Guided Via Patterning Over Metal Gratings Using DSA
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Solution Overview
Problem
The challenge in integrated circuit manufacturing is the precise control of overlay tolerances and critical dimensions of via openings as feature sizes and pitches continue to scale down, exceeding the resolution capabilities of lithographic equipment and leading to variability in line width roughness and critical dimension uniformity.
Innovation Solution
The use of directed self-assembly (DSA) with a diblock copolymer deposited over a guiding pattern to generate aligned hexagonal arrays of cylindrical structures, which are then used to form well-aligned vias, addressing the challenges of overlay tolerances and critical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lithographic equipment is used to pattern via openings, then manufacturing process is straightforward, but manufacturing precision deteriorates due to exceeding resolution capabilities and variability in line width roughness and critical dimension uniformity
Solution Approach 1:
The diblock copolymer system performs self-assembly to automatically form the via opening pattern without requiring complex lithographic equipment. The block copolymer spontaneously organizes into cylindrical domains through thermodynamic self-organization, eliminating the need for high-resolution lithography and achieving superior critical dimension uniformity through self-controlled patterning
Solution Approach 2:
The patent changes the physical and chemical parameters of the patterning system by using a diblock copolymer with specific block ratios (e.g., 70:30 or 80:20) and controlling annealing temperature and solvent conditions. These parameter changes enable the system to self-assemble into desired patterns with precise critical dimensions that cannot be achieved with conventional lithography
2Productivity
If feature sizes and pitches are scaled down to increase device density, then productivity increases, but manufacturing precision deteriorates due to overlay tolerance violations and variability in critical dimensions
Solution Approach 1:
The block copolymer system self-aligns to the guiding pattern through selective adhesion of different blocks to different regions of the grating structure. This self-alignment mechanism automatically ensures overlay tolerance compliance without requiring complex alignment equipment or processes, enabling high device density with maintained precision
Solution Approach 2:
The patent uses asymmetric block copolymer compositions (unequal block ratios) combined with a periodic guiding pattern to break symmetry and enable selective positioning. The asymmetric composition causes one block to preferentially adsorb to the guiding pattern while the other forms the via openings, achieving precise overlay control at scaled dimensions
3Manufacturing precision
If conventional lithography is used for via patterning, then process simplicity is maintained, but manufacturing precision deteriorates due to variability in line width roughness and critical dimension uniformity
Solution Approach 1:
The block copolymer system performs self-assembly to automatically form smooth, uniform via openings without requiring complex lithographic equipment or multiple processing steps. The spontaneous self-organization into cylindrical domains produces inherently smooth surfaces and uniform dimensions, improving line width roughness while maintaining reasonable process simplicity
Solution Approach 2:
The guiding pattern acts as an intermediary structure that directs the self-assembly of the block copolymer. The grating structure provides a template that mediates the formation of the via pattern, enabling precise control over line width and roughness while simplifying the overall manufacturing process by eliminating complex lithography
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 highly regular and well-aligned via arrays with precise control over pitch and diameter, improving overlay tolerances and reducing variability in critical dimensions, thus enhancing the manufacturing efficiency and accuracy of integrated circuits.
Implementation Method 1
a directed self-assembly (DSA) process is performed to generate an array of cylindrical structures
Data Source
AI summary
Described herein are IC devices include vias deposited in a regular array, e.g., a hexagonal array, and processes for depositing vias in a regular array. The process includes depositing a guiding pattern over a metal grating, depositing a diblock copolymer over the guiding pattern, and causing the diblock copolymer to self-assemble such one polymer forms an array of cylinders over metal portions of the metal grating. The polymer layer can be converted into a hard mask layer, with one hard mask material forming the cylinders, and a different hard mask material surrounding the cylinders. A cylinder can be selectively etched, and a via material deposited in the cylindrical hole to form a via.