Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography

•Use of KrF Laser micromachining for Lab-On-Chip applications at lower fluence.•Addition of Benzophenone in PDMS enhances its self development sensitivity.•Benzophenone helps efficient energy transfer for equal density of bond scissioning.•Correlation of chemical composition with laser dose and micr...

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Published in:	Applied surface science Vol. 314; pp. 292 - 300
Main Authors:	Kant, Madhushree Bute, Shinde, Shashikant D., Bodas, Dhananjay, Patil, K.R., Sathe, V.G., Adhi, K.P., Gosavi, S.W.
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier B.V 30-09-2014 Elsevier
Subjects:	Condensed matter: electronic structure, electrical, magnetic, and optical properties Condensed matter: structure, mechanical and thermal properties Cross-disciplinary physics: materials science; rheology Direct laser writing Direct write laser lithography Exact sciences and technology Excimer lasers Exposure Fourier transforms Infrared spectroscopy Lasers Microfabrication, micropatterning Physics Poly(dimethylsiloxane) (PDMS) Scanning electron microscopy Silicone resins Microfabrication, micropatterning Poly(dimethylsiloxane) (PDMS) Direct write laser lithography Lithography Doped materials Excimer lasers Microstructure
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Summary:	•Use of KrF Laser micromachining for Lab-On-Chip applications at lower fluence.•Addition of Benzophenone in PDMS enhances its self development sensitivity.•Benzophenone helps efficient energy transfer for equal density of bond scissioning.•Correlation of chemical composition with laser dose and microstructure.•Microstructures with well defined clean sidewalls. This paper discusses microfabrication process for benzophenone doped polydimethylsiloxane (PDMS) using laser lithography. KrF excimer laser of 248nm with 20ns pulse width at repetition rate of 1Hz was used for microfabrication of undoped and benzophenone doped PDMS. The doped-PDMS shows sensitivity below 365nm, permitting processing under ambient light. The analysis of etch depth revealed that doped PDMS shows self developable sensitivity at lower fluence of ∼250mJ/cm2. The unexposed and exposed surface was studied using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Scanning electron microscopy (SEM). Spectrocopic analysis indicated increase in CO, CO, SiO3 and SiO4 bonding at the expense of SiC and SiO2 bonds of PDMS. In case of laser exposed doped-PDMS, removal of benzophenone from probe depth of spectroscopy was observed. Whereas the surface morphology of exposed and unexposed doped-PDMS was observed to be same, indicating clean development of PDMS micropatterns. The present study indicates that addition of 3.0wt.% benzophenone in PDMS enhance self development sensitivity of PDMS. The self developable results on doped-PDMS are quite encouraging for its potential use in point of care Lab-On-Chip applications, for fabricating micropatterns using direct write laser lithography technology.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0169-4332 1873-5584
DOI:	10.1016/j.apsusc.2014.06.054