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Process variability in surface roughening of SU-8 by oxygen plasma

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Abstract

This study investigates variability in the topography of SU-8 photoresist subject to surface roughening by oxygen plasma treatment. Surface roughness (expressed as root mean square deviation from the mean) under the range of experimental conditions varied from 8 nm for an untreated baseline to as high as 472 nm. At 200 W RF-power and 200 mTorr chamber pressure, the mean surface roughness was 295 nm with standard deviation less than 10 nm across the specimen and 15 nm across the plasma chamber. The standard deviation in surface roughness at higher power and pressure combinations including 500 W and 800 mTorr was as high as 80 nm, with mean surface roughness less than 200 nm. Replicate runs under identical conditions revealed that run-to-run repeatability can be compromised by chamber conditions, evidenced by second runs having higher standard deviation by nearly 20 % over first runs without intermediate chamber cleaning.

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References

  • Abgrall P, Conedera V, Camon H, Gue A, Nguyen NT (2007) SU-8 as a structural material for labs-on-chips and microelectromechanical systems. Electrophoresis 28:4539–4551. doi:10.1002/elps.200700333

    Article  Google Scholar 

  • Chan CM, Ko TM, Hiraoka H (1996) Polymer surface modification by plasmas and photons. Surf Sci Rep 24:1–54. doi:10.1016/0167-5729(96)80003-3

    Article  Google Scholar 

  • Chang T, Tsai T, Yang H, Huang J (2012) “Effect of ultra-fast laser texturing on surface wettability of microfluidic channels”, Microelectronic Engineering; Special issue MNE 2011—Part II, vol 98, no 0, pp 684–688. doi:10.1016/j.mee.2012.05.057

  • Cheong FC et al (2007) Direct removal of SU-8 using focused laser writing. App Phys A Mater Sci Process 87:71–76. doi:10.1007/s00339-006-3846-z

    Article  Google Scholar 

  • Collaud M, Groening P, Nowak S, Schlapbach L (1994) Plasma treatment of polymers: the effect of the plasma parameters on the chemical, physical, and morphological states of the polymer surface and on the metal-polymer interface. J Adhes Sci Technol 8:1115–1127. doi:10.1163/156856194X00979

    Article  Google Scholar 

  • Duffy DC, McDonald JC, Schueller OJA, Whitesides GM (1998) Rapid prototyping of microfluidic systems in poly(dimethylsiloxane). Anal Chem 70:4974–4984. doi:10.1021/ac980656z

    Article  Google Scholar 

  • Erickson D, Li D (2004) Integrated microfluidic devices. Anal Chim Acta 507:11–26. doi:10.1016/j.aca.2003.09.019

    Article  Google Scholar 

  • Gottscho RA, Jurgensen CW, Vitkavage DJ (1992) Microscopic uniformity in plasma etching. J Vac Sci Technol B Microelectron Process Phenom 10:2133–2147. doi:10.1116/1.586180

    Article  Google Scholar 

  • Hong G, Holmes AS, Heaton ME (2004) SU8 resist plasma etching and its optimisation. Microsyst Technol 10:357–359. doi:10.1007/s00542-004-0413-4

    Article  Google Scholar 

  • Joshi M, Kale N, Lal R, Ramgopal Rao V, Mukherji S (2007) A novel dry method for surface modification of SU-8 for immobilization of biomolecules in bio-MEMS. Biosens Bioelectron 22:2429–2435. doi:10.1016/j.bios.2006.08.045

    Article  Google Scholar 

  • Lai J, Sunderland B, Xue J, Yan S, Zhao W, Folkard M, Wang Y (2006) Study on hydrophilicity of polymer surfaces improved by plasma treatment. Appl Surf Sci 252:3375–3379. doi:10.1016/j.apsusc.2005.05.038

    Article  Google Scholar 

  • Lee C, Hsu W (2003) Method on surface roughness modification to alleviate stiction of microstructures. J Vac Sci Technol B Microelectron Nanom Struct 21:1505–1510. doi:10.1116/1.1592809

    Article  Google Scholar 

  • Li G, Zhang X, Kawi S (1999) Relationships between sensitivity, catalytic activity, and surface areas of SnO2 gas sensors. Sens Actuators B Chem 60:64–70. doi:10.1016/S0925-4005(99)00245-2

    Article  Google Scholar 

  • Lorenz H, Despont M, Fahrni N, LaBianca N, Renaud P, Vettiger P (1997) SU-8: a low-cost negative resist for MEMS. J Micromech Microeng 7:121–124. doi:10.1088/0960-1317/7/3/010

    Article  Google Scholar 

  • Melai J, Salm C, Smits S, Blanco Carballo VM, Schmitz J, Hageluken B (2007) Considerations on using SU-8 as a construction material for high aspect ratio structures. Paper presented at the 10th Annual Workshop on Semiconductor Advances for Future Electronics and Sensors (SAFE), pp 529–534

  • Nabesawa H, Hitobo T, Wakabayashi S, Asaji T, Abe T, Seki M (2008) Polymer surface morphology control by reactive ion etching for microfluidic devices. Sens Actuators B Chem 132:637–643. doi:10.1016/j.snb.2008.01.050

    Article  Google Scholar 

  • Natrajan V, Christensen K (2010) The impact of surface roughness on flow through a rectangular microchannel from the laminar to turbulent regimes. Microfluid Nanofluid 9:95–121. doi:10.1007/s10404-009-0526-2

    Article  Google Scholar 

  • Palumbo F, Mundo DR, Cappelluti D, d’Agostino R (2011) Superhydrophic and supershydrophilic polycarbonate by tailoring chemistry and nano-texture with plasma processing. Plasma Process Polym 8:118–126. doi:10.1002/ppap.201000098

