Bosch-like method for creating high aspect ratio poly(methyl methacrylate) (PMMA) structures

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Progress in Biomedical Optics and Imaging - Proceedings of SPIE, ISSN: 1605-7422, Vol: 8248

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Marius Haiducu; Dan Sameoto; Ian Foulds; Robert W. Johnstone; Ash M. Parameswaran; Mary Ann Maher; Paul J. Resnick
SPIE-Intl Soc Optical Eng
Physics and Astronomy; Materials Science; Medicine; Deep-UV patterning; High-aspect ratio structures; MEMS; Microfluidics; Poly(methyl methacrylate) (PMMA)
conference paper description
This paper presents a method for etching millimetre-deep trenches in commercial grade PMMA using deep-UV at 254 nm. The method is based on consecutive cycles of irradiation and development of the exposed areas, respectively. The exposure segment is performed using an inexpensive, in-house built irradiation box while the development part is accomplished using an isopropyl alcohol (IPA):H2O developer. The method was tested and characterized by etching various dimension square test structures in commercial grade, mirrored acrylic. The undercut of the sidewalls due to the uncollimated nature of the irradiation light was dramatically alleviated by using a honeycomb metallic grid in between the irradiation source and the acrylic substrate and by rotating the latter using a direct current (DC) motor-driven stage. By using an extremely affordable set-up and non-toxic, environmentally friendly materials and substances, this process represents an excellent alternative to microfabricating microfluidic devices in particular and high aspect ratio structures in general using PMMA as substrate. © 2012 SPIE.