Passivated Magnetic Concentrator for Hall Sensor Sensitivity
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Solution Overview
Problem
Existing semiconductor devices with Hall sensors are insensitive to magnetic fields in the same plane due to the limitations of magnetic concentrator materials, which are prone to damage from semiconductor processing chemicals, leading to increased costs and manufacturing challenges.
Innovation Solution
A semiconductor die with a passivated magnetic concentrator formed over the Hall sensors, using a magnetic alloy layer covered by a polyimide layer to protect it from etchants and cleaning chemicals, allowing conventional semiconductor processing without damage, thereby enhancing sensitivity to in-plane magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic alloy materials are used as magnetic concentrators to improve sensitivity to in-plane magnetic fields, then sensing performance is improved, but the materials are damaged by semiconductor etch and clean chemicals
Solution Approach 1:
A polymer passivation layer is introduced as an intermediary between the magnetic alloy concentrator and the semiconductor processing chemicals. This layer acts as a protective barrier that allows the magnetic alloy to maintain its high sensitivity to in-plane magnetic fields while being shielded from damage by etch and clean chemicals during manufacturing processes
2Measurement precision
If magnetic alloy materials are used for magnetic concentrators, then sensitivity to in-plane magnetic fields is improved, but manufacturing costs increase due to modified chemistries
Solution Approach 1:
The polymer passivation layer serves as a protective intermediary that enables the use of standard, cost-effective semiconductor processing chemicals. By shielding the magnetic alloy from direct exposure to harsh chemicals, the passivation layer eliminates the need for expensive modified chemistries while maintaining manufacturing feasibility
Solution Approach 2:
The magnetic alloy concentrator is pre-passivated with the polymer layer before subsequent semiconductor processing steps. This preliminary protective action prevents chemical damage in advance, allowing the use of conventional processing methods without requiring expensive specialized chemistries during manufacturing
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 solution enables Hall sensors to effectively sense in-plane magnetic fields, improving sensitivity and reducing manufacturing costs by using existing semiconductor processing methods and materials, ensuring robust and reliable magnetic field detection.
Implementation Method 1
The magnetic concentrator can concentrate and bend the magnetic field, so that when the sensor is exposed to an in plane magnetic field, a local field perpendicular to the Hall sensor is formed within the semiconductor device
Implementation Method 2
Hall effect sensors with circuitry... A voltage proportional to a magnetic field is output while a constant current is applied to the Hall sensor
Data Source
AI summary
A described example includes: a semiconductor die including a Hall sensor arranged in a first plane that is parallel to a device side surface of the semiconductor die; a passivated magnetic concentrator including a magnetic alloy layer formed over the device side surface of the semiconductor die, the upper surface of the magnetic alloy layer covered by a layer of polymer material; a backside surface of the semiconductor die opposite the device side surface mounted to a die side surface of a die pad on a package substrate, the semiconductor die having bond pads on the device side surface spaced from the magnetic concentrator; electrical connections coupling the bond pads of the semiconductor die to leads of the package substrate; and mold compound covering the magnetic concentrator, the semiconductor die, the electrical connections, a portion of the leads, and the die side surface of the die pad.