Surface Morphology Control of Passivated Porous Silicon Using Reactive Ion Etching

• Published in: Journal of microelectromechanical systems Vol. 21; no. 3; pp. 756 - 761
• Main Authors: Meifang Lai, Parish, G., Yinong Liu, Keating, A. J.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2012; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Annealing; Chemistry; Cross-disciplinary physics: materials science; rheology; Etching; Exact sciences and technology; General and physical chemistry; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Materials science; Mechanical instruments, equipment and techniques; Microelectromechanical systems; Micromechanical devices and systems; Passivation; Physics; Porous silicon; porous silicon (PS); Reactive ion etching; reactive ion etching (RIE); Silicon; Silicon oxynitride; Surface chemistry; Surface morphology; Surface physical chemistry; Surface roughness; Surface treatments; porous silicon (PS); Porous materials; Roughness; Surface chemistry; Etching rate; surface morphology; Chemical etching; Steady state; Surface states; Reactive ion etching; reactive ion etching (RIE); Height; Silicon; Microelectromechanical device; Low temperature; Passivation
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2011.2182501

In this paper, reactive ion etching of porous silicon (PS) passivated using a low-temperature anneal in N 2 atmosphere is studied. The average etch rates of both as-fabricated PS and passivated PS required tens of seconds to stabilize due to plasma initialization. The steady-state etch rate of our passivated PS was lower than that of the as-fabricated PS, due to the change in the surface chemistry caused by the passivation process. Depending on etch conditions, the PS surface can be made smooth or rough with features up to 600 nm in height. Feature height could be controlled via the etching time, and their composition could be changed from an oxide-rich silicon oxynitride to pure silicon, depending on the etching conditions.