ALD Al2O3 Bonding Layer for III-V-on-SOI Photonic Integration

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Solution Overview

Problem

Heterogeneous bonding of dissimilar materials in semiconductor manufacturing faces challenges such as low shear strength and acid damage, leading to delamination and yield limitations in photonic integrated circuits, particularly in hybrid Si photonics where acid etching causes issues with material separation and device performance.

Innovation Solution

A thin layer of Al2O3 is deposited via atomic layer deposition (ALD) on the bonding surface of III-V compound semiconductors before bonding with a silicon-on-insulator (SOI) wafer, enhancing the bond's shear strength and protecting the material from acid etchants during processing, while also reducing defects and enabling smaller optical circuit designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If heterogeneous bonding of dissimilar materials (III-V compound semiconductor to Si substrate) is performed, then photonic integrated circuits can be manufactured with specialized material properties, but the shear strength of the bond is reduced and delamination occurs

Engineering Contradiction:

Improvematerial property specializationVSAvoidbond shear strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies composite materials by creating a layered structure consisting of SiO2, Al2O3, and III-V compound semiconductor materials. The Al2O3 layer is deposited via atomic layer deposition (ALD) to form a protective composite structure that enhances bond strength while maintaining the specialized optical properties of the dissimilar materials (Si and III-V compounds), thereby resolving the contradiction between material versatility and bond strength.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If acid etchants are used to etch the compound semiconductor after bonding, then device fabrication can be performed, but the acids wick underneath the compound semiconductor and etch the bonding interface causing delamination

Engineering Contradiction:

Improvedevice fabrication capabilityVSAvoidbonding interface integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces an Al2O3 layer as an intermediary protective barrier between the acid etchants and the bonding interface. This intermediary layer allows acid etching to be performed on the compound semiconductor for device fabrication while preventing the acid from wicking underneath and damaging the bonding interface, thus maintaining both manufacturing ease and bonding reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The Al2O3 protective layer is deposited in advance via atomic layer deposition (ALD) before any acid etching steps are performed. This preliminary protective action prevents the harmful effects of acid exposure on the bonding interface, allowing subsequent fabrication steps to proceed without compromising bond integrity.

Inventive Principle:

Principle #9Preliminary anti-action

3Strength

If a protective layer is deposited via atomic layer deposition (ALD) on the compound semiconductor, then shear strength and acid resistance are improved, but processing steps and time are increased

Engineering Contradiction:

Improvebond shear strengthVSAvoidprocessing time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The patent utilizes atomic layer deposition (ALD) to precisely control the thickness and properties of the Al2O3 protective layer. By optimizing deposition parameters such as layer thickness (typically nanometer scale) and deposition conditions, the process achieves maximum protective effect with minimal added processing time, balancing strength improvement against time 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 Al2O3 layer significantly improves the bond's shear strength, reduces acid damage, and increases yield, allowing for smaller die sizes and more efficient light coupling, resulting in improved performance and reduced material waste in photonic integrated circuits.

Implementation Method 1

The protection material protects the compound semiconductor from acid etchants during processing of the bonded structure

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

a continuous film of a protection material is deposited on a first surface of the compound semiconductor by atomic layer deposition (ALD)

Methodology Applied

Scientific EffectAtomic layer deposition:

Data Source

PatentUS11846803B2Atomic layer deposition bonding for heterogeneous integration of photonics and electronics

Publication Date: 2023.12.19 OPENLIGHT PHOTONICS INC

AI summary

Methods and systems are presented for heterogeneous integration of photonics and electronics with atomic layer deposition (ALD) bonding. One method includes operations for forming a compound semiconductor and for depositing (e.g., via atomic layer deposition) a continuous film of a protection material (e.g., Al2O3) on a first surface of the compound semiconductor. Further, the method includes an operation for forming a silicon on insulator (SOI) wafer, with the SOI wafer comprising one or more waveguides. The method further includes bonding the compound semiconductor at the first surface to the SOI wafer to form a bonded structure and processing the bonded structure. The protection material protects the compound semiconductor from acid etchants during further processing of the bonded structure.