Vasiliki Kosma

Cornell University | CU · Department of Materials Science and Engineering

Considering the scenario that polymer-based resists will possibly be struggling to satisfy all performance criteria for high volume manufacturing imposed by high power sources and high-NA imaging, it seemed necessary to introduce new materials for EUV lithography. To that end, nanometer scale metal clusters, originally designed to be building units...

A new class of solvent free, lyotropic liquid crystal nanocomposites based on gold nanorods (AuNRs) with high nanorod content is reported. Application of shear results in switchable, highly ordered alignment of the nanorods over several centimeters with excellent storage stability for months. For the synthesis, AuNRs are surface functionalized with...

Water-glass, a low-cost silica precursor solution, is used to produce mostly skinned, polymer–silicate composite membranes with a porous bulk. We explore primarily Nylon 6-10/formic acid dopes where the polymer solvent is an acid, and polysulfone/DMF dope as an example of a polymer dope based on a non-acidic water-miscible solvent. Elemental distri...

With the rapid development of semiconductors, today's optical lithography is approaching its physical limits, and thus alternative patterning technology is urgently needed. Extreme ultraviolet (EUV) lithography, using a wavelength of 13.5 nm, is considered one of the most prominent candidates for next-generation lithography. The main challenge for...

Most advanced microelectronic devices are made by using 193 nm immersion lithography systems, but it is difficult to follow the rapid development of semiconductors due to their approaching physical limits. Extreme ultraviolet (EUV) lithography which uses a shorter wavelength (i.e., 13.5 nm) light source can offer a way to print features under a 20...

A prerequisite for good photoresists is high sensitivity, but unfortunately highly sensitive resists are usually accompanied by line roughness. Even if understanding what is causing roughness in resists were not completely in its infancy, we still have not achieved complete answers and effective solutions to these issues. Our group has been working...

We report the preparation of discrete nm-scale zinc-based clusters and use them to form sub-15 nm structures by means of extreme ultraviolet (EUV) lithography. By taking advantage of a metal-containing building unit derived by MOF-2, the 3-methyl-phenyl modified cluster Zn-mTA formed is well-defined with controlled size, structure and demonstrates...

Bitumen-clay nanocomposite binders with styrene-butadienestyrene triblock copolymer, SBS, and combinations of SBS and crumb rubber (CR) with different CR/SBS ratios have been synthesized and characterized. In addition to the binder, samples containing the binder and concrete sand (with a weight ratio 1:9) were prepared. The modified binders were st...

We present a focused review of photoresist strategies that have been studied over the past few decades driven by the demands of Moore’s law. Selected results are discussed with emphasis on the choice of photoresist chemistry depending on the particulars of each radiation type or patterning strategy, while we present special architectures of photore...

We report a series of studies aimed at shedding more light on the development mechanism of zirconium (Zr)-based extreme-UV hybrid photoresists. In earlier works, our group demonstrated that Zr-based hybrid resists are capable of resolving 30-nm half-pitch features with a very high sensitivity in the range of 1 to 20 mJ/cm2, which renders these mate...

EUV lithography is a promising candidate for the manufacturing of semiconductor devices for the 7 nm node and beyond. The success of any lithography depends on the availability of a suitable resist with high resolution, sensitivity and low LWR. Though polymer type CAR (chemically amplified resist) is the current standard photoresist, entirely new r...

Methacrylate based nanoparticle materials have been investigated for their negative-tone patterning with DUV (248nm, 254nm), e-beam and EUV lithography, and show promising EUV sensitivity and resolution. In order to further extend the application of this novel class of materials and understand more about the underlying mechanism, we continue to stu...

An organically functionalized titania, TiO2-RSO3H, was evaluated as filler in sulfonated polyetheretherketone (sPEEK)-based composite membranes for application in high temperature direct methanol fuel cells. The presence of propylsulfonic acid groups covalently bound onto the TiO2 surface and the nanometric nature of the additive were analyzed by R...

Extreme ultraviolet (EUV) lithography is a promising candidate for next generation lithography. For high volume manufacturing of semiconductor devices, significant improvement of resolution and sensitivity is required for successful implementation of EUV resists. Performance requirements for such resists demand the development of entirely new resis...

Sulfated titania nanoparticles were evaluated as inorganic additives in composite Nafion-based membranes, to be considered as advanced electrolyte in proton exchange membrane (PEM) fuel cells (FCs). Three different filler loadings respect to the polymer were comparatively investigated to elucidate the effect of the inorganic particles on membrane p...

Polybenzimidazole (PBI) - based membranes are one of the systems of choice for polymer electrolyte fuel cells. Monomer sulphonation is one of the strategies suggested to improve proton transport in these membranes. Here we report a NMR and dynamic mechanical study aiming to investigate the effect of the sulphonation on the proton dynamics and the m...

Composite membranes based on Nafion with the inclusion of cationic and anionic nanoclays, Laponite, and layered double hydroxide (LDH), respectively, were used to increase the operating temperature of a direct methanol fuel cell (DMFC). The electrochemical behavior of the hybrid nanocomposites was investigated in a single cell at different temperat...

Anatase TiO2 nanoparticles and graphene oxide flakes are incorporated as fillers into Nafion membranes and the photocatalytic properties of such nanocomposites are investigated. The study has been performed by measuring the degradation of methylene blue (MB) and methyl orange (MO) under UV/visible light illumination by absorbance measurements. We s...

Fibrous hydroxyapatite (HA)–carbon nanotube composites were synthesized by the catalytic decomposition of acetylene over Fe–Co bimetallic catalysts supported on the fibrous HA. Two forms of fibrous HA (distinct needle-like monocrystals and spherulitic aggregates of needles) were synthesized using a simple precipitation method and loaded with bimeta...

This work deals with the preparation of ceramic phases similar to those encountered in natural biocomposites through relatively fast and low-cost aqueous routes and various simple reactants and additives such as urea, commercial gelatin and hexamethyldiamine. In addition to the crystallographic (or amorphous) character of targeted phases (calcite,...

Macrovoids are defects that are frequently encountered in phase inversion as well as in other solution-cast membranes. Macrovoid formation continues to hold many surprises despite several decades of pertinent studies and frequent claims for definitive answers. We have discovered conditions leading to macrovoid growth parallel to a transparent membr...

A new approach based on photolithographic processes for the fabrication of conductive polymer chemical sensors is described. The process was successfully applied in polymer/carbon black composites of the negative tone EPR and PDMS, and allows for the exact positioning and patterning of the composite polymer over the electrodes. On the other hand, p...