advances.sciencemag.org/cgi/content/full/1/10/e1500751/DC1

Supplementary Materials for

Uniform metal nanostructures with long-range order via three-step

hierarchical self-assembly

Denise J. Erb, Kai Schlage, Ralf Röhlsberger

Published 6 November 2015, Sci. Adv. 1, e1500751 (2015)

DOI: 10.1126/sciadv.1500751

The PDF file includes:

Fig. S1. AFM micrographs illustrating the dependence of the degree of lateral

domain ordering on the ratio of diblock copolymer film thickness to substrate

facet height.

Fig. S2. Large-area AFM scans of highly ordered metal nanostructure patterns.

Fig. S3. Experimental data and simulations of GISAXS patterns for hexagonal Fe

nanodot array growing at room temperature.

Fig. S4. Experimental data and simulations of GISAXS patterns for hexagonal Fe

nanodot array growing at 170°C.

Table S1. Compositional properties of the diblock copolymers used.

Table S2. List of apparatus and duration of individual process steps. Discussion of

nanopattern yield.

Fig. S1. AFM micrographs illustrating the dependence of the degree of lateral domain

ordering on the ratio of diblock copolymer film thickness and substrate facet height.

If d/h is too low, the substrate facets deform the surface of the diblock copolymer film. If d/h is

too high, the guiding effect of the substrate topography and thus the long-range lateral domain

ordering in the copolymer film is lost. Insets show fast Fourier transformations of the height

information.

Fig. S2. Large-area AFM scans of highly ordered metal nanostructure patterns. Large-area

AFM micrographs of a) nanofaceted substrate surface and b) – d) Fe nanostructure patterns

grown on symmetric and asymmetric diblock copolymer templates. Long range lateral ordering

is induced by the substrate; the different nanostructure patterns illustrate some of the

morphological options and the scalability of the domain size of the diblock copolymer templates.

Fig. S3. Experimental data and simulations of GISAXS patterns for hexagonal Fe nanodot

array growing at room temperature. Sections in qy and qz direction through a sequence of

GISAXS patterns, recorded in-situ during Fe nanodot growth at room temperature, with

simulations (red solid lines). Labels indicate the elapsed Fe deposition time.

Fig. S4. Experimental data and simulations of GISAXS patterns for hexagonal Fe nanodot

array growing at 170C. Sections in qy and qz direction through a sequence of GISAXS

patterns, recorded in-situ during Fe nanodot growth at 170 °C, with simulations (red solid lines).

Labels indicate the elapsed Fe deposition time.

Reference

name

domain

morphology

total

molecular

mass

volume

fraction of PS

poly-

dispersity

equilibrium

domain

period D0

BCP-L lamellar 100 kg/mol 47 % 1.12 48 nm

BCP-C1 cylindrical 94 kg/mol 28 % 1.18 48 nm

BCP-C2 cylindrical 205 kg/mol 31 % 1.08 83 nm

Table S1. Compositional properties of the diblock copolymers used. All listed copolymers

are linear PS-b-PMMA diblock copolymers, commercially purchased from Polymer Source, Inc.

Apparatus

Purpose Duration of process step

ultrasonic acetone bath cleaning of α-Al2O3 substrates

(15 x 15 mm² or 20 x 20 mm²)

15 minutes

(up to four substrates in parallel)

chamber furnace

faceting of α-Al2O3 substrates by

high-temperature annealing in air

18 to 20 hours

(up to ten substrates in parallel)

scale, shaker preparation of copolymer solution

(3 ml per solution)

usually overnight, min. 3 hours

(up to four solutions in parallel)

spin coater preparation of copolymer thin

films

1 minute

(per film, no parallel processing)

oven drying of copolymer thin films at

50°C in air

2.5 hours

(up to ten samples in parallel)

screw cap glass, custom-

made sample holder

chemical microphase separation

by solvent vapor annealing

2 to 3 hours

(up to ten samples in parallel)

custom-made UHV

chamber

nanostructure growth by metal

deposition and selective diffusion

about 3 hours

(per sample of up to 20 x 20 mm²)

Table S2: List of apparatus and duration of individual process steps. Discussion of

nanopattern yield. α-Al2O3 substrates were commercially purchased (CrysTec GmbH) and cleaned in an ultrasonic

acetone bath at 50°C. They were then annealed in air in a chamber furnace (borel MO-1800)

with heating rates of 300K/h and passive cooling after annealing. To achieve the desired facet

dimensions, substrates were annealed at temperatures between 1300°C and 1400°C for 8 to 10

hours. Including heating and cooling, the annealing procedure thus took about 18 to 20 hours.

We prepared the substrates in batches of up to ten pieces (15 x 15 mm² or 20 x 20 mm²) and

stored them in large quantities for later use.

Solutions of PS-b-PMMA were prepared from commercially purchased PS-b-PMMA (Polymer

Source, Inc.) within 3 hours and can be stored for several months in a cool place protected from

exposure to UV radiation.

Depositing and processing the diblock copolymer thin films to obtain the chemically

nanopatterned templates is accomplished within about 6 hours. The templates, too, can be stored

for many months at ambient conditions without deterioration.

The stated duration for metal nanostructure growth is very specific for our custom-made UHV

chamber. It includes loading and evacuating the UHV chamber, heating the sample, interrupting

the deposition to cool down the sputtering source, the actual metal deposition (about 5 minutes

for Fe, duration varies for different materials), and venting the UHV chamber.

An explicit comparison of the patterning throughput of the proposed self-assembly method with

the throughput of state-of-the-art lithographical nanostructure fabrication is not instructive: We

present a laboratory-scale demonstration of a new routine, while some lithography-based

techniques were introduced decades ago and have meanwhile reached high degrees of up-scaling

and automation. Nevertheless, some quantitative values for process durations and patterned areas

in our specific case may give an impression of the efficiency of nanopatterning by hierarchical

self-assembly.

The possibility to store substrates, solutions, and templates, reduces the metal nanopattern

fabrication time to the time required for metal deposition – typically a few hours for our setup.

The nanostructure patterns presented here cover areas of 3 cm². This results in patterning rates of

about 1 cm² per hour. The sample size was chosen for ease of handling and accounted for the

dimensions of the available fabrication and characterization devices. Since the proposed routine

employs exclusively self-assembly processes, the samples can in principle be scaled up to much

larger sizes, achieving even larger patterning rates without increasing duration or complexity of

the preparation procedure. On a laboratory scale, sample sizes of about 10 x 10 cm² are

conceivable. In an industrial context, technical equipment optimized for high throughput, such as

automated spin coaters, large-volume furnaces, or inline sputtering systems would further

increase the patterning rate. Combining both approaches – increasing the sample size and

employing high-throughput fabrication devices – can result in an increase of the patterning rate

to the order of magnitude of 1000 cm² per hour or more.