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Toward Lateral Length Standards at the Nanoscale Based on Diblock Copolymers
Giulia Aprile1,2, Federico Ferrarese Lupi1,3, Matteo Fretto1
1Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.
ACS Applied Materials & Interfaces
|April 12, 2017
Summary
Self-assembly of diblock copolymers in confined trenches offers a new method for creating nanometer-scale patterns. This technique enables the development of novel transfer standards for nanometrology, crucial for advancing device fabrication.
Area of Science:
- Materials Science
- Nanotechnology
- Metrology
Background:
- Self-assembly of diblock copolymers (DBCs) is a key technique for nanofabrication.
- Integrating top-down and bottom-up approaches addresses the need for nanostructured lateral length standards.
- Miniaturization in device fabrication requires precise nanometrology tools.
Purpose of the Study:
- Investigate the pattern characteristics of cylinder-forming polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymers confined in periodic SiO2 trenches.
- Compare confined structures with those on flat surfaces to understand dimensional changes.
- Explore the potential for creating a diblock copolymer-based transfer standard for lateral length calibration.
Main Methods:
- Studied cylinder-forming PS-b-PMMA (54 kg mol-1, 70% styrene) diblock copolymers.
- Confined self-assembly within periodic SiO2 trenches of varying widths (75-600 nm).
- Analyzed pattern dimensions (center-to-center distance L0 and diameter D) using atomic force microscopy (AFM).
Main Results:
- PMMA cylinder diameter (D) decreased with trench width (W) due to deformation.
- Center-to-center distance parallel to trenches (L0l) remained constant.
- Center-to-center distance perpendicular to trenches (L0w) varied with W, allowing fine-tuning.
- A prototype transfer standard calibrated an AFM's linear correction factor with 1.3% relative standard uncertainty.
Conclusions:
- Confined self-assembly of DBCs allows precise control over nanostructure dimensions.
- Tunable lateral dimensions (L0w) in confined structures are suitable for developing new lateral length standards.
- DBC-based standards can address the lack of calibration tools in the 20-50 nm range.
- AFM calibration using these standards demonstrates high accuracy and reveals significant nonlinear corrections.