Directed Self-Assembly of Block Copolymer for Bit Patterned Media with Areal Density of 1.5 Teradot/Inch2 and Beyond
Figure 4
(a) Schematic representation of directed self-assembly of sphere-forming PS-b-PDMS thin films by a 2D low-topographic holes array resist prepattern with . (A) 2D low-topographic holes array resist prepattern is created using imprint lithography at a low-density, (B) trim the imprint resist thickness down to 2-3 nm by O2 RIE, and (C) spin coat and DSA of BCP thin film. (b) Large-scale SEM image of imprint resist pattern (hcp) with a prepattern pitch (0.375 Td/in2). The insets show that the trimmed resist thickness from the initial thickness of approximately 30 nm (left zoom-in image) down to 2~3 nm (right zoom-in image and AFM height measurement). (c) Large-scale SEM image of PS-b-PDMS BCP pattern (hcp) with an (1.5 Td/in2). The insets are a magnified SEM image of BCP pattern and a 2D FFT graph.
