Silicon germanium as a novel mask for silicon deep reactive ion etching

Handle URI:
http://hdl.handle.net/10754/563023
Title:
Silicon germanium as a novel mask for silicon deep reactive ion etching
Authors:
Serry, Mohamed Y.; Rubin, Andrew; Ibrahem, Mohammed Aziz; Sedky, Sherif M.
Abstract:
This paper reports on the use of p-type polycrystalline silicon germanium (poly-Si1-xGex) thin films as a new masking material for the cryogenic deep reactive ion etching (DRIE) of silicon. We investigated the etching behavior of various poly-Si1-xGex:B (0<x<1) thin films deposited at a wide temperature range (250°C to 600°C). Etching selectivity for silicon, silicon oxide, and photoresist was determined at different etching temperatures, ICP and RF powers, and SF6 to O2 ratios. The study demonstrates that the etching selectivity of the SiGe mask for silicon depends strongly on three factors: Ge content; boron concentration; and etching temperature. Compared to conventional SiO2 and SiN masks, the proposed SiGe masking material exhibited several advantages, including high etching selectivity to silicon (>1:800). Furthermore, the SiGe mask was etched in SF6/O2 plasma at temperatures ≥ - 80°C and at rates exceeding 8 μm/min (i.e., more than 37 times faster than SiO2 or SiN masks). Because of the chemical and thermodynamic stability of the SiGe film as well as the electronic properties of the mask, it was possible to deposit the proposed film at CMOS backend compatible temperatures. The paper also confirms that the mask can easily be dry-removed after the process with high etching-rate by controlling the ICP and RF power and the SF6 to O2 ratios, and without affecting the underlying silicon substrate. Using low ICP and RF power, elevated temperatures (i.e., > - 80°C), and an adjusted O2:SF6 ratio (i.e., ~6%), we were able to etch away the SiGe mask without adversely affecting the final profile. Ultimately, we were able to develop deep silicon- trenches with high aspect ratio etching straight profiles. © 1992-2012 IEEE.
KAUST Department:
Advanced Nanofabrication, Imaging and Characterization Core Lab; Core Labs
Publisher:
Institute of Electrical and Electronics Engineers (IEEE)
Journal:
Journal of Microelectromechanical Systems
Issue Date:
Oct-2013
DOI:
10.1109/JMEMS.2013.2269673
Type:
Article
ISSN:
10577157
Appears in Collections:
Articles; Advanced Nanofabrication, Imaging and Characterization Core Lab

Full metadata record

DC FieldValue Language
dc.contributor.authorSerry, Mohamed Y.en
dc.contributor.authorRubin, Andrewen
dc.contributor.authorIbrahem, Mohammed Azizen
dc.contributor.authorSedky, Sherif M.en
dc.date.accessioned2015-08-03T11:33:56Zen
dc.date.available2015-08-03T11:33:56Zen
dc.date.issued2013-10en
dc.identifier.issn10577157en
dc.identifier.doi10.1109/JMEMS.2013.2269673en
dc.identifier.urihttp://hdl.handle.net/10754/563023en
dc.description.abstractThis paper reports on the use of p-type polycrystalline silicon germanium (poly-Si1-xGex) thin films as a new masking material for the cryogenic deep reactive ion etching (DRIE) of silicon. We investigated the etching behavior of various poly-Si1-xGex:B (0<x<1) thin films deposited at a wide temperature range (250°C to 600°C). Etching selectivity for silicon, silicon oxide, and photoresist was determined at different etching temperatures, ICP and RF powers, and SF6 to O2 ratios. The study demonstrates that the etching selectivity of the SiGe mask for silicon depends strongly on three factors: Ge content; boron concentration; and etching temperature. Compared to conventional SiO2 and SiN masks, the proposed SiGe masking material exhibited several advantages, including high etching selectivity to silicon (>1:800). Furthermore, the SiGe mask was etched in SF6/O2 plasma at temperatures ≥ - 80°C and at rates exceeding 8 μm/min (i.e., more than 37 times faster than SiO2 or SiN masks). Because of the chemical and thermodynamic stability of the SiGe film as well as the electronic properties of the mask, it was possible to deposit the proposed film at CMOS backend compatible temperatures. The paper also confirms that the mask can easily be dry-removed after the process with high etching-rate by controlling the ICP and RF power and the SF6 to O2 ratios, and without affecting the underlying silicon substrate. Using low ICP and RF power, elevated temperatures (i.e., > - 80°C), and an adjusted O2:SF6 ratio (i.e., ~6%), we were able to etch away the SiGe mask without adversely affecting the final profile. Ultimately, we were able to develop deep silicon- trenches with high aspect ratio etching straight profiles. © 1992-2012 IEEE.en
dc.publisherInstitute of Electrical and Electronics Engineers (IEEE)en
dc.subjectCryogenic DRIEen
dc.subjectHigh selectivity masken
dc.subjectSilicon etchingen
dc.subjectSilicon germaniumen
dc.titleSilicon germanium as a novel mask for silicon deep reactive ion etchingen
dc.typeArticleen
dc.contributor.departmentAdvanced Nanofabrication, Imaging and Characterization Core Laben
dc.contributor.departmentCore Labsen
dc.identifier.journalJournal of Microelectromechanical Systemsen
dc.contributor.institutionDepartment of Mechanical Engineering, American University in Cairo, Cairo 39827, Egypten
dc.contributor.institutionYousef Jameel Science and Technology Research Center, American University in Cairo, Cairo 39827, Egypten
dc.contributor.institutionZewail City of Science and Technology, Cairo 39827, Egypten
kaust.authorRubin, Andrewen
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