Abstract
For decades, fabrication of semiconductor devices has utilized well-established etching techniques to create complex nanostructures in silicon. The most common dry process is reactive ion etching which fabricates nanostructures through the selective removal of unmasked silicon. Generalized enhancements of etching have been reported with mask-enhanced etching with Al, Cr, Cu, and Ag masks, but there is a lack of reports exploring the ability of metallic films to catalytically enhance the local etching of silicon in plasmas. Here, metal-assisted plasma etching (MAPE) is performed using patterned nanometers-thick gold films to catalyze the etching of silicon in an SF6/O2 mixed plasma, selectively increasing the rate of etching by over 1000%. The catalytic enhancement of etching requires direct Si-metal interfacial contact, similar to metal-assisted chemical etching (MACE), but is different in terms of the etching mechanism. The mechanism of MAPE is explored by characterizing the degree of enhancement as a function of Au catalyst configuration and relative oxygen feed concentration, along with the catalytic activities of other common MACE metals including Ag, Pt, and Cu.
Highlights
Introduction etching of Si andSiO2 using Al, Cr, Cu, and Ag masks is known in fluorine-containing etch chemistries.[21,22,23,24]The increased etch rates for Si with metal masking are attrib-Silicon (Si) has long been the cornerstone material in the uted to increases in the concentration of fluorine radicals in the modern semiconductor industry, establishing a wealth of fabri- plasma surrounding the metal due to the catalytic production of cation techniques in Si nanoprocessing
We demonstrate that metal-assisted plasma etching (MAPE) necessarily relies on direct Si contact with the nanometers-thick metal, does not increase the etch rate of proximal Si, and provides an increase of the etch rate on par with that of metal-assisted chemical etching (MACE)
To explore the process of MAPE in SF6-based plasmas, nanoand microstructure arrays were patterned using electron beam www.advmatinterfaces.de and phase shift lithography on n-type and p-type (100) silicon substrates with resistivity 1–10 Ω cm
Summary
To explore the process of MAPE in SF6-based plasmas, nanoand microstructure arrays were patterned using electron beam www.advmatinterfaces.de and phase shift lithography on n-type and p-type (100) silicon substrates with resistivity 1–10 Ω cm. A thin Au layer was deposited between two layers of Cr to create a sandwich architecture (10 nm Cr/5 nm Au/10 nm Cr), isolating the catalytic layer and preventing its contact with the underlying Si. The etched Si substrates exhibited a notable decrease in MAPE with many Si areas forming pillars underneath the nanostructures, some regions still form the unmistakable cavities from enhanced etching (Figure 1g). The degree of enhancement depends on the amount of catalytic Au present, suggesting that Au is consumed during the process of MAPE via secondary mechanisms that are present in addition to Si etching; Au may diffuse into the Si, undergo a chemical reaction that likely creates gold oxides and fluorides, or be sputtered and etched away by the high-energy plasma In these experiments, the amount of remaining Au measured on the Si substrates following etching was less than the detection limit for energy-dispersive X-ray spectroscopy. The Au in direct contact with Si actively promotes enhanced etching in SF6/O2 plasmas
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
