Block Copolymer Directed Self-Assembly via Selective Sidewall Grafting
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Solution Overview
Problem
Current methods for patterning vias and trenches in integrated circuits, such as grapho-epitaxy directed self-assembly of block copolymers, face challenges in achieving high resolution and cost-effectiveness, particularly in achieving a high grafting density on sidewalls while maintaining a non-preferential bottom surface for block copolymer blocks.
Innovation Solution
A method involving a substrate with concavities where a first grafting material with a high affinity for the sidewalls and a second grafting material with a neutral affinity for both blocks are used, allowing for selective grafting on the sidewalls and bottom, enabling high-resolution patterning of vias or trenches with reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polymer brush with higher grafting reactivity is used for the sidewall of a cylindrical hole, then a higher brush grafting density on the sidewall is achieved, but the ability to generate maximal brush grafting density at the sidewall while maintaining a non-preferential bottom is lost
Solution Approach 1:
The invention divides the surface modification into two separate grafting steps: first grafting the polymer brush selectively on the sidewall, then grafting a second layer on both sidewall and bottom. This segmentation allows independent control of grafting density and wetting properties at different locations, resolving the contradiction between achieving high sidewall grafting density and maintaining a non-preferential bottom.
Solution Approach 2:
The first grafting step performs preliminary modification of the sidewall with the polymer brush before the second grafting step modifies both sidewall and bottom. This preliminary action establishes the high grafting density on sidewalls while the subsequent step balances the bottom surface properties, enabling both maximal sidewall grafting and non-preferential bottom characteristics.
2Device complexity
If grapho-epitaxy DSA is used for patterning, then the number of masks is reduced compared to conventional multiple patterning, but achieving high resolution patterning with cost-effectiveness remains challenging
Solution Approach 1:
The invention creates different surface properties at different locations within the concavity: the sidewalls have high polymer brush grafting density while the bottom has non-preferential wetting. This local quality differentiation enables precise control of block copolymer self-assembly, achieving high resolution patterning that maintains cost-effectiveness by using only one mask in the grapho-epitaxy approach.
3Reliability
If selective surface modification is applied to achieve high grafting density on sidewalls, then the affinity for the majority block at the sidewall is improved, but maintaining a non-preferential bottom becomes difficult
Solution Approach 1:
The surface modification is segmented into two distinct grafting operations with different scopes: the first step targets only the sidewall to establish strong affinity for the majority block, while the second step targets both sidewall and bottom to balance the overall wetting properties. This segmentation resolves the contradiction between achieving reliable sidewall affinity and maintaining a non-preferential bottom.
Solution Approach 2:
The invention changes the grafting parameters between the two steps: the first step uses conditions optimized for high grafting density on sidewalls, while the second step uses conditions that achieve moderate grafting on both sidewall and bottom. This parameter change allows the system to achieve both high sidewall affinity and non-preferential bottom properties.
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 high-resolution patterning of vias or trenches with improved cost-effectiveness by achieving high grafting density on sidewalls and neutral wetting on the bottom, enhancing the patterning method's efficiency and reliability.
Implementation Method 1
grafting a first grafting material onto the sidewall, selectively with respect to the bottom, the first grafting material having a preferential wetting affinity for the first block with respect to the second block
Implementation Method 2
grafting a second grafting material onto the bottom and optionally onto the sidewall, the second grafting material having a preferential wetting affinity towards the first block with respect to the second block
Implementation Method 3
directing a self-assembly of a block copolymer comprising a first and a second block
Implementation Method 4
a BCP is deposited and allowed to phase separate before one of the blocks is removed
Implementation Method 5
the bottom having a preferential wetting affinity for the second block with respect to the first block
Data Source
AI summary
A method for directing a self-assembly of a block copolymer comprising a first and a second block is provided. The method including: providing a substrate comprising at least one concavity therein, the concavity comprising at least a sidewall and a bottom, the bottom having a preferential wetting affinity for the second block with respect to the first block; grafting a first grafting material onto the sidewall, selectively with respect to the bottom, the first grafting material having a preferential wetting affinity for the first block with respect to the second block; grafting a second grafting material onto the bottom and optionally onto the sidewall, the second grafting material having a preferential wetting affinity towards the first block with respect to the second block; and providing the block copolymer on the substrate, at least within the at least one concavity.