Optical Waveguide Taper for Heterogeneous Light Coupling

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Solution Overview

Problem

Current heterogeneous integrated optical waveguide structures face challenges in completely coupling light from passive to active waveguides, leading to inefficient light usage and difficulties in aligning submicron-level structures, which hinders their application in 3D integrated circuits.

Innovation Solution

An optical waveguide structure with a first waveguide layer featuring a taper, connecting, and strip portion, and a binding layer between a second waveguide layer, formed through selective etching without the need for submicron-scaled alignment, using III-V compounds and silicon materials, and a manufacturing method that includes heterojunction treatment and photoresist patterning to improve alignment accuracy and reduce process complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heterogeneous integration of III-V compound and passive waveguide is performed after alignment process, then light coupling between waveguides is improved, but alignment difficulty increases due to submicron level structure requirements

Engineering Contradiction:

Improvelight coupling efficiencyVSAvoidalignment difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by forming the active waveguide layer (III-V compound) on the passive waveguide layer (silicon) before performing the alignment process. The heterojunction interface is created in advance, and then a single alignment step is used to bond the layers together. This eliminates the need for separate alignment processes for each layer, reducing overall alignment difficulty while maintaining high light coupling efficiency.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If submicron-scaled alignment process is used, then alignment accuracy between active and passive waveguides is improved, but process complexity and production difficulty increase

Engineering Contradiction:

Improvealignment accuracyVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple alignment operations into a single alignment process. By forming the active waveguide layer on the passive waveguide layer before alignment, the patent combines what would otherwise be separate alignment steps into one operation. This reduces process complexity while achieving the required submicron alignment accuracy through a single bonding step.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If conventional heterogeneous integration method is used, then passive waveguide structure can be formed, but light cannot be completely coupled from passive to active waveguide

Engineering Contradiction:

Improvelight coupling completenessVSAvoidlight energy loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent applies parameter changes by carefully controlling the dimensions and geometry of the active and passive waveguides at their heterojunction interface. The active waveguide layer is formed with specific thickness and width parameters that optimize mode matching between the silicon passive waveguide and III-V active waveguide. This parameter optimization enables complete light coupling from the passive to active waveguide, minimizing light energy loss.

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

The solution enables efficient coupling of light energy from passive to active waveguides, enhancing the integration of 3D ICs by improving alignment accuracy and reducing production difficulties, with measured coupling efficiency around 80% and simplified manufacturing processes.

Implementation Method 1

a binding layer disposed between the first waveguide layer and the second waveguide layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

the first waveguide layer is used for coupling a light beam through the taper portion and the connecting portion to the strip portion

Methodology Applied

Scientific EffectOptical waveguide: Waveguide (optics)

Implementation Method 3

able to completely couple the light from a passive waveguide to an active waveguide

Methodology Applied

Scientific EffectLight coupling:

Implementation Method 4

a selective etching process is performed so that an active waveguide and a passive waveguide are formed in order without a submicron-scaled alignment process

Methodology Applied

Scientific EffectSelective etching:

Data Source

PatentUS9563015B1Optical waveguide structure and manufacturing method thereof

Publication Date: 2017.02.07 NAT SUN YAT SEN UNIV

AI summary

An optical waveguide structure and a manufacturing method thereof are disclosed. The optical waveguide structure has a first waveguide layer, a binding layer, and a second waveguide layer. The first waveguide layer has a taper portion, a connecting portion, and a strip portion. The manufacturing method of the optical waveguide structure has steps of etching to form the first waveguide layer, and then etching to form the second waveguide layer under the first waveguide layer.