Molecular dynamics simulations of Si etching in Cl- and Br-based plasmas: Cl{sup +} and Br{sup +} ion incidence in the presence of Cl and Br neutrals

Journal Article · Mon Dec 21 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4937449· OSTI ID:22493052

Nakazaki, Nobuya; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi ^[1]

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1. Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8540 (Japan)

Classical molecular dynamics (MD) simulations have been performed for Cl{sup +} and Br{sup +} ions incident on Si(100) surfaces with Cl and Br neutrals, respectively, to gain a better understanding of the ion-enhanced surface reaction kinetics during Si etching in Cl- and Br-based plasmas. The ions were incident normally on surfaces with translational energies in the range E{sub i} = 20–500 eV, and low-energy neutrals of E{sub n} = 0.01 eV were also incident normally thereon with the neutral-to-ion flux ratio in the range Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 0–100, where an improved Stillinger--Weber potential form was employed for the interatomic potential concerned. The etch yields and thresholds presently simulated were in agreement with the experimental results previously reported for Si etching in Cl{sub 2} and Br{sub 2} plasmas as well as in Cl{sup +}, Cl{sub 2}{sup +}, and Br{sup +} beams, and the product stoichiometry simulated was consistent with that observed during Ar{sup +} beam incidence on Si in Cl{sub 2}. Moreover, the surface coverage of halogen atoms, halogenated layer thickness, surface stoichiometry, and depth profile of surface products simulated for Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 100 were in excellent agreement with the observations depending on E{sub i} reported for Si etching in Cl{sub 2} plasmas. The MD also indicated that the yield, coverage, and surface layer thickness are smaller in Si/Br than in Si/Cl system, while the percentage of higher halogenated species in product and surface stoichiometries is larger in Si/Br. The MD further indicated that in both systems, the translational energy distributions of products and halogen adsorbates desorbed from surfaces are approximated by two Maxwellians of temperature T{sub 1} ≈ 2500 K and T{sub 2} ≈ 7000–40 000 K. These energy distributions are discussed in terms of the desorption or evaporation from hot spots formed through chemically enhanced physical sputtering and physically enhanced chemical sputtering, which have so far been speculated to both occur in the ion-enhanced surface reaction kinetics of plasma etching.

• OSTI ID: 22493052
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ARGON IONS
BROMINE IONS
CHLORINE IONS
COMPUTERIZED SIMULATION
DEPTH DOSE DISTRIBUTIONS
DESORPTION
ENERGY SPECTRA
ETCHING
EVAPORATION
HOT SPOTS
ION BEAMS
MOLECULAR DYNAMICS METHOD
PLASMA
REACTION KINETICS
SILICON
SPUTTERING
STOICHIOMETRY
THICKNESS