Back-Side Coil Layout for Multi-Die Wireless Coupling

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Solution Overview

Problem

Existing semiconductor devices face challenges in wireless communication between multiple dies in a package, as traditional methods either limit the number of dies that can be stacked or require significant increases in coil size, leading to increased costs.

Innovation Solution

The implementation of back-side coils connected to front-side circuit elements via through-substrate vias, allowing for efficient wireless communication between adjacent dies in a front-to-back arrangement while minimizing the area consumed, using substantially spiral-shaped conductors with optimized turns and spacing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If front-side coils are used for wireless communication between dies, then wireless communication capability is achieved, but the number of dies that can be packaged together is limited to two

Engineering Contradiction:

Improvenumber of diesVSAvoidcoil arrangement complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent inverts the conventional approach by placing coils on the back side of dies instead of the front side. This allows coils to be positioned on adjacent faces of stacked dies, enabling wireless communication between multiple dies in a vertical arrangement without interfering with front-side circuit elements.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent transitions from a horizontal coil arrangement on the front side to a vertical arrangement utilizing the back side of dies. This dimensional change allows for stacking multiple dies vertically with coils positioned on adjacent faces, thereby increasing the number of dies that can communicate wirelessly.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If dies are thinned to reduce coil separation distance, then wireless communication efficiency improves, but coil size must be increased to compensate

Engineering Contradiction:

Improvewireless communication efficiencyVSAvoidcoil size

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

By inverting the coil placement to the back side of dies, the patent achieves optimal coil separation distance without requiring die thinning. The coils on adjacent faces of vertically stacked dies are naturally positioned at a suitable distance for efficient wireless communication while maintaining standard die thickness.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the spatial arrangement parameter from horizontal to vertical stacking, which optimizes the separation distance between coils. This parameter change eliminates the need to adjust die thickness or coil size to achieve optimal communication efficiency.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If coil size is increased to compensate for larger separation distance in multi-die packages, then wireless communication between more than two dies is achieved, but manufacturing cost increases dramatically

Engineering Contradiction:

Improvenumber of diesVSAvoidmanufacturing cost

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent uses vertical stacking with back-side coil placement to achieve multi-die wireless communication without increasing coil size. This dimensional arrangement allows multiple dies to be stacked with standard-sized coils positioned on adjacent faces, dramatically reducing manufacturing costs compared to horizontal arrangements requiring oversized coils.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

By changing the spatial arrangement from horizontal to vertical stacking, the patent optimizes the coil separation distance parameter. This allows standard-sized coils to achieve effective wireless communication across multiple vertically stacked dies, eliminating the need for costly oversized coils.

Inventive Principle:

Principle #35Parameter changes

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

Enables wireless communication with high efficiency between multiple dies in a stack, allowing for more than two dies to be packaged without dramatically increasing coil size, thereby reducing costs and enhancing communication distance.

Implementation Method 1

respective pairs of wireless coils on the front side (e.g., the active layer) of each die are placed in close proximity

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11823977B2Semiconductor devices with back-side coils for wireless signal and power coupling

Publication Date: 2023.11.21 MICRON TECHNOLOGY INC

AI summary

A semiconductor device includes a substrate, a plurality of circuit elements on a front side of the substrate, and a first substantially spiral-shaped conductor on a back side of the substrate is provided. The device further includes a first through-substrate via (TSV) electrically connecting a first end of the substantially spiral-shaped conductor to a first one of the plurality of circuit elements, and a second TSV electrically connecting a second end of the substantially spiral-shaped conductor to a second one of the plurality of circuit elements. The device may be a package further including a second die having a front side on which is disposed a second substantially spiral-shaped conductor. The front side of the second die is disposed facing the back side of the substrate, such that the first and second substantially spiral-shaped conductors are configured to wirelessly communicate.