Etching yields of SiO2 by low energy CF<i>x</i>+ and F+ ions

Shibano, Teruo; Fujiwara, Nobuo; Hirayama, Makoto; Nagata, Hitoshi; Demizu, Kiyoshi

doi:10.1063/1.110518

Cited by 44 publications

(19 citation statements)

References 7 publications

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“…Both etch rates, especially the SiO 2 etch rate, dropped sharply for a residence time of approximately 25 ms. For this reason, it is difficult to consider that different C 4 F 8 plasma states exist at shorter and longer residence times than 25 ms. At 25 ms residence time we noticed that the low SiO 2 and Si etch rates coincided with the maximum of the CF 1 ϩ ion density ͓see Fig. 15 According to the CF x ϩ ion bombarding energy dependence of the SiO 2 etching yield, the CF 1 ϩ ion shows an etching yield close to zero for an ion energy of 200 V, while those for CF 2 ϩ and CF 3 ϩ ions are 0.6 and 0.8, respectively. 1͑c͔͒.…”

Section: Resultsmentioning

confidence: 81%

Residence time effects on SiO2/Si selective etching employing high density fluorocarbon plasma

Chinzei

Ichikı²,

Ikegami

et al. 1998

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Articles you may be interested inSurface kinetics modeling of silicon and silicon oxide plasma etching. I. Effect of neutral and ion fluxes on etching yield of silicon oxide in fluorocarbon plasmas Effect of nonsinusoidal bias waveforms on ion energy distributions and fluorocarbon plasma etch selectivityThe residence time effects on SiO 2 etching characteristics using inductively coupled plasma of C 4 F 8 alone were first studied in the range from 6 to 300 ms. It was then found that SiO 2 and Si etch rates were minimum at a residence time of 25 ms, at which the CF 1 ϩ ion density and the fluorocarbon polymer deposition rate measured at 130°C became maximum. From this good correspondence, the SiO 2 etching was considered to follow a reaction model where the CF 1 ϩ ions might contribute to the polymer deposition, thus suppressing the SiO 2 etching, and where the dominantly observed CF 3 ϩ ions could etch SiO 2 on the assumption of elevated SiO 2 surface temperature due to the ion bombardment. Next, in the condition of short residence times ͑Ͻ25 ms͒, Ar was added to C 4 F 8 in order to allow Ar ϩ ions to remove the fluorocarbon polymer film that is responsible for the reduction of the SiO 2 etch rate. For a residence time of 10 ms the SiO 2 etch rate continuously increased with the Ar concentration up to a maximum etch rate of 0.4 m/min for 90% Ar addition. Various plasma diagnostics demonstrated that the 90% Ar addition resulted in an increase of the CF x ϩ (xϭ1 -3), C ϩ , and Ar ϩ ion densities, in contrast to a decrease of the CF 3 radical density. Metastable Ar atoms as well as highly elevated electron temperature are considered to be responsible for the increasing ion species. Consequently SiO 2 /Si contact hole features with 0.18 m opening and 2 m depth were successfully fabricated employing the 90% Ar/C 4 F 8 mixture at a residence time of 10 ms. The He addition has also been investigated and showed similar changes in plasma characteristics to those observed for Ar addition, but the ''etch stop'' occurred. This probably resulted from the poor sputtering effect of He ϩ ions due to their light mass.

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Section: Resultsmentioning

confidence: 81%

Residence time effects on SiO2/Si selective etching employing high density fluorocarbon plasma

Chinzei

Ichikı²,

Ikegami

et al. 1998

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…19͒ and CF ϩ contributes to the etching only when the ion energy is high, e.g., above 200 eV. 20 In this study, only one carbon atom was included in the feed gas, and, accordingly, it can be assumed that nondissociatively reflected CF 3 ϩ ions are major contributors to secondary etching. Because the energy of ions reflected at the same s is equal regardless of i , the x axis of Fig.…”

Section: B Range Of the Secondary Etching "R…mentioning

confidence: 99%

Characteristics of secondary etching of SiO2 by ions reflected from a primary SiO2 target in a CHF3 plasma

Lee

Hwang

Min

et al. 2003

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

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“…On the other hand, beam experiments using a selected species with controlled incident energy are suitable for basic study of surface reactions. [8][9][10][11][12] Recently, various kinds of fluorocarbon etching gases have been developed to achieve a high etch selectivity of SiO 2 / Si and to avoid a greenhouse effect. Mostly, such fluorocarbon gases are carbon rich in the atomic composition, such as C 4 F 8 or C 5 F 8 .…”

Section: Introductionmentioning

confidence: 99%

Evidence of direct SiO2 etching by fluorocarbon molecules under ion bombardment

Toyoda

Murakami

Sugai

2004

Journal of Applied Physics

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In a beam apparatus, influence of fluorocarbon gas (C5F8, C4F8, and CF4 molecules) flux onto SiO2 etching reaction is investigated in comparison to a case of CF2 radical flux. Fluorocarbon molecules or CF2 radicals are incident onto SiO2 surface with Ar+ beam of energy 100–900eV. Atomic composition of SiO2 surface under the ion and molecule incidence is measured by in situ x-ray photoelectron spectroscopy. Fluorocarbon∕Ar+ co-incidence enhances the SiO2 etching compared with pure Ar+ incidence, suggesting the etching effect of fluorocarbon molecules under Ar+ bombardment. In the case of C5F8∕Ar+ co-incidence, formation of fluorocarbon layer is observed as the case of CF2∕Ar+ co-incidence. Etching yields of SiO2 by C5F8∕Ar+ and CF2∕Ar+ co-incidences are measured for different Ar+ incident energies and fluorocarbon∕Ar+ flux ratios. The etching yield increases monotonically with the Ar+ incident energy, and reaches the value of 2.4 at 900eV in case of C5F8, which is about 1.5 times as high as in the CF2 case. In the case of C5F8 and CF2, a phenomenon like etch stop, with formation of a thick fluorocarbon layer, is observed for larger fluorocarbon flux, with the threshold of the fluorocarbon∕Ar+ flux, ratio between 2.5 and 25. These results suggest a significant contribution of direct SiO2 etching by fluorocarbon molecules in practical etching reactors, especially in case of the C5F8 molecule.

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Etching yields of SiO2 by low energy CFx+ and F+ ions

Cited by 44 publications

References 7 publications

Residence time effects on SiO2/Si selective etching employing high density fluorocarbon plasma

Residence time effects on SiO2/Si selective etching employing high density fluorocarbon plasma

Characteristics of secondary etching of SiO2 by ions reflected from a primary SiO2 target in a CHF3 plasma

Evidence of direct SiO2 etching by fluorocarbon molecules under ion bombardment

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