Effect of time-modulation bias on polysilicon gate etching

Morimoto, Michikazu; Tagaya, Motohiro; Koga, Kazunori; Shiratani, Masaharu

doi:10.35848/1347-4065/acc7ab

Cited by 3 publications

(1 citation statement)

References 38 publications

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“…The DC of the TM bias tunes the average incident ion flux and etch by-product density. 54) The detailed mechanism of the high Si 3 N 4 /Si selectivity, including the effect of the TM bias, is a topic for future research.…”

Section: Plasma Emission Observationmentioning

confidence: 99%

Highly selective Si₃N₄ etching on Si using pulsed-microwave CH₃F/O₂/Ar plasma

Morimoto

Matsui

Ikeda

et al. 2023

Jpn. J. Appl. Phys.

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Highly selective Si3N4 etching on Si was achieved in a CH3F/O2/Ar plasma using pulsed-microwave plasma and time-modulation (TM) bias. The Si3N4/Si selectivity reached infinity at a peak-to-peak voltage (Vpp) of 240 V. The effect of pulsed-microwave on CH3F gas dissociation for highly selective Si3N4 etching was investigated by deposited film analysis, optical emission spectroscopy (OES), and ion current flux measurements. As the duty cycle of the pulsed-microwave was decreased, the plasma density during the pulse on period decreased and the CH/H ratio increased. The pulsed-microwave plasma produced low-dissociation radicals by providing a low plasma density. The low-dissociation radicals in the CH3F plasma formed a fluorine (F)-rich hydrofluorocarbon (HFC) layer on the Si3N4 wafer surface. The F-rich HFC layer promotes Si3N4 etching even at low ion energy, where Si etching does not proceed, and enables highly selective Si3N4 etching on Si.

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Section: Plasma Emission Observationmentioning

confidence: 99%

Highly selective Si₃N₄ etching on Si using pulsed-microwave CH₃F/O₂/Ar plasma

Morimoto

Matsui

Ikeda

et al. 2023

Jpn. J. Appl. Phys.

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Selective mask deposition using SiCl4 plasma for highly selective etching process

Matsui,

Miura,

Kuwahara

2023

Journal of Vacuum Science &Amp; Technology A

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We developed an area-selective deposition process for forming protective layers on top of masks generated using a microwave electron-cyclotron-resonance etching system. A deposition layer is formed only on SiO2 masks without forming an unnecessary deposition layer on the Si surfaces in the etching area, such as the bottoms of the patterns and isolated etching area. The protection layers were selectively formed on a SiO2 mask without forming on a Si etching area by using a SiCl4/H2/Cl2 plasma. The pretreatment to clean the Si and SiO2 surfaces before deposition was important for achieving selective deposition because selectivity appeared by nucleation delay on the cleaned Si surface. On the Si surface, adsorbed SiClx easily desorbed again by reacting with the Cl generated from the plasma. However, adsorbed SiClx on SiO2 was more difficult to desorb by reacting with Cl due to Si–O having a larger binding energy than Si–Si. After the deposition layer was selectively formed on the SiO2 mask, the layer was oxidized by using O2 plasma treatment to improve the etching resistance during the subsequent Si etching. We also investigated a Si etching process using selective deposition during the etching of a 25 nm-pitch line-and-space Si pattern with a SiO2 mask. Extremely highly selective etching was achieved using selective deposition without forming an unnecessary deposition on an isolated Si area.

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Roughness-generation mechanism of Ru etching using Cl2/O2-based plasma for advanced interconnect

Matsui,

Ishii,

Kovatch

et al. 2024

Journal of Vacuum Science &Amp; Technology B

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We investigated the Ru-etching mechanism using a Cl2/O2-based plasma generated by a microwave electron cyclotron resonance etching system. When 20% of Cl2 gas was added to an O2 plasma, the Ru etch rate was the highest and a smooth surface was obtained by forming volatile RuO4 and RuClxOy. However, when Ru was etched using an O2-rich plasma with less than 10% Cl2 gas added, nonvolatile RuO2 was also formed, which caused surface roughness. When using Cl2-rich plasma, the formation of nonvolatile RuClx caused surface roughness by forming micro masks. We also evaluated line-and-space Ru patterns with 32 nm pitch and 95 nm pitch using Cl2/O2-based plasma. Selectivity over the Si3N4 mask was the highest when 20% of Cl2 gas was added to an O2 plasma due to the high etch rate of Ru. The Ru-sidewall profile and roughness depended on the duty cycle of wafer-bias power. When wafer bias was applied continuously, the Ru sidewall was tapered because the Si3N4 mask widened due to the deposition of by-products. When the ion flux decreased by reducing the duty cycle of the wafer-bias power, the Ru pattern was vertically etched, but larger sidewall roughness was generated. The sidewall roughness was thought to be caused by nonvolatile RuOx and RuCly formed on the sidewalls. The sidewall Ru was etched by O and Cl radicals during the off period of the wafer-bias power. To reduce the sidewall roughness, we suggested a C-coating that uniformly protects the sidewall from being etched by adding passivation gas to the Cl2/O2 plasma.

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Effect of time-modulation bias on polysilicon gate etching

Cited by 3 publications

References 38 publications

Highly selective Si₃N₄ etching on Si using pulsed-microwave CH₃F/O₂/Ar plasma

Highly selective Si₃N₄ etching on Si using pulsed-microwave CH₃F/O₂/Ar plasma

Selective mask deposition using SiCl4 plasma for highly selective etching process

Roughness-generation mechanism of Ru etching using Cl2/O2-based plasma for advanced interconnect

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Effect of time-modulation bias on polysilicon gate etching

Cited by 3 publications

References 38 publications

Highly selective Si3N4 etching on Si using pulsed-microwave CH3F/O2/Ar plasma

Highly selective Si3N4 etching on Si using pulsed-microwave CH3F/O2/Ar plasma

Selective mask deposition using SiCl4 plasma for highly selective etching process

Roughness-generation mechanism of Ru etching using Cl2/O2-based plasma for advanced interconnect

Contact Info

Product

Resources

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Highly selective Si₃N₄ etching on Si using pulsed-microwave CH₃F/O₂/Ar plasma

Highly selective Si₃N₄ etching on Si using pulsed-microwave CH₃F/O₂/Ar plasma