Si/XeF2 etching: Reaction layer dynamics and surface roughening

Vugts, M. J. M.; Eurlings, Mark; Hermans, L. J. F.; Beijerinck, H.C.W.

doi:10.1116/1.580200

Cited by 37 publications

(18 citation statements)

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“…24) plasmas, and also in XeF 2 gases with 18 and without 12 Ar þ ion beams. Correspondingly, several theoretical and/or numerical studies have been made to interpret the roughness experimentally observed in plasma etching, using a continuum model, [13][14][15][16] Monte Carlo simulation, 15,16,22,23,28,29,31 and classical molecular dynamics (MD) simulation.…”

Section: Introductionmentioning

confidence: 98%

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Tsuda¹,

Nakazaki²,

Takao³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Surface loss rates of H and Cl radicals in an inductively coupled plasma etcher derived from time-resolved electron density and optical emission measurementsModeling of fluorine-based high-density plasma etching of anisotropic silicon trenches with oxygen sidewall passivation Atomic-or nanometer-scale surface roughening and rippling during Si etching in high-density Cl 2 and Cl 2 /O 2 plasmas have been investigated by developing a three-dimensional atomic-scale cellular model (ASCeM-3D), which is a 3D Monte Carlo-based simulation model for plasma-surface interactions and the feature profile evolution during plasma etching. The model took into account the behavior of Cl þ ions, Cl and O neutrals, and etch products and byproducts of SiCl x and SiCl x O y in microstructures and on feature surfaces therein. The surface chemistry and kinetics included surface chlorination, chemical etching, ion-enhanced etching, sputtering, surface oxidation, redeposition of etch products desorbed from feature surfaces being etched, and deposition of etch byproducts coming from the plasma. The model also took into account the ion reflection or scattering from feature surfaces on incidence and/or the ion penetration into substrates, along with geometrical shadowing of the feature and surface reemission of neutrals. The simulation domain was taken to consist of small cubic cells of atomic size, and the evolving interfaces were represented by removing Si atoms from and/or allocating them to the cells concerned. Calculations were performed for square substrates 50 nm on a side by varying the ion incidence angle onto substrate surfaces, typically with an incoming ion energy, ion flux, and neutral reactant-to-ion flux ratio of E i ¼ 100 eV, C i 0 ¼ 1.0 Â 10 16 cm À2 s À1 , and C n 0 /C i 0 ¼ 100. Numerical results showed that nanoscale roughened surface features evolve with time during etching, depending markedly on ion incidence angle; in effect, at h i ¼ 0 or normal incidence, concavo-convex features are formed randomly on surfaces. On the other hand, at increased h i ¼ 45 or oblique incidence, ripple structures with a wavelength of the order of 15 nm are formed on surfaces perpendicularly to the direction of ion incidence; in contrast, at further increased h i ! 75 or grazing incidence, small ripples or slitlike grooves with a wavelength of <5 nm are formed on surfaces parallel to the direction of ion incidence. Such surface roughening and rippling in response to ion incidence angle were also found to depend significantly on ion energy and incoming fluxes of neutral reactants, oxygen, and etch byproducts. Two-dimensional power spectral density analysis of the roughened feature surfaces simulated was employed in some cases to further characterize the lateral as well as vertical extent of the roughness. The authors discuss possible mechanisms responsible for the formation and evolution of the surface roughness and ripples during plasma etching, including stochastic roughening, local micromasking, and effects of ion reflection, surface temp...

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Section: Introductionmentioning

confidence: 98%

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Tsuda¹,

Nakazaki²,

Takao³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…In previous studies by our group, 17,18,20 it was found that for spontaneous etching the ratio of these signals is independent of etching parameters like the XeF 2 flux or the sample temperature. Therefore it was concluded that both signals originate from the XeF 2 molecule and that there is no XeF desorption or fractional usage of XeF 2 .…”

Section: Reaction Of Xefmentioning

confidence: 79%

“…We attribute both effects to the reduction in surface roughness by ion bombardment. 20 Such differences in specific surface conditions could also very well be the cause of the scatter of the data points: these fluctuations disappear when we plot the difference between the spontaneous and the ion-assisted reaction coefficients, as shown in the bottom panel of Fig. 2.…”

Section: Reaction Of Xefmentioning

confidence: 98%

Ion-assisted Si/XeF2 etching: Temperature dependence in the range 100–1000 K

Vugts¹,

Hermans²,

Beijerinck³

1996

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The Ar+-ion enhanced Si(100)/XeF2 reaction is studied in a multiple beam setup for silicon temperatures from 100 K up to 1000 K. The XeF2 flux is 2.7 monolayers/s and the Ar+ flux 0.033 monolayers/s at an energy of 1000 eV. Both the XeF2 consumption and the SiFx production are measured by mass spectrometry. The enhancement of the etch rate peaks around 250 K as is observed in both the XeF2 and SiFx signals. The gradual decline above 250 K is attributed to a diminished surface fluorination and XeF2 precursor concentration. The dropoff below 250 K is presumably caused by sputtering of the XeF2 precursor, as is concluded from the temperature dependence of the XeF+/XeF2+ signal ratio. Around 175 K this decrease is so strong that the ions seem to no longer enhance, but rather reduce, the etch rate. Below 150 K the ions are driving the etch process. In this range the spontaneous process is blocked by XeF2 condensation, but the ion-assisted process continues due to sputtering or dissociation of the condensate.

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“…After monolayer saturation F 2 ceases to react with the surface, whereas XeF 2 continues to deposit fluorine by reacting with the Si−Si dimer and lattice bonds. The dose dependence of the fluorine content was shown to not follow a single exponential behavior, but to rather increase rapidly in the early stages of the uptake but much more slowly thereafter [454]. This behavior was explained by the rapid development of a monolayer of SiF x surface species in the initial regime followed by the slow formation of a steady-state multilayer of SiF-SiF 2 -SiF 3 and SiF 2 -SiF 3 chains.…”

Section: Ai Silicon Surfacesmentioning

confidence: 91%

Use of molecular beams for kinetic measurements of chemical reactions on solid surfaces

Zaera

2017

Surface Science Reports

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In this review we survey the contributions that molecular beam experiments have provided to our understanding of the dynamics and kinetics of chemical interactions of gas molecules with solid surfaces. First, we describe the experimental details of the different instrumental setups and approaches available for the study of these systems under the ultrahigh vacuum conditions and with the model planar surfaces often used in modern surface-science experiments. Next, a discussion is provided of the most important fundamental aspects of the dynamics of chemical adsorption that have been elucidated with the help of molecular beam experiments, which include the development of potential energy surfaces, the determination of the different channels for energy exchange between the incoming molecules and the surface, the identification of adsorption precursor states, the understanding of dissociative chemisorption, the determination of the contributions of corrugation, steps, and other structural details of the surface to the adsorption process, the effect to molecular steering, the identification of avenues for assisting adsorption,

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Si/XeF2 etching: Reaction layer dynamics and surface roughening

Cited by 37 publications

References 0 publications

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Ion-assisted Si/XeF2 etching: Temperature dependence in the range 100–1000 K

Use of molecular beams for kinetic measurements of chemical reactions on solid surfaces

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