title: Silicon etching using only Oxygen at high temperature: An alternative approach to Si micro-machining on 150 mm Si wafers.
abstract: Using a combination of low-pressure oxygen and high temperatures, isotropic and anisotropic silicon (Si) etch rates can be controlled up to ten micron per minute. By varying the process conditions, we show that the vertical-to-lateral etch rate ratio can be controlled from 1:1 isotropic etch to 1.8:1 anisotropic. This simple Si etching technique combines the main respective advantages of both wet and dry Si etching techniques such as fast Si etch rate, stiction-free, and high etch rate uniformity across a wafer. In addition, this alternative O2-based Si etching technique has additional advantages not commonly associated with dry etchants such as avoiding the use of halogens and has no toxic by-products, which improves safety and simplifies waste disposal. Furthermore, this process also exhibits very high selectivity (>1000:1) with conventional hard masks such as silicon carbide, silicon dioxide and silicon nitride, enabling deep Si etching. In these initial studies, etch rates as high as 9.2 μm/min could be achieved at 1150 °C. Empirical estimation for the calculation of the etch rate as a function of the feature size and oxygen flow rate are presented and used as proof of concepts.
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: Jessica
authors.initials: J
authors.lastname: Chai
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: Glenn
authors.initials: G
authors.lastname: Walker
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Massoubre
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: Say Hwa
authors.initials: SH
authors.lastname: Tan
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: Kien
authors.initials: K
authors.lastname: Chaik
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: Leonie
authors.initials: L
authors.lastname: Hold
authors.affiliation: Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, 4111 QLD, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Iacopi