Flexible Conductive Foil Carrier for Thin Film Semiconductor Chips

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Solution Overview

Problem

Existing thin film semiconductor chip production methods face challenges in achieving low overall thickness and mechanical stability, as well as simplified wafer-level testing, due to the use of rigid carriers and difficulties in transferring active layer sequences.

Innovation Solution

A method involving the application of an active epitaxial layer sequence on a growth substrate, followed by a reflective electrically conductive contact material layer, patterning, and the use of a flexible electrically conductive foil as an auxiliary carrier, allowing for easy testing and reduced thickness without increasing the risk of fracture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid carriers such as gallium arsenide or germanium wafers are used, then mechanical stability is improved, but the carrier thickness cannot be reduced below 100 μm due to fracture risk

Engineering Contradiction:

Improvemechanical stabilityVSAvoidcarrier thickness

Core Design Contradiction:

StrengthVSLength of moving object

Solution Approach 1:

The patent replaces rigid carriers with flexible thin film carriers made of materials like silicon oxide, silicon nitride, or polymer films with thicknesses of 1-50 μm. These flexible films provide mechanical support while enabling significant thinning of the carrier layer, thus resolving the contradiction between mechanical stability and reduced thickness.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs composite structures combining thin active layer sequences (1-10 μm) with flexible carrier films and reflective layers. This composite approach maintains mechanical integrity through the combination of materials with complementary properties while achieving overall thickness reduction below 100 μm.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If adhesive bonding or soldering is used to join the active layer sequence to the carrier, then the active layer sequence can be transferred, but the overall thickness of the chip increases

Engineering Contradiction:

Improvetransferability of active layer sequenceVSAvoidoverall chip thickness

Core Design Contradiction:

Ease of manufactureVSLength of moving object

Solution Approach 1:

The patent uses extremely thin flexible carrier films (1-50 μm) that eliminate the need for thick adhesive bonding layers or solder joints. The flexibility of these thin films allows for direct bonding or transfer processes that maintain minimal overall thickness while achieving secure attachment of the active layer sequence.

Inventive Principle:

Principle #30Flexible shells and thin films

3Ease of operation

If a reinforcing layer and auxiliary carrier layer are applied to the back surface, then handling of the active layer sequence is simplified, but wafer level testing becomes impossible or extremely difficult

Engineering Contradiction:

Improvehandling of active layer sequenceVSAvoidtesting capability at wafer level

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent uses flexible thin film carriers that maintain wafer-level integrity during handling while allowing direct electrical contact to the active layer sequence through the thin film substrate. This enables wafer level testing through the flexible carrier without requiring additional auxiliary layers that would block testing access.

Inventive Principle:

Principle #30Flexible shells and thin films

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 the production of thin film semiconductor chips with low overall thickness and improved mechanical stability, facilitating wafer-level testing and reduced yield losses from contaminants, while allowing for easier integration with additional components in small housing dimensions.

Implementation Method 1

an active layer sequence which is suitable for generating electromagnetic radiation

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

There is a reflective layer between the carrier and the active layer sequence

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS8728937B2Method for producing semiconductor chips using thin film technology

Publication Date: 2014.05.20 OSRAM OLED

AI summary

For semiconductor chips using thin film technology, an active layer sequence is applied to a growth substrate, on which a reflective electrically conductive contact material layer is then formed. The active layer sequence is patterned to form active layer stacks, and reflective electrically conductive contact material layer is patterned to be located on each active layer stack. Then, a flexible, electrically conductive foil is applied to the contact material layers as an auxiliary carrier layer, and the growth substrate is removed.