SU-8 photoresist
- Su-8 redirects here. For the Soviet ground attack aircraft, see Sukhoi Su-8
SU-8 is a commonly used epoxy-based negative photoresist. It is a very viscous polymer that can be spun or spread over a thickness ranging from 0.1 micrometer up to 2 millimeters and still be processed with standard contact lithography. It can be used to pattern high aspect ratio (>20) structures.[1] Its maximum absorption is for ultraviolet light with a wavelength of 365 nm. When exposed, SU-8's long molecular chains cross-link causing the solidification of the material.
SU-8 was originally developed as a photoresist for microelectronics industry, to provide a high-resolution mask for fabrication of semiconductor devices. It is now mainly used in the fabrication of microfluidics (mainly via soft lithography, but also with other imprinting techniques such as nanoimprint lithography[2]) and microelectromechanical systems parts. It is also one of the most biocompatible materials known and is often used in bio-MEMS.
SU-8 is highly transparent in the ultraviolet region, allowing fabrication of relatively thick (hundreds of micrometers) structures with nearly vertical side walls. After exposition and developing, its highly cross-linked structure gives it high stability to chemicals and radiation damage. Cured cross-linked SU-8 shows very low levels of outgassing in a vacuum.[3] However it is very difficult to remove, and tends to outgas in an unexposed state. [4]
The main developer for SU-8 is PM acetate.
Links for SU-8
SU-8: Thick Photo-Resist for MEMS A webpage with a lot of material data and process tricks.
SU-8 Forum
Microchem data sheet
SU 8 Information Provides information on how to use SU 8 to create desired thicknesses.
Suppliers: Microchem , Gersteltec
References
- ↑ Liu, J.; Cai, B.; Zhu, J.; Ding, G.; Zhao, X.; Yang, C.; Chen, D. "Process research of high aspect ratio microstructure using SU-8 resist" Microsystem Technologies 2004, V10, (4), 265.
- ↑ Jesse Greener, Wei Li, Judy Ren, Dan Voicu, Viktoriya Pakharenko, Tian Tang and Eugenia Kumacheva "Rapid, cost-efficient fabrication of microfluidic reactors in thermoplastic polymers by combining photolithography and hot embossing" Lab Chip, 2010, DOI: 10.1039/b918834g.
- ↑ SU-8 photosensitive epoxy
- ↑ SU-8 Photoresist Processing
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