Block Copolymer Chemical Contrast Pattern via Oxidized PS and SIS
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Solution Overview
Problem
Conventional sequential infiltration synthesis (SIS) methods using block copolymers (BCPs) result in discontinuous or shifted features due to low density of active sites for atomic layer deposition (ALD) precursors, leading to inadequate inorganic material formation for robust etch masks, especially at nanometer scales.
Innovation Solution
The method involves removing PMMA prior to ALD and making PS the active material, where PS is oxidized and a surface modification polymer (SMP) is deposited, allowing alumina precursors to react with the oxidized PS, forming a chemical contrast pattern that replicates the original pattern without major distortions, and can be used as a lithographic mask or to direct self-assembly of additional BCPs for enhanced pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional SIS method is used to grow inorganic material in BCP, then material deposition is achieved, but the density of active sites is extremely low resulting in discontinuous or shifted features
Solution Approach 1:
The patent applies preliminary action by oxidizing the PS component before ALD deposition to create abundant carbonyl-like active sites. This pre-treatment ensures that when ALD precursors are introduced, there are sufficient reaction sites to form continuous inorganic material patterns, preventing the discontinuity and shifting issues observed in conventional SIS methods.
Solution Approach 2:
The patent changes the chemical state of the PS component from reduced to oxidized, transforming it from an inactive material to one with high reactivity toward ALD precursors. This parameter change (oxidation state) increases the density of active sites from extremely low to high, enabling robust pattern formation while maintaining manufacturing precision.
2Quantity of substance
If all polymer material is removed after SIS, then the original pattern is replicated, but the remaining inorganic material is insufficient to make a robust etch mask
Solution Approach 1:
The patent performs preliminary oxidation of the PS component before ALD deposition, creating a high density of active sites that ensure abundant inorganic material formation. This pre-treatment guarantees that sufficient inorganic material remains after polymer removal to form a robust etch mask, directly addressing the insufficiency problem of conventional SIS.
Solution Approach 2:
By changing the oxidation state of PS from reduced to oxidized, the patent transforms the material's reactivity toward ALD precursors. This parameter change results in significantly higher inorganic material deposition density, ensuring that the remaining pattern has sufficient strength and continuity to serve as an effective etch mask.
3Ease of manufacture
If features are removed and remaining material is used as etch mask, then pattern transfer is enabled, but image quality degrades due to feature discontinuity or shifting
Solution Approach 1:
The patent applies preliminary oxidation to create abundant active sites before ALD deposition, ensuring that the inorganic material forms continuous, well-defined patterns. This pre-treatment prevents feature discontinuity and shifting during subsequent processing, maintaining high image quality while enabling effective pattern transfer for manufacturing.
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 results in a more robust chemical contrast pattern that maintains image quality and enables effective pattern transfer into substrates with improved continuity and fidelity compared to conventional SIS methods, allowing for the creation of high-quality imprint templates and lithographic masks.
Implementation Method 1
the PS is oxidized. A surface modification polymer (SMP) having functional end groups is deposited on the oxidized PS and the exposed substrate regions
Implementation Method 2
The substrate with the bound SMP and oxidized PS is then placed in an atomic layer deposition (ALD) chamber and the alumina precursors are introduced
Implementation Method 3
DSA of BCPs by use of a patterned sublayer for the BCP film is well-known. After the BCP components self-assemble on the patterned sublayer
Data Source
AI summary
A method for making a chemical contrast pattern uses directed self-assembly of block copolymers (BCPs) and sequential infiltration synthesis (SIS) of an inorganic material. For an example with poly(styrene-block-methyl methacrylate) (PS-b-PMMA) as the BCP and alumina as the inorganic material, the PS and PMMA self-assemble on a suitable substrate. The PMMA is removed and the PS is oxidized. A surface modification polymer (SMP) is deposited on the oxidized PS and the exposed substrate and the SMP not bound to the substrate is removed. The structure is placed in an atomic layer deposition chamber. Alumina precursors reactive with the oxidized PS are introduced and infuse by SIS into the oxidized PS, thereby forming on the substrate a chemical contrast pattern of SMP and alumina. The resulting chemical contrast pattern can be used for lithographic masks, for example to etch the underlying substrate to make an imprint template.