Lamellar Orientation of a Block Copolymer via an Electron-Beam Induced Polarity Switch in a Nitrophenyl Self-Assembled Monolayer or Si Etching Treatments

Abstract

Directed self-assembly (DSA) was investigated on self-assembled monolayers (SAMs) chemically modified by electron beam (EB) irradiation, which is composed of 6-(4-nitrophenoxy) hexane-1-thiol (NPHT). Irradiating a NPHT by EB could successfully induce the orientation and selective patterning of block copolymer domains. We clarified that spatially-selective lamellar orientations of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) could be achieved by a change of an underlying SAM. The change of an underlying SAM is composed of the transition of an NO2 group to an NH2 group, which is induced by EB. The modification in the polarity of different regions of the SAM with EB lithography controlled the lamellar orientation of PS-b-PMMA. The reduction of the NPHT SAM plays an important role in the orientation of block copolymer. This method might significantly simplify block copolymer DSA processes when it is compared to the conventional DSA process. By investigating the lamellae orientation with EB, it is clarified that only suitable annealing temperatures and irradiation doses lead to the vertical orientation. We also fabricated pre-patterned Si substrates by EB lithographic patterning and reactive ion etching (RIE). DSA onto such pre-patterned Si substrates was proven to be successful for subdivision of the lithographic patterns into line and space patterns.

Spatial Control of the Self-assembled Block Copolymer Domain Orientation and Alignment on Photopatterned Surfaces

“…Furthermore, pattern transfer blocking can be achieved in a single photolithographic exposure without involving additional processes. This similar concept of using directly patternable orientation layers was previously demonstrated with patterns created by photolithography, 48,50,52 electron beam, 45,53 and X-ray exposures, 54 but successful DSA of silicon-containing BCPs using photopatternable surface treatments has not yet been demonstrated. pGSTs, however, require aminopropyltriethoxysilane (APTES)-treated surfaces in order to be grafted to the substrate.…”

Quantum Beams Applying to Innovative Industrial Materials

“…(2) In addition to polymer-based materials, there are several reports on advanced ion beam technology, such as the single event effects of heavy ion beams to semiconductor devices [5], the radiation-induced modification of lattice structures and mechanical properties of metallic materials [6], and the novel preparation of nanostructured catalysts for energy devices [7,8]. (3) In the fields of nanotechnology and microfabrication processes, it was reported that low dimensional functional organic matters were created using single charged particle-induced chemical reactions in nanospace [9] and oriented lamellae of self-assembled block copolymers were designed with a single nanoscale using EB for future lithographic materials [10]. (4) Regarding novel application of quantum beam technology, this Special Issue provides the recent progress of phase imaging using synchrotron X-rays and pulsed neutron beams [11] and ultrafast electron diffractometers with relativistic electron pulses for the investigation of ultrafast structural dynamics [12].…”