Epitaxial Structure Fabrication via Selective Etching

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Solution Overview

Problem

The existing methods for fabricating optoelectronic devices face issues with thermal or electrical conductivity in substrates and the use of fluorine-containing etchants, which can cause equipment corrosion and environmental harm during the removal of epitaxial layers from temporary substrates.

Innovation Solution

A method involving the formation of a patterned sacrificial layer, lateral epitaxial growth of a temporary film, an etching-stop layer, and an epitaxial layer unit, followed by selective etching using different etchants to separate the temporary substrate, allowing for controlled removal without damaging the epitaxial layer unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fluorine-containing etchant is used to remove sacrificial layer, then etching rate is high, but equipment corrosion and environmental harm occur

Engineering Contradiction:

Improveetching rateVSAvoidequipment corrosion and environmental harm

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediate etching-stop layer between the sacrificial layer and the epitaxial layer unit. This layer acts as a mediator that allows the use of aggressive fluorine-containing etchants for rapid sacrificial layer removal while protecting the underlying epitaxial structures from corrosion and environmental release of harmful chemicals.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the etching process into multiple stages using different etchants with selective etching rates. The first etchant (fluorine-containing) rapidly removes the sacrificial layer, while subsequent etchants with lower etching rates are used for more controlled removal of other layers, reducing overall harmful effects.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If single etchant is used for removing sacrificial layer, then process is simple, but selective etching of multiple layers is difficult

Engineering Contradiction:

Improveetching process complexityVSAvoidselective etching precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical parameters of etchants used at different stages. By selecting etchants with different compositions and etching rates, the process achieves selective removal of different layers (sacrificial layer, temporary epitaxial film, etching-stop layer) with high precision while maintaining manageable process complexity.

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

This approach enables efficient separation of the epitaxial structure from the temporary substrate while minimizing the use of harmful etchants and protecting the epitaxial layer, thus improving the fabrication process and reducing environmental impact.

Implementation Method 1

growing laterally and epitaxially a temporary epitaxial film over the patterned sacrificial layer and the temporary substrate

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Implementation Method 2

removing the patterned sacrificial layer using a first etchant, the patterned sacrificial layer having an etching rate greater than that of the temporary epitaxial film

Methodology Applied

Scientific EffectSelective etching:

Implementation Method 3

removing the temporary epitaxial film using a second etchant to separate the temporary substrate from assembly of the etching-stop layer and the epitaxial layer unit, the temporary epitaxial film having an etching rate greater than that of the etching-stop layer

Methodology Applied

Scientific EffectSelective etching:

Data Source

PatentUS8603886B2Intermediate epitaxial structure and method for fabricating an epitaxial structure

Publication Date: 2013.12.10 NATIONAL CHUNG HSING UNIVERSITY

AI summary

A method for fabricating an epitaxial structure includes: (a) forming over a temporary substrate a patterned sacrificial layer that partially exposes the temporary substrate; (b) growing laterally and epitaxially a temporary epitaxial film over the patterned sacrificial layer and the temporary substrate; (c) forming over the temporary epitaxial film an etching-stop layer; (d) forming an epitaxial layer unit over the etching-stop layer; (e) removing the patterned sacrificial layer using a first etchant; and (f) removing the temporary epitaxial film using a second etchant.