<P> It can be made into a viscous polymer that can be spun or spread over a thickness ranging from below 1 micrometer up to above 300 micrometers, or Thick Film Dry Sheets (TFDS) for lamination up to above 1 millimetre thick . Up to 500μm the resist can be processed with standard contact lithography . Above 500μm absorption leads to increasing sidewall undercuts and poor curing at the substrate interface . It can be used to pattern high aspect ratio structures . An aspect ratio of (> 20) has been achieved with the solution formulation and (> 40) has been demonstrated from the dry resist . Its maximum absorption is for ultraviolet light with a wavelength of the i - line: 365 nm (it is not practical to expose SU - 8 with g - line ultraviolet light). When exposed, SU - 8's long molecular chains cross-link causing the polymerisation of the material . SU - 8 series photoresists use gamma - butyrolactone or cyclopentanone as the primary solvent . </P> <P> SU - 8 was originally developed as a photoresist for the microelectronics industry, to provide a high - resolution mask for fabrication of semiconductor devices . </P> <P> It is now mainly used in the fabrication of microfluidics (mainly via soft lithography, but also with other imprinting techniques such as nanoimprint lithography) and microelectromechanical systems parts . It is also one of the most biocompatible materials known and is often used in bio-MEMS for life science applications . </P> <P> SU - 8 is composed of Bisphenol A Novolac epoxy that is dissolved in an organic solvent (gamma - butyrolactone GBL or cyclopentanone, depending on the formulation) and up to 10 wt% of mixed Triarylsulfonium / hexafluoroantimonate salt as the photoacid generator). </P>

Which of the following are the properties of su8 pillars