High-Definition Nanoimprint Stamp Fabrication by Atomic Layer Etching

Khan, Sabbir Ahmed; Suyatin, Dmitry; Sundqvist, Jonas; Graczyk, Mariusz; Junige, Marcel; Kauppinen, Christoffer; Kvennefors, Anders; Huffman, Maria; Maximov, Ivan

doi:10.1021/acsanm.8b00509

Cited by 8 publications

(4 citation statements)

References 30 publications

(52 reference statements)

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“…( 18) and (1) into Eq. (17). For the completion of this part, the action of L H and L D on ρ(t) can be directly calculated in the form of a matrix due to the powerful capability of MATLAB to deal with matrixes.…”

Section: Discussionmentioning

confidence: 99%

“…However, ALD is generally applied to large-area deposition and is difficult to use in the fabrication of ACS features. Similar to ALD, thermal atomic layer etching (ALE) [12,13] and plasma-assisted ALE [14][15][16][17][18] were proposed to remove silicon atoms layer by layer, in which heat or plasma was used to remove the atoms modified by precursors. Nevertheless, the spatial distributions of temperature and plasma energy are difficult to control with high precision.…”

Section: Introductionmentioning

confidence: 99%

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Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Wang

2021

Nanomanuf Metrol

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This paper presents a new approach for material removal on silicon at atomic and close-to-atomic scale assisted by photons. The corresponding mechanisms are also investigated. The proposed approach consists of two sequential steps: surface modification and photon irradiation. The back bonds of silicon atoms are first weakened by the chemisorption of chlorine and then broken by photon energy, leading to the desorption of chlorinated silicon. The mechanisms of photon-induced desorption of chlorinated silicon, i.e., SiCl2 and SiCl, are explained by two models: the Menzel–Gomer–Redhead (MGR) and Antoniewicz models. The desorption probability associated with the two models is numerically calculated by solving the Liouville–von Neumann equations for open quantum systems. The calculation accuracy is verified by comparison with the results in literatures in the case of the NO/Pt (111) system. The calculation method is then applied to the cases of SiCl2/Si and SiCl/Si systems. The results show that the value of desorption probability first increases dramatically and then saturates to a stable value within hundreds of femtoseconds after excitation. The desorption probability shows a super-linear dependence on the lifetime of excited states.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Wang

2021

Nanomanuf Metrol

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“…In contrast, dry, gas-phase methods can achieve distortion-free profiles for miniaturized, high-density patterns. Anisotropic, vertical pattern transfer relies on directional reactive ion etching using plasmas. − However, ion etching typically roughens and damages the surface to depths of several nanometers. , In contrast, thermally activated dry etching processes yield minimal damage to underlying materials.…”

Section: Introductionmentioning

confidence: 99%

Selectivity between SiO₂ and SiN_x during Thermal Atomic Layer Etching Using Al(CH₃)₃/HF and Spontaneous Etching Using HF and Effect of HF + NH₃ Codosing

Junige,

George

2024

Chem. Mater.

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Selectivity was examined between SiO 2 and SiN x during thermal atomic layer etching (ALE) and spontaneous etching. Thermal ALE of SiO 2 and SiN x was explored using sequential trimethylaluminum (TMA) and hydrogen fluoride (HF) with reactant exposures of 3 Torr for 45 s at 275 °C. SiO 2 thermal ALE achieved an etch per cycle (EPC) of 0.20 Å/cycle and near-ideal synergy up to 95%. SiN x thermal ALE exhibited a higher EPC of 1.06 Å/cycle. The selectivity factor was ∼5:1 for SiN x etching compared to SiO 2 etching (preferential SiN x removal) during thermal ALE using TMA and HF. Spontaneous etching was then quantified using repeated exposures of HF vapor alone at 3 Torr and 275 °C. SiO 2 spontaneous etching was minor at an etch rate of 0.03 Å/min, enabling near-ideal synergy for SiO 2 thermal ALE. In contrast, major SiN x spontaneous etching displayed an etch rate of 1.72 Å/min and predominated over SiN x thermal ALE. The selectivity factor was ∼50:1 for SiN x spontaneous etching compared to SiO 2 spontaneous etching using an HF pressure of 3 Torr. This selective SiN x spontaneous etching was attributed to F − surface species during HF exposures. NH 3 codosing with HF was then examined during thermal ALE and spontaneous etching. Thermal ALE of SiO 2 and SiN x was examined using sequential TMA and HF + NH 3 codosing with reactant exposures of 3 Torr for 45 s at 275 °C. SiO 2 thermal ALE with HF + NH 3 codosing had a high EPC of 8.83 Å/cycle. In contrast, SiN x thermal ALE with HF + NH 3 codosing was negligible. The selectivity factor was reversed and much higher at >1000:1 for SiO 2 etching compared to SiN x etching (preferential SiO 2 removal) during thermal ALE with HF + NH 3 codosing. Rapid SiO 2 spontaneous etching with HF + NH 3 codosing at 3 Torr had an etch rate of 27.50 Å/min. In contrast, SiN x spontaneous etching with HF + NH 3 codosing produced a very low etch rate of 0.02 Å/min. The selectivity factor was >1000:1 for SiO 2 spontaneous etching compared to SiN x spontaneous etching with HF + NH 3 codosing. This selective SiO 2 spontaneous etching was attributed to HF 2 − surface species during HF + NH 3 exposures. These studies revealed that the NH 3 coadsorbate during HF exposures modified the active etch species and dramatically influenced the etch selectivity between SiO 2 and SiN x . Reciprocal etch selectivity should be important for the selective removal of SiO 2 or SiN x in composite structures.

