Magnetic Sensor Inclined Surface Etching Protrusion Control
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Solution Overview
Problem
In magnetic sensors with inclined sensor elements, the etching of insulating films embedded with metallic structures can lead to protrusions beyond the film surface due to differing etching rates, complicating the formation process and reducing sensor accuracy.
Innovation Solution
A sensor design featuring a support member with a first and second layer, where at least one inclined surface is formed across these layers, allowing the functional layer of the sensor element to be disposed on the inclined surface, thus enabling the embedding of structures within the support member without excessive protrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dry etching is performed on an insulating film embedded with metallic structures to form protruding portions, then the insulating film can be etched, but the metallic structures protrude beyond the top surface due to different etching rates
Solution Approach 1:
The insulating film is segmented into multiple layers (first insulating film and second insulating film) with different etching rates. The first insulating film has a higher etching rate than the second insulating film, allowing selective removal to form protruding portions without excessive protrusion of embedded metallic structures. This segmentation resolves the contradiction by creating controlled differential etching.
Solution Approach 2:
Different regions of the insulating film structure are assigned different properties: the first insulating film region has higher etchability while the second insulating film region has lower etchability. This local quality differentiation allows the etching process to selectively remove material at different rates in different regions, achieving both manufacturability and surface precision.
2Reliability
If sensor elements are formed on inclined surfaces, then magnetic field detection capability is improved, but the formation process becomes more complex
Solution Approach 1:
The inclined surfaces are formed on the insulating film structure before the sensor elements are formed. By pre-forming the inclined surfaces through selective etching of the multi-layer insulating film structure, the subsequent sensor element formation becomes simpler as it only requires deposition on the pre-prepared inclined surfaces, rather than forming inclined surfaces during sensor element fabrication.
Solution Approach 2:
The solution moves the complexity from the sensor element formation dimension to the substrate preparation dimension. Instead of making sensor element formation complex by forming inclined surfaces during that process, the inclined surfaces are created in advance on the substrate, adding complexity to the substrate preparation step but simplifying the sensor element fabrication step.
Data Source
AI summary
A magnetic sensor includes an insulating layer, a first MR element, and a second MR element. The insulating layer includes a first layer and a second layer, and also includes first and second inclined surfaces formed across the first layer and the second layer. Each of the first and second MR elements includes a magnetization pinned layer and a free layer. The magnetization pinned layer and the free layer of the first MR element are disposed on the first inclined surface. The magnetization pinned layer and the free layer of the second MR element are disposed on the second inclined surface.