Polycarbosilane Curing via Catalyst-Mediated Crosslinking
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Solution Overview
Problem
Existing polycarbosilane production methods for semiconductor applications face issues with increased wiring resistance due to oxidation of metal wires and deterioration from high Si—H bond content, leading to reduced thermal stability and mechanical strength, as well as decreased resistance to processing such as etching and plasma processing.
Innovation Solution
A polycarbosilane with a main chain of alternately repeated silicon and carbon atoms, containing structural units with Si—H and Si—O bonds, is produced through a method involving reaction with an alcohol in an organic solvent and water, using a basic catalyst, which allows for crosslinking and curing under reduced pressure or inert gas, preventing gelation and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polycarbosilane with high Si—H bond content is used to enable dehydrogenation coupling reaction for curing, then curability is improved, but storage stability deteriorates due to gradual dehydrogenation coupling during storage
Solution Approach 1:
The patent introduces an organometallic catalyst as an intermediary substance to enable curing at lower temperatures without requiring high Si-H bond content. The catalyst mediates the crosslinking reaction, allowing the polymer to cure effectively while maintaining storage stability by reducing the need for reactive Si-H bonds that would otherwise degrade during storage.
Solution Approach 2:
The patent changes the curing mechanism from dehydrogenation coupling (which requires high Si-H content) to catalyst-mediated crosslinking. This parameter change in the curing approach allows the use of polymers with lower Si-H bond content, thereby improving storage stability while maintaining curability through the catalytic action.
2Reliability
If curing is performed by forming Si—O—Si bonds through oxidation in air, then curability is improved, but metal wires on substrates are oxidized causing increased wiring resistance
Solution Approach 1:
The patent employs an inert atmosphere (such as nitrogen or argon) during the curing process to prevent oxidation of metal wires while still allowing the polycarbosilane to cure through catalyst-mediated crosslinking. This creates an inert environment that protects sensitive metal components from oxidation while permitting the necessary chemical reactions for curing to proceed.
Solution Approach 2:
The organometallic catalyst serves as an intermediary that enables curing to proceed without requiring oxidative conditions. The catalyst facilitates crosslinking through an alternative mechanism that does not involve oxygen, thereby allowing curing to occur in inert atmospheres that protect metal wires from oxidation.
3Reliability
If the number of crosslinked sites in the polymer is increased to improve curability, then curability is improved, but thermal stability and mechanical strength decrease when crosslinked site is an organic group
Solution Approach 1:
The patent changes the nature of crosslinked sites from organic groups to siloxane structures through controlled hydrolysis and condensation reactions. This parameter change in the crosslinking chemistry allows for increased crosslink density while maintaining thermal stability and mechanical strength, as siloxane crosslinks provide superior thermal resistance compared to organic crosslinks.
Solution Approach 2:
The patent creates a composite structure combining organic polycarbosilane chains with inorganic siloxane crosslinks. This composite approach allows the organic backbone to provide flexibility and processability while the inorganic siloxane crosslinks contribute thermal stability and mechanical strength, resolving the contradiction between curability and performance.
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 resulting polycarbosilane exhibits excellent curability, thermal stability, and etching resistance, making it suitable for electronic materials, semiconductor devices, and optical functional materials without affecting other materials, and producing uniform silica films.
Implementation Method 1
a curing reaction proceeds to a larger extent as the Si—H bond content of the polymer increases. However, a dehydrogenation coupling reaction gradually occurs during storage due to the high Si—H bond content
Implementation Method 2
forming Si—O—Si bonds by firing in an oxidizing atmosphere
Implementation Method 3
reacting a raw material polymer having a main chain in which silicon atoms and carbon atoms are alternately repeated and containing a structural unit shown by the following general formula (1) and a structural unit shown by the following general formula (2) with an alcohol in an organic solvent in the presence of a basic catalyst
Data Source
AI summary
A polycarbosilane has a main chain in which silicon atoms and carbon atoms are alternately repeated, and includes a structural unit shown by the following general formula (1), a structural unit shown by the following general formula (2), a structural unit shown by the following general formula (3), and a structural unit shown by the following general formula (4).