Highly selective and vertical etch of silicon dioxide using ruthenium films as an etch mask

Mitchell, William J.; Thibeault, B.J.; John, Demis D.; Reynolds, T.E.

doi:10.1116/6.0001030

Cited by 12 publications

(16 citation statements)

References 39 publications

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“…For example, mask materials such as ruthenium provide selectivities of over 300 in fluorine plasma when patterning thermal SiO 2 thin films. 72 A targeted discharge of conductive metal masks also shows an influence on the patterning process in current studies. 61…”

Section: Reactive Ion Etching Processmentioning

confidence: 62%

Perspectives of reactive ion etching of silicate glasses for optical microsystems

Weigel

Brokmann

Hofmann

et al. 2021

J. Optical Microsystems

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We provide a review of the latest research findings as well as the future potential of plasma-based etching technology for the fabrication of micro-optical components and systems. Reactive ion etching (RIE) in combination with lithographic patterning is a well-established technology in the field of micro-and nanofabrication. Nevertheless, practical implementation, especially for plasma-based patterning of complex optical materials such as alumino-silicate glasses or glass-ceramics, is still largely based on technological experience rather than established models. Such models require an in-depth understanding of the underlying chemical and physical processes within the plasma and at the glass-plasma/mask-plasma interfaces. We therefore present results that should pave the way for a better understanding of processes and thus for the extension of RIE processes toward innovative three-dimensional (3D) patterning as well as for the processing of chemically and structurally inhomogeneous silicate-based substrates. To this end, we present and discuss the results of a variety of microstructuring strategies for different application areas with a focus on micro-optics. We consider the requirements for refractive and diffractive micro-optical systems and highlight potentials for 3D dry chemical etching by selective tailoring of the material structure. The results thus provide first steps toward a knowledge-based approach to RIE processing of universal dielectric glass materials for optical microsystems, which also has a significant impact on other microscale applications. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Reactive Ion Etching Processmentioning

confidence: 62%

Perspectives of reactive ion etching of silicate glasses for optical microsystems

Weigel

Brokmann

Hofmann

et al. 2021

J. Optical Microsystems

View full text Add to dashboard Cite

show abstract

“…The increased need for etching of HAR structures is driving further mask innovation [ 18 ]. There are many nonidealities which arise due to variations in mask geometry, such as mask erosion and undercutting during etching.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mask Geometry Variation on Plasma Etching Profiles

et al. 2023

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It is becoming quite evident that, when it comes to the further scaling of advanced node transistors, increasing the flash memory storage capacity, and enabling the on-chip integration of multiple functionalities, “there’s plenty of room at the top”. The fabrication of vertical, three-dimensional features as enablers of these advanced technologies in semiconductor devices is commonly achieved using plasma etching. Of the available plasma chemistries, SF6/O2 is one of the most frequently applied. Therefore, having a predictive model for this process is indispensable in the design cycle of semiconductor devices. In this work, we implement a physical SF6/O2 plasma etching model which is based on Langmuir adsorption and is calibrated and validated to published equipment parameters. The model is implemented in a broadly applicable in-house process simulator ViennaPS, which includes Monte Carlo ray tracing and a level set-based surface description. We then use the model to study the impact of the mask geometry on the feature profile, when etching through circular and rectangular mask openings. The resulting dimensions of a cylindrical hole or trench can vary greatly due to variations in mask properties, such as its etch rate, taper angle, faceting, and thickness. The peak depth for both the etched cylindrical hole and trench occurs when the mask is tapered at about 0.5°, and this peak shifts towards higher angles in the case of high passivation effects during the etch. The minimum bowing occurs at the peak depth, and it increases with an increasing taper angle. For thin-mask faceting, it is observed that the maximum depth increases with an increasing taper angle, without a significant variation between thin masks. Bowing is observed to be at a maximum when the mask taper angle is between 15° and 20°. Finally, the mask etch rate variation, describing the etching of different mask materials, shows that, when a significant portion of the mask is etched away, there is a notable increase in vertical etching and a decrease in bowing. Ultimately, the implemented model and framework are useful for providing a guideline for mask design rules.

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“…Surface reactions and topography dependencies are thus a major research focus of modeling [3][4][5][6][7][8][9][10][11]. Additionally, different materials that can be used as thinner and inert masks to improve etch selectivity are being experimentally explored [12].…”

Section: Introductionmentioning

confidence: 99%

3D modeling of feature-scale fluorocarbon plasma etching in silica

et al. 2023

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Fluorocarbon dry etching of vertical silica-based structures is essential to the fabrication of advanced complementary metal-oxide-semiconductor and dynamic random access memory devices. However, the development of etching technology is challenged by the lack of understanding of complex surface reaction mechanisms and by the intricacy of etchant flux distribution on the feature-scale. To study these effects, we present a three-dimensional, TCAD-compatible, feature-scale modeling methodology. The methodology combines a level-set topography engine, Langmuir kinetics surface reaction modeling, and a combination of reactant flux evaluation schemes. We calibrate and evaluate our model to a novel, highly selective, etching process of a $$\mathrm {SiO_2}$$ SiO 2 via and a $$\textrm{Ru}$$ Ru hardmask by $$\mathrm {CF_4/C_4F_8}$$ CF 4 / C 4 F 8 . We adapt our surface reaction model to the novel stack of materials, and we are able to accurately reproduce the etch rates, topography, and critical dimensions of the reported experiments. Our methodology is therefore able to prototype and study novel etching processes and can be integrated into process-aware three-dimensional device simulation workflows.

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Highly selective and vertical etch of silicon dioxide using ruthenium films as an etch mask

Cited by 12 publications

References 39 publications

Perspectives of reactive ion etching of silicate glasses for optical microsystems

Perspectives of reactive ion etching of silicate glasses for optical microsystems

Effect of Mask Geometry Variation on Plasma Etching Profiles

3D modeling of feature-scale fluorocarbon plasma etching in silica

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