Stress-Induced Directed Self-Assembly of Perpendicularly Oriented Block Copolymer Lamellae for Lithographic Density...

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Science

Background:

• Block copolymer (BCP) thin films are crucial for nanopatterning.
• Achieving controlled orientation of BCP lamellae is challenging.
• Existing methods often lack efficiency or scalability.

Purpose of the Study:

• To develop a stress-induced directed self-assembly (DSA) approach for producing unidirectionally oriented perpendicular lamellae in BCP thin films.
• To achieve smaller line widths and higher aspect ratios for pattern transfer.
• To enhance lithographic density multiplication.

Main Methods:

• Utilized a free-standing polystyrene-block-polydimethylsiloxane (PS-b-PDMS) thin film on a TEM grid.
• Employed in situ, temperature-resolved TEM for thermal annealing under high vacuum.
• Applied finite element analysis to understand stress distribution.
• Transferred BCP films to substrates with trenches for nanopatterning followed by O2 reactive ion etching.

Main Results:

• Demonstrated stress-induced DSA for unidirectionally oriented perpendicular lamellae.
• High vacuum annealing created neutral surfaces, facilitating self-alignment.
• Tensile stress gradient at the grid edge induced edge-parallel lamellae alignment.
• Successfully fabricated well-defined SiO2 line patterns within trenches.

Conclusions:

• The integrated method combines vacuum-driven perpendicular orientation and stress-induced DSA for controlled BCP film orientation.
• This facile approach offers significant potential for fabricating highly ordered line patterns in advanced lithographic applications.
• The technique enables precise control over lamellar orientation, improving pattern transfer fidelity and density.