Thin Chip Direct Bonding With a Temporary Substrate Carrier

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Solution Overview

Problem

Existing chip bonding methods for thin chips (less than 200 μm thick) face challenges due to surface roughness and contamination issues, particularly when bonding materials like silicon oxide and copper, leading to numerous defects.

Innovation Solution

A method involving direct bonding of a donor substrate to a temporary substrate, followed by thinning and separation, which includes protective layer application to maintain surface cleanliness and reduce roughness, allowing for defect-free bonding to a receiver substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the donor substrate is thinned by abrasion using diamond wheels, then the substrate thickness is reduced to less than 200 μm, but the roughness of the front face increases to exceed 100 nm RMS

Engineering Contradiction:

Improvesubstrate thicknessVSAvoidsurface roughness

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The substrate processing is divided into separate stages: thinning the back face first, then bonding to a temporary substrate to protect the front face during cutting and handling. This segmentation allows the front face to maintain its original smoothness while the back face is thinned.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The back face thinning is performed before the front face is exposed to cutting operations. By preparing the substrate in advance with the correct thickness while the front face is still protected, the subsequent cutting and handling operations do not affect the front face roughness.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If the front face of chips is in contact with adhesive tape during handling, then the chips can be manipulated easily, but the front face becomes contaminated and difficult to clean

Engineering Contradiction:

Improvechip handlingVSAvoidsurface contamination

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Instead of bonding the front face to the adhesive tape, the method inverts the approach by bonding the back face to the temporary substrate. This reversal ensures that the front face, which requires high cleanliness for bonding, never contacts the adhesive tape during handling operations.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

A temporary substrate acts as an intermediary carrier for the donor substrate during processing. This temporary substrate provides the handling interface, allowing the front face of the chips to remain protected and uncontaminated while still enabling easy manipulation of the entire assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the front face of the donor substrate is bonded to the adhesive tape, then the substrate can be handled, but the front face roughness increases making it incompatible with direct bonding

Engineering Contradiction:

Improvesubstrate handlingVSAvoidfront face roughness

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The method inverts the conventional approach by bonding the back face instead of the front face to the temporary substrate. This ensures that the front face, which must remain smooth for direct bonding compatibility, is never subjected to the roughening effects of adhesive tape contact or handling operations.

Inventive Principle:

Principle #13The other way round (Inversion)

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 achieves high-quality, defect-free bonding of thin chips by protecting the front face during thinning and cutting, ensuring a clean and smooth surface compatible with direct bonding, thus enhancing the reliability of the bonding process.

Implementation Method 1

Direct bonding is spontaneous bonding without the use of liquid adhesive material. It is generally performed at room temperature, although hot surfaces can also be bonded.

Methodology Applied

Scientific EffectDirect bonding: Diffusion Welding

Implementation Method 2

bonding the assembly consisting of the donor substrate and the temporary substrate to a handling device comprising a solid support and an adhesive film

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentUS20250391698A1Chips direct bonding method

Publication Date: 2025.12.25 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method for bonding chips including the following steps: a) providing a donor substrate wherein chips are formed, the donor substrate including a front face and a back face, b) mounting the front face of the donor substrate to a temporary substrate, by direct bonding, c) preferably thinning the donor substrate, d) bonding the assembly consisting of donor substrate and temporary substrate on a handling device including a solid frame and an adhesive film, with the back face of the donor substrate bonded to the adhesive film, e) separating the temporary substrate from the donor substrate, f) cutting the donor substrate so as to singularize the chips, g) bonding the chips to the receiver substrate by direct bonding.