    Google Scholar 

  • Prentner S, Allen D, Larcombe L, Marson S, Jenkins K, Saumer M (2010) Effects of channel surface finish on blood flow in microfluidic devices. Microsyst Technol 16:091–1096. doi:10.1007/s00542-009-1004-1

    Article  Google Scholar 

  • Qiao R (2007) Effects of molecular level surface roughness on electroosmotic flow. Microfluid Nanofluid 3:33–38. doi:10.1007/s10404-006-0103-x

    Article  Google Scholar 

  • Shadpour H, Allbritton LN (2010) In situ roughening of polymeric microstructures. ACS Appl Mater Interfaces 2:1086–1093. doi:10.1021/am900860s

    Article  Google Scholar 

  • Stalder AF, Kulik G, Sage G, Barbieri L, Hoffmann P (2006) A snake-based approach to accurate determination of both contact points and contact angles. Colloids Surf A Physicochem Eng Aspects 286(1–3):92–103

    Article  Google Scholar 

  • Tominaka S, Nakamura Y, Osaka T (2010) Nanostructured catalyst with hierarchical porosity and large surface area for on-chip fuel cells. J Power Sour 195:1054–1058. doi:10.1016/j.jpowsour.2009.08.082

    Article  Google Scholar 

  • Tserepi A, Gogolides E, Constantoudis V, Cordoyiannis G, Raptis I, Valamontes ES (2003) Surface roughness induced by plasma etching of si-containing polymers. J Adhes Sci Technol 17:1083–1091

    Article  Google Scholar 

  • Tsougeni K, Petrou PS, Tserepi A, Kakabakos SE, Gogolides E (2011) Plasma nanotextured polystyrene for intense DNA microarrays. Procedia Eng 25:1573–1576

    Article  Google Scholar 

  • Tsougeni K, Petrou PS, Papageorgiou DP, Kakabakos SE, Tserepi A, Gogolides E (2012) Controlled protein adsorption on microfluidic channels with engineered roughness and wettability. Sensors Actuators B Chem 161:216–222

    Article  Google Scholar 

  • Ullal SJ, Singh H, Daugherty J, Vahedi V, Aydil ES (2009) Maintaining reproducible plasma reactor wall conditions: SF6 plasma etching of films deposited on chamber walls during Cl2/O2 plasma etching of Si. J Vac Sci Technol A Vac Surf Films 20(4):1195–1201. doi:10.1116/1.1479733

    Article  Google Scholar 

  • Waghmare PR, Mitra SK (2008) Investigation of combined electro-osmotic and pressure-driven flow in rough microchannels. J Fluid Eng Trans ASME 130:061204–061210. doi:10.1115/1.2928333

    Article  Google Scholar 

  • Wagterveld RM, Berendsen CWJ, Bouaidat S, Jonsmann J (2006) Ultralow hysteresis superhydrophobic surfaces by excimer laser modification of SU-8. Langmuir 22:10904–10908. doi:10.1021/la0620298

    Article  Google Scholar 

  • Walther F, Heckl WM, Stark RW (2008) Evaluation of nanoscale roughness measurements on a plasma treated SU-8 polymer surface by atomic force microscopy. Appl Surf Sci 254:7290–7295. doi:10.1016/j.apsusc.2008.05.323

    Article  Google Scholar 

  • Williams JA, Le HR (2006) Tribology and MEMS. J Phys D Appl Phys 39:R201–R214. doi:10.1088/0022-3727/39/12/R01

    Article  Google Scholar 

  • Wu T, Suzuki H, Yomo T (2011) Bio-inspired 3D self-patterning of functional coatings for PDMS microdluidics. Transducers 2311–2314. doi: 10.1109/TRANSDUCERS.2011.5969541

  • Yang D, Liu Y (2008) Numerical simulation of electroosmotic flow in microchannels with sinusoidal roughness. Coll Surf A Physicochem Eng Aspects 328:28–33. doi:10.1016/j.colsurfa.2008.06.029

    Article  Google Scholar 

  • Young PL, Kandlikar SG (2008) Surface roughness effects on heat transfer in microscale single phase flow: a critical review. In: Proceedings of the 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008, June 2008, pp 189–201

  • Zhang X, Yu S, He Z, Miao Y (2004) Wetting of rough surfaces. Surf Rev Lett 11:7–13. doi:10.1142/S0218625X04005925

    Article  Google Scholar 

  • Zhang J, Zhou WX, Chan-Park M, Conner SR (2005) Argon plasma modification of SU-8 for very high aspect ratio and dense copper electroforming. J Electrochem Soc 152:716–721. doi:10.1149/1.2034519

    Article  Google Scholar 

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Acknowledgments

This work was supported by Defense Microelectronics Activity Cooperative Agreement #H94003-08-2-0806.

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Author notes

  1. Nagaraju Oruganti

    Present address: Coherent Inc., 5100 Patrick Henry Drive, Santa Clara, CA, 95054, USA

Authors and Affiliations

  1. Biomedical, Chemical, and Materials Engineering, San José State University, One Washington Square, San José, CA, 95192, USA

    Nagaraju Oruganti & Michel Goedert

  2. Mechanical and Aerospace Engineering, San José State University, One Washington Square, San José, CA, 95192, USA

    Sang-Joon John Lee

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  1. Nagaraju Oruganti
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  2. Michel Goedert
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Correspondence to Sang-Joon John Lee.

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Oruganti, N., Goedert, M. & Lee, SJ.J. Process variability in surface roughening of SU-8 by oxygen plasma. Microsyst Technol 19, 971–978 (2013). https://doi.org/10.1007/s00542-012-1680-0

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  • DOI: https://doi.org/10.1007/s00542-012-1680-0

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