Block Copolymer Graphoepitaxy for Sub-Lithographic Via Formation
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Solution Overview
Problem
Conventional optical lithography struggles to create vias with smaller critical dimensions and tighter pitches, and existing non-optical lithographic techniques are not yet viable for high-volume manufacturing, while block copolymer self-assembly lacks spatial registration and alignment control.
Innovation Solution
The use of block copolymer graphoepitaxy with substrates featuring convex, contoured sidewalls and protrusions to guide the self-assembly of block copolymers, allowing for precise control of domain placement and increased pattern density, compatible with conventional optical lithography tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithography is used to form vias, then manufacturing process is simple, but the critical dimension and pitch cannot be reduced below current limits
Solution Approach 1:
The patent segments the prepattern features into multiple smaller features with reduced dimensions. By dividing the original lithographic pattern into segmented components, the effective pitch and critical dimensions are reduced below the conventional lithography limits, enabling formation of smaller vias while maintaining compatibility with existing optical lithography tools
Solution Approach 2:
The patent transitions from direct 2D lithographic patterning to 3D self-assembled block copolymer structures. By utilizing the vertical dimension and self-assembly processes, the method achieves sub-lithographic resolution in the lateral dimension, forming vias with smaller critical dimensions than the original lithographic pattern would allow
2Manufacturing precision
If block copolymer self-assembly is used without guidance, then nanoscale features with smaller CDs can be formed, but spatial registration and alignment are lost
Solution Approach 1:
The patent introduces lithographically formed prepatterns as intermediary guiding structures. These prepatterns act as mediators between the substrate and the block copolymer self-assembly process, providing topographical cues that direct the spatial arrangement and registration of self-assembled features without eliminating the benefits of self-assembly
Solution Approach 2:
The patent applies different properties to different regions of the substrate through the prepattern structure. The prepatterned regions provide localized guidance for block copolymer assembly, creating areas with controlled spatial registration while maintaining self-assembled features in other regions, thus achieving both precision and ease of operation
3Manufacturing precision
If e-beam lithography is used for high resolution, then via placement precision is improved, but wafer throughput decreases
Solution Approach 1:
The patent employs self-assembled block copolymers that automatically organize into ordered structures without requiring direct-write lithographic techniques. This self-service mechanism provides high placement precision comparable to e-beam lithography while maintaining compatibility with high-volume manufacturing processes, thus preserving wafer throughput
Solution Approach 2:
The patent replaces the mechanical direct-write process of e-beam lithography with a chemical self-assembly process. By substituting the mechanical positioning system with thermodynamic self-organization of block copolymers, the method achieves similar precision outcomes without the throughput limitations of direct-write techniques
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 method enables the formation of arrays of holes with higher density and precise registration, suitable for semiconductor devices, overcoming the limitations of conventional lithography and self-assembly techniques.
Implementation Method 1
the blocks of such copolymers phase separate into microdomains (also known as 'microphase-separated domains' or 'domains') to reduce the total free energy
Implementation Method 2
One DSA technique is graphoepitaxy, in which self-assembly is guided by topographical features of lithographically pre-patterned substrates
Data Source
AI summary
An opening in a substrate is formed, e.g., using optical lithography, with the opening having sidewalls whose cross section is given by segments that are contoured and convex. The cross section of the opening may be given by overlapping circular regions, for example. The sidewalls adjoin at various points, where they define protrusions. A layer of polymer including a block copolymer is applied over the opening and the substrate, and allowed to self-assemble. Discrete, segregated domains form in the opening, which are removed to form holes, which can be transferred into the underlying substrate. The positions of these domains and their corresponding holes are directed to predetermined positions by the sidewalls and their associated protrusions. The distances separating these holes may be greater or less than what they would be if the block copolymer (and any additives) were to self-assemble in the absence of any sidewalls.