Development of an Alkaline-Compatible Porous-Silicon Photolithographic Process

A technique for masking porous-silicon (PS) films by optical photolithography without significant film degradation is demonstrated for the first time. The chemical resistance of the PS films is achieved by low-temperature passivation via nitrogen annealing. The effect of the various photolithographi...

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Bibliographic Details
Published in:Journal of microelectromechanical systems 2011-04, Vol.20 (2), p.418-423
Main Authors: Meifang Lai, Parish, G, Yinong Liu, Dell, J M, Keating, A J
Format: Article
Language:English
Subjects:
Alkaline developer
Annealing
Applied sciences
Degradation
Electronics
Exact sciences and technology
Fourier transforms
Masking
Microelectronic fabrication (materials and surfaces technology)
Optical device fabrication
Optical imaging
Optical refraction
Optical sensors
Optical variables control
passivation
Photolithography
Photoresists
Polymers
Polystyrene resins
porous silicon (PS)
Protective
Reduction
Resists
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Silicon
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Summary:A technique for masking porous-silicon (PS) films by optical photolithography without significant film degradation is demonstrated for the first time. The chemical resistance of the PS films is achieved by low-temperature passivation via nitrogen annealing. The effect of the various photolithographic process steps is investigated by determining the changes in the optical properties of the films. The passivated PS films are shown to be resistant to strong alkaline-based solutions (dilute AZ400K developer) for up to 100 s with minimal reduction in optical thickness. Fourier transform infrared and spectral reflectance measurements show that the passivated PS films are relatively unaffected by a complete photolithography process, apart from the seepage of photoresist into the pores, which can be prevented by applying a thin protective polymer layer. Metal was deposited and patterned via the standard liftoff process on PS surface to demonstrate the feasibility of this technique.
ISSN:1057-7157
1941-0158
DOI:10.1109/JMEMS.2011.2111356