Gate spacers etching of Si3N4 using cyclic approach for 3D CMOS devices

Bacquié, Valentin; Tavernier, Aurélien; Boulard, F.; Pollet, Olivier; Possémé, N.

doi:10.1116/6.0000871

Cited by 4 publications

(4 citation statements)

References 39 publications

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“…What is specific to Si3N4 in comparison of Si, SiO2 or SiCO to explain that etching is favored over silicon oxifluoride deposition? The larger Si-O (800 kJ.mol -1 ) than Si-N (437 kJ.mol -1 ) bond energy 27 is sometimes assumed as the cause of etch selectivity 15,21,28 .…”

Section: Discussionmentioning

confidence: 99%

“…As there is a significant SiOxFy deposition when landing on c-Si of the active, some oxide accumulation might occur around the active corner and prevent parasitic spacer etch removal on 3D architectures. Thus, the necessity to cycle the SiCl4-based etch process with a carefully designed oxide etch step in order to overcome this issue has been demonstrated recently 7 , followed by process development and optimization of this etching sequence 15 . However, mechanisms of SiOxFy selective deposition on c-Si and SiO2 while Si3N4 is etched remain unclear.…”

Section: Introductionmentioning

confidence: 99%

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Role of SiCl4 addition in CH3F/O2 based chemistry for Si3N4 etching selectively to SiO2, SiCO, and Si

Boulard

Bacquié

Tavernier

et al. 2023

Journal of Vacuum Science &Amp; Technology A

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Dry etching of amorphous silicon nitride (Si3N4) selectively toward silicon dioxide (SiO2), silicon oxicarbide (SiCO), and crystalline silicon (c-Si) in an inductive coupled plasma reactor using CHF3/O2/He chemistry with SiCl4 addition is studied. Plasma exposure of c-Si, SiO2, and SiCO leads to an oxifluoride deposition. The deposition rate is the same for all these materials and increases linearly with the amount of SiCl4 added. On the other hand, Si3N4 etching is observed at very small amount of SiCl4 added (2 SCCM), while oxide deposition takes place at higher SiCl4 flow (10 SCCM). Quasi- in situ angle resolved x-ray photoelectron spectroscopy investigation shows oxifluoride SiOxFy deposition on c-Si and SiCO, while a thin F-rich reactive layer is observed on Si3N4. The oxidation of the Si3N4 surface with O2 plasma prior to CHF3/O2/He with small SiCl4 addition plasma treatment showed that the oxidation state plays a significant role in the etching/deposition equilibrium. In addition, it is found that oxifluoride deposition on Si3N4 is driven by ion energy, with deposition observed at 0 V substrate bias voltage, while etching is observed for values higher than 150 V. All these results show that a competition takes place between silicon oxifluoride deposition and etching, depending on the substrate material, surface oxidation, and ion energy. Based on the additional optical emission spectroscopy data, we proposed insights to explain the different etching and deposition behaviors observed. It is focused on the crucial role of ion energy and the nitrogen presence in Si3N4 leading to the formation of CN and HCN, helping to get a thinner reactive layer and to evacuate etch by-products on Si3N4 while an oxifluoride buildup on the other materials takes place.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of SiCl4 addition in CH3F/O2 based chemistry for Si3N4 etching selectively to SiO2, SiCO, and Si

Boulard

Bacquié

Tavernier

et al. 2023

Journal of Vacuum Science &Amp; Technology A

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“…At the same time, it provides excellent coverage in field-effect transistors while maintaining its good carrier mobility [10,11]. With the development of technology, researches on Si 3 N 4 have became more mature, the current technology can make good use of it chemistry has high directivity and high selectivity to Si and SiO2 [12], it might be a good substitute of SiO2 for gate dielectric.…”

Section: Relevant Theoriesmentioning

confidence: 99%

Investigating the inhibition of short channel effects using different materials of gate insulator layers in FinFET

2024

ACE

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As the evolution of FinFET technology continues, traditional gate insulator materials, such as SiO2, face challenges in meeting the demands of modern applications, especially when it comes to gate leakage current control. Emerging as promising contenders to replace SiO2, materials with higher dielectric constants, notably HfO2 and Si3N4, are drawing significant attention in the semiconductor community. Leveraging the advanced capabilities of tools like Silvaco TCAD, an in-depth analysis was conducted to compare the performance and gate leakage current control abilities of SiO2, HfO2, and Si3N4, utilizing the Quantum examples 3D FinFET model. The findings not only highlight the potential of HfO2 and Si3N4 as worthy replacements for SiO2 but also accentuate the distinct advantages of SiO2, making it particularly well-suited as a substitute. This exploration goes beyond a mere comparison of materials. It dives deep into understanding their behaviors under various operational conditions, laying a foundation for potential breakthroughs and fostering the next wave of innovations in semiconductor technology.

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“…The Si 3 N 4 spacer around the fin made of Si is required to be etched without loss of the fin. [9][10][11] Here, it is necessary to preserve the Si 3 N 4 around the dummy gate without etching it. Isotropic Si 3 N 4 etching causes loss of Si 3 N 4 spacer around the dummy gate; therefore, anisotropic etching using ion energy must be applied for the Si 3 N 4 spacer etching.…”

Section: Introductionmentioning

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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Gate spacers etching of Si3N4 using cyclic approach for 3D CMOS devices

Cited by 4 publications

References 39 publications

Role of SiCl4 addition in CH3F/O2 based chemistry for Si3N4 etching selectively to SiO2, SiCO, and Si

Role of SiCl4 addition in CH3F/O2 based chemistry for Si3N4 etching selectively to SiO2, SiCO, and Si

Investigating the inhibition of short channel effects using different materials of gate insulator layers in FinFET

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

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Gate spacers etching of Si3N4 using cyclic approach for 3D CMOS devices

Cited by 4 publications

References 39 publications

Role of SiCl4 addition in CH3F/O2 based chemistry for Si3N4 etching selectively to SiO2, SiCO, and Si

Role of SiCl4 addition in CH3F/O2 based chemistry for Si3N4 etching selectively to SiO2, SiCO, and Si

Investigating the inhibition of short channel effects using different materials of gate insulator layers in FinFET

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

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Product

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About

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