Chemically Amplified Resist Adhesion to Metal and SiN Substrates
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Solution Overview
Problem
Chemically amplified negative resist compositions face challenges with adhesion to substrates, particularly on metal wirings, electrodes, and SiN substrates, leading to stripping issues, and struggle to form uniform layers on substrates with rugged surfaces, limiting their application in high-density packaging technologies.
Innovation Solution
A chemically amplified negative resist composition comprising a silicone structure-bearing polymer, a crosslinker, a photoacid generator, and an isocyanuric acid, which improves adhesion and allows for the formation of fine patterns on substrates with a wide range of thicknesses, using radiation exposure and post-curing to enhance substrate bonding and pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spin coating technique is used to form photo-curable resin composition, then film formation is simple, but film thickness is limited to below 30 μm due to high viscosity requirements
Solution Approach 1:
A release film is introduced as an intermediary layer between the substrate and the photo-curable resin composition. The release film serves as a mobile support that enables the resin to be applied at lower viscosities while achieving greater thickness, then the release film is peeled off to transfer the cured resin layer to the substrate.
Solution Approach 2:
The problem of film thickness limitation is solved by moving the support function from the substrate to a separate release film dimension. This allows the resin composition to be applied independently of substrate constraints, achieving thicknesses exceeding 30 μm that would be impossible with direct spin coating onto the substrate.
2Adaptability or versatility
If spray coating is used to replace spin coating, then coating can be applied differently, but defects are formed including height difference, film rupture, and pinholes
Solution Approach 1:
The release film acts as an intermediary support that enables uniform film formation during the coating process. By providing a stable, flat surface during application, the release film prevents the formation of height differences and pinholes that occur when coating directly onto rugged substrates or without support.
Solution Approach 2:
The resin composition is applied and cured on the release film before being transferred to the final substrate. This preliminary action on a controlled surface prevents defect formation, and the cured film is then transferred to the target substrate, achieving both versatility and uniformity.
3Area of stationary object
If negative resist composition is applied to metal wirings, electrodes, or SiN substrates, then pattern coverage is achieved, but adhesion is poor causing pattern stripping
Solution Approach 1:
The release film serves as an intermediary during the curing process, allowing the photo-curable resin to be cured uniformly without direct contact issues with the substrate. After curing, the release film is peeled off, and the cured resin forms strong adhesion to the substrate through its crosslinked structure, preventing pattern stripping while maintaining full coverage.
Solution Approach 2:
The photo-curable resin composition uses a composite formulation including crosslinking agents and specific resin components that enhance adhesion to metal and SiN substrates. The crosslinked network structure provides strong bonding while the composition maintains coverage over various substrate types.
4Area of stationary object
If photo-curable resin composition is applied on substrates with rugged surface, then coverage is attempted, but uniform layer formation is difficult with voids near steps
Solution Approach 1:
The release film serves as a flat intermediary surface during the resin application and curing process. The resin is applied and cured on this smooth surface, ensuring uniform layer formation without voids. After curing, the release film is peeled off and the uniformly cured resin is transferred to the rugged substrate, achieving both coverage and uniformity.
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 solution significantly improves adhesion to substrates, enabling the formation of fine patterns and reducing pattern feature sizes, thus addressing the stripping problem and enhancing the suitability for high-density chip integration and electronic part protection.
Implementation Method 1
a photoacid generator which is decomposed to generate an acid upon exposure to light of wavelength 190 to 500 nm
Implementation Method 2
a crosslinker which has a crosslinking reaction site susceptible to crosslinking reaction within the molecule
Implementation Method 3
an isocyanuric acid, and wherein the isocyanuric acid enhances an adhesion between a cured layer or a pattern and a substrate
Data Source
Figure 1
AI summary
A chemically amplified negative resist composition is provided comprising (A) a resin having a crosslinking group, (B) a crosslinker, (C) a photoacid generator capable of generating an acid upon exposure to light of wavelength 190-500 nm, (D) a solvent, and (E) an isocyanuric acid. The resist composition overcomes the stripping problem that the film is stripped from metal wirings of Cu or Al, electrodes, and SiN substrates.