Crosslinkable Graft Polymer Neutral Wetting Layer for Sub-100 nm Arrays
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Solution Overview
Problem
Conventional methods for fabricating nanoscale devices face limitations in achieving structures below 100 nm, and self-assembling diblock copolymers struggle with forming perpendicular structures due to preferential wetting surfaces, which are difficult to produce and result in incomplete domain extension to the substrate.
Innovation Solution
A method involving the use of a crosslinkable random graft copolymer that provides a neutral wetting surface for PS-b-PEO block copolymers, allowing both blocks to wet the surface equally, enabling perpendicular orientation of self-assembled domains through graphoepitaxy and solvent annealing, and subsequent selective removal for etching features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithographic processing methods are used, then fabrication processes are simple and costs are low, but structures below 100 nm cannot be achieved
Solution Approach 1:
A neutral wetting layer is introduced as an intermediary between the substrate and the self-assembling block copolymer film. This layer mediates the interaction by providing equal affinity to both polymer blocks, enabling perpendicular orientation of cylindrical domains and achieving sub-100 nm resolution without requiring complex lithographic equipment
2Manufacturing precision
If preferential wetting surfaces are used, then self-assembling is straightforward, but structures perpendicular to the surface cannot be formed and domain extension is incomplete
Solution Approach 1:
The wetting parameters of the substrate surface are changed by applying a neutral wetting layer with specific chemical composition. This layer has equal surface energy interaction with both PS and PMMA blocks, transforming the preferential wetting condition into a neutral wetting condition that allows perpendicular cylindrical domain orientation and complete extension to the substrate
3Manufacturing precision
If neutral wetting surfaces are created, then perpendicular structures can be formed, but surface modification is required which increases process complexity
Solution Approach 1:
A thin film of neutral wetting polymer is applied as a disposable intermediate layer that performs the surface modification function temporarily. This layer is later removed along with the self-assembled polymer structures, avoiding permanent substrate modification and reducing overall process complexity
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 enables the formation of ordered nanometer-scale arrays and patterns on substrates with improved resolution and cost-effectiveness compared to traditional lithographic techniques, exceeding the limitations of conventional photolithography while reducing fabrication costs.
Implementation Method 1
neutral wetting surface (equal affinity for both blocks (AB) of the block copolymer to allow both blocks of the copolymer material to wet the surface, and using entropic forces to drive both blocks to wet the neutral wetting surface)
Implementation Method 2
Diblock copolymer films spontaneously assemble into periodic structures by microphase separation of the constituent polymer blocks after annealing
Implementation Method 3
crosslinked using UV radiation or thermal processing to form a neutral-wetting mat that loses solubility and adheres to the surface
Implementation Method 4
crosslinked using UV radiation
Implementation Method 5
solvent annealing, which caused initial domain segregation at the film-air interface with both polymer blocks wetting the air interface, which was driven downward toward the underlying substrate as the solvent evaporated
Implementation Method 6
as the solvent evaporated and the film dried
Data Source
AI summary
Methods for fabricating a random graft PS-r-PEO copolymer and its use as a neutral wetting layer in the fabrication of sublithographic, nanoscale arrays of elements including openings and linear microchannels utilizing self-assembling block copolymers, and films and devices formed from these methods are provided. In some embodiments, the films can be used as a template or mask to etch openings in an underlying material layer.