Rapid Thermal Processing for Spintronic Pinned Layer Programming
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Solution Overview
Problem
Current methods for manufacturing push-pull bridge magnetic sensors with pinned layers of opposite magnetic moments on the same silicon chip are complex and result in poor consistency due to the need for separate depositions and subsequent annealing processes, leading to deviations in performance.
Innovation Solution
A rapid thermal processing method and apparatus that improves spatial resolution and processing time for programming the pinned layer of spintronic devices, using a reflective cover and precise laser annealing to heat and cool specific areas of the wafer within a controlled magnetic field, allowing for the production of high-performance single-chip TMR, GMR, or MTJ sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate deposition processes are used for MTJ elements with pinned layers having opposite directions, then the magnetic moments can be properly oriented, but the manufacturing process becomes complex and consistency between films deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the wafer into different regions (first region and second region) with opposite magnetic field directions during the annealing process. This allows pinned layers in different regions to acquire opposite magnetic moments through in-situ annealing, eliminating the need for separate deposition processes while maintaining precise magnetic moment orientation.
Solution Approach 2:
The patent merges the magnetic moment orientation function into a single annealing process that simultaneously handles both pinned layers. By applying opposite magnetic fields to different regions during annealing, the system combines what would otherwise require separate deposition steps into one unified process, reducing manufacturing complexity while maintaining precision.
2Manufacturing precision
If separate deposition processes are used for MTJ elements with pinned layers having opposite directions, then the magnetic moments can be properly oriented, but the thermal budget increases and processing time extends
Solution Approach 1:
The patent applies preliminary action by performing the magnetic moment orientation during the annealing process itself, rather than relying on subsequent separate deposition steps. The annealing process with applied magnetic fields pre-establishes the correct magnetic moments before final device assembly, reducing total processing time while maintaining precision.
3Manufacturing precision
If conventional laser annealing is used, then localized heating can be achieved, but the processing speed and precision are insufficient for mass production
Solution Approach 1:
The patent replaces the mechanical scanning laser system with a mask-based optical system. The mask with patterned openings allows parallel illumination of multiple regions simultaneously, eliminating the need for slow mechanical scanning while maintaining precise spatial control over which areas receive annealing treatment, thus improving both speed and precision.
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 enables the rapid production of sensors with improved performance and consistency, suitable for mass production by enhancing the precision and speed of the annealing process, reducing thermal budget, and maintaining temperature compensation.
Implementation Method 1
During laser irradiation, the solid is bombarded with a photon beam focused on a sample. The photons interact with energy transferred from the sample to crystal lattices, and the energy locally heats the sample.
Implementation Method 2
a reflective cover and precise laser annealing to heat and cool specific areas of the wafer
Implementation Method 3
A rapid thermal processing method and apparatus for programming the pinned layer of spintronic devices
Implementation Method 4
programming the pinned layer of spintronic devices... production of high-performance single-chip TMR, GMR, or MTJ sensors
Data Source
Figure 1(a)~2
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AI summary
A rapid thermal processing method and apparatus used for programming the pinned layer of spintronic devices, the apparatus comprising a rapid thermal annealing light source (31), a reflective cover, a magnet, a wafer (34), a substrate (55). The light source is used for heating the substrate. The reflective cover at least comprises a transparent insulating layer (33, 51, 53) and a reflective layer (32, 52). The magnet is used to produce a constant magnetic field. An antiferromagnetic layer (47) on a wafer may be locally programmed by controlling the exposure time, for heating a specific area on the wafer (34) to a temperature above the blocking temperature of the antiferromagnetic layer (47), and then turning off the magnetic field after the heating area has cooled in the presence of the applied magnetic field. This rapid thermal processing method is used to improve the spatial resolution of laser annealing. It provides excellent performance, and it is suitable for mass production.