3D MRAM Magnetic Shielding via Through Silicon Vias
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Solution Overview
Problem
Magnetoresistive random access memory (MRAM) devices are susceptible to reliability issues due to external magnetic interferences, which affect READ and WRITE operations and are challenging to integrate vertically with other chips in a 3D IC package without effective magnetic shielding.
Innovation Solution
The implementation of MRAM chips with through silicon via (TSV) and/or through silicon trench (TST) magnetic shield structures, along with front and back side magnetic shield layers, to protect the MRAM chip from external magnetic fields and enable vertical stacking with other chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MRAM chips are integrated vertically with other chips in a 3D IC package, then integration capability and productivity are improved, but susceptibility to external magnetic interferences worsens
Solution Approach 1:
A magnetic shield layer is introduced as an intermediary component between the MRAM chip and external environment. This shield layer, positioned at the backside of the substrate, acts as a mediator that blocks external magnetic fields from reaching the MTJ elements, thereby enabling vertical integration in 3D IC packages without compromising the chip's susceptibility to magnetic interference
Solution Approach 2:
The magnetic shield structure extends in the vertical dimension by forming a via structure that penetrates through the substrate from the front surface to the backside. This via structure, filled with conductive material and coupled to the magnetic shield layer, creates a three-dimensional shielding architecture that protects the MRAM chip from external magnetic fields while enabling vertical stacking
2Reliability
If magnetic shield structures are added to protect MRAM chips, then reliability is improved, but device complexity increases
Solution Approach 1:
The magnetic shield structure is segmented into distinct functional components: a magnetic shield layer positioned at the backside of the substrate, and a via structure that penetrates through the substrate. This segmentation allows each component to be optimized independently - the shield layer provides magnetic protection while the via structure provides electrical coupling and structural support, thereby managing complexity through functional decomposition
Solution Approach 2:
The via structure serves multiple functions simultaneously: it provides electrical coupling between the magnetic shield layer and external circuitry, provides structural support for the shield layer, and acts as part of the magnetic shielding architecture. This multi-functionality reduces the need for separate components, thereby improving reliability without proportionally increasing device complexity
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 shield structures effectively protect the MRAM chip from external magnetic interferences, ensuring reliable operation and enabling the vertical stacking of MRAM chips in 3D IC packages, thereby enhancing the reliability and integration capabilities of MRAM devices.
Implementation Method 1
The magnetic shield structures effectively protect the MRAM chip from external magnetic interferences
Data Source
AI summary
Emerging memory chips and methods for forming an emerging memory chip are presented. For example, magnetoresistive random access memory (MRAM) chip magnetic shielding and vertical stacking capabilities processed at the wafer-level are disclosed. The method includes providing a magnetic shield in the through silicon vias and/or through silicon trenches surrounding or adjacent to magnetic tunnel junction (MTJ) array within the MRAM region and also at the front side and back side of the chip. Magnetic shield in the through silicon trenches connects front side and back side magnetic shield. Magnetic shield in the through silicon vias provides vertical stacking, magnetic shielding and electrical connection of the MRAM chips to form 3D IC packages. This magnetic shielding method is applicable for both in-plane and perpendicular MRAM chips. The MTJ array is formed in the MRAM region and in between adjacent inter layer dielectric (ILD) levels of the upper ILD layer in the back end of line (BEOL) of the MRAM chip.