Wetting of deep hydrophilic nanoholes by aqueous solutions

Ice-VII-like Structure Observed By XRD in Water Confined in Silica Nanoholes

“…The shape of the OH stretching peak after 2 hours exposure (grey curve) is given in Figure 2 in comparison with that for bulk water (dotted curve). The peak shape of the condensing water was similar to that of water wetting nanoholes (5). Particularly, the absorbance at 2800-3200 cm-1, which was absent in the peak of bulk water, indicated the presence of so-called structured water.…”

“…Nanoconfined water was characterized by the presence of H-bonds with a stronger vibration frequency as compared to ice. Using CO 2 as a probe molecule in ATR-FTIR measurements on nanoholes, it was also shown that nanoconfined water was characterized by a slower diffusivity and a lower permittivity compared to bulk water (5). Also, the decreased rate of a model surface reaction performed in nanotrenches of decreasing width correlated well with water structuring characterized by IR spectroscopy (11).…”

“…For example, there are nanoholes at the cross points of the gate and channel lines in the RMG module of FinFETs, supervias from M3 to M1 to achieve the required area scaling in the BEOL of the 3 nm node, and deep contact holes with an aspect ratio higher than 60 in 3D-NAND memory (1)(2)(3). Wetting of high aspect ratio nanoholes was shown to be incomplete by acoustic reflectometry and Fourier Transformed Infra-Red (FTIR) characterization (4,5), in contradiction to models predicting a fast wetting (6). Also, wet processing in nanoconfined volumes was found not to follow the rates encountered on flat surfaces, but without a clear mechanism proposed.…”

“…It has been first proposed to occur in water confined in nanochannels used in nanofluidics based on NMR and dielectric constant measurements (9,10). This was confirmed by Attenuated Total Reflection -Fourier Transformed Infra-Red (ATR-FTIR) measurements on nanoholes (5). Nanoconfined water was characterized by the presence of H-bonds with a stronger vibration frequency as compared to ice.…”

“…Samples consisted in nanoholes in an oxide matrix with a diameter of about 20 nm, a pitch of 90 nm, and a depth of about 300 nm, manufactured on Si wafers as described in previous work (5). The structures covered the whole surface of dies.…”