Competitive effect between roughness and mask pattern on charging phenomena during plasma etching

In plasma etching process, the edge roughness and mask pattern usually play a significant role in the deformation of holes under the influence of charging effect. The competitive effect between these two factors has been investigated, focusing on the surface charging in a hexagonal array, with various values of roughness parameters (amplitude (A) and wavelength (W)) and distances between holes (L). A series of classical particle dynamic simulations of surface charging, surface etching and profile evolution were used to investigate the effect of roughness and pattern on charging. This study showed that various roughness and patterns (represented by different values of L) can significantly influence surface distributions of the electric-field (E-field) and the etching rates on the mask surface. The simulations also showed that (1) the shape of the pattern array influences the mask hole profile during etching process, i.e. a hexagonal array pattern tends to deform the profile of a circular mask hole into a hexagonal hole; (2) pattern roughness is aggravated during etching process. These factors were found to be significant only at a small feature pitch and may be ignored at a large feature pitch. Possible mechanisms of these results during etching process are discussed. This work sheds light on the ways to maintain pattern integrity and further improve the quality of the pattern transfer onto the substrate.

Colloidal Stability of Silica-Modified Magnetite Nanoparticles: Comparison of Various Dispersion Techniques

The production of stable and homogeneous batches during nanoparticle fabrication is challenging. Surface charging, as a stability determinant, was estimated for 3-aminopropyltriethoxysilane (APTES) coated pre-formed magnetite nanoparticles (MNPs). An important consideration for preparing stable and homogenous MNPs colloidal systems is the dispersion stage of pre-formed samples, which makes it feasible to increase the MNP reactive binding sites, to enhance functionality. The results gave evidence that the samples that had undergone stirring had a higher loading capacity towards polyanions, in terms of filler content, compared to the sonicated ones. These later results were likely due to the harsh effects of sonication (extremely high temperature and pressure in the cavities formed at the interfaces), which induced the destruction of the MNPs.

Determining the depth of surface charging layer of single Prussian blue nanoparticles with pseudocapacitive behaviors

Based on the dependence of the light scattering intensity of single Prussian blue nanoparticles (PBNPs) on their oxidation state during sinusoidal potential modulation at varying frequencies, we present an electro-optical microscopic imaging approach to optically acquire the Faradaic electrochemical impedance spectroscopy (oEIS) of single PBNPs. Frequency analysis revealed typical pseudocapacitive behavior with hybrid charge-storage mechanisms depending on the modulation frequency. In the low-frequency range (0.04–1 Hz), the optical amplitude was inversely proportional to the square root of the modulation frequency (i.e., ∆I ∝ f− 0.5; diffusion-limited process), while in the high-frequency range (1.25–100 Hz), it was inversely proportional to the modulation frequency (∆I ∝ f− 1; surface charging process). The contribution of each process was, therefore, determined and quantified using oEIS at the single-nanoparticle level. Because the geometry of single cuboid-shaped PBNPs can be precisely determined by scanning electron microscopy and atomic force microscopy, oEIS of single PBNPs allowed the determination of the depth of the surface charging layer, revealing it to be ~ 2 unit cells regardless of the nanoparticle size.