Influence of Oxygen Addition and Wafer Bias Voltage on Bromine Atom Surface Reaction in a HBr/Ar Inductively Coupled Plasma

Iino, Daiki; Nojiri, Yasuhiro; Suzuki, Keiji; Oike, T.; Fujii, Yoshitaka; Toyoda, Hirotaka

doi:10.7567/jjap.52.11nc01

Cited by 3 publications

(1 citation statement)

References 58 publications

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“…[1][2][3][4][5][6][7] A bromine-containing gas that is often used for silicon etching is HBr, which is commonly mixed with Cl 2 and/or CF 4 . [8][9][10][11][12][13] Furthermore, HBr can also be combined with a noble gas like helium, to tune the ratio between physical ion sputtering and chemical etching, or with O 2 , for controlling the anisotropy during etching. [14][15][16][17] Since HBr is a polar molecule, the vibrational excitation cross sections are typically very large, and a significant fraction of HBr is believed to be in vibrational states.…”

Section: Introductionmentioning

confidence: 99%

Role of vibrationally excited HBr in a HBr/He inductively coupled plasma used for etching of silicon

Tinck

Bogaerts

2016

J. Phys. D: Appl. Phys.

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In this work, the role of vibrationally excited HBr (HBr (vib) ) is computationally investigated for a HBr/He inductively coupled plasma applied for Si etching. It is found that at least 50% of all dissociations of HBr occur through HBr (vib) . This additional dissociation pathway through HBr (vib) makes the plasma significantly more atomic. It also results in a slightly higher electron temperature (i.e., about 0.2 eV higher compared to simulation results where HBr (vib) is not included), as well as a higher gas temperature (i.e., about 50 K higher than without including HBr (vib) ), due to the enhanced Franck-Condon heating through HBr (vib) dissociation, at the conditions investigated. Most importantly, the calculated etch rate with HBr (vib) included in the model is a factor 3 higher than in the case without HBr (vib) , due to the higher fluxes of etching species (i.e., H and Br), while the chemical composition of the wafer surface shows no significant difference. Our calculations clearly show the importance of including HBr (vib) for accurate modeling of HBr-containing plasmas.

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Section: Introductionmentioning

confidence: 99%

Role of vibrationally excited HBr in a HBr/He inductively coupled plasma used for etching of silicon

Tinck

Bogaerts

2016

J. Phys. D: Appl. Phys.

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A numerical study of the effect of various reactions, pressure and gas mixture ratio on the density distribution of etchant species (H, Br, Br+, and HBr+) in HBr/He plasma

Gul

Rehman

2016

Physics of Plasmas

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In this study, a fluid model has been used to study the effect of gas mixing ratio and pressure on the density distribution of important etchant species, i.e., hydrogen (H), bromine (Br), Br+, and HBr+ in HBr/He plasma. Our simulation results show that the densities of active etchant species H, Br, and HBr+ increase with the increase in pressure as well as the HBr fraction in HBr/He mixture. On the contrary, the density of Br+ decreases with the increase in He percentage in HBr/He mixture and with the increase in the pressure. Time averaged reaction rates (of the reactions involved in the production and consumption of these species) have been calculated to study the effect of these reactions on the density distribution of these species. The spatial distribution of these species is explained with the help of the time averaged reaction rates. Important reactions have been identified that contribute considerably to the production and consumption of these active species. The code has been optimized by identifying 26 reactions (out of 40 reactions which contribute in the production and consumption of these species) that have insignificant effect on the densities of H, Br, Br+, and HBr+. This shows that out of 40 reactions, only 14 reactions can be used to calculate the density and distribution of the important species in HBr/He plasma discharge.

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Model analysis of the feature profile evolution during Si etching in HBr-containing plasmas

Mori

Irie

Osano

et al. 2021

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

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Feature profiles of Si etched in HBr-containing plasmas have been analyzed through a comparison between experiments and simulations. The emphasis was placed on a mechanistic understanding of the difference in the evolution of profile anomalies (such as tapering, footing, and microtrenching) during Si etching between HBr- and Cl2-based plasmas. Experiments were made with Cl2/O2/HBr chemistry by varying the HBr mixing ratio, using a commercial ultrahigh-frequency electron cyclotron resonance plasma etching reactor, where HCl/O2 chemistry was also employed to compare with that of Cl2/O2 and HBr/O2. Numerical simulations of feature profile evolution were made using a semiempirical atomic-scale cellular model based on the Monte Carlo method that we developed for Si etching in Br2, HBr, and Cl2 plasmas, where surface chemistry and kinetics include the effects of ion reflection from and/or penetration into feature surfaces on incidence. The experiments showed more vertical sidewalls with less footing and microtrenching with HBr; concretely, with increasing HBr mixing ratio in Cl2/O2/HBr plasmas, the tapering is reduced and minimized at 80% HBr where slight lateral or side etching tends to occur, the footing is reduced gradually, and the microtrenching fades away at more than 20% HBr. A comparison with simulations, with the help of separate analyses of ion reflection from surfaces on incidence, indicated that the smaller reflection probability and reflected energy fraction of Br+ on tapered sidewalls (compared to Cl+) are responsible for reduced tapering, footing, and microtrenching in HBr-containing plasmas; moreover, chemical etching effects of neutral H atoms at the feature bottom and sidewalls, arising from the larger reaction probability of H (compared to Cl), are also responsible for reduced microtrenching and for reduced tapering (and the lateral or side etching induced) therein.

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Influence of Oxygen Addition and Wafer Bias Voltage on Bromine Atom Surface Reaction in a HBr/Ar Inductively Coupled Plasma

Cited by 3 publications

References 58 publications

Role of vibrationally excited HBr in a HBr/He inductively coupled plasma used for etching of silicon

Role of vibrationally excited HBr in a HBr/He inductively coupled plasma used for etching of silicon

A numerical study of the effect of various reactions, pressure and gas mixture ratio on the density distribution of etchant species (H, Br, Br+, and HBr+) in HBr/He plasma

Model analysis of the feature profile evolution during Si etching in HBr-containing plasmas

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