Javaneh Boroumand Azad, Imen Rezadad, Robert E. Peale, Justin W. Cleary, and Kurt Eyink
Process heating of microelectromechanical
systems (MEMSs) devices hardens polyimide sacrificial layers,
complicating the final release and lowering yield for delicate
structures. This paper reports ultraviolet (UV)-assisted release,
which is demonstrated on an MEMS cantilever fabricated
by an eight-mask photolithographic process. A commercial
co-developable polyimide ProLift 100 (Brewer Science) sacrificial
layer was used. The process subjects the device to multiple heat
treatment steps. Both wet chemical etching and dry reactive
ion etching were explored. During the former, large sheets of
hardened polyimide floated free of the substrate to damage
delicate MEMS structures. The latter is typically slow, so
that grass appears during long exposures to plasma ions. The
solution reported here is UV exposure prior to release. Optical
constants of the sacrificial layer material, which were baked to
simulate thermal histories during various fabrication steps, were
measured to understand the effectiveness of UV exposure. Wet
and dry etch rates were measured as a function of UV dose.
Finally, the advantages of UV pretreatment were demonstrated
during the release of actual MEMS cantilevers.
Ultraviolet-Assisted Release of Microelectromechanical Systems From Polyimide Sacrificial Layer
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Javaneh Boroumand Azad, Imen Rezadad, Robert E. Peale, Justin W. Cleary, and Kurt Eyink, Ultraviolet-Assisted Release of Microelectromechanical Systems From Polyimide Sacrificial Layer, J. Microelectricalmechanical Systems 24(6) 2027-2032 (2015).
Farnood Khalilzadeh-Rezaie, Christian W. Smith, Janardan Nath, Nima Nader, Monas Shahzad, Justin W. Cleary, Ivan Avrutsky, and Robert E. Peale, Infrared surface polaritons on bismuth, J. Nanophotonics 9, 093792 (2015).
Deep Panjwani, Mehmet Yesiltas, Janardan Nath, D. E. Maukonen, Imen Rezadad, Evan M. Smith, R. E. Peale, Miriam Unger, Julia Sedlemair, Ralf Wehlitz, Carol Hirschmugl, Glenn Boreman, Patterning of oxide-hardened gold black by photolithography and metal lift-off, Infrared Physics & Technology 62, 94-99 (2014).
Janardan Nath, Evan Smith, Douglas Maukonen, and Robert E. Peale, Optical Salisbury screen with design-tunable resonant absorption bands, J. Applied Physics 115, 193103 (2014).
D. Panjwani, M. Yesiltas, S. Singh, E.D. Barco, R.E. Peale, C. Hirschmugl, J. Sedlemair, Stencil lithography of gold-black IR absorption coatings, Infrared Physics & Technology 66, 1-5 (2014), doi:http://dx.doi.org/10.1016/j.infrared.2014.05.002
Imen Rezadad, Javaneh Boroumand, Evan M. Smith, and Robert E. Peale, Micro electro mechanical cantilever with electrostatically controlled tip contact, Appl. Phys. Lett. 105, 033514 (2014) http://dx.doi.org/10.1063/1.4891496.
N. Nader Esfahani, R. E. Peale, W. R. Buchwald, C. J. Fredricksen, J. R. Hendrickson, and J. W. Cleary, Millimeter-wave photoresponse due to excitation of two-dimensional plasmons in InGaAs/InP high-electron-mobility transistors, J. Appl. Phys. 114, 033105 (2013).
Justin W. Cleary, Gautam Medhi, Monas Shahzad, Imen Rezadad, Doug Maukonen, Robert E. Peale, Glenn D. Boreman, Sandy Wentzell, and Walter R. Buchwald, Infrared surface polaritons on antimony, Optics Express 20 (3), 2693-2705 (2012).