Semiconductor Tether Etching for Precise Micro-Transfer Printing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional chip bonding processes for integrating III-V semiconductor based electro-optical devices with silicon-on-insulator platforms suffer from high optical coupling losses, low yield, and reliability issues due to alignment difficulties and unreliable tethers in micro-transfer printing.

Innovation Solution

A method of etching semiconductor layers to form uniform and optimally designed tethers that secure the device coupon to supports, improving alignment and reliability in the micro-transfer printing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If photoresist is used to form tethers, then the tether formation process is simple, but the tethers are non-uniform and unreliable

Engineering Contradiction:

Improvetether formation process simplicityVSAvoidtether reliability and uniformity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the material parameter from photoresist to semiconductor material for tether formation. This material substitution enables uniform tether dimensions through controlled etching processes and achieves reliable, reproducible tether properties that are critical for high-volume micro-transfer printing processing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces a break region with locally modified properties (reduced width, lower shear strength) within the tether structure. This localized modification allows the tether to break at a predetermined position during MTP while maintaining uniform and reliable properties in the anchor regions, resolving the contradiction between ease of manufacture and reliability.

Inventive Principle:

Principle #3Local quality

2Productivity

If conventional flip-chip bonding is used, then device integration is achieved, but alignment precision between waveguides is poor

Engineering Contradiction:

Improvedevice integration capabilityVSAvoidwaveguide alignment precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The invention performs preliminary alignment setup by forming tethers with predetermined geometries and positions during the device fabrication process. This preliminary action establishes precise reference structures that guide subsequent MTP alignment, achieving high manufacturing precision without requiring complex real-time alignment procedures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces the mechanical alignment approach of flip-chip bonding with a predetermined geometric alignment system. The tether structures serve as built-in alignment references, eliminating the need for complex mechanical alignment mechanisms and achieving superior waveguide-to-waveguide alignment precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If photoresist tethers are used, then tether formation is straightforward, but debris is generated during breakage

Engineering Contradiction:

Improvetether formation simplicityVSAvoiddebris generation during tether breakage

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The invention changes the material parameter from photoresist to semiconductor material for tether formation. This material substitution eliminates debris generation during tether breakage because semiconductor materials fracture cleanly without producing the particulate debris characteristic of photoresist breakdown, thereby removing the harmful factor while maintaining manufacturing simplicity.

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 method enhances the yield and reliability of the micro-transfer printing process by providing uniform and optimally strong tethers, reducing debris-related issues and improving the precision of the alignment between III-V semiconductor devices and SOI waveguides.

Implementation Method 1

etching the multi-layered stack to form a multi-layered device coupon, including an optical component; and etching a semiconductor layer of the multi-layered device coupon to form one or more tethers

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS12532574B2Method of preparing a device coupon for micro-transfer printing, device wafer including said device coupon, and optoelectronic device manufactured from said device wafer

Publication Date: 2026.01.20 ROCKLEY PHOTONICS LTD

AI summary

A method of preparing a device coupon for a micro-transfer printing process from a multi-layered stack located on a device wafer substrate. The multi-layered stack comprises a plurality of semiconductor layers. The method comprises steps of: (a) etching the multi-layered stack to form a multi-layered device coupon, including an optical component; and (b) etching a semiconductor layer of the multi-layered device coupon to form one or more tethers, said tethers securing the multi-layered device coupon to one or more supports.