Block Copolymer Planarization for Uniform Pattern Transfer
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Solution Overview
Problem
Current directed self-assembly techniques of block copolymers for pattern formation on substrates face challenges due to variations in copolymer layer thickness, leading to inconsistent pattern performance across different substrate areas, especially in areas with varying guide pattern densities, resulting in defects such as increased critical dimension or missing patterns.
Innovation Solution
A method involving the formation of an assembly guide with varying opening rates on the substrate, followed by depositing a block copolymer layer that completely fills the guide and undergoes planarization to achieve uniform thickness, allowing for uniform thinning and subsequent pattern transfer, independent of guide pattern configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If block copolymer layer is deposited by spin coating to fill guide patterns, then the copolymer layer thickness varies with guide pattern density and area, but this leads to inconsistent pattern transfer performance and defects in areas with varying guide pattern densities
Solution Approach 1:
The patent applies preliminary planarization action by depositing an additional copolymer layer over the entire substrate surface after the initial spin coating step. This additional layer compensates for thickness variations in the guide pattern areas, ensuring uniform final thickness across the substrate regardless of local guide pattern density variations.
Solution Approach 2:
The patent implements local quality by allowing different regions of the substrate to have different guide pattern densities while maintaining uniform copolymer layer thickness through the two-step deposition process. The first step adapts to local guide pattern characteristics, while the second step provides uniform compensation across all regions.
2Adaptability or versatility
If guide patterns are formed with varying opening rates to accommodate different pattern densities, then the copolymer layer thickness becomes dependent on guide pattern configuration, but this causes critical dimension variations and missing patterns
Solution Approach 1:
The patent changes the parameter of copolymer layer thickness by implementing a two-step deposition process. The first step deposits copolymer that fills guide patterns with thickness varying according to local opening rates, while the second step adds a uniform layer that compensates for these variations, transforming the final thickness parameter to be uniform across the substrate.
3Ease of manufacture
If spin coating is used to deposit copolymer layer, then the process is simple and widely applicable, but the layer thickness is highly sensitive to guide pattern density and area variations
Solution Approach 1:
The patent merges two spin coating deposition steps into a single process flow. The first spin coating step deposits copolymer that fills guide patterns with thickness dependent on local geometry, and the second spin coating step deposits an additional uniform layer, combining both actions to achieve thickness uniformity while maintaining the simplicity of spin coating methodology.
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 ensures consistent pattern performance and transfer across the substrate, regardless of guide pattern density, by maintaining organized copolymer layers of uniform thickness, reducing defects and achieving precise pattern formation.
Implementation Method 1
When sufficient mobility is given to the chains, for example by heating these block copolymers, chain A and chain B tend to separate into phases or blocks and to reorganize themselves under specific conformations
Implementation Method 2
The guide patterns are conventionally formed by photolithography in a layer of resin
Data Source
Figure 1A~1C
Figure 1D~1G
Figure 2~3B
AI summary
The invention relates to a method for creating patterns on the surface of a substrate (2) by self-assembly of block copolymer, comprising the following steps: - forming an assembly guide (1) on first and second zones (20a, 20b) of the substrate, the assembly guide having, with respect to a reference surface (1a), openings with an opening ratio in the first zone (20a) greater than that of the second zone (20b); - depositing a layer of block copolymer (4) on the substrate (2), such that the layer of block copolymer (4) completely fills the assembly guide (1) and forms an overthickness on the reference surface (1a); - assembling (F4) the block copolymer, resulting in an organized portion (4a) of the block copolymer layer inside the openings of the assembly guide (1);- uniformly thin the block copolymer layer (4), until it reaches a thickness corresponding to the organized portion (4a) of the block copolymer layer; - eliminate one of the phases of the assembled block copolymer, resulting in a plurality of initial motifs extending into the block copolymer layer; and - transfer the initial motifs from the block copolymer layer into the substrate (2) to form said final motifs.