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“…Isotropic ALE is deemed essential for patterning of the gate spacer in future gate-all-around FETs where highly selective and conformal material removal is required . Moreover, isotropic ALE has been proposed for achieving high-resolution nanoimprint lithography and lateral etching in 3D-NAND flash memories fabrication . ALE has also great potential in replacing wet etching processes where the liquid etchants with their critical surface tensions may cause capillary effects that make nanometer-sized patterns collapse .…”

Section: Introductionmentioning

confidence: 99%

Isotropic Atomic Layer Etching of ZnO Using Acetylacetone and O₂ Plasma

Mameli

Verheijen

Mackus

et al. 2018

ACS Appl. Mater. Interfaces

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Atomic layer etching (ALE) provides Ångström-level control over material removal and holds potential for addressing the challenges in nanomanufacturing faced by conventional etching techniques. Recent research has led to the development of two main classes of ALE: ion-driven plasma processes yielding anisotropic (or directional) etch profiles and thermally driven processes for isotropic material removal. In this work, we extend the possibilities to obtain isotropic etching by introducing a plasma-based ALE process for ZnO which is radical-driven and utilizes acetylacetone (Hacac) and O2 plasma as reactants. In situ spectroscopic ellipsometry measurements indicate self-limiting half-reactions with etch rates ranging from 0.5 to 1.3 Å/cycle at temperatures between 100 and 250 °C. The ALE process was demonstrated on planar and three-dimensional substrates consisting of a regular array of semiconductor nanowires (NWs) conformally covered using atomic layer deposition of ZnO. Transmission electron microscopy studies conducted on the ZnO-covered NWs before and after ALE proved the isotropic nature and the damage-free characteristics of the process. In situ infrared spectroscopy measurements were used to elucidate the self-limiting nature of the ALE half-reactions and the reaction mechanism. During the Hacac etching reaction that is assumed to produce Zn(acac)2, carbonaceous species adsorbed on the ZnO surface are suggested as the cause of the self-limiting behavior. The subsequent O2 plasma step resets the surface for the next ALE cycle. High etch selectivities (∼80:1) over SiO2 and HfO2 were demonstrated. Preliminary results indicate that the etching process can be extended to other oxides such as Al2O3.

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High-Definition Nanoimprint Stamp Fabrication by Atomic Layer Etching

Cited by 8 publications

References 30 publications

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Selectivity between SiO₂ and SiN_x during Thermal Atomic Layer Etching Using Al(CH₃)₃/HF and Spontaneous Etching Using HF and Effect of HF + NH₃ Codosing

Isotropic Atomic Layer Etching of ZnO Using Acetylacetone and O₂ Plasma

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High-Definition Nanoimprint Stamp Fabrication by Atomic Layer Etching

Cited by 8 publications

References 30 publications

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Selectivity between SiO2 and SiNx during Thermal Atomic Layer Etching Using Al(CH3)3/HF and Spontaneous Etching Using HF and Effect of HF + NH3 Codosing

Isotropic Atomic Layer Etching of ZnO Using Acetylacetone and O2 Plasma

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Selectivity between SiO₂ and SiN_x during Thermal Atomic Layer Etching Using Al(CH₃)₃/HF and Spontaneous Etching Using HF and Effect of HF + NH₃ Codosing

Isotropic Atomic Layer Etching of ZnO Using Acetylacetone and O₂ Plasma