Direct top-down ordering of diblock copolymers through nanoimprint lithography
SEM images of 200 nm wide PS-b-PMMA BCP lines formed by nanoimprinting (15 min imprint) and thermally annealed afterward (18 h at 170 °C). (a) General morphology after thermal annealing and (b) corresponding cross-section schematic. The nonuniform bright areas correspond to the polymer-dewetted silicon wafer surface, whereas the gray areas correspond to the PS matrix, except the small top lines being the PMMA lines. (c) Defective area due to an uncontrolled polymer reflow (c, areas A and B).
Image of a 8 in. diameter silicon wafer with a BCP layer imprinted for 15 h at 170 °C.
(a) SEM image of 1 μm large squares obtained by NIL (15 h imprint at 170 °C) on an initially 45 nm thick BCP layer without a complete filling of the mold. (b) SEM image of a 1 μm wide 35 nm thick BCP line obtained by NIL without a complete filling of the mold. Inset of (b): corresponding cross-section schematic. On both images, the light gray area corresponds to the pressed BCP residual layer, whereas the dark gray areas are square or line protrusions.
SEM images of BCP self-assembled layer obtained (left) under an antisticking treated mold (15 h imprint at 170 °C) and (right) in an oven (noncontact 18 h annealing at 170 °C).
SEM image of a 1 μm large square obtained by NIL in a lamellar BCP layer: (a) before and (b) after a 17 s Ar/O2 plasma etching step. The light gray area corresponds to the pressed BCP residual layer, whereas the dark gray area is the square protrusion. At the bottom: corresponding cross-section schematics.
SEM images of 1 μm wide, 105 nm thick polymer ridges formed by NIL in a cylindrical BCP layer. The light gray area corresponds to the BCP residual layer, measured to be ∼20 nm, and the dark gray area corresponds to the polymer ridges.
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