Auxiliary Nitride Layer for Residue-Free Wafer Bond Surface Stripping
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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 nitrides or carbides of transition metals, such as titanium nitride or tungsten carbide, which allows for the removal of temporary polymer layers without residues, ensuring the integrity of dielectric or hybrid bonding surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If organic solvents or aqueous chemicals are used to strip polymer layers, then polymer removal is achieved, but polymer residues remain on the bonding surface
Solution Approach 1:
A sacrificial layer is introduced as an intermediary between the bonding surface and the polymer layer. This sacrificial layer absorbs the polymer residues during stripping, protecting the bonding surface from contamination. The sacrificial layer is subsequently removed along with the residues, leaving the bonding surface clean without requiring aggressive chemistries that could damage the surface.
Solution Approach 2:
The sacrificial layer is deposited on the bonding surface before the polymer layer is applied. This preliminary action prepares the surface to receive the polymer while ensuring that any subsequent residue removal will not damage the underlying bonding surface, as the sacrificial layer serves as a protective buffer.
2Manufacturing precision
If aggressive chemistries are used to remove polymer residues, then surface cleanliness is improved, but the metal and dielectric surfaces are damaged
Solution Approach 1:
The sacrificial layer acts as a mediator that allows gentle stripping chemistries to be used. Instead of applying aggressive chemistries directly to the bonding surface, the sacrificial layer is stripped first, carrying away polymer residues. This intermediary approach enables effective cleaning without exposing the sensitive metal and dielectric surfaces to damaging conditions.
Solution Approach 2:
The sacrificial layer provides beforehand cushioning protection to the bonding surface. By having this protective layer in place before stripping operations, the bonding surface is shielded from the harmful effects of stripping chemistries, preventing corrosion and damage while still allowing effective polymer removal.
3Quantity of substance
If sacrificial layers of silicon oxide, aluminium or titanium are used, then polymer residues can be removed, but the bonding surface roughness increases and metal pads oxidize
Solution Approach 1:
The invention changes the material parameter of the sacrificial layer from traditional materials (silicon oxide, aluminium, titanium) to a specifically engineered material that exhibits different chemical properties. This new sacrificial layer material is designed to be removable by gentle chemistries that do not cause roughening or oxidation, while still effectively capturing polymer residues. The parameter change in material composition enables simultaneous achievement of residue removal and surface integrity preservation.
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 effectively removes temporary polymer layers from semiconductor bonding surfaces, preventing void formation and surface damage, while maintaining the low roughness and planarity required for advanced bonding technologies.
Implementation Method 1
The auxiliary layer is removable from the surface of the substrate essentially without leaving residues on said surface
Implementation Method 2
The stripping of such polymers is carried out using one or more organic solvents or aqueous chemicals
Data Source
Figure 1a~1c
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AI summary
The invention is related to removing a temporary polymer bonding layer (16) from a dielectric or hybrid bonding surface of a process wafer (1) comprising a plurality of dies (3) 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 (15) precedes the production of the polymer bonding layer (16) on the die side of the wafer, i.e. on the bonding surfaces of the dies (3). According to the invention, the auxiliary layer (15) 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 (15) including any polymer residue, without negatively affecting the dielectric or hybrid dielectric/metal bonding surfaces (8) of the dies (3).