In situplasma sputtering and angular distribution measurements for structured molybdenum surfaces

Abstract

We present in situ sputtering yield measurements of the time-dependent erosion of flat and micro-architectured molybdenum samples in a plasma environment. The measurements are performed using the plasma interactions (Pi) Facility at UCLA, which focuses a magnetized hollow cathode plasma to a material target with an exposure diameter of approximately 1.5 cm. During plasma exposure, a scanning quartz crystal microbalance (QCM) provides angular sputtering profiles that are integrated to estimate the total sputtering yield. This technique is validated to within the scatter of previous experimental data for a planar molybdenum target exposed to argon ion energies from 100 to 300 eV. The QCM is then used to obtain in situ measurements during a 17 h exposure of a micro-architectured-surface molybdenum sample to 300 eV incident argon ions. The time-dependent angular sputtering profile is shown to deviate from classical planar profiles, demonstrating the unique temporal and spatial sputtering effects of micro-architectured materials. Notably, the sputtering yield for the micro-architectured sample is initially much less than that for planar molybdenum, but then gradually asymptotes to the value for planar molybdenum after approximately 10 h as the surface features are eroded away.

Ion-plasma sputtering of Co and Mo nanometer thin films near the sputtering threshold

“…The sputtering thresholds and the dependences of the metal sputtering rate on the ion energy can be estimated from the data obtained in experiments with Ar + ion beams [8][9][10], as well as from the data of sputtering modelling by the molecular dynamics method, or from calculations using the semiempirical equations of Tawara et al [11][12][13]. The dependences of the sputtering yield of Mo, W, Ru and Au on the energy of Ar + ions (E i = 50-200 eV) determined in such experiments were in good agreement with the calculated data [4,8,9]. However, in plasma, the sputtering yield Y of materials may differ from the calculated value due to possible effects of redeposition [14].…”

“…The processes of low-energy (Е i < 200 eV) sputtering of materials by ions of inert gases, such as Ar + , are widely applied in various fields of nanotechnology. They are used for surface modification, formation of nanostructures and for determination of the erosion rate in plasma of metallic optical and protective coatings [1][2][3][4]. In modern technology of nanoelectronics, low-energy ion-plasma sputtering is a crucial stage of the developed multistage processes of atomiclayer etching (ALE) of materials [5][6][7].…”

“…As in the case of studying the sputtering of materials by ion beams, they are determined using a planar Langmuir probe and an ion energy analyzer [3,19]. The ion energy can be set by supplying a potential from a separate voltage source [4]. However, in plasma etching reactor setups in which high-density plasma is generated, the energy of ions incident on the sample lying on the RF electrode is set by supplying a certain RF bias power P sb to it [20,21].…”

Experimental Insights Into Space Weathering of Phobos: Laboratory Investigation of Sputtering by Atomic and Molecular Planetary Ions

“…Then the mass increase by sputtered atoms sticking to the catcher QCM can be measured (Berger et al, 2017). Such a setup can also give insights into the angular distribution of sputtered particles (see Li et al [2017] for measurements with structured molybdenum surfaces, and Stadlmayr et al [2020] for experiments with highly porous tungsten fuzz structures).…”

Charge and discharge behavior of elemental sulfur in isochoric high temperature thermal energy storage systems

“…Textured surfaces have been shown experimentally [12][13][14] and computationally [15,16] to suppress SEE by capturing emitted and backscattered secondary electrons. This suppression is due to geometric effects and can also be observed in sputtering of featured surfaces exposed to plasma [17][18][19]. In electric propulsion devices, carbon velvet has been used to improve performance; a similar effect could be realized in fusion devices via surface fuzz formation at the divertor plate.…”