Elemental evolution of the SiOxFy self-masking layer of plasma textured silicon and its modification during air exposure

Abstract

The influence of the SiOxFy selfmasking process on the formation of black-Silicon (b-Si) textures by maskless SF6/O2 plasma etching is of great interest with regard to the optimization of the texturing process for highly antireflective silicon. For that reason, the elemental composition of plasma textured silicon surfaces is analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy. The chemical composition of a fluorine containing oxide layer on top of the surface was confirmed and determined quantitatively. A strongly reduced F content was found after ambient air exposure. A qualitative model of the chemical and physical processes caused by maskless plasma texturing was developed to explain the observed experimental results. The decrease in the F content is assumed to be caused by hydrolysis of F by air moisture, resulting in a successive desorption of HF and transformation of SiOxFy to silicon oxide.

Influence of Carbonate Solvents on Solid Electrolyte Interphase Composition over Si Electrodes Monitored by In Situ and Ex Situ Spectroscopies

“…Looking at the presence and relative intensity ratios of F-like components (F 1s profiles in Figure ), the SiOF signal is the principle peak on the electrode cycled in 1 M LiPF 6 /DMC, while the Li–F is the principle peak on the electrode cycled in 1 M LiPF 6 /EC-DMC and 1 M LiPF 6 /PC. The SiOF signal can be attributed to the formation of SiO x F y on the bulk electrode material. , Therefore, the SiOF signal decrease can be attributed to the increase of the SEI layer thickness. On the other hand, the volume variations of Si during the lithiation and delithiation processes could lead to the fracture of the SEI layer and the exposition of the Si electrode not covered by the SEI layer.…”

Silicon Nanostructuring Using SF6/O2 Downstram Plasma Etching: Morphological, Optical and Sensing Properties

“…9 Indeed, it is demonstrated that F and O react with Si to form the selfmasking layer SiO x F y on the surface, which acts as etching inhibitor at certain points on the surface. 4 This passivation layer is not very stable and dissociates by heating or under the ion bombardment of the plasma. 9,10 Since our system is a remote plasma configuration, where the concentrations of ions and electrons are relatively low and the concentration of free radicals is relatively high in the remote region far from the primary plasma, 17 the behavior of the etching rate as a function of O 2 content in the SF 6 /O 2 plasma, may be related to the fact that the passivation layer resists the degradation by plasma ions bombardment in the downstream etching region.…”

“…[1][2][3] The so-called 'Black Silicon' (b-Si) describes nano or micro textured silicon surfaces, 4 it can be produced by Si surface etching using plasma technique, which is compatible with the silicon fabrication technology. [4][5][6][7][8] Plasma is a versatile and environmentally friendly technique which uses gases as reactants to modify materials surface. Gas discharges environments have active species such as ions, free radicals, electrons, molecular fragments and photons that are simultaneously generated and can induce surface modification of different materials.…”

Low surface damage dry etched black silicon

“…The etching process was set based on previously optimized parameters such as SF 6 and O 2 partial pressures, process temperature, and DC bias voltage measured at the wafer stage. In-depth understanding of black Si formation can be obtained elsewhere, 18 including the experimental analysis of Gaudig et al, 21 Otto et al, 19 and the theoretical model developed by Saab et al 17 The shapes of these nanostructures were observed by Jansen et al 18 and can be modified depending on the process parameters. The shape can be changed from parabolic to randomly distributed etch pits that eventually overlap and leave needle-like Si features inbetween in agreement with simulations conducted by Saab et al 17 and observation from other studies and in this report (Fig.…”