Block Copolymer Nanostructure Etching via Organic Solvent
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Solution Overview
Problem
Current methods for forming fine patterns using phase-separated block copolymers face challenges in achieving sufficient etching resistance and precise control over nanostructure formation, particularly due to surface disintegration during liquid etching and the need for expensive vacuum equipment in dry etching.
Innovation Solution
A method involving phase separation of a block copolymer on a substrate, followed by selective removal using a developing solution with an organic solvent having a specific solubility parameter and vapor pressure, and the inclusion of metal alkoxide to enhance etching resistance, allowing for precise control over nanostructure formation and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is used to selectively remove a specific block region of a block copolymer, then selective removal is achieved by using the difference in decomposition rate, but the surface of the block region with slower decomposition rate is also decomposed and removed, making it hard to accurately reflect the nano phase separated structure in the obtained nano pattern
Solution Approach 1:
The patent introduces a specific organic solvent as an intermediary medium between the block copolymer and the etching process. The solvent selectively dissolves the decomposed block regions while protecting the intact regions, enabling accurate transfer of the nano phase separated structure to the final pattern without unwanted surface decomposition
Solution Approach 2:
The patent changes the parameter of the developing solution from aqueous to organic solvent with specific solubility parameters. This parameter change enables selective dissolution of decomposed polymer blocks while maintaining the integrity of the nano structure, thereby achieving accurate pattern reflection
2Reliability
If dry etching is used for selective removal, then selective decomposition is achieved, but expensive vacuum equipment is required and sequential process is difficult to realize
Solution Approach 1:
The patent replaces the mechanical vacuum system with a chemical solution-based process. Instead of using vacuum environments and reactive gases, the invention uses liquid organic developing solutions to achieve selective removal, eliminating the need for expensive vacuum equipment while maintaining selective removal capability
Solution Approach 2:
The patent transitions from gas-phase (pneumatic) dry etching to liquid-phase (hydraulic) wet etching. By using liquid developing solutions, the process becomes simpler, allows sequential operations, and eliminates vacuum requirements while preserving the ability to selectively remove specific block regions
3Manufacturing precision
If aqueous developing solution is used for liquid etching, then selective dissolution of decomposed blocks is achieved, but the high surface tension of water causes disintegration of the nano structure during manipulation and drying
Solution Approach 1:
The patent changes the key parameter of the developing solution from water-based to organic solvent-based. This changes the surface tension characteristics from high (water) to low (organic solvent), preventing nano structure disintegration during manipulation and drying while maintaining selective dissolution capability
Solution Approach 2:
The patent discards the conventional aqueous developing solution approach and recovers/adopts organic solvents with appropriate solubility parameters. This substitution resolves the surface tension issue that causes nano structure disintegration while preserving the selective dissolution function
4Manufacturing precision
If phase separation of block copolymer is used to form nano structure as mask, then fine pattern formation is enabled, but it is difficult to select a material that provides both sufficient phase separation and sufficient etching resistance
Solution Approach 1:
The patent changes the parameter of the developing solution from aqueous to organic solvent with specific solubility parameters (SP value 7.5-11.5 cal/cm³)¹/². This parameter change enables the use of block copolymers that provide good phase separation, as the organic solvent selectively dissolves the decomposed blocks without requiring the blocks to have extreme solubility differences, thus expanding material selection flexibility
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 method enables the formation of fine patterns with sufficient etching resistance and surface uniformity, reducing equipment costs and preventing pattern disintegration, while allowing for precise control over nanostructure size and shape.
Implementation Method 1
a phase separation step in which a layer containing a block copolymer having a plurality of blocks bonded is formed on a substrate, and then the layer is heated for phase separation of the layer
Implementation Method 2
a method has been disclosed in which a fine pattern is formed using a phase-separated structure formed by self-assembly of a block copolymer having mutually incompatible blocks bonded together
Implementation Method 3
a selective removal step in which the layer is immersed in a developing solution to selectively remove a phase containing blocks decomposed in the decomposition step to form a nano structure
Implementation Method 4
a main component of the aforementioned developing solution is an organic solvent having an SP value of 7.5 to 11.5(cal/cm3)1/2, and having vapor pressure of less than 2.1 kPa at 25° C.
Data Source
AI summary
A method of forming a fine pattern, including: a phase separation step in which a layer containing a block copolymer having a plurality of blocks bonded is formed on a substrate, and then the layer is heated for phase separation of the layer; a decomposition step in which at least a portion of a phase of at least one block of the plurality of blocks constituting the block copolymer is decomposed; a selective removal step in which the layer is immersed in a developing solution to selectively remove a phase containing decomposed blocks to form a nano structure; and an etching step in which the substrate is subjected to etching by using the nano structure as a mask; and a main component of the developing solution is an organic solvent having an SP value of 7.5 to 11.5 (cal/cm3)1/2, and having vapor pressure of less than 2.1 kPa at 25° C., or is benzene that may be substituted by an alkyl group, an alkoxy group, or a halogen atom, and the developing solution further contains metal alkoxide.