detection signals.
Innovation Solution
A magnetoresistive device design with a connection portion having a contact surface identical to the free layer shape and a circumferential surface in the stacking direction, allowing for a cylindrical or substantially cylindrical configuration of electrodes, which facilitates precise alignment and reduces the distance between elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are enlarged to reduce resistance, then resistance is reduced, but alignment precision deteriorates and number of elements per unit area cannot be increased
Solution Approach 1:
The patent applies spheroidality by making the contact holes and upper electrodes cylindrical instead of planar. The contact holes are formed with a cylindrical shape extending vertically, and the upper electrodes are designed with a cylindrical configuration. This curved geometry allows the contact holes to be smaller in planar footprint while maintaining adequate contact area through vertical extension, thus reducing resistance without compromising alignment precision.
Solution Approach 2:
The patent transitions from a two-dimensional planar contact structure to a three-dimensional cylindrical contact structure. By making contact holes cylindrical and extending them vertically through the insulating layer, the contact area is increased in the vertical dimension rather than expanding the planar footprint. This dimensional change allows smaller planar contact hole sizes while maintaining adequate electrical contact.
2Reliability
If plane shapes of upper electrodes are made larger to completely fill contact holes, then connection reliability is improved, but distance between adjacent elements increases and number of elements per unit area cannot be increased
Solution Approach 1:
The upper electrodes are designed with a cylindrical configuration rather than expanding their planar footprint. The cylindrical shape allows the electrode to completely fill the cylindrical contact hole through vertical extension, ensuring reliable electrical connection. At the same time, the planar footprint remains compact, allowing elements to be packed closer together and increasing the number of elements per unit area.
Solution Approach 2:
The patent uses three-dimensional cylindrical geometry to achieve complete filling of contact holes without increasing planar dimensions. The upper electrodes extend vertically to match the cylindrical contact holes, providing adequate contact area in the vertical dimension while maintaining a compact planar footprint that enables higher element density.
3Manufacturing precision
If plane shapes of magnetoresistive elements are made larger to improve alignment precision, then alignment precision is improved, but number of elements per unit area decreases
Solution Approach 1:
The patent applies cylindrical geometry to contact holes and upper electrodes, which changes the alignment reference from planar shapes to circular cross-sections. The cylindrical contact holes provide a well-defined circular footprint that is easier to align with cylindrical upper electrodes. This geometric approach maintains alignment precision while allowing smaller planar dimensions, thus increasing the number of elements that can be packed into a unit area.
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 design enables a higher density of magnetoresistive elements per unit area, reducing resistance and noise, thereby enhancing the sensitivity and accuracy of magnetic field detection.
Implementation Method 1
a free layer having a magnetic vortex structure and configured so that a center of the magnetic vortex structure moves depending on a magnetic field to be applied
Implementation Method 2
a magnetization pinned layer having a magnetization whose direction is fixed, a free layer having a magnetization whose direction is variable depending on a magnetic field to be applied
Data Source
AI summary
A magnetoresistive device includes at least one magnetoresistive element and at least one electrode including at least one connection portion connected to the at least one magnetoresistive element. The at least one magnetoresistive element includes a magnetization pinned layer, a free layer configured to have a magnetic vortex structure and configured so that a center of the magnetic vortex structure moves depending on a target magnetic field, and a gap layer. The magnetization pinned layer, the free layer, and the gap layer are stacked in a certain stacking direction. The at least one connection portion has a contact surface being in contact with the at least one magnetoresistive element and having an identical shape to that of the free layer when seen in the stacking direction, and a circumferential surface connected to the contact surface and having a certain dimension in the stacking direction.