Flow-Induced Microdomain Alignment During Block Copolymer Graphoepitaxy

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Science

Background:

• Block copolymer (BCP) graphoepitaxy is a key nanofabrication technique relying on self-assembly.
• The influence of substrate topography on polymer flow and resulting microdomain patterns in BCP graphoepitaxy is not fully understood.

Purpose of the Study:

• To investigate the polymer flow dynamics during solvent vapor annealing in BCP graphoepitaxy.
• To elucidate the relationship between flow processes, film thickness, and microdomain orientation relative to substrate topography.

Main Methods:

• Analysis of film thickness profiles over time during solvent vapor annealing.
• Characterization of microdomain morphologies and their orientation within etched trenches.
• Correlation of flow timescales (capillary flow, dewetting) with observed microdomain alignment.

Main Results:

• Capillary flow rapidly planarizes the BCP film to an incommensurate thickness within the first minute of annealing.
• Dewetting occurs via island and hole formation, with extension direction (isotropic or anisotropic) dependent on film thickness.
• Isotropic dewetting leads to microdomains transverse to trench sidewalls; anisotropic dewetting promotes alignment parallel to sidewalls.

Conclusions:

• Polymer flow, specifically capillary flow and dewetting, significantly dictates the in-plane orientation of BCP microdomains.
• Film thickness and trench topography are critical factors controlling dewetting behavior and subsequent microdomain alignment.
• This work provides fundamental principles for controlling BCP microdomain orientation in graphoepitaxy for advanced nanofabrication.