Styrenic Polymer Pinning Layers for Block Copolymer Self-Assembly
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Solution Overview
Problem
Current methods in chemoepitaxy face challenges in forming uniform and dense pinning layers on substrates like Si or SiO2 for directed self-assembly of block copolymers, which affects the perpendicular orientation of domains and leads to defects during pattern transfer in microelectronic device fabrication.
Innovation Solution
Development of novel styrenic polymers with a benzylic alcohol end group and low polydispersity, which form dense and uniform grafted layers when coated with a solvent, acting as effective pinning layers in conjunction with neutral layers to facilitate perpendicular orientation of block copolymer domains during self-assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional brush precursors are used to form pinning layers on substrates, then the substrate can be treated for directed self-assembly, but the pinning layers are not uniform and dense enough, leading to defects during pattern transfer
Solution Approach 1:
The patent modifies the chemical structure of the brush precursor by incorporating specific end groups (carboxyl, hydroxyl, or amine groups) and controlling polydispersity index (PDI) within 1.05-1.30. These parameter changes enable the formation of uniform and dense pinning layers on substrates like Si or SiO2, resolving the issue of defects during pattern transfer while maintaining the directed self-assembly functionality.
Solution Approach 2:
The invention uses composite brush precursor structures combining poly(styrene-co-methacrylate) or poly(ethylene oxide-co-ethylene propylene) main chains with specific end groups (carboxyl, hydroxyl, or amine). This composite approach creates pinning layers with enhanced uniformity and density, eliminating defects during pattern transfer while preserving the substrate's directed self-assembly capabilities.
2Measurement precision
If block copolymers are used for directed self-assembly to achieve high resolution patterns, then pattern resolution is enhanced, but the formation of uniform pinning layers remains challenging
Solution Approach 1:
The patent optimizes the polydispersity index (PDI) of the brush precursor to within 1.05-1.30 and incorporates specific end groups (carboxyl, hydroxyl, or amine) to enhance the uniformity of pinning layer formation. These parameter changes enable consistent parallel lamellar orientation of block copolymer domains while maintaining high pattern resolution through directed self-assembly.
Solution Approach 2:
The invention applies local chemical modification by incorporating specific end groups (carboxyl, hydroxyl, or amine) at the terminal positions of the brush precursor chains. This local quality enhancement creates uniform interaction sites that guide consistent block copolymer orientation, achieving both high pattern resolution and uniform pinning layer formation.
3Ease of manufacture
If existing brush precursors are used, then the process is simple, but the pinning layers lack density and uniformity, affecting domain orientation
Solution Approach 1:
The patent maintains the simplicity of the coating process while improving pinning layer quality by changing the chemical parameters of the brush precursor - specifically incorporating end groups with carboxyl, hydroxyl, or amine functionality and controlling polydispersity within 1.05-1.30. These parameter changes achieve dense, uniform pinning layers that ensure consistent block copolymer domain orientation without complicating the manufacturing process.
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 novel styrenic polymer composition enables the creation of consistent, parallel lamellar formations over large areas, preventing defects and ensuring uniform etching rates, thereby enhancing the resolution and accuracy of pattern transfer in microelectronic devices.
Implementation Method 1
capable of forming dense and uniform grafted layers when coated with a solvent and baked
Implementation Method 2
Directed self-assembly of block copolymers is a method useful for generating smaller and smaller patterned features
Implementation Method 3
treating the coating after step b1) with an organic solvent to remove ungrafted polymer, leaving an insoluble grafted pinning layer
Data Source
Figure 1a~1d
Figure 2A~2B
AI summary
The present invention relates to a novel styrenic polymer and to the novel composition comprised of this polymer and a solvent; wherein the styrenic polymer has a polydispersity from 1 to 1.3 and further wherein each polymer chain of the styrenic polymer is capped with one end group of structure 1), wherein, and L1 is a linking group selected from the group consisting of a direct valence bond, oxy (-O-), carbonyloxy, (-(C=O)-O-), carbonate (-O-(C=O)-O-); L2 is a C-1 to C-20 substituted or unsubstituted alkylene spacer, an arylene spacer or a direct valence bond, R, is hydrogen, a halide, a C-1 to C-20 alkyl moiety, or a C-1 to C-20 alkyloxy moiety, m is an integer from 1 to 3; and represent the direct valence bond attaching the end group 1) to the end of the polymer chain of the styrenic polymer. In another aspect of this invention it pertains to the use of this composition to create a grafted film on a substrate, and in a further aspect this grafted film may be used in a directed self-assembly process.