AFM‐Based Hamaker Constant Determination with Blind Tip Reconstruction

Abstract

Particle contamination of extreme ultraviolet (EUV) photomasks is one of the numerous challenges in nanoscale semiconductor fabrication, since it can lead to systematic device failures when disturbed patterns are projected repeatedly onto wafers during EUV exposure.Understanding adhesion of particle contamination is key in devising a strategy for cleaning of photomasks. In this work, particle contamination is treated as a particle-plane problem in which surface roughness and the interacting materials have major influences. For this purpose, we perform vacuum atomic force microscopy (AFM) contact measurements to quantify the van der Waals (vdW) forces between tip and sample. We introduce this as a vacuum AFM-based methodology that combines numerical Hamaker theory and Blind Tip Reconstruction (BTR).We have determined the Hamaker constants of 15×10 -20 J and 13×10 -20 J for the material systems of a silicon (Si) tip with both aluminum oxide (Al2O3) and native silicon dioxide (SiO2) on Si substrates, respectively. Our methodology allows an alternative, quick and low-cost approach to characterize the Hamaker constant within the right order of magnitude for any material combination.

Evasion of opsonization of macromolecules using novel surface‐modification and biological‐camouflage‐mediated techniques for next‐generation drug delivery

“…36 Models developed in this domain, such as Hamaker model described the complete mechanistic approach involving the formation of the van der Waals bond in opsonization. 37 Higher ionic strength of I = 0.2 M hindered the bonding potential via hydrophobic interaction due to increase in surface charges at higher ionic strength (0.2 M) by reducing amount of adsorbed lysosome to 0.8 mg/m 2 . 40 3 | POLYMERS…”

“…The difference between measured volumes and actual volume was negligible, indicating van der Waals forces to be the mechanism for adsorption of micromolecular‐opsonins 36 . Models developed in this domain, such as Hamaker model described the complete mechanistic approach involving the formation of the van der Waals bond in opsonization 37 . Jeon et al performed studies on interaction of polyethylene oxide (PEO) hydrophobic solid nanoparticles with macromolecular‐proteins in water as a medium where diffusion of protein to PEO surface, proximity of protein and PEO leads to the formation of van der Waals bond stabilized by solvation effect of water.…”

Button shear testing for adhesion measurements of 2D materials

“…Although there are approaches to generally improve adhesion 8 , 9 , a quantitative and reliable method for measuring and evaluating the adhesion of 2D materials is lacking. Existing methodologies for measuring absolute adhesion energy values like blister tests 10 – 16 , nanoparticles 17 – 19 , and atomic force microscopy (AFM) 20 – 26 are predominantly rather time-consuming. A shearing technique for interlayer cleavage energy of graphite was proposed by Wang et al 27 .…”

Fast and high-resolution mapping of van der Waals forces of 2D materials interfaces with bimodal AFM

“…Several AFM-based methods have been developed to determine the Hamaker constant ( H ) of materials and interfaces. 9–30 Among them are quasistatic methods based on recording force–distance curves. In those methods, the Hamaker constant is deduced from the adhesion force value measured in the tip's approach or in the jump into contact discontinuity.…”