Block Copolymer Cross-Linking for Lithography Placement Accuracy
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Solution Overview
Problem
Current lithography methods face challenges in achieving precise and predictable placement of self-assembled block copolymer domains within recesses, leading to random placement errors and defects, which limits the resolution and accuracy of nanostructures in semiconductor devices.
Innovation Solution
The method involves causing self-assemblable block copolymers to cross-link in a directional manner within lithography recesses, initiated at the side-walls and proceeding towards the center, using acid catalysts and photo-acid generators to control the placement of domains and reduce random movement, allowing for accurate positioning of lithography features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If self-assemblable block copolymers are used to form lithography features, then feature resolution is improved to smaller dimensions, but placement accuracy deteriorates due to random placement errors and defects
Solution Approach 1:
The patent applies preliminary action by forming a patterned resist layer with recesses before introducing the block copolymer. The resist pattern pre-defines the locations where lithography features should form, and the recesses confine the block copolymer to specific regions, ensuring accurate placement while maintaining small feature dimensions through self-assembly
Solution Approach 2:
The patent applies local quality by creating recesses with specific geometric configurations (varying depths, widths, and shapes) in different locations of the resist layer. These locally varied recess structures guide the block copolymer self-assembly to produce features with precise placement and controlled dimensions at each specific location, rather than using a uniform structure throughout
2Measurement precision
If conventional lithography methods are used, then placement accuracy is maintained, but feature resolution is limited by radiation wavelength and numerical aperture
Solution Approach 1:
The patent uses block copolymers as an intermediary material between the resist pattern and the final lithography features. The block copolymer self-assembles within the recesses to form domains at the nanoscale (below 10 nm), enabling feature resolution beyond the limits of direct lithography while the resist pattern serves as a template to maintain placement accuracy
Solution Approach 2:
The patent changes the dimensional parameters by using block copolymer self-assembly to create features with critical dimensions below 10 nm, which is smaller than what can be achieved by conventional lithography methods limited by radiation wavelength and numerical aperture. The recess geometry parameters (depth, width) are optimized to control the self-assembly process and achieve the desired feature size
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 enables the formation of lithography features with improved placement accuracy and reduced defects, achieving smaller feature sizes and higher resolution than conventional methods, with features such as contact holes having dimensions of about 40 nm or less.
Implementation Method 1
Self-assemblable BCPs are compounds useful in nanofabrication because they may undergo an order-disorder transition on cooling below a certain temperature (order-disorder transition temperature To/d) resulting in phase separation of copolymer blocks of different chemical nature to form ordered, chemically distinct domains
Implementation Method 2
causing the self-assemblable block copolymer to cross-link in a directional manner... using acid catalysts and photo-acid generators to control the placement of domains
Data Source
AI summary
A method of forming at least one lithography feature, the method including: providing at least one lithography recess on a substrate, the or each lithography recess having at least one side-wall and a base, with the at least one side-wall having a width between portions thereof; providing a self-assemblable block copolymer having first and second blocks in the or each lithography recess; causing the self-assemblable block copolymer to self-assemble into an ordered layer within the or each lithography recess, the ordered layer including at least a first domain of first blocks and a second domain of second blocks; causing the self-assemblable block copolymer to cross-link in a directional manner; and selectively removing the first domain to form lithography features of the second domain within the or each lithography recess.