Underlayer Composition for Lithographic Patterning of Block Copolymers
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Solution Overview
Problem
Current methods for forming patterns using block copolymers lack the ability to lithographically adjust the surface polarity of polymer brushes, limiting the formation of patterned surfaces for self-assembling layers.
Innovation Solution
A method involving a photosensitive layer with a photoacid generator is used to diffuse acid into an underlayer containing an acid-sensitive copolymer, creating a patterned surface by decomposing acid-decomposable groups, which then aligns with a self-assembling block copolymer layer to form phase-separated domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a polymer brush underlayer is used to provide a neutral or patterned surface for block copolymer self-assembly, then the surface can support pattern formation, but the surface polarity cannot be lithographically adjusted
Solution Approach 1:
The patent applies parameter changes by incorporating acid-labile groups into the polymer brush underlayer composition. When acid is introduced through photolithography, these groups decompose to change the surface polarity parameter, enabling lithographic patterning of the underlayer surface without requiring a completely different underlayer structure.
Solution Approach 2:
The patent uses an intermediary approach by introducing acid-labile functional groups as mediators between the photolithography process and the block copolymer self-assembly. These intermediary groups respond to acid from the photolithography step by decomposing and altering surface polarity, thereby translating the lithographic pattern into a chemically active surface pattern that guides block copolymer assembly.
2Ease of manufacture
If end-group functionalization or reactive-group containing monomers are incorporated to provide functional sites for grafting, then grafting capability is improved, but the ability to create patterned surfaces lithographically is not achieved
Solution Approach 1:
The patent changes the chemical parameter of the underlayer by incorporating acid-labile groups that can be selectively decomposed. This allows the functional groups to be present throughout the underlayer (providing grafting capability) while enabling spatially selective activation through acid exposure, achieving both ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent applies preliminary action by pre-incorporating acid-labile functional groups into the polymer brush underlayer during its formation. This preliminary preparation enables subsequent lithographic patterning to work effectively, as the functional groups are already in place and ready to respond to acid exposure with selective decomposition and polarity change.
3Manufacturing precision
If a photosensitive layer with photoacid generator is used to diffuse acid into the underlayer, then patterned surface formation is enabled, but additional process steps are required
Solution Approach 1:
The patent applies universality by designing the polymer brush underlayer to serve multiple functions: it provides the neutral surface for block copolymer self-assembly, contains latent acid-labile functional groups for future patterning, and enables lithographic pattern transfer. This multi-functionality reduces the need for separate dedicated components or processes.
Solution Approach 2:
The patent implements self-service through the self-assembling block copolymer layer, which automatically organizes itself on the patterned underlayer surface based on the polarity patterns created by acid diffusion. The block copolymer performs its own patterning function by responding to the chemical gradients in the underlayer, eliminating the need for additional complex patterning equipment.
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 allows for the formation of precise, patterned surfaces that enable efficient self-assembly of block copolymers, overcoming the limitations of existing technologies by creating aligned domains with controlled surface energies and polarities.
Implementation Method 1
diffusing an acid, generated in a photosensitive layer comprising a photoacid generator, by irradiating a portion of the photosensitive layer
Implementation Method 2
the acid sensitive group of the acid sensitive copolymer in the underlayer reacts with the diffused acid to form a polar region at the surface of the underlayer
Implementation Method 3
forming a self-assembling layer on the surface of the underlayer, the self-assembling layer comprising a block copolymer having a first block with an affinity for the polar region, and a second block having less affinity for the polar region than the first block
Implementation Method 4
diffusing comprises heating the underlayer and photosensitive layer
Data Source
AI summary
A method of forming a pattern comprises diffusing an acid formed by irradiating a portion of a photosensitive layer, into an underlayer comprising an acid sensitive copolymer having acid decomposable groups and attachment groups covalently bonded to the surface of the substrate and/or forming an interpolymer crosslink. Diffusing comprises heating the underlayer and photosensitive layer. The acid sensitive group reacts with the diffused acid to form a polar region on the underlayer, with the shape of the pattern. The photosensitive layer is removed, forming a self-assembling layer comprising a block copolymer having a first block with an affinity for the polar region, and a second block having less affinity for the polar region. The first block forms a domain aligned to the polar region, and the second block forms another domain aligned to the first. Removing either domain exposes a portion of the underlayer.