Characteristics of high aspect ratio SiO2 etching using C4H2F6 isomers

Lee, Hye Joo; Tak, Hyun Woo; Kim, Seong Bae; Kim, Seul Ki; Park, Taehyun; Kim, Ji Yeun; Sung, Dain; Lee, Wonseok; Lee, Seung Bae; Kim, Keunsuk; Cho, Byeong Ok; Kim, Young Lea; Lee, Ki Chan; Kim, Dong Woo; Yeom, Geun Young

doi:10.1016/j.apsusc.2023.158190

Cited by 7 publications

(2 citation statements)

References 45 publications

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“…Aspect-ratio-dependent etching (ARDE) − is a serious problem in the microfabrication using the RIE process. The linear trench structures of different widths on the same SiO 2 substrate were fabricated via HF gas-phase anisotropic etching, as shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Atmospheric Gas-Phase Catalyst Etching of SiO₂ for Deep Microfabrication Using HF Gas and Patterned Photoresist

Sano,

Ono,

Tobinaga

et al. 2024

ACS Appl. Mater. Interfaces

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Micro/nanoscale structure fabrication is an important process for designing miniaturized devices. Recently, threedimensional (3D) integrated circuits using SiO 2 via-holes interlayer filling by copper have attracted attention to extend the lifetime of Moore's law. However, the fabrication of vertical and smoothsidewall via-hole structures on SiO 2 has not been achieved using the conventional dry etching method due to the limitation of the selective etching ratio of SiO 2 and hard mask materials. In this study, we developed a unique method for the deep anisotropic dry etching of SiO 2 using atmospheric gas-phase HF and a patterned photoresist. The hydroxyl groups in the photoresist catalyzed the HF gas-phase dry etching of SiO 2 at high-temperature conditions. Therefore, fabrication of vertical with smooth-sidewall deep microstructures was demonstrated in the photoresist-covered area on SiO 2 at a processing rate of 1.3 μm/min, which is 2−3 times faster than the conventional dry etching method. Additionally, the chemical reaction pathway in the photoresist-covered area on SiO 2 with HF gas was revealed via density functional theory (DFT) calculations. This simple and high-speed microfabrication process will expand the commercial application scope of next-generation microfabricated SiO 2 -based devices.

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Section: Resultsmentioning

confidence: 99%

Atmospheric Gas-Phase Catalyst Etching of SiO₂ for Deep Microfabrication Using HF Gas and Patterned Photoresist

Sano,

Ono,

Tobinaga

et al. 2024

ACS Appl. Mater. Interfaces

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“…We anticipated that there is still room to improve the etch rate by replacing CH 2 F 2 with larger gas molecules that can transport more fluorine. In recent years, there has been a focus on the fundamental etching characteristics of various highly polymerizing FC and HFC gases and liquids, such as C 3 H 2 F 6 , 18) C 4 H 2 F 6 , 19) C 5 F 8 , 20) C 6 F 6 , 21) C 7 F 8 , 20) and C 7 F 14 . 22,23) Their appeal stems from their lower global warming potentials (GWPs) and polymerization characteristics which improve mask selectivity.…”

Section: Introductionmentioning

confidence: 99%

High aspect ratio SiO₂/SiN (ON) stacked layer etching using C₃HF₅, C₄H₂F₆, and C₄H₄F₆

Abe,

Sasaki,

Kondo

et al. 2024

Jpn. J. Appl. Phys.

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High aspect ratio SiO2/SiN (ON) stacked layer etching using hydrofluorocarbon gases was conducted with various ratios of H, F, and C to achieve higher etching rates and precise profile control. The experimental gases were C3HF5, C4HF5, C4H2F4, C4H2F6, C4H4F6 and C5H2F10. The oxygen gas flow rate and mixing ratio were optimized to maximize mask selectivity while avoiding clogging at the top of the mask. For comparison, C4F6/CH2F2/Ar/O2, and C4F6/C4F8/CH2F2/Ar/O2 were used as reference gas mixtures. The initial screening narrowed the candidate pool to 3 gases: C3HF5, C4H2F6, and C4H4F6. At equivalent power, the C3HF5 condition achieved a 15% faster ON etch rate, and C4H2F6 achieved a 9% faster ON etch rate compared to the reference condition. Only C4H4F6 showed a worse ON etch rate than the reference (~33%) due to severe mask clogging. Furthermore, C3HF5 achieved a 29% faster ON etch rate under high power conditions. It also achieved a 57% faster ON etch rate without excessively compromising selectivity or bow CD expansion after optimization. We report detailed comparisons of etch rate and clogging while controlling the CD profile in the ON stack process.

