The next generation of hard disk drive technology for data storage densities beyond 5 Tb/in² will require single-bit patterning of features with sub-10 nm dimensions by nanoimprint lithography. To address this challenge master templates are fabricated using pattern multiplication with atomic layer deposition (ALD). Sub-10 nm lithography requires a solid understanding of materials and their interactions. In this work we study two important oxide materials, silicon dioxide and titanium dioxide, as the pattern spacer and look at their interactions with carbon, chromium and silicon dioxide. We found that thermal titanium dioxide ALD allows for the conformal deposition of a spacer layer without damaging the carbon mandrel and eliminates the surface modification due to the reactivity of the metal-organic precursor. Finally, using self-assembled block copolymer lithography and thermal titanium dioxide spacer fabrication, we demonstrate pattern doubling with 7.5 nm half-pitch spacer features.

Phonons can display both wave-like and particle-like behaviour during thermal transport. While thermal transport in silicon nanomeshes has been previously interpreted by phonon wave effects due to interference with periodic structures, as well as phonon particle effects including backscattering, the dominant mechanism responsible for thermal conductivity reductions below classical predictions still remains unclear. Here we isolate the wave-related coherence effects by comparing periodic and aperiodic nanomeshes, and quantify the backscattering effect by comparing variable-pitch nanomeshes. We measure identical (within 6% uncertainty) thermal conductivities for periodic and aperiodic nanomeshes of the same average pitch, and reduced thermal conductivities for nanomeshes with smaller pitches. Ray tracing simulations support the measurement results. We conclude phonon coherence is unimportant for thermal transport in silicon nanomeshes with periodicities of 100 nm and higher and temperatures above 14 K, and phonon backscattering, as manifested in the classical size effect, is responsible for the thermal conductivity reduction.

Plasmonic nanostructures serve as optical antennas for concentrating the energy of incoming light in localized hotspots close to their surface. By positioning nanoemitters in the antenna hotspots, energy transfer is enabled, leading to novel hybrid antenna-emitter-systems, where the antenna can be used to manipulate the optical properties of the nano-objects. The challenge remains how to precisely position emitters within the hotspots. We report a self-aligned process based on dry laser ablation of a calixarene that enables the attachment of molecules within the electromagnetic hotspots at the tips of gold nanocones. Within the laser focus, the ablation threshold is exceeded in nanoscale volumes, leading to selective access of the hotspot areas. A first indication of the site-selective functionalization process is given by attaching fluorescently labelled proteins to the nanocones. In a second example, Raman-active molecules are selectively attached only to nanocones that were previously exposed in the laser focus, which is verified by surface enhanced Raman spectroscopy. Enabling selective functionalization is an important prerequisite e.g. for preparing single photon sources for quantum optical technologies, or multiplexed Raman sensing platforms.

Previously, we demonstrated an all dry, selective laser ablation development in methyl acetoxy calixarene (MAC6) which produced high resolution (15-25 nm half-pitch), high aspect ratio features not achievable with wet development. In this paper, we investigate the selective laser ablation process as a means to create a block copolymer derived lithographic pattern through the selective removal of one block. Two block copolymer systems were investigated PS-b-PHOST, and P2VP-b-PS-b-P2VP. The selective laser ablations process on block copolymers offers an alternative to plasma etching when plasma etching is not effective.

New photoresists are needed to advance extreme ultraviolet (EUV) lithography. The tailored design of efficient photoresists is enabled by a fundamental understanding of EUV induced chemistry. Processes that occur in the resist film after absorption of an EUV photon are discussed, and a new approach to study these processes on a fundamental level is described. The processes of photoabsorption, electron emission, and molecular fragmentation were studied experimentally in the gas-phase on analogs of the monomer units employed in chemically amplified EUV resists. To demonstrate the dependence of the EUV absorption cross section on selective light harvesting substituents, halogenated methylphenols were characterized employing the following techniques. Photoelectron spectroscopy was utilized to investigate kinetic energies and yield of electrons emitted by a molecule. The emission of Auger electrons was detected following photoionization in the case of iodo-methylphenol. Mass-spectrometry was used to deduce the molecular fragmentation pathways following electron emission and atomic relaxation. To gain insight on the interaction of emitted electrons with neutral molecules in a condensed film, the fragmentation pattern of neutral gas-phase molecules, interacting with an electron beam, was studied and observed to be similar to EUV photon fragmentation. Below the ionization threshold, electrons were confirmed to dissociate iodo-methylphenol by resonant electron attachment.