Highly Selective Directional Atomic Layer Etching of Silicon

Tan, Samantha; Yang, Wan Suk; Kanarik, Keren J.; Lill, Thorsten; Vahedi, Vahid; Marks, Jeff; Gottscho, Richard A.

doi:10.1149/2.0031506jss

Cited by 44 publications

(30 citation statements)

References 15 publications

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“…It is possible that at the lower temperature the substrate thermally expanded less and therefore resulted in a spacing that was larger than 100μm and promoted more precursor mixing resulting in the higher growth rate. Another possible explanation lies in classical ALD theory, where higher deposition temperatures outside of the 'ALD window' result in desorption of the precursor from the substrate [52][53][54][55]. This phenomena may be more relevant to higher growth rates at 150°C than 200°C for both 30 and 50 mm s −1 oscillation speeds, whereas the anomaly observed at 100°C versus 150°C is most likely due to the previous two explanations.…”

Section: Film Nucleation and Growthmentioning

confidence: 99%

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

et al. 2020

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Atmospheric pressure-spatial atomic layer deposition (AP-SALD) is a promising open-air deposition technique for high-throughput manufacturing of nanoscale films, yet the nucleation and property evolution in these films has not been studied in detail. In this work, in situ reflectance spectroscopy was implemented in an AP-SALD system to measure the properties of Zinc oxide (ZnO) and Aluminum oxide (Al 2 O 3 ) films during their deposition. For the first time, this revealed a substrate nucleation period for this technique, where the length of the nucleation time was sensitive to the deposition parameters. The in situ characterization of thickness showed that varying the deposition parameters can achieve a wide range of growth rates (0.1-3 nm/cycle), and the evolution of optical properties throughout film growth was observed. For ZnO, the initial bandgap increased when deposited at lower temperatures and subsequently decreased as the film thickness increased. Similarly, for Al 2 O 3 the refractive index was lower for films deposited at a lower temperature and subsequently increased as the film thickness increased. Notably, where other implementations of reflectance spectroscopy require previous knowledge of the film's optical properties to fit the spectra to optical dispersion models, the approach developed here utilizes a large range of initial guesses that are inputted into a Levenberg-Marquardt fitting algorithm in parallel to accurately determine both the film thickness and complex refractive index.

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Section: Film Nucleation and Growthmentioning

confidence: 99%

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

et al. 2020

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“…Tan et al developed highly selective and directional ALE of silicon by using plasma assisted chlorine adsorption followed by Ar + ion-assisted etching in a commercial plasma etching chamber [19]. They measured the etching per cycle (EPC) while varying ion-energy.…”

Section: Introductionmentioning

confidence: 99%

Atomic layer etching of silicon dioxide using alternating C₄F₈and energetic Ar⁺plasma beams

Kaler

Lou

Donnelly

et al. 2017

J. Phys. D: Appl. Phys.

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Atomic layer etching (ALE) of SiO 2 was studied by alternating exposure of a 5 nm-thick SiO 2 film on Si substrate to (1) a plasma beam emanating from a cC 4 F 8 inductively coupled plasma (ICP), to grow a fluorocarbon (FC) film composed mainly of CF 2 , and (2) an energetic (130 eV) Ar + ion beam extracted from a separate Ar ICP. In situ x-ray photoelectron spectroscopy was used to analyze the chemical composition of the near-surface region, and to quantify the thickness of the FC and SiO 2 films. A very thin (3-6 Å), near self-limiting thickness CF 2-rich FC film was found to deposit on the SiO 2 surface with exposure to continuous or pulsed power C 4 F 8 plasma beams, under conditions that generated a large relative flux of CF 2. Following this, a FC film of similar composition grew at ~10 times slower rate. Exposure of the thin film to the Ar + beam led to removal of 1.9 Å SiO 2. An estimated yield of 1.3 SiO 2 molecules-per-Ar + was found for a single ALE step. The rate of 1.9 Å/cycle persisted over multiple ALE cycles, but a carbon-rich residual film did build up. This film can be removed by a brief exposure to an O 2-containing plasma beam.

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“…13 The ability to selectively remove one material with respect to another is an additional requirement for anisotropic plasma ALE. 3,4,20 Consequently, there also exists a selectivity window in terms of the ion energy for removing only the targeted material by anisotropic plasma ALE, as listed in Fig. 1(c) for hypothetical examples.…”

Section: Journal Of Applied Physicsmentioning

confidence: 99%

Precise ion energy control with tailored waveform biasing for atomic scale processing

Faraz

Verstappen

Verheijen

et al. 2020

Journal of Applied Physics

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Highly Selective Directional Atomic Layer Etching of Silicon

Cited by 44 publications

References 15 publications

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

Atomic layer etching of silicon dioxide using alternating C₄F₈and energetic Ar⁺plasma beams

Precise ion energy control with tailored waveform biasing for atomic scale processing

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Highly Selective Directional Atomic Layer Etching of Silicon

Cited by 44 publications

References 15 publications

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

Atomic layer etching of silicon dioxide using alternating C4F8and energetic Ar+plasma beams

Precise ion energy control with tailored waveform biasing for atomic scale processing

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Product

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Atomic layer etching of silicon dioxide using alternating C₄F₈and energetic Ar⁺plasma beams