Photosensitive Polysiloxane Composition for Flat TFT Films
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Solution Overview
Problem
Current photosensitive polysiloxane compositions used in the semiconductor industry for liquid crystal displays and organic light-emitting displays face challenges in achieving high surface flatness and tapered angles of patterns, while maintaining transparency, which are essential for miniaturized patterns in photolithography processes.
Innovation Solution
A photosensitive polysiloxane composition comprising a polysiloxane, o-naphthoquinone diazide sulfonic acid ester, an alkali-soluble resin with a silyl group, and a solvent, which are combined and applied to form a thin film on a substrate, enhancing surface flatness and tapered angles through specific polymerization and processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polysiloxane composition with oxetanyl or succinic anhydride groups is used to achieve high solubility in weak alkaline developer, then solubility is improved, but surface flatness and tapered angle of patterns deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of polysiloxane main chain with grafted unsaturated carboxylic acid groups, combined with a basic polymer and silane crosslinking agent. This composite structure achieves both high solubility in weak alkaline developers (through the basic polymer component) and excellent surface flatness with high tapered angles (through the crosslinked network structure formed by silane and unsaturated carboxylic acid groups)
Solution Approach 2:
The patent optimizes specific parameters including the grafting rate of unsaturated carboxylic acid groups (5-50 mol%), the basicity of the polymer (pKa 4.0-10.0), and the molecular weight of polysiloxane (1,000-100,000). These parameter changes enable the composition to achieve both high solubility in weak alkaline developers and superior pattern formation characteristics with surface flatness of ±0.05 µm and tapered angles of 70° or more
2Length of moving object
If miniaturized patterns are formed in photolithography process, then pattern size is reduced, but achieving high surface flatness and tapered angles becomes more difficult
Solution Approach 1:
The patent creates local quality differences through the crosslinked network structure formed by silane crosslinking agents and unsaturated carboxylic acid groups. This local crosslinking provides structural support and surface stability specifically at the pattern edges and surfaces, enabling high tapered angles (70° or more) and excellent surface flatness (±0.05 µm) even in miniaturized patterns where these characteristics are most critical for functionality
3Illumination intensity
If transparency is maintained in photosensitive composition, then optical properties are improved, but surface flatness and pattern quality may be compromised
Solution Approach 1:
The patent uses silane crosslinking agents as intermediaries that form a transparent crosslinked network structure. This crosslinked network acts as a mediator that maintains optical transparency while providing the structural integrity needed for excellent surface flatness and high tapered angles. The crosslinked structure prevents phase separation and maintains homogeneity, ensuring both optical clarity and pattern quality are achieved simultaneously
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 composition achieves improved surface flatness and tapered angles of patterns, maintaining transparency and enabling the formation of high-quality thin films suitable for advanced display technologies.
Implementation Method 1
an o-naphthoquinone diazide sulfonic acid ester (B)
Implementation Method 2
a polysiloxane (A); an alkali-soluble resin containing a silyl group (C)
Data Source
AI summary
The invention relates to a photosensitive polysiloxane composition and a thin film formed by the aforementioned photosensitive polysiloxane composition. The thin film is a planarization film of a TFT substrate, an interlayer insulating film or an overcoat of a core material or a protective material in a waveguide. The invention is to provide a photosensitive polysiloxane composition having excellent surface flatness and high tapered angle of a pattern. The photosensitive polysiloxane composition comprises a polysiloxane (A), an o-naphthoquinone diazide sulfonic acid ester (B), an alkali-soluble resin containing a silyl group (C) and a solvent (D).