Selective etching of silicon nitride over silicon oxide using ClF3/H2 remote plasma

Lee, Won Oh; Kim, Ki‐Hyun; Kim, Doo San; Ji, You Jin; Kang, Ji Eun; Tak, Hyun Woo; Park, Jin Woo; Song, Honghua; Kim, Ki-Seok; Cho, Byeong Ok; Kim, Young Lae; Yeom, Geun Young

doi:10.1038/s41598-022-09252-3

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…The etching rate of SiO x reached a maximum of 940 nm min −1 at 2.5 slm and decreased to 550 nm min −1 with increasing F H from 2.5 to 5 slm. The etching rate of SiN x was lower than that of SiO x , which is different from the conventional dry etching using F-based plasma [18][19][20][21].…”

Section: Effect Of H 2 Flow Rate On Etching Behaviormentioning

confidence: 63%

“…The obtained activation energies were small, comparable, and negative. Several studies on plasma dry etching of SiO x and SiN x films reported that etching rate increased with temperature [10,12,[18][19][20]37]. Meanwhile, the etching rate of Si by H 2 plasma is known to decrease with rising substrate temperature over approximately 70 • C [38].…”

Section: Effects Of Stage Temperature On Etching Behaviormentioning

confidence: 99%

“…This difference in the film bond density may be one reason for the observed etching rate difference between SiO x and SiN x films. For F-based plasma etching [18][19][20], the etching rate of SiN x is higher than that of SiO x because the binding energy of Si-N is much lower than that of Si-O. Etching behavior in H 2 plasma is affected by several elementary processes, such as the adsorption of H atoms, diffusion of H atoms into SiO x /SiN x , and bond breakage by H atoms at the surface and in the bulk of SiO x /SiN x .…”

Section: Effects Of Stage Temperature On Etching Behaviormentioning

confidence: 99%

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High-rate etching of silicon oxide and nitride using narrow-gap high-pressure (3.3 kPa) hydrogen plasma

Nomura,

Kakiuchi,

Ohmi

2024

J. Phys. D: Appl. Phys.

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We investigated the etching behavior of silicon oxide (SiOx) and silicon nitride (SiNx) in narrow-gap, high-pressure (3.3 kPa) hydrogen (H2) plasma under various etching conditions. Maximum etching rates of 940 and 240 nm/min for SiOx and SiNx, respectively, were obtained by optimizing the H2 gas flow rate. The dependence of the etching rate on gas flow rate implied that effective elimination of etching products is important for achieving high etching rates because it prevents redeposition. The sample surfaces, especially the oxide surfaces, were roughened and contained numerous asperities after etching. Etching rates of both SiOx and SiNx decreased as the temperature was raised. This suggests that atomic H adsorption, rather than H-ion bombardment, is an important step in the etching process. X-ray photoelectron spectroscopy revealed that the etched nitride surface was enriched in silicon (Si), suggesting that the rate-limiting process in high-pressure H2 plasma etching is Si etching rather than nitrogen abstraction. The etching rate of SiOx was three times higher than that of SiNx despite the higher stability of Si–O bonds than Si–N ones. One reason for the etching difference may be the difference between the bond densities of SiOx and SiNx. This study presents a relatively non-toxic, low-cost, and eco-friendly dry etching process for Si-based dielectrics using only H2 gas in comparison with the conventional F-based plasma etching methods.

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Section: Effect Of H 2 Flow Rate On Etching Behaviormentioning

confidence: 63%

Section: Effects Of Stage Temperature On Etching Behaviormentioning

confidence: 99%

Section: Effects Of Stage Temperature On Etching Behaviormentioning

confidence: 99%

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High-rate etching of silicon oxide and nitride using narrow-gap high-pressure (3.3 kPa) hydrogen plasma

Nomura,

Kakiuchi,

Ohmi

2024

J. Phys. D: Appl. Phys.

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Highly selective etching of SiN_x over SiO₂ using ClF₃/Cl₂ remote plasma

Yoo

Kang

et al. 2023

Nanotechnology

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Highly selective etching of silicon nitride over silicon oxide is one of the most important processes especially for the fabrication of vertical semiconductor devices including 3D NAND (Not And) devices. In this study, isotropic dry etching characteristics of SiNx and SiO2 using ClF3/Cl2 remote plasmas have been investigated. The increase of Cl2 percent in ClF3/Cl2 gas mixture increased etch selectivity of SiNx over SiO2 while decreasing SiNx etch rate. By addition of 15% Cl2 to ClF3/Cl2, the etch selectivity higher than 500 could be obtained with the SiNx etch rate of ~ 8 nm/min, and the increase of Cl percent to 20% further increased the etch selectivity to higher than 1000. It was found that SiNx can be etched through the reaction from Si-N to Si-F and Si-Cl (also from Si-Cl to Si-F) while SiO2 can be etched only through the reaction from Si-O to Si-F, and which is also in extremely low reaction at room temperature. When SiNx/SiO2 layer stack was etched using ClF3/Cl2(15%), extremely selective removal of SiNx layer in the SiNx/SiO2 layer stack could be obtained without noticeable etching of SiO2 layer in the stack and without etch loading effect.

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Dry etching in the presence of physisorption of neutrals at lower temperatures

Lill

Berry

Shen

et al. 2023

Journal of Vacuum Science &Amp; Technology A

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In this article, we give an overview about the chemical and physical processes that play a role in etching at lower wafer temperatures. Conventionally, plasma etching processes rely on the formation of radicals, which readily chemisorb at the surface. Molecules adsorb via physisorption at low temperatures, but they lack enough energy to overcome the energy barrier for a chemical reaction. The density of radicals in a typical plasma used in semiconductor manufacturing is one to two orders of magnitude lower than the concentration of the neutrals. Physisorption of neutrals at low temperatures, therefore, increases the neutral concentration on the surface meaningfully and contributes to etching if they are chemically activated. The transport of neutrals in high aspect ratio features is enhanced at low temperatures because physisorbed species are mobile. The temperature window of low temperature etching is bracketed at the low end by condensation including capillary effects and diminished physisorption at the high end. The useful temperature window is chemistry dependent. Besides illuminating the fundamental effects, which make low temperature processing unique, this article illustrates its utility for semiconductor etching applications.

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Selective etching of silicon nitride over silicon oxide using ClF3/H2 remote plasma

Cited by 4 publications

References 25 publications

High-rate etching of silicon oxide and nitride using narrow-gap high-pressure (3.3 kPa) hydrogen plasma

High-rate etching of silicon oxide and nitride using narrow-gap high-pressure (3.3 kPa) hydrogen plasma

Highly selective etching of SiN_x over SiO₂ using ClF₃/Cl₂ remote plasma

Dry etching in the presence of physisorption of neutrals at lower temperatures

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Selective etching of silicon nitride over silicon oxide using ClF3/H2 remote plasma

Cited by 4 publications

References 25 publications

High-rate etching of silicon oxide and nitride using narrow-gap high-pressure (3.3 kPa) hydrogen plasma

High-rate etching of silicon oxide and nitride using narrow-gap high-pressure (3.3 kPa) hydrogen plasma

Highly selective etching of SiNx over SiO2 using ClF3/Cl2 remote plasma

Dry etching in the presence of physisorption of neutrals at lower temperatures

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Highly selective etching of SiN_x over SiO₂ using ClF₃/Cl₂ remote plasma