Planar Polymer Stack Crosslinking for Nanolithography
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Solution Overview
Problem
Existing methods for controlling the planarity of polymer stacks and preventing dewetting and inter-diffusion phenomena in polymer systems, particularly in directed self-assembly nanolithography, are complex and not industrially viable, leading to unstable polymer films and defects in nanolithography masks.
Innovation Solution
A method involving the deposition of a prepolymer composition that undergoes heat treatment to form a crosslinked top coat layer, which prevents dewetting and stabilizes the underlying polymer layer, ensuring a flat and clear interface, and allows for the orientation of nanodomains perpendicular to the interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a polymer layer is deposited in liquid or viscous state onto an underlying layer, then the deposition process is simple and efficient, but dewetting phenomenon occurs leading to non-planar surfaces and film instability
Solution Approach 1:
The patent applies a preliminary action by depositing the polymer layer in liquid/viscous state and then immediately subjecting it to heat treatment to induce crosslinking before dewetting can occur. This preliminary crosslinking action stabilizes the film structure, preventing the harmful dewetting phenomenon while maintaining the benefits of liquid-state deposition.
Solution Approach 2:
The patent changes the physical and chemical parameters of the polymer layer by controlling the transition from liquid/viscous state during deposition to solid crosslinked state after heat treatment. This parameter change (temperature and molecular structure) resolves the contradiction by enabling simple deposition followed by stable film formation through crosslinking.
2Adaptability or versatility
If the polymer layer is left to evolve freely over time, then the material can self-organize, but dewetting occurs causing loss of film continuity and thickness variation
Solution Approach 1:
The patent applies a preliminary crosslinking action through heat treatment that occurs before significant dewetting can develop. This preliminary stabilization allows controlled self-organization while preventing the uncontrolled dewetting that would otherwise occur during free evolution, thereby maintaining film uniformity.
Solution Approach 2:
The patent rushes through the critical time window by applying rapid heat treatment to induce crosslinking before dewetting phenomena have time to develop. This skipping of the unstable free-evolution period prevents thickness variation and maintains manufacturing precision while still allowing controlled self-organization.
3Productivity
If multiple polymer layers are stacked in liquid or viscous state, then the stack can be formed efficiently, but inter-diffusion and solubilization occur at interfaces leading to poor interface definition
Solution Approach 1:
The patent applies preliminary heat treatment to induce crosslinking in each polymer layer before subsequent layers are deposited or before inter-diffusion can occur. This preliminary crosslinking creates clear, stable interfaces between layers while maintaining the efficiency of multi-layer stack formation.
Solution Approach 2:
The patent changes the physical state and chemical structure of polymer layers from liquid/viscous to solid crosslinked state through heat treatment. This parameter change prevents inter-diffusion and solubilization at interfaces, ensuring clear interface definition while maintaining efficient stack formation procedures.
4Ease of manufacture
If the polymer material has low surface energy and low cohesion energy, then the material is easier to process and deposit, but the material is more susceptible to deformation and dewetting under force
Solution Approach 1:
The patent changes the physical and chemical parameters of the polymer material by inducing crosslinking through heat treatment. This transforms the material from a soft, easily deformed state with low cohesion energy to a rigid, deformation-resistant crosslinked network, while maintaining the ease of initial processing during deposition.
Solution Approach 2:
The patent applies preliminary heat treatment to create the crosslinked network structure before the material is subjected to forces that would cause deformation. This preliminary strengthening action maintains processing ease during deposition while providing deformation resistance when the material is in service.
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 effectively prevents dewetting and inter-diffusion, resulting in perfectly flat polymer stacks with clear interfaces and enables the correct orientation of nanodomains, improving the quality and usability of polymer films in nanolithography applications.
Implementation Method 1
an additional step consists in submitting said upper layer to a heat treatment, capable of causing a crosslinking reaction of the molecular chains within said prepolymer layer
Implementation Method 2
capable of causing a crosslinking reaction of the molecular chains within said prepolymer layer and allowing the production of a crosslinked so-called top coat layer
Implementation Method 3
The upper layer thus crosslinked makes it possible to solve several different technical problems presented previously. Firstly, this crosslinking makes it possible to eliminate the dewetting inherent in the top coat layer
Implementation Method 4
depositing on a substrate a first layer of non-crosslinked (co)polymer, and then a second layer of (co)polymer, at least one of the (co)polymer layers initially being in a liquid or viscous state
Data Source
AI summary
The invention relates to a method for manufacturing a flat polymeric stack, said stack comprising one or more first and one second layer of (co)polymer (20, 30) stacked one on the other, the first underlying (co)polymer layer (20) not having undergone any prior treatment allowing its crosslinking, at least one of the (co)polymer layers initially being in a liquid or viscous state, said method being characterized in that the upper layer (30), known as the top coat (TC), is deposited on the first layer (20) in the form of a prepolymer composition (pre-TC), comprising one or more monomer(s) and/or dimer(s) and/or oligomer(s) and/or polymer(s) in solution, and in that it is then subjected to a heat treatment capable of causing a crosslinking reaction of the molecular chains within said layer (30, TC).