Composite Bonding Layer for Residue-Free Die Release

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Solution Overview

Problem

Existing methods for temporarily bonding substrates or dies to carriers face challenges such as slow chemical release, residue removal difficulties, and inefficient thermal decomposition, particularly for large bonded areas, and require uniform radiation for illumination-based release, which can be complex and leave residues.

Innovation Solution

A method involving a composite bonding layer comprising a sacrificial layer and a removable attachment layer that undergoes a phase change at a temperature below a critical temperature, allowing easy release and subsequent removal of residues using an etching agent or solvent, while avoiding damage to the substrate or die.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single glue layer is used for bonding, then the bonding process is simple, but release is slow and leaves residues that are difficult to remove

Engineering Contradiction:

Improvebonding process simplicityVSAvoidrelease speed

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The bonding layer is divided into two distinct layers: a sacrificial layer (first layer) that enables fast chemical release, and a removable attachment layer (second layer) that provides stable bonding. This segmentation allows each layer to perform its specific function optimally - the sacrificial layer enables rapid release from outer regions inward, while the attachment layer ensures strong initial bonding without the drawbacks of single-layer systems.

Inventive Principle:

Principle #1Segmentation

2Productivity

If thermally decomposable glue layers are used, then carrier release is faster, but residues are left that are very difficult to remove

Engineering Contradiction:

Improverelease speedVSAvoidresidue formation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The sacrificial layer acts as an intermediary between the substrate/die and the removable attachment layer. During release, the sacrificial layer is chemically removed first, enabling fast release without thermal decomposition. The removable attachment layer is then removed separately, avoiding residue formation on the substrate or die. This intermediary approach allows fast release kinetics while protecting the substrate from residue contamination.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If chemical release is used, then the bonding layer is removed, but the process is slow for large bonded areas

Engineering Contradiction:

Improvecomplete removalVSAvoidrelease time

Core Design Contradiction:

Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The bonding system is segmented into a sacrificial layer designed for rapid chemical removal and a removable attachment layer. The sacrificial layer's composition allows fast chemical etching from outer regions inward, significantly reducing release time for large bonded areas compared to single-layer chemical release systems.

Inventive Principle:

Principle #1Segmentation

4Strength

If high temperature processing is applied, then bonding is achieved, but polymer glue layers are affected leaving non-removable residues

Engineering Contradiction:

Improvebond strengthVSAvoidresidue formation

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The sacrificial layer's chemical composition and removal conditions are specifically optimized to enable low-temperature or mild chemical removal. This parameter change allows complete removal of the sacrificial layer without subjecting the substrate or die to high temperatures that would cause residue formation or material degradation, while still achieving sufficient bonding strength through the removable attachment layer.

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

Enables efficient and residue-free release of substrates or dies from carriers, facilitating handling, thinning, and processing without damaging the components, and allows for easier handling and processing of temporarily bonded substrates or dies.

Implementation Method 1

a removable attachment layer (4) on top of the sacrificial layer or on top of a first main carrier surface; bonding the first element (2) to the second element (3) by means of a bonding layer comprising a stack of sub layers formed by the sacrificial layer and the removable attachment layer

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

removing the sacrificial layer (5) after the release of the first and second elements by an etching agent or a solvent, thereby also removing residues left from the removable attachment layer

Methodology Applied

Scientific EffectChemical etching:

Data Source

PatentUS7795113B2Method for bonding a die or substrate to a carrier

Publication Date: 2010.09.14 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

A method is disclosed for bonding two elements by means of a bonding agent such as a glue layer, wherein the bonding agent is removable, and wherein between the bonding agent and at least one element, a sacrificial layer is applied which is selectively removable with respect to that element. According to embodiments, the elements comprise a die or a substrate bonded to a carrier wafer. The nature and type of the die or substrate and of the carrier can vary within the scope of embodiments of the invention. Also disclosed is a composite substrate obtainable by methods of the invention.