Low damage patterning of In<sub>0.53</sub>Ga<sub>0.47</sub>As film for its integration as n-channel in a fin metal oxide semiconductor field effect transistor architecture

Journal of Vacuum Science &Amp; Technology A

Pargon

2022

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In this study, we have performed a thorough characterization of the GaN surface after etching up to 100 nm in Cl2 plasma under various bias voltages and according to the carrier wafer used (Si, SiO2, Si3N4, and photoresist). The objective of this article is to evaluate the etch damage and contamination of the GaN surface when materials with other chemical nature are present during etching. The effects of etching conditions on surface morphology and chemical compositions of etched GaN films are studied in detail using XPS and AFM measurements. To this aim, a universal methodology is proposed to estimate accurately by XPS the stoichiometry of the GaN surface exposed to reactive plasmas when only an Al Kα x-ray source is available. The results indicate that the GaN etching mechanisms are very sensitive to the chlorine radical density present in the plasma, the latter being strongly influenced by the carrier wafer. Substrates that are more chemically reactive with Cl2 plasma such as silicon or photoresist compared to SiO2 or Si3N4 will lead to a greater loading of atomic chlorine, which in turn will lead to lower GaN etch rates. Moreover, the GaN surface contamination will depend on the etch by-products ejected by the carrier wafer. The GaN surface exposed to Cl2 plasma shows a Ga-depleted surface because of the more important reactivity of Cl with Ga rather than N, except in the SiO2 carrier wafer case. In this latter case, the formation of Ga–O bond limits the Ga removal. Regarding the surface roughness, it seems that the contaminants play a little role in the roughness formation except for the oxygen released by the SiO2 carrier wafer. On the other hand, the surface roughness evolution is clearly driven by the chlorine radical flux reaching the GaN surface. At low bias voltage, a preferential crystalline orientation etching driven by the Cl radicals leads to the formation of hexagonal shaped defects that are associated to screw-type threading dislocations already present in the pristine GaN material. At higher bias, the enlargement of the defects is limited, leading to a very low surface roughness value but to amorphized surfaces.

Section: Introductionmentioning

confidence: 99%

Influence of the carrier wafer during GaN etching in Cl2 plasma

Meyer

Journal of Vacuum Science &Amp; Technology A

Pargon

2022

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“…The oxidation of InGaAs after He implantation has also been observed in relatively similar conditions by Bizouerne and co-workers. 29 They explained that if contaminants are present in…”

Section: Journal Of Applied Physicsmentioning

confidence: 99%

Two-step cycling process alternating implantation and remote plasma etching for topographically selective etching: Application to Si3N4 spacer etching

Renaud

Journal of Applied Physics

Barnes

et al. 2019

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This article proposes an original method to achieve topographically selective etching. It relies on cycling a two-step process comprising a plasma implantation step and a removal etching step using remote plasma source process. Both steps can be achieved in the same reactor prototype chamber, which has the capability to produce both capacitively coupled plasma and remote plasma (RP) discharges. It is shown that in RP processes, an incubation time exists before the etching starts. The introduction of a plasma implantation step prior to the RP step allows us to selectively functionalize the horizontal surfaces of the material with respect to the vertical surfaces, thanks to the ion directionality. The modifications induced by the implantation allow us to modify the incubation time between an implanted and a nonimplanted material offering a process window with infinite etch selectivity between horizontal and vertical surfaces. This approach has been demonstrated on Si 3 N 4 blanket films with the perspective to be applied to the Si 3 N 4 spacer etching process in which etch selectivity is a key issue. For this particular application, a cycling process comprising an H 2 plasma implantation and a He/NH 3 /NF 3 remote plasma process has been developed. The H 2 implantation modifies the Si 3 N 4 surface state by incorporating oxygen contaminants coming from the reactor wall and creating dangling bonds. This surface functionalization considerably reduces the incubation time. New insights into the etching mechanisms of Si 3 N 4 films exposed to NH 3 /NF 3 remote plasma are proposed and explain why the presence of Si-O bonds is mandatory for the initiation of the etching.

“…The carrier wafer temperature and the reactor body are maintained at 60 and 65 °C, respectively. More detail about the experimental setup can be found in the literature . Samples were patched on 300 mm Si wafers with Kapton adhesive tape.…”

Section: Methodsmentioning

confidence: 99%

“…More detail about the experimental set-up can be found in the litterature. 13 Samples were patched on 300 mm Si wafers with Kapton® adhesive tape. Chamber conditioning starts with a wafer-less clean: NF3/Cl2 for 45 s, Cl2/O2/Ar for 45 s, and O2 for 30 s. For H2/N2 experiments, the clean is followed by a 300s-long H2/N2 conditioning plasma on Si blanket wafer.…”

Section: Plasma Etchmentioning

confidence: 99%

Dry-Etching Processes for High-Aspect-Ratio Features with Sub-10 nm Resolution High-χ Block Copolymers

Pound-Lana

Bézard

ACS Appl. Mater. Interfaces

et al. 2021

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Directed self-assembly of block copolymers (BCP) is a very attractive technique for the realization of functional nanostructures at high resolution. In this work, we developed full dry-etching strategies for BCP nanolithography using an 18-nm pitch lamellar silicon-containing block copolymer. Both an oxidizing Ar/O2 plasma and a non-oxidizing H2/N2 plasma are used to remove the topcoat material of our BCP stack and reveal the perpendicular lamellae. Under Ar/O2 plasma, an interfacial layer stops the etch process at the top-coat/BCP interface, which provides an etch-stop but also requires an additional CF4-based breakthrough plasma for further etching. This interfacial layer is not present in H2/N2. Increasing the H2/N2 ratio leads to more profound modifications of the silicon-containing lamellas, for which a chemistry in He/N2/O2 rather than Ar/O2 plasma produces a smoother and more regular lithographic mask. Finally, these features are successfully transferred into silicon, silicon-on-insulator and silicon nitride substrates. This work highlights the performance of a silicon-containing block-copolymer at 18 nm pitch to pattern relevant hardmask materials for various applications, including microelectronics.