The ideal method would be to use "covered-chuck" technology provided on the QSSE Spin coaters OPTICOAT SB/ST 20 Or the DOMINUS coating ( a spray coating method ) also provided by QSSE Sister Semiconductor Equipment. The covered chuck technology is almost eliminating turbulence caused by the corners of the substrate and also allows a almost constant viscosity of the resist during spreading and thinning of the resist. The atmosphere between the chuck and the rotating cover is closed and will move in the same speed as the substrate. You will also sue less resist for the coating. The DOMINUS Coating is a spray coating method where the substrate is static during coating and the nozzle scans the surface of the substrate in cross sections. With this technology the Edge bead is also reduced to a minimum. The unique micro nozzle allows all type of standard resist to be applied. You can also try to use a static plate placed in a small distance ( apprx 2 mm) over the substrate during spreading and thinning for this smaler size of substrate this "airbarriere" plate effect might also work. You can contact me directly for more details. Best Regards Markus Reuter SSE Sister Semiconductor Equipment GmbH Josef-Schüttler-Str. 2 D-78224 Singen GERMANY Phone: +49 (0) 7731 189 - 230 Mobile: +49 (0) 151 1205 5053 Fax: +49 (0) 7731 189 - 100 m.reuter@sse-semi.com WWW.QSSE.COM -----Ursprüngliche Nachricht----- Von: Zheng Xia [mailto:zxia@ufl.edu] Gesendet: Freitag, 27. Februar 2004 17:30 An: mems-talk@memsnet.org Betreff: [mems-talk] resist on rectangular shape slides Hi, Does anyone have suggestion on how to apply uniform resist on rectangular shape glass slides (1 x 3 inch)? I tried to spin them with full coverage of resist on slides, but the result is not good. Resist sometimes cannot reach corners, and it shows certain interference pattern under light, indicating the unevenness of resist thickness. Thank you. Best, ------------------------- XIA, ZHENG Microfluidics and BioMEMS Lab Interdisciplinary Microsystems Group Department of Mechanical and Aerospace Engineering University of Florida -------------------------