The CORE Sequence: A Nanoscale Fluorocarbon-Free Silicon Plasma Etch Process Based on SF6/O2 Cycles with Excellent 3D Profile Control at Room Temperature

Vy Thi Hoang Nguyen, Chantal Silvestre, Peixiong Shi, Roy Cork, Flemming Jensen, Jorg Hubner, Kechun Ma, Pele Leussink, Meint de Boer, Henri Jansen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

This study focuses on the development of a fluorocarbon-free directional silicon etching process, called CORE (Clear, Oxidize, Remove, and Etch) in which a switching sequence of SF6 and O2 is operated at room temperature. This distinguishes it from the
old-fashioned room temperature and cryogenic mixed RIE processes as CORE enables a higher selectivity, creates pattern
independency of etching profiles and works excellent at room temperature. The CORE process resembles the well-known
SF6-based Bosch process, but the usual C4F8 inhibitor is replaced by O2 oxidation with self-limiting characteristics. Therefore the
CORE result is similar to Bosch, however has the advantage of preventing the pile-up of fluorocarbon deposits at the topside of
deep-etched or nano-sized features. At the same time, process drift is minimized as the reactor wall is staying perfectly clean. The CORE process has shown an excellent performance in high aspect ratio (3D) nanoscale structures with an accurate and controllable etch rate between 1 and 50 nm min−1 (and SiO2-selectivity of ca. 35) using the etch-tool in the RIE-mode. By adding the ICP source (DRIE-mode), a directional etch rate up to 1 μm min−1 (at 50 sccm SF6 flow) and selectivity >200 for SiO2 is possible.
Original languageEnglish
Article number024002
JournalECS Journal of Solid State Science and Technology
Volume9
Issue number2
Number of pages14
ISSN2162-8769
DOIs
Publication statusPublished - 2020

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