Random Copolymer Neutral Layer for Directed Self-Assembly
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Solution Overview
Problem
Current methods for forming a neutral layer in directed self-assembly pattern formation, such as using hydroxy terminated random copolymers or benzocyclobutene-based crosslinkable random copolymers, are inefficient due to long process times and high costs, which hinder the formation of high-quality, vertically oriented patterns in semiconductor and LCD processes.
Innovation Solution
A random copolymer with specific structural units, represented by Chemical Formulae 1 to 3, is used to form a neutral layer that reduces process time and costs by providing a high degree of crosslinking and stable vertical orientation of block copolymers, with a thickness variation value due to washing satisfying T0-T1/T0 < 0.08, ensuring the neutral layer is not adversely affected by follow-up processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydroxy terminated random copolymer is used to form neutral layer, then neutral layer formation is achieved, but process time is excessively long (about three days for heat treatment)
Solution Approach 1:
The patent changes the chemical composition parameters of the random copolymer by incorporating isocyanate groups (specifically 2-isocyanatoethyl methacrylate) at controlled ratios (1-20 mol%). This compositional parameter change enables the neutral layer to achieve sufficient crosslinking and stability with dramatically reduced heat treatment time (from 3 days to 2-30 minutes), while maintaining vertical orientation quality.
2Strength
If benzocyclobutene-based crosslinkable random copolymer is used to form neutral layer, then crosslinking is achieved, but synthesis process is complicated and costs are high
Solution Approach 1:
The patent replaces the complex benzocyclobutene-based copolymer with a simpler random copolymer containing isocyanate groups. This substitution uses more readily available monomers and simpler synthesis routes, reducing manufacturing complexity and cost while achieving comparable or superior crosslinking performance through the isocyanate functionality.
Solution Approach 2:
The patent creates a composite random copolymer structure combining multiple monomer units (styrene, methyl methacrylate, and 2-isocyanatoethyl methacrylate) in specific ratios. This composite approach allows tuning of both crosslinking density and neutral layer properties, achieving optimal performance with simplified synthesis compared to specialized crosslinkable polymers.
3Productivity
If heat treatment time is reduced to improve productivity, then process efficiency increases, but neutral layer stability may be compromised
Solution Approach 1:
The patent changes the chemical reactivity parameters of the neutral layer material by incorporating isocyanate groups that undergo rapid crosslinking reactions. This parameter change allows the system to achieve sufficient crosslinking density and stability in 2-30 minutes of heat treatment, enabling high productivity without compromising neutral layer stability during subsequent washing and processing steps.
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 random copolymer significantly reduces process time and costs while maintaining a high-quality, vertically oriented lamellar phase pattern formation, ensuring the neutral layer's stability and precision even with short-time heat treatment.
Implementation Method 1
A random copolymer for forming a neutral layer including structural units of Chemical Formulae 1 to 3... providing a high degree of crosslinking
Implementation Method 2
directed self-assembly pattern formation... self-aligning of a block copolymer (BCP)... rearranging, self-aligning or self-orienting the block copolymer
Data Source
AI summary
The present invention provides a random copolymer including structural units represented by the following Chemical Formulae 1 to 3for forming a neutral layer for significantly reducing process time and process costs, and promoting directed self-assembly pattern formation of a block copolymer. The present invention further provides a laminate for forming a pattern including a neutral layer having a small thickness variation value due to washing, by including the random copolymer for forming a neutral layer. The present invention further provides a method for forming a pattern capable of stably vertically orienting a block copolymer on a laminate for forming a neutralized pattern.