View source for SU-8 photoresist

:''Su-8 redirects here. For the Soviet ground attack aircraft, see [[Sukhoi Su-8]]''

[[Image:SU-8 photoresist.png|right|thumb|250px|SU-8 molecule]]
<!-- SMILES structure: CC(C)(c8ccc(OCC%13OC%13)cc8)c1cc(Cc2cc(C(C)(c9ccc(OCC%14OC%14)cc9)C)cc(Cc4cc(C(C)(c%10ccc(OCC%15OC%15)cc%10)C)cc(Cc6cc(C(C)(c%11ccc(OCC%16OC%16)cc%11)C)ccc6OCC7OC7)c4OCC5OC5)c2OCC3OC3)c(OCC%12OC%12)cc1 
Can anybody find its corresponding CAS number? -->
'''SU-8''' is a commonly used [[epoxy]]-based negative [[photoresist]]. It is a very [[viscous]] [[polymer]] that can be [[spin coating|spun]] or spread over a thickness ranging from 0.1 [[Micrometre|micrometer]] up to 2 millimeters and still be processed with standard [[contact lithography]]. It can be used to pattern high [[aspect ratio]] (>20) structures.<ref name="aspect_ratio">Liu, J.; Cai, B.; Zhu, J.; Ding, G.; Zhao, X.; Yang, C.; Chen, D. "[http://dx.doi.org/10.1007/s00542-002-0242-2 Process research of high aspect ratio microstructure using SU-8 resist]" Microsystem Technologies 2004, V10, (4), 265.</ref> Its maximum [[absorption (electromagnetic radiation)|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]]<ref name="imprint lithography"> Jesse Greener, Wei Li, Judy Ren, Dan Voicu, Viktoriya Pakharenko, Tian Tang and Eugenia Kumacheva "[http://www.rsc.org/Publishing/Journals/LC/article.asp?doi=b918834g Rapid, cost-efficient fabrication of microfluidic reactors in thermoplastic polymers by combining photolithography and hot embossing]" Lab Chip, 2010, DOI: 10.1039/b918834g.</ref>) 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]].<ref>[http://www.cnm.es/projects/microdets/su8.htm SU-8 photosensitive epoxy]</ref> However it is very difficult to remove, and tends to outgas in an unexposed state. <ref>[http://engineering.tufts.edu/microfab/index_files/SOP/SU-8%20Processing.pdf SU-8 Photoresist Processing]</ref>

The main developer for SU-8 is [[1-Methoxy-2-propanol acetate|PM acetate]].


==Links for SU-8==

[http://memscyclopedia.org/su8.html SU-8: Thick Photo-Resist for MEMS] A webpage with a lot of material data and process tricks.<br />
[http://www.sporian.com/forum_su8.html SU-8 Forum]<br />
[http://www.microchem.com/products/pdf/SU-82000DataSheet2000_5thru2015Ver4.pdf Microchem data sheet]<br />
[http://cleanroom.byu.edu/su8.phtml SU 8 Information] Provides information on how to use SU 8 to create desired thicknesses. <br />
Suppliers: [http://www.microchem.com Microchem ], [http://www.gersteltec.ch Gersteltec]<br />

==References==
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[[Category:Polymer chemistry]]
[[Category:Polymers]]
[[Category:Materials science]]

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