DSA Guide Patterns with SDRAF for Contact Hole Fidelity
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Solution Overview
Problem
Existing manufacturing flows for directed self-assembly (DSA) in semiconductor fabrication are not fully optimized, particularly in terms of guide pattern shapes and sizes, and the use of sub-resolution assistant features (SRAF) has not been optimized for the DSA process, leading to challenges in forming small, periodic patterns like contact holes or via holes in integrated circuits.
Innovation Solution
The implementation of DSA-aware guide patterns with irregular shapes and connected by sub-DSA resolution assistant features (SDRAF), where the shape and size of guide patterns are determined through an iterative process considering the characteristics of the DSA process, including block copolymer properties, to enhance pattern fidelity and process window during photolithography and self-assembly processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography is used to form small periodic patterns, then existing fabrication processes can be maintained, but manufacturing precision deteriorates due to continuously shrinking feature size limits
Solution Approach 1:
The block copolymer system performs self-assembly to form the periodic patterns automatically based on its intrinsic micelle formation properties. The guide pattern serves only as a template, while the actual pattern formation is driven by the self-organizing behavior of the block copolymer chains during annealing, eliminating the need for direct lithographic patterning at the nanoscale
Solution Approach 2:
The guide pattern acts as an intermediary between the lithography process and the final self-assembled pattern. It provides a structured template that guides the block copolymer self-assembly, enabling the transfer of larger lithographic features into smaller, more densely packed final patterns through the mediating role of the guide structure
2Manufacturing precision
If guide patterns use conventional shapes and sizes, then existing design rules are maintained, but pattern fidelity deteriorates because shapes are not optimized for the DSA process
Solution Approach 1:
The guide pattern dimensions, shapes, and spacing parameters are specifically optimized for the block copolymer self-assembly process. By adjusting these parameters to match the characteristic micelle spacing and size of the block copolymer system, the guide pattern enables faithful reproduction of the desired periodic patterns with high precision
Solution Approach 2:
The guide pattern incorporates irregular shapes rather than conventional symmetric geometries. This asymmetry allows for optimization of the self-assembly process by creating non-uniform spacing and configuration that better matches the intrinsic ordering tendencies of the block copolymer micelles, thereby improving pattern fidelity
3Manufacturing precision
If sub-resolution assistant features are not used, then photolithography process is simpler, but pattern uniformity deteriorates for small periodic patterns
Solution Approach 1:
The sub-DSA resolution assistant features act as intermediary elements that mediate between the guide pattern and the block copolymer self-assembly process. These features provide additional structural guidance and spacing control that enhances the uniformity of the self-assembled patterns, particularly in regions where the guide pattern alone would be insufficient
Solution Approach 2:
The guide pattern is segmented into distinct functional regions including the primary guide features and the sub-DSA resolution assistant features. This segmentation allows each component to perform its specific function independently, with the assistant features providing localized support for pattern uniformity without interfering with the overall self-assembly process
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 improves pattern fidelity and uniformity, increasing the process window for forming small, periodic patterns, such as contact holes, by allowing guide patterns to have irregular shapes and connecting them with SDRAF, thereby enhancing the precision and stability of DSA processes in semiconductor manufacturing.
Implementation Method 1
directed self-assembly (DSA) has been proven as a promising candidate to generate periodic patterns
Implementation Method 2
a block copolymer is deposited into the guide pattern and annealed to form polymeric cylinders
Implementation Method 3
a guide pattern (also called a template) is formed over a wafer by a lithography process
Data Source
AI summary
A method includes receiving a first target pattern of an integrated circuit (IC) that includes two first target features and two second target features. The method further includes deriving a second target pattern based on the first target pattern and a directed self-assembly (DSA) process, wherein the first target pattern is to be produced by a process that includes performing the DSA process with a guide pattern derived from the second target pattern. The second target pattern includes a third feature and a fourth feature. The third feature is designed for producing the two first target features with the DSA process, and the fourth feature is designed for producing the two second target features with the DSA process. The method further includes inserting one or more sub-DSA-resolution assistant features (SDRAF) into the second target pattern, the one or more SDRAF connecting the third and fourth features.