MRAM Package Magnetic Shielding for Interference Protection
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Solution Overview
Problem
Magnetic random access memory (MRAM) devices are susceptible to reliability issues due to external magnetic interferences, which distort magnetic signals and affect READ and WRITE operations.
Innovation Solution
The implementation of magnetic shielding in MRAM packages, including a top magnetic shield layer on the inactive surface of the die and magnetic shield traces or permeable underfill dielectric material, to protect the magnetic storage elements from external magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external magnetic shielding is added to MRAM packages, then reliability against magnetic interference is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The magnetic shielding is segmented into multiple functional layers: a first magnetic shield layer formed on the backside of the substrate, and a second magnetic shield layer formed on the inactive surface of the die. This segmentation allows each layer to address specific magnetic interference pathways independently, improving overall shielding effectiveness while maintaining manageable manufacturing complexity through modular fabrication processes.
Solution Approach 2:
The magnetic shielding structure implements a nested configuration where the first magnetic shield layer on the substrate backside and the second magnetic shield layer on the die inactive surface create concentric shielding zones. The die is mounted on the substrate with its inactive surface facing the substrate backside, forming a nested arrangement where magnetic fields must pass through multiple layered barriers, significantly enhancing protection against external magnetic interference.
2Object-affected harmful factors
If magnetic shield layers are formed on both substrate and die, then protection against magnetic fields is improved, but manufacturing precision requirements increase
Solution Approach 1:
The first magnetic shield layer is formed on the backside of the substrate before the die is mounted to the substrate. This preliminary formation of the substrate-side shield layer establishes a baseline magnetic barrier early in the manufacturing process, reducing the magnetic field strength that reaches the die interface. Subsequently, the second magnetic shield layer is formed on the inactive surface of the die after mounting, completing the nested shielding structure without requiring high-precision alignment between the two layers during a single fabrication step.
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 effectively prevents disturbances from external magnetic fields, enhancing the reliability and stability of MRAM devices by isolating the magnetic storage elements.
Implementation Method 1
a top magnetic shield layer formed on the inactive surface of the die
Implementation Method 2
MTJ element which uses magnetic polarization to store information
Data Source
AI summary
Magnetic random access memory (MRAM) packages with magnetic shield protections and methods of forming thereof are presented. Package contact traces are formed on the first major surface of the package substrate and package balls are formed on the second major surface of the package substrate. A die having active and inactive surfaces is provided on the first major surface of the package substrate. The die includes a magnetic storage element, such as an array of magnetic tunnel junctions (MTJs), formed in the die, die microbumps formed on the active surface. The package includes a top magnetic shield layer formed on the inactive surface of the die. The package may also include a first bottom magnetic shield in the form of magnetic shield traces disposed below the package contact traces. The package may further include a second bottom magnetic shield in the form of magnetic permeable underfill dielectric material. The package may also include a third bottom magnetic shield sandwiched between two thin package substrate layers of the package substrate.