Soft Magnetic Shielding for MRAM Array Immunity
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Solution Overview
Problem
Magnetoresistive random access memory (MRAM) systems lack immunity to ambient magnetic fields, which can disturb or corrupt data stored in magnetic bit cells, posing a hurdle for mainstream applications.
Innovation Solution
A magnetic shielding structure made of soft magnetic material with high relative permeability is implemented to redirect magnetic flux around the MRAM cell array, reducing magnetic field strength and suppressing disturbances. This structure includes a top cover with a recess over the MRAM array and a bottom cover spanning the active side of the semiconductor die, with openings for external connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If MRAM uses magnetic polarization to store data, then data retention without power is achieved, but immunity to ambient magnetic fields is lost
Solution Approach 1:
A magnetic shielding layer made of soft magnetic material is introduced as an intermediary between the ambient magnetic field and the MRAM cell array. This shielding layer redirects magnetic flux around the MRAM cells, protecting them from external magnetic field disturbances while allowing the magnetic polarization storage mechanism to function normally. The shielding layer acts as a mediator that blocks harmful magnetic fields without interfering with the internal magnetic storage operation.
2Object-affected harmful factors
If a magnetic shielding structure is added to protect MRAM, then magnetic field immunity is improved, but device complexity increases
Solution Approach 1:
The magnetic shielding layer is designed to serve multiple functions: it provides magnetic field protection for the MRAM cell array, maintains a compact device footprint, and can be integrated with existing MRAM fabrication processes. The shielding structure is positioned to simultaneously protect multiple MRAM cells while maintaining compatibility with standard semiconductor manufacturing techniques, thereby reducing overall device complexity despite the added protection function.
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 magnetic shielding structure effectively minimizes magnetic field interference, ensuring data integrity and enabling MRAM technology for broader applications by maintaining magnetic field strength below saturation thresholds.
Implementation Method 1
A magnetic shielding structure made of soft magnetic material with high relative permeability is implemented to redirect magnetic flux around the MRAM cell array, reducing magnetic field strength and suppressing disturbances
Implementation Method 2
The magnetic shielding structure effectively minimizes magnetic field interference, ensuring data integrity and enabling MRAM technology for broader applications by maintaining magnetic field strength below saturation thresholds
Data Source
AI summary
Embodiments are provided for a packaged semiconductor device including: a semiconductor die having an active side and an opposite back side, the semiconductor die including a magnetoresistive random access memory (MRAM) cell array formed within an MRAM area on the active side of the semiconductor die; and a top cover including a soft-magnetic material positioned on the back side of the semiconductor die, wherein the top cover includes a recess formed in a first major surface of the top cover, the first major surface faces the back side of the semiconductor die, and the recess is positioned over the MRAM cell array.