Pseudo-Wet Plasma Mechanism Enabling High-Throughput Dry Etching of SiO2 by Cryogenic-Assisted Surface Reactions.

Manufacturing semiconductor devices requires advanced patterning technologies, including reactive ion etching (RIE) based on the synergistic interactions between ions and etch gas. However, these interactions weaken as devices continuously scale down to sub-nanoscale, primarily attributed to the diminished transport of radicals and ions into the small features. This leads to a significant decrease in etch rate (ER). Here, a novel synergistic interaction involving ions, surface-adsorbed chemistries, and materials at cryogenic temperatures is found to exhibit a significant increase in the ER of SiO2 using CF4/H2 plasmas. The ER increases twofold when plasma with H2/(CF4 + H2) = 33% is used and the substrate temperature is lowered from 20 to -60 °C. The adsorption of HF and H2O on the SiO2 surface at cryogenic temperatures is confirmed using in situ Fourier transform infrared spectroscopy. The synergistic interactions of the surface-adsorbed HF/H2O as etching catalysts and plasma species result in the ER enhancement. Therefore, a mechanism called "pseudo-wet plasma etching" is proposed to explain the cryogenic etching process. This synergy demonstrates that the enhanced etch process is determined by the surface interactions between ions, surface-adsorbed chemistry, and the material being etched, rather than interactions between ion and gas phase, as observed in the conventional RIE.

Double-sided computer-generated holography.

We present a method for computer-generated holography (CGH) in which different images are reproduced on both sides of a hologram with a single illumination source. In the proposed method, we use a transmissive spatial light modulator (SLM) and a half mirror (HM) located downstream of the SLM. The light modulated by the SLM is partially reflected by the HM, and the reflected light is modulated again by the SLM for the double-sided image reproduction. We derive an algorithm for double-sided CGH and experimentally demonstrate it.

Incoherent computer-generated holography: publisher's note.

This publisher's note contains a correction to Opt. Lett.47, 3844 (2022)10.1364/OL.464454.

Incoherent computer-generated holography.

We present a method for computer-generated holography (CGH) using spatially and temporally incoherent light. The proposed method synthesizes a hologram cascade by solving an inverse problem for the propagation of incoherent light. The spatial incoherence removes speckle noise in CGH, and the temporal incoherence simplifies the optical setup, including the light source. We demonstrate two- and three-dimensional color image reproductions by a two-layer grayscale hologram cascade with a chip-on-board white light-emitting diode.

Formation scheme of quantum point contacts based on nanogaps using field-emission-induced electromigration.

We propose a new fabrication scheme of quantum point contacts (QPCs) composed of nanogaps at room temperature. This scheme is based on electromigration induced by a field emission current, which is so-called "activation." By applying the activation to ferromagnetic Ni nanogaps with sub-10 nm separation, QPCs can be easily obtained at room temperature. The conductance changed in quantized steps of 0.5G0 (G0 = 2e2/h) at the final stage of activation with a preset current Is of 0.5 mA. Then, the conductance during the activation was varied from 2G0 to 9.5G0 by increasing the preset current Is from 0.5 mA to 1.5 mA. Furthermore, after performing the activation with the preset current Is of 1.5 mA, the QPC device formed by the activation exhibited magnetoresistance (MR) ratio of approximately 1.5%. These results indicate that few-atom Ni contacts are achieved using Ni nanogaps controlled by the activation with precisely tuned preset current.