Auxiliary Layer Stripping for Residue-Free Hybrid Bonding Surfaces

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Solution Overview

Problem

Existing semiconductor processing methods struggle to completely remove temporary polymer layers from dielectric or hybrid bonding surfaces without leaving residues, which can lead to micro-voids and surface modifications such as corrosion.

Innovation Solution

A method involving the use of an auxiliary layer, formed from materials like titanium nitride or tungsten carbide, on which the temporary polymer layer is deposited. This auxiliary layer is removable without leaving residues, effectively taking the polymer residues with it, thus ensuring a residue-free bonding surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional stripping methods are used to remove polymer layers, then the polymer can be removed, but residues remain on the bonding surface causing micro-voids

Engineering Contradiction:

Improvebonding surface cleanlinessVSAvoidpolymer residues

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an auxiliary layer as an intermediary between the polymer layer and the bonding surface. This auxiliary layer serves as a sacrificial substrate that captures polymer residues during stripping, preventing them from contaminating the bonding surface. The auxiliary layer is subsequently removed along with the polymer residues, leaving the bonding surface clean and free of micro-voids.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The auxiliary layer is designed as a disposable, sacrificial layer that is intentionally deposited and then completely removed after serving its protective function. This temporary layer absorbs the harm of polymer residue accumulation, allowing the use of aggressive stripping chemistries without damaging the underlying bonding surface or leaving residues behind.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If aggressive chemistries are used to remove polymer residues, then residues can be removed, but the metal surface undergoes corrosion

Engineering Contradiction:

Improvepolymer residue removalVSAvoidmetal corrosion

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The auxiliary layer acts as a protective intermediary that shields the metal bonding surface from aggressive stripping chemistries. Conventional solvents and chemicals can be used to remove the polymer layer and residues from the auxiliary layer without fear of corroding the metal, as the auxiliary layer provides a safe barrier between the harsh chemistry and the sensitive metal surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The auxiliary layer is deposited in advance before the polymer layer is applied. This preliminary protective measure ensures that when aggressive stripping is later performed, the metal surface is already protected and can withstand the harsh chemicals without corrosion, while still allowing complete removal of polymer residues.

Inventive Principle:

Principle #10Preliminary action

3Object-generated harmful factors

If sacrificial layers of silicon oxide, aluminium or titanium are used, then polymer residues can be captured, but the bonding surface roughness increases and metal pads oxidize

Engineering Contradiction:

Improvepolymer residue captureVSAvoidbonding surface roughness and metal oxidation

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter of the sacrificial layer from conventional materials (silicon oxide, aluminium, titanium) to a specifically engineered auxiliary layer with different properties. This new material is selected to be removable by mild chemistries that do not cause roughening or oxidation, while still effectively capturing polymer residues. The key parameter change is selecting a material whose removal chemistry is selective and gentle on the underlying bonding surface.

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 enables the removal of temporary polymer layers from semiconductor bonding surfaces without leaving residues, preventing void formation and surface damage during hybrid or dielectric-to-dielectric bonding.

Implementation Method 1

an auxiliary layer is produced on a surface of the substrate

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

The stripping of such polymers is carried out using one or more organic solvents

Methodology Applied

Scientific EffectSolvation: Solvation

Data Source

PatentUS20250183088A1Method for removing residues from a substrate surface

Publication Date: 2025.06.05 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

The disclosure is related to removing a temporary polymer bonding layer from a dielectric or hybrid bonding surface of a process wafer including a plurality of dies which are to be bonded to other dies or to a substrate by hybrid bonding or direct dielectric-to-dielectric bonding. Producing an auxiliary layer precedes the production of the polymer bonding layer on the die side of the wafer, e.g. on the bonding surfaces of the dies. According to the disclosure, the auxiliary layer is formed of a nitride or a carbide of a transition metal, for example titanium nitride or tungsten carbide. These materials enable removing the auxiliary layer including any polymer residue, without negatively affecting the dielectric or hybrid dielectric and/or metal bonding surfaces of the dies.