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Etch characteristics of maskless oxide/nitride/oxide/nitride (ONON) stacked structure using C4H2F6-based gas

Cho,

Hong,

Yoo

et al. 2024

Sci Rep

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Oxide/Nitride/Oxide/Nitride (ONON; SiO 2 /SiN x /SiO 2 /SiN x ) stacked structure is widely used in the 3D vertical structure of semiconductor cells. Previously, to form a 3D cells, photoresist (PR) was patterned and repeatedly trimmed on the top of ONON after the etching of one ON layer. Due to the time-consuming process of etching layer-by-layer of ON layer, two-step etch processing using C 4 F 8 -based or C 4 F 6 -based gases composed of maskless ONON stack feature etching and followed one ON layer-by layer etching by PR trimming in the ONON stack feature are employed these days. However, the two-step etching method resulted in poor etch profiles of maskless ONON stack feature in addition to high global warming potential of C 4 F 8 and C 4 F 6 . In this study, we investigated the etching of maskless ONON stack feature using C 4 H 2 F 6 -based gas having a low global warming potential and the effects of C 4 H 2 F 6 -based gas on the etch characteristics of maskless ONON stack feature such as etch rate, etch profile, change in critical dimensional (CD), and etch selectivity between SiO 2 and SiN x have been investigated. C 4 H 2 F 6 -based gas showed the highest etch rates compared to C 4 F 6 and C 4 F 8 -based gases in addition to the etch selectivity of ~ 1:1 between SiO 2 and SiN x due to hydrogen included in the gas structure. In addition, the change in horizontal CD was lower in the order of C 4 H 2 F 6 , C 4 F 6 , and C 4 F 8 -based gases due to the more effective sidewall passivation in the order of C 4 F 8 , C 4 F 6 , and C 4 H 2 F 6 -based gases. The thicker carbon-based polymer layer on the sidewall also played an important role in maintaining the shape of the top edge shape of maskless ONON stack feature when etching a line feature in an environment without a mask.

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Characteristics of high aspect ratio SiO2 etching using C4H2F6 isomers

Cited by 7 publications

References 45 publications

Atmospheric Gas-Phase Catalyst Etching of SiO₂ for Deep Microfabrication Using HF Gas and Patterned Photoresist

Atmospheric Gas-Phase Catalyst Etching of SiO₂ for Deep Microfabrication Using HF Gas and Patterned Photoresist

High aspect ratio SiO₂/SiN (ON) stacked layer etching using C₃HF₅, C₄H₂F₆, and C₄H₄F₆

Etch characteristics of maskless oxide/nitride/oxide/nitride (ONON) stacked structure using C4H2F6-based gas

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Characteristics of high aspect ratio SiO2 etching using C4H2F6 isomers

Cited by 7 publications

References 45 publications

Atmospheric Gas-Phase Catalyst Etching of SiO2 for Deep Microfabrication Using HF Gas and Patterned Photoresist

Atmospheric Gas-Phase Catalyst Etching of SiO2 for Deep Microfabrication Using HF Gas and Patterned Photoresist

High aspect ratio SiO2/SiN (ON) stacked layer etching using C3HF5, C4H2F6, and C4H4F6

Etch characteristics of maskless oxide/nitride/oxide/nitride (ONON) stacked structure using C4H2F6-based gas

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Product

Resources

About

Atmospheric Gas-Phase Catalyst Etching of SiO₂ for Deep Microfabrication Using HF Gas and Patterned Photoresist

Atmospheric Gas-Phase Catalyst Etching of SiO₂ for Deep Microfabrication Using HF Gas and Patterned Photoresist

High aspect ratio SiO₂/SiN (ON) stacked layer etching using C₃HF₅, C₄H₂F₆, and C₄H₄F₆