Magnetoresistance Sensor Fabrication with Polyimide Masking
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Solution Overview
Problem
The conventional fabricating process of magnetoresistance sensors often damages the bonding pad during the formation of the magnetic shielding and/or concentrator structure, leading to reduced production yield and increased costs.
Innovation Solution
A method where the bonding pad opening is formed after the magnetic shielding and/or concentrator structure is created, using a polymeric mask layer to expose the bonding pad without damaging it, and allowing the magnetic shielding and/or concentrator structure to be formed without additional process conditions, thereby protecting the bonding pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic shielding and/or concentrator structure is formed before the bonding pad opening, then the bonding pad is damaged during the process, but if the bonding pad opening is formed first, then the magnetic shielding structure cannot be properly formed
Solution Approach 1:
The patent applies preliminary action by forming the bonding pad opening through the passivation layer before forming the magnetic shielding and/or concentrator structure. This sequence prevents the bonding pad from being damaged during subsequent magnetic structure formation processes, while still allowing the magnetic structure to be properly formed afterward to enhance sensor performance.
2Reliability
If additional process conditions are added to protect the bonding pad, then the bonding pad damage is reduced, but the fabricating process becomes more complicated and costs increase
Solution Approach 1:
The patent inverts the conventional fabrication sequence by forming the bonding pad opening before the magnetic shielding structure, rather than adding special protection measures. This reversal of the process sequence naturally protects the bonding pad without requiring additional process steps, thereby reducing fabrication complexity and costs while maintaining bonding pad integrity.
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 minimizes bonding pad damage, simplifies the fabricating process, and reduces costs by allowing the use of various magnetic materials and thicknesses without new process conditions, thereby increasing production yield and reducing fabricating costs.
Implementation Method 1
The magnetic shielding and/or concentrator structure 105 is used for shielding external magnetic or electromagnetic field so as to reduce influence of the electromagnetic interference (EMI) on the magnetoresistance structure 102
Implementation Method 2
The magnetic shielding and/or concentrator structure 105 may strengthen the influence of the external magnetic field on the magnetoresistance structure 102
Data Source
AI summary
A fabricating method of a magnetoresistance sensor is provided with cost effective and process flexibility features. Firstly, a substrate is provided. Then, at least one magnetoresistance structure and at least one bonding pad are formed over the substrate, wherein the bonding pad is electrically connected with the magnetoresistance structure. Then, a passivation layer is formed over the magnetoresistance structure and the bonding pad. Then, a magnetic shielding and concentrator structure is formed over the passivation layer at a location corresponding to the magnetoresistance structure. Finally, bonding pad openings is formed on the passivation layer by patterned polyimide, thereby exposing the bonding pad. After bonding pad was opened, the patterned polyimide can be removed or retained as an additional protection layer.