Stacked Photonic Die Waveguides for Fiber-Free 3DIC Coupling

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Solution Overview

Problem

Existing technologies face challenges in efficiently integrating optical and electrical components in a compact form factor without the need for optical fibers, while maintaining low optical signal loss and enabling efficient optical signal transmission between stacked photonic dies.

Innovation Solution

The method involves stacking photonic dies with silicon and silicon nitride waveguides, forming electrical and optical through-vias, and using transparent dielectric layers to facilitate optical coupling, eliminating the need for optical fibers and reducing signal loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical fibers are used to transmit optical signals between photonic dies, then optical signal transmission is enabled, but device complexity and footprint increase

Engineering Contradiction:

Improveoptical signal transmissionVSAvoidpackage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes optical fibers from the package structure by extracting this external transmission medium. Instead, optical signals are transmitted directly through the silicon substrate and interconnect structures that are already present in the photonic die stack, eliminating the need for separate optical fiber components and their associated alignment and coupling structures.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the optical signal transmission function with the existing electrical interconnect structures. The same silicon substrate and through-silicon vias that conduct electrical signals are also used to guide optical signals, combining multiple functions into a single integrated structure and reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If optical fibers are used for optical signal transmission, then signal transmission is achieved, but the footprint and area occupied increase

Engineering Contradiction:

Improveoptical signal transmissionVSAvoidpackage footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent transitions from a lateral/optical-fiber-based transmission approach to a vertical transmission approach through the stacked die structure. Optical signals propagate vertically through the thickness of the photonic dies and interconnect layers, utilizing the third dimension (z-axis) for signal transmission rather than requiring lateral space for optical fibers.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The optical signal transmission path is nested within the existing vertical stack of photonic dies and interconnect structures. The optical transmission function is embedded within the same physical structure that houses the photonic components, eliminating the need for external optical fibers that would occupy additional package area.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Ease of manufacture

If traditional packaging methods are used, then manufacturing is simplified, but optical signal loss increases

Engineering Contradiction:

Improvepackaging processVSAvoidoptical signal loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The silicon substrate and interconnect structures serve dual purposes: they provide both mechanical support and optical signal transmission pathways. The existing structural materials inherently guide optical signals without requiring additional specialized optical transmission components, allowing the structure to serve itself for both mechanical and optical functions.

Inventive Principle:

Principle #25Self-service

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

This approach allows for a compact integration of optical and electrical components with reduced optical signal loss, enabling efficient optical signal transmission between stacked photonic dies, thus enhancing the performance and efficiency of integrated 3DIC packages.

Implementation Method 1

using transparent dielectric layers to facilitate optical coupling

Methodology Applied

Scientific EffectOptical transmission through transparent dielectric: Refraction

Implementation Method 2

stacking photonic dies with silicon and silicon nitride waveguides

Methodology Applied

Scientific EffectWaveguide: Waveguide (optics)

Data Source

PatentUS12517298B2Integrated 3DIC with stacked photonic dies and method forming same

Publication Date: 2026.01.06 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes forming a first photonic die, which includes forming a first silicon waveguide, and forming a first nitride waveguide. The method further includes forming a first through-via extending into a first plurality of dielectric layers in the first photonic die, and bonding a second photonic die to the first photonic die. The second photonic die includes a second nitride waveguide. The first silicon waveguide is optically coupled to the second nitride waveguide through the first nitride waveguide. A second through-via extends into a second plurality of dielectric layers in the second photonic die.