Ferromagnetic Core for 3D IC Wireless Power Transfer

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Solution Overview

Problem

Current 3D IC packaging techniques using through-silicon-vias (TSV) for power transfer are costly and inefficient, while 2.5D ICs with microbumps are fragile and prone to damage during testing, and existing contactless communication methods in stacked packages face limitations in mutual inductance and area utilization.

Innovation Solution

Incorporating ferromagnetic cores within the 3D or 2.5D IC packages to increase mutual inductance between coils, allowing for more efficient wireless signal and power transfer by positioning the cores between or around the coils, thereby enhancing communication performance and reducing the need for additional TSVs and microbumps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If through-silicon-vias (TSV) are used for power transfer in 3D IC packaging, then power can be transferred between stacked ICs, but the manufacturing cost increases and fabrication complexity increases

Engineering Contradiction:

Improvepower transfer capabilityVSAvoidfabrication cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical/electrical TSV system with a magnetic field-based wireless power transfer system. Coils are formed on the front and back faces of the IC, and power is transferred through magnetic coupling between these coils, eliminating the need for physical through-silicon vias and their associated complex fabrication processes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces ferromagnetic material positioned between the front and back face coils to act as a magnetic flux concentrator and guide. This intermediary material enhances the magnetic coupling between coils, improving power transfer efficiency while allowing for larger spacing between the coils compared to direct TSV approaches

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If through-silicon-vias (TSV) are used for connections, then connections between front and back face can be made, but area is consumed by the TSVs

Engineering Contradiction:

Improveconnection capabilityVSAvoiddie area

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

The patent replaces the physical TSV connection system with a wireless magnetic coupling system. Power and signals are transferred through magnetic fields generated by coils on the IC surfaces, eliminating the need for physical vias and freeing up die area that would otherwise be occupied by TSV structures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from a planar connection approach (TSVs passing through the die thickness) to a three-dimensional magnetic field approach. The magnetic field extends through the space between the front and back faces, allowing power transfer without consuming lateral die area

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of operation

If microbumps are used for interconnections in 2.5D IC, then connections between IC chips and silicon interposer can be made, but the microbumps are fragile and may be damaged during testing

Engineering Contradiction:

Improveinterconnection capabilityVSAvoidmicrobump durability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the mechanical microbump connection system with a wireless magnetic coupling system. This eliminates the fragile microbumps entirely, as power and signal transfer is achieved through electromagnetic fields rather than physical contacts that are susceptible to damage during probe card testing and handling

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 use of ferromagnetic cores increases mutual inductance by up to 30%, improving the efficiency and quality of signal and power transfer in contactless communication, while also reducing the number of required TSVs and microbumps, thus addressing the limitations of existing packaging techniques.

Implementation Method 1

A ferromagnetic core is positioned at least partially within the boundary, such that a mutual inductance is provided between the first and second coils for wireless transmission of signals or power between the first and second coils

Methodology Applied

Scientific EffectMutual inductance: Electromagnetic Induction

Implementation Method 2

Incorporating ferromagnetic cores within the 3D or 2.5D IC packages to increase mutual inductance between coils

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentUS9412721B2Contactless communications using ferromagnetic material

Publication Date: 2016.08.09 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A communications structure comprises a first semiconductor substrate having a first coil, and a second semiconductor substrate having a second coil above the first semiconductor substrate. Inner edges of the first and second coils define a boundary of a volume that extends below the first coil and above the second coil. A ferromagnetic core is positioned at least partially within the boundary, such that a mutual inductance is provided between the first and second coils for wireless transmission of signals or power between the first and second coils.